]> git.proxmox.com Git - mirror_edk2.git/blobdiff - MdeModulePkg/Bus/Usb/UsbKbDxe/KeyBoard.c
The USB keyboard driver use too high TPL event (Notify) to a ckeck repeated key stoke...
[mirror_edk2.git] / MdeModulePkg / Bus / Usb / UsbKbDxe / KeyBoard.c
index 9af221daaddeaf0a98e0e7b7635953603b95baec..51ab18223e5ef2ce50fc64b655094bb29db95d3a 100644 (file)
@@ -1,5 +1,4 @@
 /** @file\r
-\r
   Helper functions for USB Keyboard Driver.\r
 \r
 Copyright (c) 2004 - 2008, Intel Corporation\r
@@ -14,126 +13,146 @@ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
 **/\r
 \r
 #include "KeyBoard.h"\r
-#include <Library/UefiUsbLib.h>\r
 \r
-//\r
-// Static English keyboard layout\r
-// Format:<efi key>, <unicode without shift>, <unicode with shift>, <Modifier>, <AffectedAttribute>\r
-//\r
-UINT8 KeyboardLayoutTable[USB_KEYCODE_MAX_MAKE + 8][5] = {\r
-  {EfiKeyC1,         'a',      'A',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},   // 0x04\r
-  {EfiKeyB5,         'b',      'B',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},   // 0x05\r
-  {EfiKeyB3,         'c',      'C',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},   // 0x06\r
-  {EfiKeyC3,         'd',      'D',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},   // 0x07\r
-  {EfiKeyD3,         'e',      'E',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},   // 0x08\r
-  {EfiKeyC4,         'f',      'F',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},   // 0x09\r
-  {EfiKeyC5,         'g',      'G',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},   // 0x0A\r
-  {EfiKeyC6,         'h',      'H',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},   // 0x0B\r
-  {EfiKeyD8,         'i',      'I',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},   // 0x0C\r
-  {EfiKeyC7,         'j',      'J',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},   // 0x0D\r
-  {EfiKeyC8,         'k',      'K',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},   // 0x0E\r
-  {EfiKeyC9,         'l',      'L',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},   // 0x0F\r
-  {EfiKeyB7,         'm',      'M',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},   // 0x10\r
-  {EfiKeyB6,         'n',      'N',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},   // 0x11\r
-  {EfiKeyD9,         'o',      'O',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},   // 0x12\r
-  {EfiKeyD10,        'p',      'P',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},   // 0x13\r
-  {EfiKeyD1,         'q',      'Q',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},   // 0x14\r
-  {EfiKeyD4,         'r',      'R',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},   // 0x15\r
-  {EfiKeyC2,         's',      'S',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},   // 0x16\r
-  {EfiKeyD5,         't',      'T',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},   // 0x17\r
-  {EfiKeyD7,         'u',      'U',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},   // 0x18\r
-  {EfiKeyB4,         'v',      'V',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},   // 0x19\r
-  {EfiKeyD2,         'w',      'W',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},   // 0x1A\r
-  {EfiKeyB2,         'x',      'X',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},   // 0x1B\r
-  {EfiKeyD6,         'y',      'Y',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},   // 0x1C\r
-  {EfiKeyB1,         'z',      'Z',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},   // 0x1D\r
-  {EfiKeyE1,         '1',      '!',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},   // 0x1E\r
-  {EfiKeyE2,         '2',      '@',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},   // 0x1F\r
-  {EfiKeyE3,         '3',      '#',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},   // 0x20\r
-  {EfiKeyE4,         '4',      '$',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},   // 0x21\r
-  {EfiKeyE5,         '5',      '%',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},   // 0x22\r
-  {EfiKeyE6,         '6',      '^',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},   // 0x23\r
-  {EfiKeyE7,         '7',      '&',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},   // 0x24\r
-  {EfiKeyE8,         '8',      '*',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},   // 0x25\r
-  {EfiKeyE9,         '9',      '(',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},   // 0x26\r
-  {EfiKeyE10,        '0',      ')',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},   // 0x27\r
-  {EfiKeyEnter,      0x0d,     0x0d,  EFI_NULL_MODIFIER,   0},                                // 0x28   Enter\r
-  {EfiKeyEsc,        0x1b,     0x1b,  EFI_NULL_MODIFIER,   0},                                // 0x29   Esc\r
-  {EfiKeyBackSpace,  0x08,     0x08,  EFI_NULL_MODIFIER,   0},                                // 0x2A   Backspace\r
-  {EfiKeyTab,        0x09,     0x09,  EFI_NULL_MODIFIER,   0},                                // 0x2B   Tab\r
-  {EfiKeySpaceBar,   ' ',      ' ',   EFI_NULL_MODIFIER,   0},                                // 0x2C   Spacebar\r
-  {EfiKeyE11,        '-',      '_',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},   // 0x2D\r
-  {EfiKeyE12,        '=',      '+',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},   // 0x2E\r
-  {EfiKeyD11,        '[',      '{',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},   // 0x2F\r
-  {EfiKeyD12,        ']',      '}',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},   // 0x30\r
-  {EfiKeyD13,        '\\',     '|',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},   // 0x31\r
-  {EfiKeyC12,        '\\',     '|',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},   // 0x32  Keyboard Non-US # and ~\r
-  {EfiKeyC10,        ';',      ':',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},   // 0x33\r
-  {EfiKeyC11,        '\'',     '"',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},   // 0x34\r
-  {EfiKeyE0,         '`',      '~',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},   // 0x35  Keyboard Grave Accent and Tlide\r
-  {EfiKeyB8,         ',',      '<',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},   // 0x36\r
-  {EfiKeyB9,         '.',      '>',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},   // 0x37\r
-  {EfiKeyB10,        '/',      '?',   EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},   // 0x38\r
-  {EfiKeyCapsLock,   0x00,     0x00,  EFI_CAPS_LOCK_MODIFIER,            0},                  // 0x39   CapsLock\r
-  {EfiKeyF1,         0x00,     0x00,  EFI_FUNCTION_KEY_ONE_MODIFIER,     0},                  // 0x3A\r
-  {EfiKeyF2,         0x00,     0x00,  EFI_FUNCTION_KEY_TWO_MODIFIER,     0},                  // 0x3B\r
-  {EfiKeyF3,         0x00,     0x00,  EFI_FUNCTION_KEY_THREE_MODIFIER,   0},                  // 0x3C\r
-  {EfiKeyF4,         0x00,     0x00,  EFI_FUNCTION_KEY_FOUR_MODIFIER,    0},                  // 0x3D\r
-  {EfiKeyF5,         0x00,     0x00,  EFI_FUNCTION_KEY_FIVE_MODIFIER,    0},                  // 0x3E\r
-  {EfiKeyF6,         0x00,     0x00,  EFI_FUNCTION_KEY_SIX_MODIFIER,     0},                  // 0x3F\r
-  {EfiKeyF7,         0x00,     0x00,  EFI_FUNCTION_KEY_SEVEN_MODIFIER,   0},                  // 0x40\r
-  {EfiKeyF8,         0x00,     0x00,  EFI_FUNCTION_KEY_EIGHT_MODIFIER,   0},                  // 0x41\r
-  {EfiKeyF9,         0x00,     0x00,  EFI_FUNCTION_KEY_NINE_MODIFIER,    0},                  // 0x42\r
-  {EfiKeyF10,        0x00,     0x00,  EFI_FUNCTION_KEY_TEN_MODIFIER,     0},                  // 0x43\r
-  {EfiKeyF11,        0x00,     0x00,  EFI_FUNCTION_KEY_ELEVEN_MODIFIER,  0},                  // 0x44   F11\r
-  {EfiKeyF12,        0x00,     0x00,  EFI_FUNCTION_KEY_TWELVE_MODIFIER,  0},                  // 0x45   F12\r
-  {EfiKeyPrint,      0x00,     0x00,  EFI_PRINT_MODIFIER,                0},                  // 0x46   PrintScreen\r
-  {EfiKeySLck,       0x00,     0x00,  EFI_SCROLL_LOCK_MODIFIER,          0},                  // 0x47   Scroll Lock\r
-  {EfiKeyPause,      0x00,     0x00,  EFI_PAUSE_MODIFIER,                0},                  // 0x48   Pause\r
-  {EfiKeyIns,        0x00,     0x00,  EFI_INSERT_MODIFIER,               0},                  // 0x49\r
-  {EfiKeyHome,       0x00,     0x00,  EFI_HOME_MODIFIER,                 0},                  // 0x4A\r
-  {EfiKeyPgUp,       0x00,     0x00,  EFI_PAGE_UP_MODIFIER,              0},                  // 0x4B\r
-  {EfiKeyDel,        0x00,     0x00,  EFI_DELETE_MODIFIER,               0},                  // 0x4C\r
-  {EfiKeyEnd,        0x00,     0x00,  EFI_END_MODIFIER,                  0},                  // 0x4D\r
-  {EfiKeyPgDn,       0x00,     0x00,  EFI_PAGE_DOWN_MODIFIER,            0},                  // 0x4E\r
-  {EfiKeyRightArrow, 0x00,     0x00,  EFI_RIGHT_ARROW_MODIFIER,          0},                  // 0x4F\r
-  {EfiKeyLeftArrow,  0x00,     0x00,  EFI_LEFT_ARROW_MODIFIER,           0},                  // 0x50\r
-  {EfiKeyDownArrow,  0x00,     0x00,  EFI_DOWN_ARROW_MODIFIER,           0},                  // 0x51\r
-  {EfiKeyUpArrow,    0x00,     0x00,  EFI_UP_ARROW_MODIFIER,             0},                  // 0x52\r
-  {EfiKeyNLck,       0x00,     0x00,  EFI_NUM_LOCK_MODIFIER,             0},                  // 0x53   NumLock\r
-  {EfiKeySlash,      '/',      '/',   EFI_NULL_MODIFIER,                 0},                  // 0x54\r
-  {EfiKeyAsterisk,   '*',      '*',   EFI_NULL_MODIFIER,                 0},                  // 0x55\r
-  {EfiKeyMinus,      '-',      '-',   EFI_NULL_MODIFIER,                 0},                  // 0x56\r
-  {EfiKeyPlus,       '+',      '+',   EFI_NULL_MODIFIER,                 0},                  // 0x57\r
-  {EfiKeyEnter,      0x0d,     0x0d,  EFI_NULL_MODIFIER,                 0},                  // 0x58\r
-  {EfiKeyOne,        '1',      '1',   EFI_END_MODIFIER,         EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_NUM_LOCK},   // 0x59\r
-  {EfiKeyTwo,        '2',      '2',   EFI_DOWN_ARROW_MODIFIER,  EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_NUM_LOCK},   // 0x5A\r
-  {EfiKeyThree,      '3',      '3',   EFI_PAGE_DOWN_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_NUM_LOCK},   // 0x5B\r
-  {EfiKeyFour,       '4',      '4',   EFI_LEFT_ARROW_MODIFIER,  EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_NUM_LOCK},   // 0x5C\r
-  {EfiKeyFive,       '5',      '5',   EFI_NULL_MODIFIER,        EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_NUM_LOCK},   // 0x5D\r
-  {EfiKeySix,        '6',      '6',   EFI_RIGHT_ARROW_MODIFIER, EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_NUM_LOCK},   // 0x5E\r
-  {EfiKeySeven,      '7',      '7',   EFI_HOME_MODIFIER,        EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_NUM_LOCK},   // 0x5F\r
-  {EfiKeyEight,      '8',      '8',   EFI_UP_ARROW_MODIFIER,    EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_NUM_LOCK},   // 0x60\r
-  {EfiKeyNine,       '9',      '9',   EFI_PAGE_UP_MODIFIER,     EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_NUM_LOCK},   // 0x61\r
-  {EfiKeyZero,       '0',      '0',   EFI_INSERT_MODIFIER,      EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_NUM_LOCK},   // 0x62\r
-  {EfiKeyPeriod,     '.',      '.',   EFI_DELETE_MODIFIER,      EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_NUM_LOCK},   // 0x63\r
-  {EfiKeyB0,         '\\',     '|',   EFI_NULL_MODIFIER,        EFI_AFFECTED_BY_STANDARD_SHIFT}, // 0x64 Keyboard Non-US \ and |\r
-  {EfiKeyA4,         0x00,     0x00,  EFI_MENU_MODIFIER,        0},                              // 0x65 Keyboard Application\r
-\r
-  {EfiKeyLCtrl,      0,        0,     EFI_LEFT_CONTROL_MODIFIER,    0},  // 0xe0\r
-  {EfiKeyLShift,     0,        0,     EFI_LEFT_SHIFT_MODIFIER,      0},  // 0xe1\r
-  {EfiKeyLAlt,       0,        0,     EFI_LEFT_ALT_MODIFIER,        0},  // 0xe2\r
-  {EfiKeyA0,         0,        0,     EFI_LEFT_LOGO_MODIFIER,       0},  // 0xe3\r
-  {EfiKeyRCtrl,      0,        0,     EFI_RIGHT_CONTROL_MODIFIER,   0},  // 0xe4\r
-  {EfiKeyRShift,     0,        0,     EFI_RIGHT_SHIFT_MODIFIER,     0},  // 0xe5\r
-  {EfiKeyA2,         0,        0,     EFI_RIGHT_ALT_MODIFIER,       0},  // 0xe6\r
-  {EfiKeyA3,         0,        0,     EFI_RIGHT_LOGO_MODIFIER,      0},  // 0xe7\r
+EFI_GUID  mUsbKeyboardLayoutPackageGuid = USB_KEYBOARD_LAYOUT_PACKAGE_GUID;\r
+EFI_GUID  mUsbKeyboardLayoutKeyGuid = USB_KEYBOARD_LAYOUT_KEY_GUID;\r
+\r
+USB_KEYBOARD_LAYOUT_PACK_BIN  mUsbKeyboardLayoutBin = {\r
+  sizeof (USB_KEYBOARD_LAYOUT_PACK_BIN),   // Binary size\r
+\r
+  //\r
+  // EFI_HII_PACKAGE_HEADER\r
+  //\r
+  {\r
+    sizeof (USB_KEYBOARD_LAYOUT_PACK_BIN) - sizeof (UINT32),\r
+    EFI_HII_PACKAGE_KEYBOARD_LAYOUT\r
+  },\r
+  1,  // LayoutCount\r
+  sizeof (USB_KEYBOARD_LAYOUT_PACK_BIN) - sizeof (UINT32) - sizeof (EFI_HII_PACKAGE_HEADER) - sizeof (UINT16), // LayoutLength\r
+  USB_KEYBOARD_LAYOUT_KEY_GUID,  // KeyGuid\r
+  sizeof (UINT16) + sizeof (EFI_GUID) + sizeof (UINT32) + sizeof (UINT8) + (USB_KEYBOARD_KEY_COUNT * sizeof (EFI_KEY_DESCRIPTOR)), // LayoutDescriptorStringOffset\r
+  USB_KEYBOARD_KEY_COUNT, // DescriptorCount\r
+  {\r
+    //\r
+    // EFI_KEY_DESCRIPTOR (total number is USB_KEYBOARD_KEY_COUNT)\r
+    //\r
+    {EfiKeyC1,         'a',      'A',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},\r
+    {EfiKeyB5,         'b',      'B',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},\r
+    {EfiKeyB3,         'c',      'C',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},\r
+    {EfiKeyC3,         'd',      'D',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},\r
+    {EfiKeyD3,         'e',      'E',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},\r
+    {EfiKeyC4,         'f',      'F',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},\r
+    {EfiKeyC5,         'g',      'G',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},\r
+    {EfiKeyC6,         'h',      'H',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},\r
+    {EfiKeyD8,         'i',      'I',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},\r
+    {EfiKeyC7,         'j',      'J',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},\r
+    {EfiKeyC8,         'k',      'K',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},\r
+    {EfiKeyC9,         'l',      'L',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},\r
+    {EfiKeyB7,         'm',      'M',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},\r
+    {EfiKeyB6,         'n',      'N',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},\r
+    {EfiKeyD9,         'o',      'O',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},\r
+    {EfiKeyD10,        'p',      'P',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},\r
+    {EfiKeyD1,         'q',      'Q',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},\r
+    {EfiKeyD4,         'r',      'R',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},\r
+    {EfiKeyC2,         's',      'S',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},\r
+    {EfiKeyD5,         't',      'T',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},\r
+    {EfiKeyD7,         'u',      'U',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},\r
+    {EfiKeyB4,         'v',      'V',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},\r
+    {EfiKeyD2,         'w',      'W',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},\r
+    {EfiKeyB2,         'x',      'X',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},\r
+    {EfiKeyD6,         'y',      'Y',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},\r
+    {EfiKeyB1,         'z',      'Z',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_CAPS_LOCK},\r
+    {EfiKeyE1,         '1',      '!',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},\r
+    {EfiKeyE2,         '2',      '@',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},\r
+    {EfiKeyE3,         '3',      '#',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},\r
+    {EfiKeyE4,         '4',      '$',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},\r
+    {EfiKeyE5,         '5',      '%',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},\r
+    {EfiKeyE6,         '6',      '^',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},\r
+    {EfiKeyE7,         '7',      '&',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},\r
+    {EfiKeyE8,         '8',      '*',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},\r
+    {EfiKeyE9,         '9',      '(',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},\r
+    {EfiKeyE10,        '0',      ')',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},\r
+    {EfiKeyEnter,      0x0d,     0x0d, 0, 0,  EFI_NULL_MODIFIER,   0},\r
+    {EfiKeyEsc,        0x1b,     0x1b, 0, 0,  EFI_NULL_MODIFIER,   0},\r
+    {EfiKeyBackSpace,  0x08,     0x08, 0, 0,  EFI_NULL_MODIFIER,   0},\r
+    {EfiKeyTab,        0x09,     0x09, 0, 0,  EFI_NULL_MODIFIER,   0},\r
+    {EfiKeySpaceBar,   ' ',      ' ',  0, 0,  EFI_NULL_MODIFIER,   0},\r
+    {EfiKeyE11,        '-',      '_',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},\r
+    {EfiKeyE12,        '=',      '+',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},\r
+    {EfiKeyD11,        '[',      '{',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},\r
+    {EfiKeyD12,        ']',      '}',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},\r
+    {EfiKeyD13,        '\\',     '|',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},\r
+    {EfiKeyC10,        ';',      ':',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},\r
+    {EfiKeyC11,        '\'',     '"',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},\r
+    {EfiKeyE0,         '`',      '~',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},\r
+    {EfiKeyB8,         ',',      '<',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},\r
+    {EfiKeyB9,         '.',      '>',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},\r
+    {EfiKeyB10,        '/',      '?',  0, 0,  EFI_NULL_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT},\r
+    {EfiKeyCapsLock,   0x00,     0x00, 0, 0,  EFI_CAPS_LOCK_MODIFIER,            0},\r
+    {EfiKeyF1,         0x00,     0x00, 0, 0,  EFI_FUNCTION_KEY_ONE_MODIFIER,     0},\r
+    {EfiKeyF2,         0x00,     0x00, 0, 0,  EFI_FUNCTION_KEY_TWO_MODIFIER,     0},\r
+    {EfiKeyF3,         0x00,     0x00, 0, 0,  EFI_FUNCTION_KEY_THREE_MODIFIER,   0},\r
+    {EfiKeyF4,         0x00,     0x00, 0, 0,  EFI_FUNCTION_KEY_FOUR_MODIFIER,    0},\r
+    {EfiKeyF5,         0x00,     0x00, 0, 0,  EFI_FUNCTION_KEY_FIVE_MODIFIER,    0},\r
+    {EfiKeyF6,         0x00,     0x00, 0, 0,  EFI_FUNCTION_KEY_SIX_MODIFIER,     0},\r
+    {EfiKeyF7,         0x00,     0x00, 0, 0,  EFI_FUNCTION_KEY_SEVEN_MODIFIER,   0},\r
+    {EfiKeyF8,         0x00,     0x00, 0, 0,  EFI_FUNCTION_KEY_EIGHT_MODIFIER,   0},\r
+    {EfiKeyF9,         0x00,     0x00, 0, 0,  EFI_FUNCTION_KEY_NINE_MODIFIER,    0},\r
+    {EfiKeyF10,        0x00,     0x00, 0, 0,  EFI_FUNCTION_KEY_TEN_MODIFIER,     0},\r
+    {EfiKeyF11,        0x00,     0x00, 0, 0,  EFI_FUNCTION_KEY_ELEVEN_MODIFIER,  0},\r
+    {EfiKeyF12,        0x00,     0x00, 0, 0,  EFI_FUNCTION_KEY_TWELVE_MODIFIER,  0},\r
+    {EfiKeyPrint,      0x00,     0x00, 0, 0,  EFI_PRINT_MODIFIER,                0},\r
+    {EfiKeySLck,       0x00,     0x00, 0, 0,  EFI_SCROLL_LOCK_MODIFIER,          0},\r
+    {EfiKeyPause,      0x00,     0x00, 0, 0,  EFI_PAUSE_MODIFIER,                0},\r
+    {EfiKeyIns,        0x00,     0x00, 0, 0,  EFI_INSERT_MODIFIER,               0},\r
+    {EfiKeyHome,       0x00,     0x00, 0, 0,  EFI_HOME_MODIFIER,                 0},\r
+    {EfiKeyPgUp,       0x00,     0x00, 0, 0,  EFI_PAGE_UP_MODIFIER,              0},\r
+    {EfiKeyDel,        0x00,     0x00, 0, 0,  EFI_DELETE_MODIFIER,               0},\r
+    {EfiKeyEnd,        0x00,     0x00, 0, 0,  EFI_END_MODIFIER,                  0},\r
+    {EfiKeyPgDn,       0x00,     0x00, 0, 0,  EFI_PAGE_DOWN_MODIFIER,            0},\r
+    {EfiKeyRightArrow, 0x00,     0x00, 0, 0,  EFI_RIGHT_ARROW_MODIFIER,          0},\r
+    {EfiKeyLeftArrow,  0x00,     0x00, 0, 0,  EFI_LEFT_ARROW_MODIFIER,           0},\r
+    {EfiKeyDownArrow,  0x00,     0x00, 0, 0,  EFI_DOWN_ARROW_MODIFIER,           0},\r
+    {EfiKeyUpArrow,    0x00,     0x00, 0, 0,  EFI_UP_ARROW_MODIFIER,             0},\r
+    {EfiKeyNLck,       0x00,     0x00, 0, 0,  EFI_NUM_LOCK_MODIFIER,             0},\r
+    {EfiKeySlash,      '/',      '/',  0, 0,  EFI_NULL_MODIFIER,                 0},\r
+    {EfiKeyAsterisk,   '*',      '*',  0, 0,  EFI_NULL_MODIFIER,                 0},\r
+    {EfiKeyMinus,      '-',      '-',  0, 0,  EFI_NULL_MODIFIER,                 0},\r
+    {EfiKeyPlus,       '+',      '+',  0, 0,  EFI_NULL_MODIFIER,                 0},\r
+    {EfiKeyEnter,      0x0d,     0x0d, 0, 0,  EFI_NULL_MODIFIER,                 0},\r
+    {EfiKeyOne,        '1',      '1',  0, 0,  EFI_END_MODIFIER,         EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_NUM_LOCK},\r
+    {EfiKeyTwo,        '2',      '2',  0, 0,  EFI_DOWN_ARROW_MODIFIER,  EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_NUM_LOCK},\r
+    {EfiKeyThree,      '3',      '3',  0, 0,  EFI_PAGE_DOWN_MODIFIER,   EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_NUM_LOCK},\r
+    {EfiKeyFour,       '4',      '4',  0, 0,  EFI_LEFT_ARROW_MODIFIER,  EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_NUM_LOCK},\r
+    {EfiKeyFive,       '5',      '5',  0, 0,  EFI_NULL_MODIFIER,        EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_NUM_LOCK},\r
+    {EfiKeySix,        '6',      '6',  0, 0,  EFI_RIGHT_ARROW_MODIFIER, EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_NUM_LOCK},\r
+    {EfiKeySeven,      '7',      '7',  0, 0,  EFI_HOME_MODIFIER,        EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_NUM_LOCK},\r
+    {EfiKeyEight,      '8',      '8',  0, 0,  EFI_UP_ARROW_MODIFIER,    EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_NUM_LOCK},\r
+    {EfiKeyNine,       '9',      '9',  0, 0,  EFI_PAGE_UP_MODIFIER,     EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_NUM_LOCK},\r
+    {EfiKeyZero,       '0',      '0',  0, 0,  EFI_INSERT_MODIFIER,      EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_NUM_LOCK},\r
+    {EfiKeyPeriod,     '.',      '.',  0, 0,  EFI_DELETE_MODIFIER,      EFI_AFFECTED_BY_STANDARD_SHIFT | EFI_AFFECTED_BY_NUM_LOCK},\r
+    {EfiKeyA4,         0x00,     0x00, 0, 0,  EFI_MENU_MODIFIER,            0},\r
+    {EfiKeyLCtrl,      0,        0,    0, 0,  EFI_LEFT_CONTROL_MODIFIER,    0},\r
+    {EfiKeyLShift,     0,        0,    0, 0,  EFI_LEFT_SHIFT_MODIFIER,      0},\r
+    {EfiKeyLAlt,       0,        0,    0, 0,  EFI_LEFT_ALT_MODIFIER,        0},\r
+    {EfiKeyA0,         0,        0,    0, 0,  EFI_LEFT_LOGO_MODIFIER,       0},\r
+    {EfiKeyRCtrl,      0,        0,    0, 0,  EFI_RIGHT_CONTROL_MODIFIER,   0},\r
+    {EfiKeyRShift,     0,        0,    0, 0,  EFI_RIGHT_SHIFT_MODIFIER,     0},\r
+    {EfiKeyA2,         0,        0,    0, 0,  EFI_RIGHT_ALT_MODIFIER,       0},\r
+    {EfiKeyA3,         0,        0,    0, 0,  EFI_RIGHT_LOGO_MODIFIER,      0},\r
+  },\r
+  1,                          // DescriptionCount\r
+  {'e', 'n', '-', 'U', 'S'},  // RFC4646 language code\r
+  ' ',                        // Space\r
+  {'E', 'n', 'g', 'l', 'i', 's', 'h', ' ', 'K', 'e', 'y', 'b', 'o', 'a', 'r', 'd', '\0'}, // DescriptionString[]\r
 };\r
 \r
 //\r
-// EFI_KEY to USB Scan Code convertion table\r
+// EFI_KEY to USB Keycode conversion table\r
+// EFI_KEY is defined in UEFI spec.\r
+// USB Keycode is defined in USB HID Firmware spec.\r
 //\r
-UINT8 UsbScanCodeConvertionTable[] = {\r
+UINT8 EfiKeyToUsbKeyCodeConvertionTable[] = {\r
   0xe0,  //  EfiKeyLCtrl\r
   0xe3,  //  EfiKeyA0\r
   0xe2,  //  EfiKeyLAlt\r
@@ -242,9 +261,10 @@ UINT8 UsbScanCodeConvertionTable[] = {
 };\r
 \r
 //\r
-// Keyboard Layout Modifier to EFI Scan Code convertion table\r
+// Keyboard modifier value to EFI Scan Code convertion table\r
+// EFI Scan Code and the modifier values are defined in UEFI spec.\r
 //\r
-UINT8 EfiScanCodeConvertionTable[] = {\r
+UINT8 ModifierValueToEfiScanCodeConvertionTable[] = {\r
   SCAN_NULL,       // EFI_NULL_MODIFIER\r
   SCAN_NULL,       // EFI_LEFT_CONTROL_MODIFIER\r
   SCAN_NULL,       // EFI_RIGHT_CONTROL_MODIFIER\r
@@ -281,61 +301,65 @@ UINT8 EfiScanCodeConvertionTable[] = {
   SCAN_F12,        // EFI_FUNCTION_KEY_TWELVE_MODIFIER\r
 };\r
 \r
-EFI_GUID  mKeyboardLayoutEventGuid = EFI_HII_SET_KEYBOARD_LAYOUT_EVENT_GUID;\r
-\r
-\r
-KB_MODIFIER  KB_Mod[8] = {\r
-  { MOD_CONTROL_L,  0xe0 }, // 11100000\r
-  { MOD_CONTROL_R,  0xe4 }, // 11100100\r
-  { MOD_SHIFT_L,    0xe1 }, // 11100001\r
-  { MOD_SHIFT_R,    0xe5 }, // 11100101\r
-  { MOD_ALT_L,      0xe2 }, // 11100010\r
-  { MOD_ALT_R,      0xe6 }, // 11100110\r
-  { MOD_WIN_L,      0xe3 }, // 11100011\r
-  { MOD_WIN_R,      0xe7 }, // 11100111 \r
-};\r
-\r
-\r
 /**\r
-  Initialize KeyConvertionTable by using default keyboard layout.\r
+  Initialize Key Convention Table by using default keyboard layout.\r
 \r
   @param  UsbKeyboardDevice    The USB_KB_DEV instance.\r
-  @retval None.\r
 \r
+  @retval EFI_SUCCESS          The default keyboard layout was installed successfully\r
+  @retval Others               Failure to install default keyboard layout.\r
 **/\r
-VOID\r
+EFI_STATUS\r
 EFIAPI\r
-LoadDefaultKeyboardLayout (\r
-  IN USB_KB_DEV                 *UsbKeyboardDevice\r
+InstallDefaultKeyboardLayout (\r
+   IN OUT USB_KB_DEV           *UsbKeyboardDevice\r
   )\r
 {\r
-  UINTN               Index;\r
-  EFI_KEY_DESCRIPTOR  *KeyDescriptor;\r
+  EFI_STATUS                   Status;\r
+  EFI_HII_DATABASE_PROTOCOL    *HiiDatabase;\r
+  EFI_HII_HANDLE               HiiHandle;\r
 \r
   //\r
-  // Construct KeyConvertionTable by default keyboard layout\r
+  // Locate Hii database protocol\r
   //\r
-  KeyDescriptor = &UsbKeyboardDevice->KeyConvertionTable[0];\r
-\r
-  for (Index = 0; Index < (USB_KEYCODE_MAX_MAKE + 8); Index++) {\r
-    KeyDescriptor->Key                 = (EFI_KEY) KeyboardLayoutTable[Index][0];\r
-    KeyDescriptor->Unicode             = KeyboardLayoutTable[Index][1];\r
-    KeyDescriptor->ShiftedUnicode      = KeyboardLayoutTable[Index][2];\r
-    KeyDescriptor->AltGrUnicode        = 0;\r
-    KeyDescriptor->ShiftedAltGrUnicode = 0;\r
-    KeyDescriptor->Modifier            = KeyboardLayoutTable[Index][3];\r
-    KeyDescriptor->AffectedAttribute   = KeyboardLayoutTable[Index][4];\r
+  Status = gBS->LocateProtocol (\r
+                  &gEfiHiiDatabaseProtocolGuid,\r
+                  NULL,\r
+                  (VOID **) &HiiDatabase\r
+                  );\r
+  if (EFI_ERROR (Status)) {\r
+    return Status;\r
+  }\r
 \r
-    KeyDescriptor++;\r
+  //\r
+  // Install Keyboard Layout package to HII database\r
+  //\r
+  HiiHandle = HiiAddPackages (\r
+                &mUsbKeyboardLayoutPackageGuid,\r
+                UsbKeyboardDevice->ControllerHandle,\r
+                &mUsbKeyboardLayoutBin,\r
+                NULL\r
+                );\r
+  if (HiiHandle == NULL) {\r
+    return EFI_OUT_OF_RESOURCES;\r
   }\r
+\r
+  //\r
+  // Set current keyboard layout\r
+  //\r
+  Status = HiiDatabase->SetKeyboardLayout (HiiDatabase, &mUsbKeyboardLayoutKeyGuid);\r
+\r
+  return Status;\r
 }\r
 \r
 \r
 /**\r
-  Uses USB I/O to check whether the device is a USB Keyboard device.\r
+  Uses USB I/O to check whether the device is a USB keyboard device.\r
+\r
+  @param  UsbIo    Pointer to a USB I/O protocol instance.\r
 \r
-  @param  UsbIo    Points to a USB I/O protocol instance.\r
-  @retval None\r
+  @retval TRUE     Device is a USB keyboard device.\r
+  @retval FALSE    Device is a not USB keyboard device.\r
 \r
 **/\r
 BOOLEAN\r
@@ -348,8 +372,7 @@ IsUSBKeyboard (
   EFI_USB_INTERFACE_DESCRIPTOR  InterfaceDescriptor;\r
 \r
   //\r
-  // Get the Default interface descriptor, currently we\r
-  // assume it is interface 1\r
+  // Get the default interface descriptor\r
   //\r
   Status = UsbIo->UsbGetInterfaceDescriptor (\r
                     UsbIo,\r
@@ -364,7 +387,6 @@ IsUSBKeyboard (
       InterfaceDescriptor.InterfaceSubClass == SUBCLASS_BOOT &&\r
       InterfaceDescriptor.InterfaceProtocol == PROTOCOL_KEYBOARD\r
       ) {\r
-\r
     return TRUE;\r
   }\r
 \r
@@ -374,7 +396,8 @@ IsUSBKeyboard (
 /**\r
   Get current keyboard layout from HII database.\r
 \r
-  @retval Pointer to EFI_HII_KEYBOARD_LAYOUT.\r
+  @return Pointer to HII Keyboard Layout.\r
+          NULL means failure occurred while trying to get keyboard layout.\r
 \r
 **/\r
 EFI_HII_KEYBOARD_LAYOUT *\r
@@ -389,7 +412,7 @@ GetCurrentKeyboardLayout (
   UINT16                    Length;\r
 \r
   //\r
-  // Locate Hii database protocol\r
+  // Locate HII Database Protocol\r
   //\r
   Status = gBS->LocateProtocol (\r
                   &gEfiHiiDatabaseProtocolGuid,\r
@@ -422,7 +445,7 @@ GetCurrentKeyboardLayout (
                             KeyboardLayout\r
                             );\r
     if (EFI_ERROR (Status)) {\r
-      gBS->FreePool (KeyboardLayout);\r
+      FreePool (KeyboardLayout);\r
       KeyboardLayout = NULL;\r
     }\r
   }\r
@@ -431,44 +454,51 @@ GetCurrentKeyboardLayout (
 }\r
 \r
 /**\r
-  Find Key Descriptor in KeyConvertionTable given its scan code.\r
+  Find Key Descriptor in Key Convertion Table given its USB keycode.\r
 \r
   @param  UsbKeyboardDevice   The USB_KB_DEV instance.\r
-  @param  ScanCode            USB scan code.\r
+  @param  KeyCode             USB Keycode.\r
 \r
-  @return The Key descriptor in KeyConvertionTable.\r
+  @return The Key Descriptor in Key Convertion Table.\r
+          NULL means not found.\r
 \r
 **/\r
 EFI_KEY_DESCRIPTOR *\r
 EFIAPI\r
 GetKeyDescriptor (\r
   IN USB_KB_DEV        *UsbKeyboardDevice,\r
-  IN UINT8             ScanCode\r
+  IN UINT8             KeyCode\r
   )\r
 {\r
   UINT8  Index;\r
 \r
-  if (((ScanCode > 0x65) && (ScanCode < 0xe0)) || (ScanCode > 0xe7)) {\r
+  //\r
+  // Make sure KeyCode is in the range of [0x4, 0x65] or [0xe0, 0xe7]\r
+  //\r
+  if ((!USBKBD_VALID_KEYCODE (KeyCode)) || ((KeyCode > 0x65) && (KeyCode < 0xe0)) || (KeyCode > 0xe7)) {\r
     return NULL;\r
   }\r
 \r
-  if (ScanCode <= 0x65) {\r
-    Index = (UINT8) (ScanCode - 4);\r
+  //\r
+  // Calculate the index of Key Descriptor in Key Convertion Table\r
+  //\r
+  if (KeyCode <= 0x65) {\r
+    Index = (UINT8) (KeyCode - 4);\r
   } else {\r
-    Index = (UINT8) (ScanCode - 0xe0 + USB_KEYCODE_MAX_MAKE);\r
+    Index = (UINT8) (KeyCode - 0xe0 + NUMBER_OF_VALID_NON_MODIFIER_USB_KEYCODE);\r
   }\r
 \r
   return &UsbKeyboardDevice->KeyConvertionTable[Index];\r
 }\r
 \r
 /**\r
-  Find Non-Spacing key for given KeyDescriptor.\r
+  Find Non-Spacing key for given Key descriptor.\r
 \r
   @param  UsbKeyboardDevice    The USB_KB_DEV instance.\r
   @param  KeyDescriptor        Key descriptor.\r
 \r
-  @retval NULL                 Key list is empty.\r
-  @return Other                The Non-Spacing key.\r
+  @return The Non-Spacing key corresponding to KeyDescriptor\r
+          NULL means not found.\r
 \r
 **/\r
 USB_NS_KEY *\r
@@ -479,29 +509,37 @@ FindUsbNsKey (
   )\r
 {\r
   LIST_ENTRY      *Link;\r
+  LIST_ENTRY      *NsKeyList;\r
   USB_NS_KEY      *UsbNsKey;\r
-\r
-  Link = GetFirstNode (&UsbKeyboardDevice->NsKeyList);\r
-  while (!IsNull (&UsbKeyboardDevice->NsKeyList, Link)) {\r
+  \r
+  NsKeyList = &UsbKeyboardDevice->NsKeyList;\r
+  Link = GetFirstNode (NsKeyList);\r
+  while (!IsNull (NsKeyList, Link)) {\r
     UsbNsKey = USB_NS_KEY_FORM_FROM_LINK (Link);\r
 \r
     if (UsbNsKey->NsKey[0].Key == KeyDescriptor->Key) {\r
       return UsbNsKey;\r
     }\r
 \r
-    Link = GetNextNode (&UsbKeyboardDevice->NsKeyList, Link);\r
+    Link = GetNextNode (NsKeyList, Link);\r
   }\r
 \r
   return NULL;\r
 }\r
 \r
 /**\r
-  Find physical key definition for a given Key stroke.\r
+  Find physical key definition for a given key descriptor.\r
 \r
-  @param  UsbNsKey          The Non-Spacing key information.\r
-  @param  KeyDescriptor     The key stroke.\r
+  For a specified non-spacing key, there are a list of physical\r
+  keys following it. This function traverses the list of\r
+  physical keys and tries to find the physical key matching\r
+  the KeyDescriptor.\r
+\r
+  @param  UsbNsKey          The non-spacing key information.\r
+  @param  KeyDescriptor     The key descriptor.\r
 \r
   @return The physical key definition.\r
+          If no physical key is found, parameter KeyDescriptor is returned.\r
 \r
 **/\r
 EFI_KEY_DESCRIPTOR *\r
@@ -530,17 +568,21 @@ FindPhysicalKey (
 }\r
 \r
 /**\r
-  The notification function for SET_KEYBOARD_LAYOUT_EVENT.\r
+  The notification function for EFI_HII_SET_KEYBOARD_LAYOUT_EVENT_GUID.\r
+\r
+  This function is registered to event of EFI_HII_SET_KEYBOARD_LAYOUT_EVENT_GUID\r
+  group type, which will be triggered by EFI_HII_DATABASE_PROTOCOL.SetKeyboardLayout().\r
+  It tries to get curent keyboard layout from HII database.\r
 \r
-  @param  Event           The instance of EFI_EVENT.\r
-  @param  Context         passing parameter.\r
+  @param  Event        Event being signaled.\r
+  @param  Context      Points to USB_KB_DEV instance.\r
 \r
 **/\r
 VOID\r
 EFIAPI\r
 SetKeyboardLayoutEvent (\r
-  EFI_EVENT                  Event,\r
-  VOID                       *Context\r
+  IN EFI_EVENT              Event,\r
+  IN VOID                   *Context\r
   )\r
 {\r
   USB_KB_DEV                *UsbKeyboardDevice;\r
@@ -553,12 +595,12 @@ SetKeyboardLayoutEvent (
   UINTN                     Index;\r
   UINTN                     Index2;\r
   UINTN                     KeyCount;\r
-  UINT8                     ScanCode;\r
+  UINT8                     KeyCode;\r
 \r
   UsbKeyboardDevice = (USB_KB_DEV *) Context;\r
 \r
   //\r
-  // Try to get current Keyboard Layout from HII database\r
+  // Try to get current keyboard layout from HII database\r
   //\r
   KeyboardLayout = GetCurrentKeyboardLayout ();\r
   if (KeyboardLayout == NULL) {\r
@@ -566,12 +608,15 @@ SetKeyboardLayoutEvent (
   }\r
 \r
   //\r
-  // Allocate resource for KeyConvertionTable\r
+  // Re-allocate resource for KeyConvertionTable\r
   //\r
   ReleaseKeyboardLayoutResources (UsbKeyboardDevice);\r
-  UsbKeyboardDevice->KeyConvertionTable = AllocateZeroPool ((USB_KEYCODE_MAX_MAKE + 8) * sizeof (EFI_KEY_DESCRIPTOR));\r
+  UsbKeyboardDevice->KeyConvertionTable = AllocateZeroPool ((NUMBER_OF_VALID_USB_KEYCODE) * sizeof (EFI_KEY_DESCRIPTOR));\r
   ASSERT (UsbKeyboardDevice->KeyConvertionTable != NULL);\r
 \r
+  //\r
+  // Traverse the list of key descriptors following the header of EFI_HII_KEYBOARD_LAYOUT\r
+  //\r
   KeyDescriptor = (EFI_KEY_DESCRIPTOR *) (((UINT8 *) KeyboardLayout) + sizeof (EFI_HII_KEYBOARD_LAYOUT));\r
   for (Index = 0; Index < KeyboardLayout->DescriptorCount; Index++) {\r
     //\r
@@ -580,16 +625,16 @@ SetKeyboardLayoutEvent (
     CopyMem (&TempKey, KeyDescriptor, sizeof (EFI_KEY_DESCRIPTOR));\r
 \r
     //\r
-    // Fill the key into KeyConvertionTable (which use USB Scan Code as index)\r
+    // Fill the key into KeyConvertionTable, whose index is calculated from USB keycode.\r
     //\r
-    ScanCode = UsbScanCodeConvertionTable [(UINT8) (TempKey.Key)];\r
-    TableEntry = GetKeyDescriptor (UsbKeyboardDevice, ScanCode);\r
+    KeyCode = EfiKeyToUsbKeyCodeConvertionTable [(UINT8) (TempKey.Key)];\r
+    TableEntry = GetKeyDescriptor (UsbKeyboardDevice, KeyCode);\r
     CopyMem (TableEntry, KeyDescriptor, sizeof (EFI_KEY_DESCRIPTOR));\r
 \r
+    //\r
+    // For non-spacing key, create the list with a non-spacing key followed by physical keys.\r
+    //\r
     if (TempKey.Modifier == EFI_NS_KEY_MODIFIER) {\r
-      //\r
-      // Non-spacing key\r
-      //\r
       UsbNsKey = AllocatePool (sizeof (USB_NS_KEY));\r
       ASSERT (UsbNsKey != NULL);\r
 \r
@@ -600,7 +645,7 @@ SetKeyboardLayoutEvent (
       NsKey = KeyDescriptor + 1;\r
       for (Index2 = Index + 1; Index2 < KeyboardLayout->DescriptorCount; Index2++) {\r
         CopyMem (&TempKey, NsKey, sizeof (EFI_KEY_DESCRIPTOR));\r
-        if (TempKey.Modifier & EFI_NS_KEY_DEPENDENCY_MODIFIER) {\r
+        if (TempKey.Modifier == EFI_NS_KEY_DEPENDENCY_MODIFIER) {\r
           KeyCount++;\r
         } else {\r
           break;\r
@@ -627,17 +672,17 @@ SetKeyboardLayoutEvent (
   }\r
 \r
   //\r
-  // There are two EfiKeyEnter, duplicate its Key Descriptor\r
+  // There are two EfiKeyEnter, duplicate its key descriptor\r
   //\r
   TableEntry = GetKeyDescriptor (UsbKeyboardDevice, 0x58);\r
   KeyDescriptor = GetKeyDescriptor (UsbKeyboardDevice, 0x28);\r
   CopyMem (TableEntry, KeyDescriptor, sizeof (EFI_KEY_DESCRIPTOR));\r
 \r
-  gBS->FreePool (KeyboardLayout);\r
+  FreePool (KeyboardLayout);\r
 }\r
 \r
 /**\r
-  Destroy resources for Keyboard layout.\r
+  Destroy resources for keyboard layout.\r
 \r
   @param  UsbKeyboardDevice    The USB_KB_DEV instance.\r
 \r
@@ -645,7 +690,7 @@ SetKeyboardLayoutEvent (
 VOID\r
 EFIAPI\r
 ReleaseKeyboardLayoutResources (\r
-  IN USB_KB_DEV              *UsbKeyboardDevice\r
+  IN OUT USB_KB_DEV              *UsbKeyboardDevice\r
   )\r
 {\r
   USB_NS_KEY      *UsbNsKey;\r
@@ -667,24 +712,30 @@ ReleaseKeyboardLayoutResources (
 }\r
 \r
 /**\r
-  Initialize USB Keyboard layout.\r
+  Initialize USB keyboard layout.\r
+\r
+  This function initializes Key Convertion Table for the USB keyboard device.\r
+  It first tries to retrieve layout from HII database. If failed and default\r
+  layout is enabled, then it just uses the default layout.\r
 \r
   @param  UsbKeyboardDevice      The USB_KB_DEV instance.\r
 \r
-  @retval EFI_SUCCESS            Initialization Success.\r
-  @retval Other                  Keyboard layout initial failed.\r
+  @retval EFI_SUCCESS            Initialization succeeded.\r
+  @retval EFI_NOT_READY          Keyboard layout cannot be retrieve from HII\r
+                                 database, and default layout is disabled.\r
+  @retval Other                  Fail to register event to EFI_HII_SET_KEYBOARD_LAYOUT_EVENT_GUID group.\r
 \r
 **/\r
 EFI_STATUS\r
 EFIAPI\r
 InitKeyboardLayout (\r
-  IN USB_KB_DEV   *UsbKeyboardDevice\r
+  OUT USB_KB_DEV   *UsbKeyboardDevice\r
   )\r
 {\r
   EFI_HII_KEYBOARD_LAYOUT   *KeyboardLayout;\r
   EFI_STATUS                Status;\r
 \r
-  UsbKeyboardDevice->KeyConvertionTable = AllocateZeroPool ((USB_KEYCODE_MAX_MAKE + 8) * sizeof (EFI_KEY_DESCRIPTOR));\r
+  UsbKeyboardDevice->KeyConvertionTable = AllocateZeroPool ((NUMBER_OF_VALID_USB_KEYCODE) * sizeof (EFI_KEY_DESCRIPTOR));\r
   ASSERT (UsbKeyboardDevice->KeyConvertionTable != NULL);\r
 \r
   InitializeListHead (&UsbKeyboardDevice->NsKeyList);\r
@@ -692,40 +743,41 @@ InitKeyboardLayout (
   UsbKeyboardDevice->KeyboardLayoutEvent = NULL;\r
 \r
   //\r
-  // Register SET_KEYBOARD_LAYOUT_EVENT notification\r
+  // Register event to EFI_HII_SET_KEYBOARD_LAYOUT_EVENT_GUID group,\r
+  // which will be triggered by EFI_HII_DATABASE_PROTOCOL.SetKeyboardLayout().\r
   //\r
   Status = gBS->CreateEventEx (\r
                   EVT_NOTIFY_SIGNAL,\r
                   TPL_NOTIFY,\r
                   SetKeyboardLayoutEvent,\r
                   UsbKeyboardDevice,\r
-                  &mKeyboardLayoutEventGuid,\r
+                  &gEfiHiiKeyBoardLayoutGuid,\r
                   &UsbKeyboardDevice->KeyboardLayoutEvent\r
                   );\r
   if (EFI_ERROR (Status)) {\r
     return Status;\r
   }\r
 \r
-  //\r
-  // Try to get current keyboard layout from HII database\r
-  //\r
   KeyboardLayout = GetCurrentKeyboardLayout ();\r
   if (KeyboardLayout != NULL) {\r
     //\r
-    // Force to initialize the keyboard layout\r
+    // If current keyboard layout is successfully retrieved from HII database,\r
+    // force to initialize the keyboard layout.\r
     //\r
     gBS->SignalEvent (UsbKeyboardDevice->KeyboardLayoutEvent);\r
   } else {\r
     if (FeaturePcdGet (PcdDisableDefaultKeyboardLayoutInUsbKbDriver)) {\r
-      return EFI_NOT_READY;\r
-    } else {\r
-\r
       //\r
-      // Fail to get keyboard layout from HII database,\r
-      // use default keyboard layout\r
+      // If no keyboard layout can be retrieved from HII database, and default layout\r
+      // is disabled, then return EFI_NOT_READY.\r
       //\r
-      LoadDefaultKeyboardLayout (UsbKeyboardDevice);\r
+      return EFI_NOT_READY;\r
     }\r
+    //\r
+    // If no keyboard layout can be retrieved from HII database, and default layout\r
+    // is enabled, then load the default keyboard layout.\r
+    //\r
+    InstallDefaultKeyboardLayout (UsbKeyboardDevice);\r
   }\r
   \r
   return EFI_SUCCESS;\r
@@ -733,18 +785,18 @@ InitKeyboardLayout (
 \r
 \r
 /**\r
-  Initialize USB Keyboard device and all private data structures.\r
+  Initialize USB keyboard device and all private data structures.\r
 \r
   @param  UsbKeyboardDevice  The USB_KB_DEV instance.\r
 \r
   @retval EFI_SUCCESS        Initialization is successful.\r
-  @retval EFI_DEVICE_ERROR   Configure hardware failed.\r
+  @retval EFI_DEVICE_ERROR   Keyboard initialization failed.\r
 \r
 **/\r
 EFI_STATUS\r
 EFIAPI\r
 InitUSBKeyboard (\r
-  IN USB_KB_DEV   *UsbKeyboardDevice\r
+  IN OUT USB_KB_DEV   *UsbKeyboardDevice\r
   )\r
 {\r
   UINT8               ConfigValue;\r
@@ -754,37 +806,33 @@ InitUSBKeyboard (
   EFI_STATUS          Status;\r
   UINT32              TransferResult;\r
 \r
-  KbdReportStatusCode (\r
-    UsbKeyboardDevice->DevicePath,\r
+  REPORT_STATUS_CODE_WITH_DEVICE_PATH (\r
     EFI_PROGRESS_CODE,\r
-    PcdGet32 (PcdStatusCodeValueKeyboardSelfTest)\r
+    PcdGet32 (PcdStatusCodeValueKeyboardSelfTest),\r
+    UsbKeyboardDevice->DevicePath\r
     );\r
 \r
   InitUSBKeyBuffer (&(UsbKeyboardDevice->KeyboardBuffer));\r
 \r
   //\r
-  // default configurations\r
+  // Uses default configuration to configure the USB keyboard device.\r
   //\r
   ConfigValue = 0x01;\r
-\r
-  //\r
-  // Uses default configuration to configure the USB Keyboard device.\r
-  //\r
   Status = UsbSetConfiguration (\r
-            UsbKeyboardDevice->UsbIo,\r
-            (UINT16) ConfigValue,\r
-            &TransferResult\r
-            );\r
+             UsbKeyboardDevice->UsbIo,\r
+             (UINT16) ConfigValue,\r
+             &TransferResult\r
+             );\r
   if (EFI_ERROR (Status)) {\r
     //\r
     // If configuration could not be set here, it means\r
     // the keyboard interface has some errors and could\r
     // not be initialized\r
     //\r
-    KbdReportStatusCode (\r
-      UsbKeyboardDevice->DevicePath,\r
+    REPORT_STATUS_CODE_WITH_DEVICE_PATH (\r
       EFI_ERROR_CODE | EFI_ERROR_MINOR,\r
-      PcdGet32 (PcdStatusCodeValueKeyboardInterfaceError)\r
+      PcdGet32 (PcdStatusCodeValueKeyboardInterfaceError),\r
+      UsbKeyboardDevice->DevicePath\r
       );\r
 \r
     return EFI_DEVICE_ERROR;\r
@@ -796,9 +844,8 @@ InitUSBKeyboard (
     &Protocol\r
     );\r
   //\r
-  // Sets boot protocol for the USB Keyboard.\r
+  // Set boot protocol for the USB Keyboard.\r
   // This driver only supports boot protocol.\r
-  // !!BugBug: How about the device that does not support boot protocol?\r
   //\r
   if (Protocol != BOOT_PROTOCOL) {\r
     UsbSetProtocolRequest (\r
@@ -807,17 +854,15 @@ InitUSBKeyboard (
       BOOT_PROTOCOL\r
       );\r
   }\r
-  //\r
-  // the duration is indefinite, so the endpoint will inhibit reporting forever,\r
-  // and only reporting when a change is detected in the report data.\r
-  //\r
 \r
   //\r
-  // idle value for all report ID\r
+  // ReportId is zero, which means the idle rate applies to all input reports.\r
   //\r
   ReportId = 0;\r
   //\r
-  // idle forever until there is a key pressed and released.\r
+  // Duration is zero, which means the duration is infinite.\r
+  // so the endpoint will inhibit reporting forever,\r
+  // and only reporting when a change is detected in the report data.\r
   //\r
   Duration = 0;\r
   UsbSetIdleRequest (\r
@@ -827,70 +872,78 @@ InitUSBKeyboard (
     Duration\r
     );\r
 \r
-  UsbKeyboardDevice->CtrlOn     = 0;\r
-  UsbKeyboardDevice->AltOn      = 0;\r
-  UsbKeyboardDevice->ShiftOn    = 0;\r
-  UsbKeyboardDevice->NumLockOn  = 0;\r
-  UsbKeyboardDevice->CapsOn     = 0;\r
-  UsbKeyboardDevice->ScrollOn   = 0;\r
+  UsbKeyboardDevice->CtrlOn     = FALSE;\r
+  UsbKeyboardDevice->AltOn      = FALSE;\r
+  UsbKeyboardDevice->ShiftOn    = FALSE;\r
+  UsbKeyboardDevice->NumLockOn  = FALSE;\r
+  UsbKeyboardDevice->CapsOn     = FALSE;\r
+  UsbKeyboardDevice->ScrollOn   = FALSE;\r
   \r
-  UsbKeyboardDevice->LeftCtrlOn   = 0;\r
-  UsbKeyboardDevice->LeftAltOn    = 0;\r
-  UsbKeyboardDevice->LeftShiftOn  = 0;\r
-  UsbKeyboardDevice->LeftLogoOn   = 0;\r
-  UsbKeyboardDevice->RightCtrlOn  = 0;\r
-  UsbKeyboardDevice->RightAltOn   = 0;\r
-  UsbKeyboardDevice->RightShiftOn = 0;\r
-  UsbKeyboardDevice->RightLogoOn  = 0;\r
-  UsbKeyboardDevice->MenuKeyOn    = 0;\r
-  UsbKeyboardDevice->SysReqOn     = 0;\r
-\r
-  UsbKeyboardDevice->AltGrOn      = 0;\r
+  UsbKeyboardDevice->LeftCtrlOn   = FALSE;\r
+  UsbKeyboardDevice->LeftAltOn    = FALSE;\r
+  UsbKeyboardDevice->LeftShiftOn  = FALSE;\r
+  UsbKeyboardDevice->LeftLogoOn   = FALSE;\r
+  UsbKeyboardDevice->RightCtrlOn  = FALSE;\r
+  UsbKeyboardDevice->RightAltOn   = FALSE;\r
+  UsbKeyboardDevice->RightShiftOn = FALSE;\r
+  UsbKeyboardDevice->RightLogoOn  = FALSE;\r
+  UsbKeyboardDevice->MenuKeyOn    = FALSE;\r
+  UsbKeyboardDevice->SysReqOn     = FALSE;\r
+\r
+  UsbKeyboardDevice->AltGrOn      = FALSE;\r
 \r
   UsbKeyboardDevice->CurrentNsKey = NULL;\r
 \r
   //\r
-  // Sync the initial state of lights\r
+  // Sync the initial state of lights on keyboard.\r
   //\r
   SetKeyLED (UsbKeyboardDevice);\r
 \r
   ZeroMem (UsbKeyboardDevice->LastKeyCodeArray, sizeof (UINT8) * 8);\r
 \r
   //\r
-  // Set a timer for repeat keys' generation.\r
+  // Create event for repeat keys' generation.\r
   //\r
   if (UsbKeyboardDevice->RepeatTimer != NULL) {\r
     gBS->CloseEvent (UsbKeyboardDevice->RepeatTimer);\r
-    UsbKeyboardDevice->RepeatTimer = 0;\r
+    UsbKeyboardDevice->RepeatTimer = NULL;\r
   }\r
 \r
-  Status = gBS->CreateEvent (\r
-                  EVT_TIMER | EVT_NOTIFY_SIGNAL,\r
-                  TPL_NOTIFY,\r
-                  USBKeyboardRepeatHandler,\r
-                  UsbKeyboardDevice,\r
-                  &UsbKeyboardDevice->RepeatTimer\r
-                  );\r
+  gBS->CreateEvent (\r
+         EVT_TIMER | EVT_NOTIFY_SIGNAL,\r
+         TPL_CALLBACK,\r
+         USBKeyboardRepeatHandler,\r
+         UsbKeyboardDevice,\r
+         &UsbKeyboardDevice->RepeatTimer\r
+         );\r
 \r
+  //\r
+  // Create event for delayed recovery, which deals with device error.\r
+  //\r
   if (UsbKeyboardDevice->DelayedRecoveryEvent != NULL) {\r
     gBS->CloseEvent (UsbKeyboardDevice->DelayedRecoveryEvent);\r
-    UsbKeyboardDevice->DelayedRecoveryEvent = 0;\r
+    UsbKeyboardDevice->DelayedRecoveryEvent = NULL;\r
   }\r
 \r
-  Status = gBS->CreateEvent (\r
-                  EVT_TIMER | EVT_NOTIFY_SIGNAL,\r
-                  TPL_NOTIFY,\r
-                  USBKeyboardRecoveryHandler,\r
-                  UsbKeyboardDevice,\r
-                  &UsbKeyboardDevice->DelayedRecoveryEvent\r
-                  );\r
+  gBS->CreateEvent (\r
+         EVT_TIMER | EVT_NOTIFY_SIGNAL,\r
+         TPL_NOTIFY,\r
+         USBKeyboardRecoveryHandler,\r
+         UsbKeyboardDevice,\r
+         &UsbKeyboardDevice->DelayedRecoveryEvent\r
+         );\r
 \r
   return EFI_SUCCESS;\r
 }\r
 \r
 \r
 /**\r
-  Handler function for USB Keyboard's asynchronous interrupt transfer.\r
+  Handler function for USB keyboard's asynchronous interrupt transfer.\r
+\r
+  This function is the handler function for USB keyboard's asynchronous interrupt transfer\r
+  to manage the keyboard. It parses the USB keyboard input report, and inserts data to\r
+  keyboard buffer according to state of modifer keys and normal keys. Timer for repeat key\r
+  is also set accordingly.\r
 \r
   @param  Data             A pointer to a buffer that is filled with key data which is\r
                            retrieved via asynchronous interrupt transfer.\r
@@ -898,8 +951,8 @@ InitUSBKeyboard (
   @param  Context          Pointing to USB_KB_DEV instance.\r
   @param  Result           Indicates the result of the asynchronous interrupt transfer.\r
 \r
-  @retval EFI_SUCCESS      Handler is successful.\r
-  @retval EFI_DEVICE_ERROR Hardware Error\r
+  @retval EFI_SUCCESS      Asynchronous interrupt transfer is handled successfully.\r
+  @retval EFI_DEVICE_ERROR Hardware error occurs.\r
 \r
 **/\r
 EFI_STATUS\r
@@ -917,6 +970,7 @@ KeyboardHandler (
   UINT8               *OldKeyCodeBuffer;\r
   UINT8               CurModifierMap;\r
   UINT8               OldModifierMap;\r
+  UINT8               Mask;\r
   UINT8               Index;\r
   UINT8               Index2;\r
   BOOLEAN             Down;\r
@@ -928,27 +982,27 @@ KeyboardHandler (
   UINT32              UsbStatus;\r
   EFI_KEY_DESCRIPTOR  *KeyDescriptor;\r
 \r
-  ASSERT (Context);\r
+  ASSERT (Context != NULL);\r
 \r
   NewRepeatKey      = 0;\r
   UsbKeyboardDevice = (USB_KB_DEV *) Context;\r
   UsbIo             = UsbKeyboardDevice->UsbIo;\r
 \r
   //\r
-  // Analyzes the Result and performs corresponding action.\r
+  // Analyzes Result and performs corresponding action.\r
   //\r
   if (Result != EFI_USB_NOERROR) {\r
     //\r
     // Some errors happen during the process\r
     //\r
-    KbdReportStatusCode (\r
-      UsbKeyboardDevice->DevicePath,\r
+    REPORT_STATUS_CODE_WITH_DEVICE_PATH (\r
       EFI_ERROR_CODE | EFI_ERROR_MINOR,\r
-      PcdGet32 (PcdStatusCodeValueKeyboardInputError)\r
+      PcdGet32 (PcdStatusCodeValueKeyboardInputError),\r
+      UsbKeyboardDevice->DevicePath\r
       );\r
 \r
     //\r
-    // stop the repeat key generation if any\r
+    // Stop the repeat key generation if any\r
     //\r
     UsbKeyboardDevice->RepeatKey = 0;\r
 \r
@@ -968,37 +1022,48 @@ KeyboardHandler (
 \r
     //\r
     // Delete & Submit this interrupt again\r
+    // Handler of DelayedRecoveryEvent triggered by timer will re-submit the interrupt. \r
     //\r
-\r
     UsbIo->UsbAsyncInterruptTransfer (\r
-                      UsbIo,\r
-                      UsbKeyboardDevice->IntEndpointDescriptor.EndpointAddress,\r
-                      FALSE,\r
-                      0,\r
-                      0,\r
-                      NULL,\r
-                      NULL\r
-                      );\r
-\r
+             UsbIo,\r
+             UsbKeyboardDevice->IntEndpointDescriptor.EndpointAddress,\r
+             FALSE,\r
+             0,\r
+             0,\r
+             NULL,\r
+             NULL\r
+             );\r
+    //\r
+    // EFI_USB_INTERRUPT_DELAY is defined in USB standard for error handling.\r
+    //\r
     gBS->SetTimer (\r
-          UsbKeyboardDevice->DelayedRecoveryEvent,\r
-          TimerRelative,\r
-          EFI_USB_INTERRUPT_DELAY\r
-          );\r
+           UsbKeyboardDevice->DelayedRecoveryEvent,\r
+           TimerRelative,\r
+           EFI_USB_INTERRUPT_DELAY\r
+           );\r
 \r
     return EFI_DEVICE_ERROR;\r
   }\r
 \r
+  //\r
+  // If no error and no data, just return EFI_SUCCESS.\r
+  //\r
   if (DataLength == 0 || Data == NULL) {\r
     return EFI_SUCCESS;\r
   }\r
 \r
+  //\r
+  // Following code checks current keyboard input report against old key code buffer.\r
+  // According to USB HID Firmware Specification, the report consists of 8 bytes.\r
+  // Byte 0 is map of Modifier keys.\r
+  // Byte 1 is reserved.\r
+  // Bytes 2 to 7 are keycodes.\r
+  //\r
   CurKeyCodeBuffer  = (UINT8 *) Data;\r
   OldKeyCodeBuffer  = UsbKeyboardDevice->LastKeyCodeArray;\r
 \r
   //\r
-  // checks for new key stroke.\r
-  // if no new key got, return immediately.\r
+  // Checks for new key stroke.\r
   //\r
   for (Index = 0; Index < 8; Index++) {\r
     if (OldKeyCodeBuffer[Index] != CurKeyCodeBuffer[Index]) {\r
@@ -1006,35 +1071,47 @@ KeyboardHandler (
     }\r
   }\r
 \r
+  //\r
+  // If no new key, return EFI_SUCCESS immediately.\r
+  //\r
   if (Index == 8) {\r
     return EFI_SUCCESS;\r
   }\r
 \r
   //\r
-  // Parse the modifier key\r
+  // Parse the modifier key, which is the first byte of keyboard input report.\r
   //\r
   CurModifierMap  = CurKeyCodeBuffer[0];\r
   OldModifierMap  = OldKeyCodeBuffer[0];\r
 \r
   //\r
-  // handle modifier key's pressing or releasing situation.\r
+  // Handle modifier key's pressing or releasing situation.\r
+  // According to USB HID Firmware spec, Byte 0 uses folloing map of Modifier keys:\r
+  // Bit0: Left Control,  Keycode: 0xe0\r
+  // Bit1: Left Shift,    Keycode: 0xe1\r
+  // Bit2: Left Alt,      Keycode: 0xe2\r
+  // Bit3: Left GUI,      Keycode: 0xe3\r
+  // Bit4: Right Control, Keycode: 0xe4\r
+  // Bit5: Right Shift,   Keycode: 0xe5\r
+  // Bit6: Right Alt,     Keycode: 0xe6\r
+  // Bit7: Right GUI,     Keycode: 0xe7\r
   //\r
   for (Index = 0; Index < 8; Index++) {\r
-\r
-    if ((CurModifierMap & KB_Mod[Index].Mask) != (OldModifierMap & KB_Mod[Index].Mask)) {\r
+    Mask = (UINT8) (1 << Index);\r
+    if ((CurModifierMap & Mask) != (OldModifierMap & Mask)) {\r
       //\r
-      // if current modifier key is up, then\r
-      // CurModifierMap & KB_Mod[Index].Mask = 0;\r
-      // otherwize it is a non-zero value.\r
-      // Inserts the pressed modifier key into key buffer.\r
+      // If current modifier key is up, then CurModifierMap & Mask = 0;\r
+      // otherwise it is a non-zero value.\r
+      // Insert the changed modifier key into key buffer.\r
       //\r
-      Down = (UINT8) (CurModifierMap & KB_Mod[Index].Mask);\r
-      InsertKeyCode (&(UsbKeyboardDevice->KeyboardBuffer), KB_Mod[Index].Key, Down);\r
+      Down = (BOOLEAN) ((CurModifierMap & Mask) != 0);\r
+      InsertKeyCode (&(UsbKeyboardDevice->KeyboardBuffer), (UINT8) (0xe0 + Index), Down);\r
     }\r
   }\r
 \r
   //\r
-  // handle normal key's releasing situation\r
+  // Handle normal key's releasing situation\r
+  // Bytes 2 to 7 are for normal keycodes\r
   //\r
   KeyRelease = FALSE;\r
   for (Index = 2; Index < 8; Index++) {\r
@@ -1042,7 +1119,10 @@ KeyboardHandler (
     if (!USBKBD_VALID_KEYCODE (OldKeyCodeBuffer[Index])) {\r
       continue;\r
     }\r
-\r
+    //\r
+    // For any key in old keycode buffer, if it is not in current keycode buffer,\r
+    // then it is released. Otherwise, it is not released.\r
+    //\r
     KeyRelease = TRUE;\r
     for (Index2 = 2; Index2 < 8; Index2++) {\r
 \r
@@ -1060,10 +1140,10 @@ KeyboardHandler (
       InsertKeyCode (\r
         &(UsbKeyboardDevice->KeyboardBuffer),\r
         OldKeyCodeBuffer[Index],\r
-        0\r
+        FALSE\r
         );\r
       //\r
-      // the original reapeat key is released.\r
+      // The original repeat key is released.\r
       //\r
       if (OldKeyCodeBuffer[Index] == UsbKeyboardDevice->RepeatKey) {\r
         UsbKeyboardDevice->RepeatKey = 0;\r
@@ -1072,18 +1152,18 @@ KeyboardHandler (
   }\r
 \r
   //\r
-  // original repeat key is released, cancel the repeat timer\r
+  // If original repeat key is released, cancel the repeat timer\r
   //\r
   if (UsbKeyboardDevice->RepeatKey == 0) {\r
     gBS->SetTimer (\r
-          UsbKeyboardDevice->RepeatTimer,\r
-          TimerCancel,\r
-          USBKBD_REPEAT_RATE\r
-          );\r
+           UsbKeyboardDevice->RepeatTimer,\r
+           TimerCancel,\r
+           USBKBD_REPEAT_RATE\r
+           );\r
   }\r
 \r
   //\r
-  // handle normal key's pressing situation\r
+  // Handle normal key's pressing situation\r
   //\r
   KeyPress = FALSE;\r
   for (Index = 2; Index < 8; Index++) {\r
@@ -1091,7 +1171,10 @@ KeyboardHandler (
     if (!USBKBD_VALID_KEYCODE (CurKeyCodeBuffer[Index])) {\r
       continue;\r
     }\r
-\r
+    //\r
+    // For any key in current keycode buffer, if it is not in old keycode buffer,\r
+    // then it is pressed. Otherwise, it is not pressed.\r
+    //\r
     KeyPress = TRUE;\r
     for (Index2 = 2; Index2 < 8; Index2++) {\r
 \r
@@ -1106,76 +1189,81 @@ KeyboardHandler (
     }\r
 \r
     if (KeyPress) {\r
-      InsertKeyCode (&(UsbKeyboardDevice->KeyboardBuffer), CurKeyCodeBuffer[Index], 1);\r
+      InsertKeyCode (&(UsbKeyboardDevice->KeyboardBuffer), CurKeyCodeBuffer[Index], TRUE);\r
+\r
       //\r
-      // NumLock pressed or CapsLock pressed\r
+      // Handle repeat key\r
       //\r
       KeyDescriptor = GetKeyDescriptor (UsbKeyboardDevice, CurKeyCodeBuffer[Index]);\r
+      ASSERT (KeyDescriptor != NULL);\r
+\r
       if (KeyDescriptor->Modifier == EFI_NUM_LOCK_MODIFIER || KeyDescriptor->Modifier == EFI_CAPS_LOCK_MODIFIER) {\r
+        //\r
+        // For NumLock or CapsLock pressed, there is no need to handle repeat key for them.\r
+        //\r
         UsbKeyboardDevice->RepeatKey = 0;\r
       } else {\r
-        NewRepeatKey = CurKeyCodeBuffer[Index];\r
         //\r
-        // do not repeat the original repeated key\r
+        // Prepare new repeat key, and clear the original one.\r
         //\r
+        NewRepeatKey = CurKeyCodeBuffer[Index];\r
         UsbKeyboardDevice->RepeatKey = 0;\r
       }\r
     }\r
   }\r
 \r
   //\r
-  // Update LastKeycodeArray[] buffer in the\r
-  // Usb Keyboard Device data structure.\r
+  // Update LastKeycodeArray buffer in the UsbKeyboardDevice data structure.\r
   //\r
   for (Index = 0; Index < 8; Index++) {\r
     UsbKeyboardDevice->LastKeyCodeArray[Index] = CurKeyCodeBuffer[Index];\r
   }\r
 \r
   //\r
-  // pre-process KeyboardBuffer, pop out the ctrl,alt,del key in sequence\r
-  // and judge whether it will invoke reset event.\r
+  // Pre-process KeyboardBuffer to check if Ctrl + Alt + Del is pressed.\r
   //\r
-  SavedTail = UsbKeyboardDevice->KeyboardBuffer.bTail;\r
-  Index     = UsbKeyboardDevice->KeyboardBuffer.bHead;\r
+  SavedTail = UsbKeyboardDevice->KeyboardBuffer.BufferTail;\r
+  Index     = UsbKeyboardDevice->KeyboardBuffer.BufferHead;\r
   while (Index != SavedTail) {\r
     RemoveKeyCode (&(UsbKeyboardDevice->KeyboardBuffer), &UsbKey);\r
 \r
     KeyDescriptor = GetKeyDescriptor (UsbKeyboardDevice, UsbKey.KeyCode);\r
+    ASSERT (KeyDescriptor != NULL);\r
 \r
     switch (KeyDescriptor->Modifier) {\r
 \r
     case EFI_LEFT_CONTROL_MODIFIER:\r
     case EFI_RIGHT_CONTROL_MODIFIER:\r
-      if (UsbKey.Down != 0) {\r
-        UsbKeyboardDevice->CtrlOn = 1;\r
+      if (UsbKey.Down) {\r
+        UsbKeyboardDevice->CtrlOn = TRUE;\r
       } else {\r
-        UsbKeyboardDevice->CtrlOn = 0;\r
+        UsbKeyboardDevice->CtrlOn = FALSE;\r
       }\r
       break;\r
 \r
     case EFI_LEFT_ALT_MODIFIER:\r
     case EFI_RIGHT_ALT_MODIFIER:\r
-      if (UsbKey.Down != 0) {\r
-        UsbKeyboardDevice->AltOn = 1;\r
+      if (UsbKey.Down) {\r
+        UsbKeyboardDevice->AltOn = TRUE;\r
       } else {\r
-        UsbKeyboardDevice->AltOn = 0;\r
+        UsbKeyboardDevice->AltOn = FALSE;\r
       }\r
       break;\r
 \r
     case EFI_ALT_GR_MODIFIER:\r
-      if (UsbKey.Down != 0) {\r
-        UsbKeyboardDevice->AltGrOn = 1;\r
+      if (UsbKey.Down) {\r
+        UsbKeyboardDevice->AltGrOn = TRUE;\r
       } else {\r
-        UsbKeyboardDevice->AltGrOn = 0;\r
+        UsbKeyboardDevice->AltGrOn = FALSE;\r
       }\r
       break;\r
 \r
     //\r
-    // Del Key Code\r
+    // For Del Key, check if Ctrl + Alt + Del occurs for reset.\r
     //\r
     case EFI_DELETE_MODIFIER:\r
-      if (UsbKey.Down != 0) {\r
-        if ((UsbKeyboardDevice->CtrlOn != 0) && (UsbKeyboardDevice->AltOn != 0)) {\r
+      if (UsbKey.Down) {\r
+        if ((UsbKeyboardDevice->CtrlOn) && (UsbKeyboardDevice->AltOn)) {\r
           gRT->ResetSystem (EfiResetWarm, EFI_SUCCESS, 0, NULL);\r
         }\r
       }\r
@@ -1186,7 +1274,7 @@ KeyboardHandler (
     }\r
 \r
     //\r
-    // insert the key back to the buffer.\r
+    // Insert the key back to the buffer,\r
     // so the key sequence will not be destroyed.\r
     //\r
     InsertKeyCode (\r
@@ -1194,24 +1282,24 @@ KeyboardHandler (
       UsbKey.KeyCode,\r
       UsbKey.Down\r
       );\r
-    Index = UsbKeyboardDevice->KeyboardBuffer.bHead;\r
+    Index = UsbKeyboardDevice->KeyboardBuffer.BufferHead;\r
 \r
   }\r
   //\r
-  // If have new key pressed, update the RepeatKey value, and set the\r
+  // If there is new key pressed, update the RepeatKey value, and set the\r
   // timer to repeate delay timer\r
   //\r
   if (NewRepeatKey != 0) {\r
     //\r
-    // sets trigger time to "Repeat Delay Time",\r
+    // Sets trigger time to "Repeat Delay Time",\r
     // to trigger the repeat timer when the key is hold long\r
     // enough time.\r
     //\r
     gBS->SetTimer (\r
-          UsbKeyboardDevice->RepeatTimer,\r
-          TimerRelative,\r
-          USBKBD_REPEAT_DELAY\r
-          );\r
+           UsbKeyboardDevice->RepeatTimer,\r
+           TimerRelative,\r
+           USBKBD_REPEAT_DELAY\r
+           );\r
     UsbKeyboardDevice->RepeatKey = NewRepeatKey;\r
   }\r
 \r
@@ -1220,92 +1308,100 @@ KeyboardHandler (
 \r
 \r
 /**\r
-  Retrieves a key character after parsing the raw data in keyboard buffer.\r
+  Retrieves a USB keycode after parsing the raw data in keyboard buffer.\r
+\r
+  This function parses keyboard buffer. It updates state of modifier key for\r
+  USB_KB_DEV instancem, and returns keycode for output.\r
 \r
   @param  UsbKeyboardDevice    The USB_KB_DEV instance.\r
-  @param  KeyChar              Points to the Key character after key parsing.\r
+  @param  KeyCode              Pointer to the USB keycode for output.\r
 \r
-  @retval EFI_SUCCESS          Parse key is successful.\r
-  @retval EFI_NOT_READY        Device is not ready.\r
+  @retval EFI_SUCCESS          Keycode successfully parsed.\r
+  @retval EFI_NOT_READY        Keyboard buffer is not ready for a valid keycode\r
 \r
 **/\r
 EFI_STATUS\r
 EFIAPI\r
 USBParseKey (\r
   IN OUT  USB_KB_DEV  *UsbKeyboardDevice,\r
-  OUT     UINT8       *KeyChar\r
+     OUT  UINT8       *KeyCode\r
   )\r
 {\r
   USB_KEY             UsbKey;\r
   EFI_KEY_DESCRIPTOR  *KeyDescriptor;\r
 \r
-  *KeyChar = 0;\r
+  *KeyCode = 0;\r
 \r
   while (!IsUSBKeyboardBufferEmpty (&UsbKeyboardDevice->KeyboardBuffer)) {\r
     //\r
-    // pops one raw data off.\r
+    // Pops one raw data off.\r
     //\r
     RemoveKeyCode (&(UsbKeyboardDevice->KeyboardBuffer), &UsbKey);\r
 \r
     KeyDescriptor = GetKeyDescriptor (UsbKeyboardDevice, UsbKey.KeyCode);\r
-    if (UsbKey.Down == 0) {\r
+    ASSERT (KeyDescriptor != NULL);\r
+\r
+    if (!UsbKey.Down) {\r
+      //\r
+      // Key is released.\r
+      //\r
       switch (KeyDescriptor->Modifier) {\r
 \r
       //\r
-      // CTRL release\r
+      // Ctrl release\r
       //\r
       case EFI_LEFT_CONTROL_MODIFIER:\r
-        UsbKeyboardDevice->LeftCtrlOn = 0;\r
-        UsbKeyboardDevice->CtrlOn = 0;\r
+        UsbKeyboardDevice->LeftCtrlOn = FALSE;\r
+        UsbKeyboardDevice->CtrlOn = FALSE;\r
         break;\r
       case EFI_RIGHT_CONTROL_MODIFIER:\r
-        UsbKeyboardDevice->RightCtrlOn = 0;\r
-        UsbKeyboardDevice->CtrlOn = 0;\r
+        UsbKeyboardDevice->RightCtrlOn = FALSE;\r
+        UsbKeyboardDevice->CtrlOn = FALSE;\r
         break;\r
 \r
       //\r
       // Shift release\r
       //\r
       case EFI_LEFT_SHIFT_MODIFIER:\r
-        UsbKeyboardDevice->LeftShiftOn = 0;\r
-        UsbKeyboardDevice->ShiftOn = 0;\r
+        UsbKeyboardDevice->LeftShiftOn = FALSE;\r
+        UsbKeyboardDevice->ShiftOn = FALSE;\r
         break;\r
       case EFI_RIGHT_SHIFT_MODIFIER:\r
-        UsbKeyboardDevice->RightShiftOn = 0;\r
-        UsbKeyboardDevice->ShiftOn = 0;\r
+        UsbKeyboardDevice->RightShiftOn = FALSE;\r
+        UsbKeyboardDevice->ShiftOn = FALSE;\r
         break;\r
 \r
       //\r
       // Alt release\r
       //\r
       case EFI_LEFT_ALT_MODIFIER:\r
-        UsbKeyboardDevice->LeftAltOn = 0;\r
-        UsbKeyboardDevice->AltOn = 0;\r
+        UsbKeyboardDevice->LeftAltOn = FALSE;\r
+        UsbKeyboardDevice->AltOn = FALSE;\r
         break;\r
       case EFI_RIGHT_ALT_MODIFIER:\r
-        UsbKeyboardDevice->RightAltOn = 0;\r
-        UsbKeyboardDevice->AltOn = 0;\r
+        UsbKeyboardDevice->RightAltOn = FALSE;\r
+        UsbKeyboardDevice->AltOn = FALSE;\r
         break;\r
 \r
       //\r
       // Left Logo release\r
       //\r
       case EFI_LEFT_LOGO_MODIFIER:\r
-        UsbKeyboardDevice->LeftLogoOn = 0;\r
+        UsbKeyboardDevice->LeftLogoOn = FALSE;\r
         break;\r
 \r
       //\r
       // Right Logo release\r
       //\r
       case EFI_RIGHT_LOGO_MODIFIER:\r
-        UsbKeyboardDevice->RightLogoOn = 0;\r
+        UsbKeyboardDevice->RightLogoOn = FALSE;\r
         break;\r
 \r
       //\r
       // Menu key release\r
       //\r
       case EFI_MENU_MODIFIER:\r
-        UsbKeyboardDevice->MenuKeyOn = 0;\r
+        UsbKeyboardDevice->MenuKeyOn = FALSE;\r
         break;\r
 \r
       //\r
@@ -1313,14 +1409,14 @@ USBParseKey (
       //\r
       case EFI_PRINT_MODIFIER:\r
       case EFI_SYS_REQUEST_MODIFIER:\r
-        UsbKeyboardDevice->SysReqOn = 0;\r
+        UsbKeyboardDevice->SysReqOn = FALSE;\r
         break;\r
 \r
       //\r
       // AltGr release\r
       //\r
       case EFI_ALT_GR_MODIFIER:\r
-        UsbKeyboardDevice->AltGrOn = 0;\r
+        UsbKeyboardDevice->AltGrOn = FALSE;\r
         break;\r
 \r
       default:\r
@@ -1336,16 +1432,16 @@ USBParseKey (
     switch (KeyDescriptor->Modifier) {\r
 \r
     //\r
-    // CTRL press\r
+    // Ctrl press\r
     //\r
     case EFI_LEFT_CONTROL_MODIFIER:\r
-      UsbKeyboardDevice->LeftCtrlOn = 1;\r
-      UsbKeyboardDevice->CtrlOn = 1;\r
+      UsbKeyboardDevice->LeftCtrlOn = TRUE;\r
+      UsbKeyboardDevice->CtrlOn = TRUE;\r
       continue;\r
       break;\r
     case EFI_RIGHT_CONTROL_MODIFIER:\r
-      UsbKeyboardDevice->RightCtrlOn = 1;\r
-      UsbKeyboardDevice->CtrlOn = 1;\r
+      UsbKeyboardDevice->RightCtrlOn = TRUE;\r
+      UsbKeyboardDevice->CtrlOn = TRUE;\r
       continue;\r
       break;\r
 \r
@@ -1353,13 +1449,13 @@ USBParseKey (
     // Shift press\r
     //\r
     case EFI_LEFT_SHIFT_MODIFIER:\r
-      UsbKeyboardDevice->LeftShiftOn = 1;\r
-      UsbKeyboardDevice->ShiftOn = 1;\r
+      UsbKeyboardDevice->LeftShiftOn = TRUE;\r
+      UsbKeyboardDevice->ShiftOn = TRUE;\r
       continue;\r
       break;\r
     case EFI_RIGHT_SHIFT_MODIFIER:\r
-      UsbKeyboardDevice->RightShiftOn = 1;\r
-      UsbKeyboardDevice->ShiftOn = 1;\r
+      UsbKeyboardDevice->RightShiftOn = TRUE;\r
+      UsbKeyboardDevice->ShiftOn = TRUE;\r
       continue;\r
       break;\r
 \r
@@ -1367,13 +1463,13 @@ USBParseKey (
     // Alt press\r
     //\r
     case EFI_LEFT_ALT_MODIFIER:\r
-      UsbKeyboardDevice->LeftAltOn = 1;\r
-      UsbKeyboardDevice->AltOn = 1;\r
+      UsbKeyboardDevice->LeftAltOn = TRUE;\r
+      UsbKeyboardDevice->AltOn = TRUE;\r
       continue;\r
       break;\r
     case EFI_RIGHT_ALT_MODIFIER:\r
-      UsbKeyboardDevice->RightAltOn = 1;\r
-      UsbKeyboardDevice->AltOn = 1;\r
+      UsbKeyboardDevice->RightAltOn = TRUE;\r
+      UsbKeyboardDevice->AltOn = TRUE;\r
       continue;\r
       break;\r
 \r
@@ -1381,21 +1477,21 @@ USBParseKey (
     // Left Logo press\r
     //\r
     case EFI_LEFT_LOGO_MODIFIER:\r
-      UsbKeyboardDevice->LeftLogoOn = 1;\r
+      UsbKeyboardDevice->LeftLogoOn = TRUE;\r
       break;\r
 \r
     //\r
     // Right Logo press\r
     //\r
     case EFI_RIGHT_LOGO_MODIFIER:\r
-      UsbKeyboardDevice->RightLogoOn = 1;\r
+      UsbKeyboardDevice->RightLogoOn = TRUE;\r
       break;\r
 \r
     //\r
     // Menu key press\r
     //\r
     case EFI_MENU_MODIFIER:\r
-      UsbKeyboardDevice->MenuKeyOn = 1;\r
+      UsbKeyboardDevice->MenuKeyOn = TRUE;\r
       break;\r
 \r
     //\r
@@ -1403,7 +1499,7 @@ USBParseKey (
     //\r
     case EFI_PRINT_MODIFIER:\r
     case EFI_SYS_REQUEST_MODIFIER:\r
-      UsbKeyboardDevice->SysReqOn = 1;\r
+      UsbKeyboardDevice->SysReqOn = TRUE;\r
       continue;\r
       break;\r
 \r
@@ -1411,46 +1507,43 @@ USBParseKey (
     // AltGr press\r
     //\r
     case EFI_ALT_GR_MODIFIER:\r
-      UsbKeyboardDevice->AltGrOn = 1;\r
+      UsbKeyboardDevice->AltGrOn = TRUE;\r
       break;\r
 \r
     case EFI_NUM_LOCK_MODIFIER:\r
-      UsbKeyboardDevice->NumLockOn ^= 1;\r
       //\r
-      // Turn on the NumLock light on KB\r
+      // Toggle NumLock\r
       //\r
+      UsbKeyboardDevice->NumLockOn = (BOOLEAN) (!(UsbKeyboardDevice->NumLockOn));\r
       SetKeyLED (UsbKeyboardDevice);\r
       continue;\r
       break;\r
 \r
     case EFI_CAPS_LOCK_MODIFIER:\r
-      UsbKeyboardDevice->CapsOn ^= 1;\r
       //\r
-      // Turn on the CapsLock light on KB\r
+      // Toggle CapsLock\r
       //\r
+      UsbKeyboardDevice->CapsOn = (BOOLEAN) (!(UsbKeyboardDevice->CapsOn));\r
       SetKeyLED (UsbKeyboardDevice);\r
       continue;\r
       break;\r
 \r
     case EFI_SCROLL_LOCK_MODIFIER:\r
-      UsbKeyboardDevice->ScrollOn ^= 1;\r
       //\r
-      // Turn on the ScrollLock light on KB\r
+      // Toggle ScrollLock\r
       //\r
+      UsbKeyboardDevice->ScrollOn = (BOOLEAN) (!(UsbKeyboardDevice->ScrollOn));\r
       SetKeyLED (UsbKeyboardDevice);\r
       continue;\r
       break;\r
 \r
     //\r
-    // F11,F12,PrintScreen,Pause/Break\r
-    // could not be retrieved via SimpleTxtInEx protocol\r
+    // PrintScreen, Pause/Break could not be retrieved via SimpleTextInEx protocol\r
     //\r
-    case EFI_FUNCTION_KEY_ELEVEN_MODIFIER:\r
-    case EFI_FUNCTION_KEY_TWELVE_MODIFIER:\r
     case EFI_PAUSE_MODIFIER:\r
     case EFI_BREAK_MODIFIER:\r
       //\r
-      // fall through\r
+      // Fall through\r
       //\r
       continue;\r
       break;\r
@@ -1460,15 +1553,15 @@ USBParseKey (
     }\r
 \r
     //\r
-    // When encountered Del Key...\r
+    // When encountering Ctrl + Alt + Del, then warm reset.\r
     //\r
     if (KeyDescriptor->Modifier == EFI_DELETE_MODIFIER) {\r
-      if ((UsbKeyboardDevice->CtrlOn != 0) && (UsbKeyboardDevice->AltOn != 0)) {\r
+      if ((UsbKeyboardDevice->CtrlOn) && (UsbKeyboardDevice->AltOn)) {\r
         gRT->ResetSystem (EfiResetWarm, EFI_SUCCESS, 0, NULL);\r
       }\r
     }\r
 \r
-    *KeyChar = UsbKey.KeyCode;\r
+    *KeyCode = UsbKey.KeyCode;\r
     return EFI_SUCCESS;\r
   }\r
 \r
@@ -1477,77 +1570,85 @@ USBParseKey (
 \r
 \r
 /**\r
-  Converts USB Keyboard code to EFI Scan Code.\r
+  Converts USB Keycode ranging from 0x4 to 0x65 to EFI_INPUT_KEY.\r
 \r
-  @param  UsbKeyboardDevice    The USB_KB_DEV instance.\r
-  @param  KeyChar              Indicates the key code that will be interpreted.\r
-  @param  Key                  A pointer to a buffer that is filled in with\r
-                               the keystroke information for the key that\r
-                               was pressed.\r
+  @param  UsbKeyboardDevice     The USB_KB_DEV instance.\r
+  @param  KeyCode               Indicates the key code that will be interpreted.\r
+  @param  Key                   A pointer to a buffer that is filled in with\r
+                                the keystroke information for the key that\r
+                                was pressed.\r
 \r
-  @retval EFI_NOT_READY        Device is not ready\r
-  @retval EFI_SUCCESS          Success.\r
+  @retval EFI_SUCCESS           Success.\r
+  @retval EFI_INVALID_PARAMETER KeyCode is not in the range of 0x4 to 0x65.\r
+  @retval EFI_INVALID_PARAMETER Translated EFI_INPUT_KEY has zero for both ScanCode and UnicodeChar.\r
+  @retval EFI_NOT_READY         KeyCode represents a dead key with EFI_NS_KEY_MODIFIER\r
+  @retval EFI_DEVICE_ERROR      Keyboard layout is invalid.\r
 \r
 **/\r
 EFI_STATUS\r
 EFIAPI\r
-USBKeyCodeToEFIScanCode (\r
+UsbKeyCodeToEfiInputKey (\r
   IN  USB_KB_DEV      *UsbKeyboardDevice,\r
-  IN  UINT8           KeyChar,\r
+  IN  UINT8           KeyCode,\r
   OUT EFI_INPUT_KEY   *Key\r
   )\r
 {\r
-  UINT8               Index;\r
   EFI_KEY_DESCRIPTOR  *KeyDescriptor;\r
 \r
-  if (!USBKBD_VALID_KEYCODE (KeyChar)) {\r
-    return EFI_NOT_READY;\r
-  }\r
-\r
   //\r
-  // valid USB Key Code starts from 4\r
+  // KeyCode must in the range of 0x4 to 0x65\r
   //\r
-  Index = (UINT8) (KeyChar - 4);\r
-\r
-  if (Index >= USB_KEYCODE_MAX_MAKE) {\r
-    return EFI_NOT_READY;\r
+  if (!USBKBD_VALID_KEYCODE (KeyCode)) {\r
+    return EFI_INVALID_PARAMETER;\r
+  }\r
+  if ((KeyCode - 4) >= NUMBER_OF_VALID_NON_MODIFIER_USB_KEYCODE) {\r
+    return EFI_INVALID_PARAMETER;\r
   }\r
 \r
-  KeyDescriptor = GetKeyDescriptor (UsbKeyboardDevice, KeyChar);\r
+  KeyDescriptor = GetKeyDescriptor (UsbKeyboardDevice, KeyCode);\r
+  ASSERT (KeyDescriptor != NULL);\r
 \r
-  //\r
-  // Check for Non-spacing key\r
-  //\r
   if (KeyDescriptor->Modifier == EFI_NS_KEY_MODIFIER) {\r
+    //\r
+    // If this is a dead key with EFI_NS_KEY_MODIFIER, then record it and return.\r
+    //\r
     UsbKeyboardDevice->CurrentNsKey = FindUsbNsKey (UsbKeyboardDevice, KeyDescriptor);\r
     return EFI_NOT_READY;\r
   }\r
 \r
-  //\r
-  // Check whether this keystroke follows a Non-spacing key\r
-  //\r
   if (UsbKeyboardDevice->CurrentNsKey != NULL) {\r
+    //\r
+    // If this keystroke follows a non-spacing key, then find the descriptor for corresponding\r
+    // physical key.\r
+    //\r
     KeyDescriptor = FindPhysicalKey (UsbKeyboardDevice->CurrentNsKey, KeyDescriptor);\r
     UsbKeyboardDevice->CurrentNsKey = NULL;\r
   }\r
 \r
-  Key->ScanCode = EfiScanCodeConvertionTable[KeyDescriptor->Modifier];\r
+  //\r
+  // Make sure modifier of Key Descriptor is in the valid range according to UEFI spec.\r
+  //\r
+  if (KeyDescriptor->Modifier > EFI_FUNCTION_KEY_TWELVE_MODIFIER) {\r
+    return EFI_DEVICE_ERROR;\r
+  }\r
+\r
+  Key->ScanCode = ModifierValueToEfiScanCodeConvertionTable[KeyDescriptor->Modifier];\r
   Key->UnicodeChar = KeyDescriptor->Unicode;\r
 \r
-  if (KeyDescriptor->AffectedAttribute & EFI_AFFECTED_BY_STANDARD_SHIFT) {\r
-    if (UsbKeyboardDevice->ShiftOn != 0) {\r
+  if ((KeyDescriptor->AffectedAttribute & EFI_AFFECTED_BY_STANDARD_SHIFT)!= 0) {\r
+    if (UsbKeyboardDevice->ShiftOn) {\r
       Key->UnicodeChar = KeyDescriptor->ShiftedUnicode;\r
 \r
       //\r
       // Need not return associated shift state if a class of printable characters that\r
       // are normally adjusted by shift modifiers. e.g. Shift Key + 'f' key = 'F'\r
       //\r
-      if (KeyDescriptor->AffectedAttribute & EFI_AFFECTED_BY_CAPS_LOCK) {\r
-        UsbKeyboardDevice->LeftShiftOn = 0;\r
-        UsbKeyboardDevice->RightShiftOn = 0;\r
+      if ((KeyDescriptor->AffectedAttribute & EFI_AFFECTED_BY_CAPS_LOCK) != 0) {\r
+        UsbKeyboardDevice->LeftShiftOn = FALSE;\r
+        UsbKeyboardDevice->RightShiftOn = FALSE;\r
       }\r
 \r
-      if (UsbKeyboardDevice->AltGrOn != 0) {\r
+      if (UsbKeyboardDevice->AltGrOn) {\r
         Key->UnicodeChar = KeyDescriptor->ShiftedAltGrUnicode;\r
       }\r
     } else {\r
@@ -1556,31 +1657,27 @@ USBKeyCodeToEFIScanCode (
       //\r
       Key->UnicodeChar = KeyDescriptor->Unicode;\r
 \r
-      if (UsbKeyboardDevice->AltGrOn != 0) {\r
+      if (UsbKeyboardDevice->AltGrOn) {\r
         Key->UnicodeChar = KeyDescriptor->AltGrUnicode;\r
       }\r
     }\r
   }\r
 \r
-  if (KeyDescriptor->AffectedAttribute & EFI_AFFECTED_BY_CAPS_LOCK) {\r
-    if (UsbKeyboardDevice->CapsOn != 0) {\r
-\r
+  if ((KeyDescriptor->AffectedAttribute & EFI_AFFECTED_BY_CAPS_LOCK) != 0) {\r
+    if (UsbKeyboardDevice->CapsOn) {\r
       if (Key->UnicodeChar == KeyDescriptor->Unicode) {\r
-\r
         Key->UnicodeChar = KeyDescriptor->ShiftedUnicode;\r
-\r
       } else if (Key->UnicodeChar == KeyDescriptor->ShiftedUnicode) {\r
-\r
         Key->UnicodeChar = KeyDescriptor->Unicode;\r
-\r
       }\r
     }\r
   }\r
 \r
   //\r
-  // Translate the CTRL-Alpha characters to their corresponding control value  (ctrl-a = 0x0001 through ctrl-Z = 0x001A)\r
+  // Translate the CTRL-Alpha characters to their corresponding control value\r
+  // (ctrl-a = 0x0001 through ctrl-Z = 0x001A)\r
   //\r
-  if (UsbKeyboardDevice->CtrlOn != 0) {\r
+  if (UsbKeyboardDevice->CtrlOn) {\r
     if (Key->UnicodeChar >= 'a' && Key->UnicodeChar <= 'z') {\r
       Key->UnicodeChar = (UINT8) (Key->UnicodeChar - 'a' + 1);\r
     } else if (Key->UnicodeChar >= 'A' && Key->UnicodeChar <= 'Z') {\r
@@ -1588,12 +1685,14 @@ USBKeyCodeToEFIScanCode (
     }\r
   }\r
 \r
-  if (KeyDescriptor->AffectedAttribute & EFI_AFFECTED_BY_NUM_LOCK) {\r
-\r
-    if ((UsbKeyboardDevice->NumLockOn != 0) && (UsbKeyboardDevice->ShiftOn == 0)) {\r
-\r
+  if ((KeyDescriptor->AffectedAttribute & EFI_AFFECTED_BY_NUM_LOCK) != 0) {\r
+    //\r
+    // For key affected by NumLock, if NumLock is on and Shift is not pressed, then it means\r
+    // normal key, instead of original control key. So the ScanCode should be cleaned.\r
+    // Otherwise, it means control key, so preserve the EFI Scan Code and clear the unicode keycode.\r
+    //\r
+    if ((UsbKeyboardDevice->NumLockOn) && (!(UsbKeyboardDevice->ShiftOn))) {\r
       Key->ScanCode = SCAN_NULL;\r
-\r
     } else {\r
       Key->UnicodeChar = 0x00;\r
     }\r
@@ -1607,6 +1706,9 @@ USBKeyCodeToEFIScanCode (
     Key->UnicodeChar = 0x00;\r
   }\r
 \r
+  //\r
+  // Not valid for key without both unicode key code and EFI Scan Code.\r
+  //\r
   if (Key->UnicodeChar == 0 && Key->ScanCode == SCAN_NULL) {\r
     return EFI_NOT_READY;\r
   }\r
@@ -1615,44 +1717,44 @@ USBKeyCodeToEFIScanCode (
   //\r
   // Save Shift/Toggle state\r
   //\r
-  if (UsbKeyboardDevice->LeftCtrlOn == 1) {\r
+  if (UsbKeyboardDevice->LeftCtrlOn) {\r
     UsbKeyboardDevice->KeyState.KeyShiftState |= EFI_LEFT_CONTROL_PRESSED;\r
   }\r
-  if (UsbKeyboardDevice->RightCtrlOn == 1) {\r
+  if (UsbKeyboardDevice->RightCtrlOn) {\r
     UsbKeyboardDevice->KeyState.KeyShiftState |= EFI_RIGHT_CONTROL_PRESSED;\r
   }\r
-  if (UsbKeyboardDevice->LeftAltOn == 1) {\r
+  if (UsbKeyboardDevice->LeftAltOn) {\r
     UsbKeyboardDevice->KeyState.KeyShiftState |= EFI_LEFT_ALT_PRESSED;\r
   }\r
-  if (UsbKeyboardDevice->RightAltOn == 1) {\r
+  if (UsbKeyboardDevice->RightAltOn) {\r
     UsbKeyboardDevice->KeyState.KeyShiftState |= EFI_RIGHT_ALT_PRESSED;\r
   }\r
-  if (UsbKeyboardDevice->LeftShiftOn == 1) {\r
+  if (UsbKeyboardDevice->LeftShiftOn) {\r
     UsbKeyboardDevice->KeyState.KeyShiftState |= EFI_LEFT_SHIFT_PRESSED;\r
   }\r
-  if (UsbKeyboardDevice->RightShiftOn == 1) {\r
+  if (UsbKeyboardDevice->RightShiftOn) {\r
     UsbKeyboardDevice->KeyState.KeyShiftState |= EFI_RIGHT_SHIFT_PRESSED;\r
   }\r
-  if (UsbKeyboardDevice->LeftLogoOn == 1) {\r
+  if (UsbKeyboardDevice->LeftLogoOn) {\r
     UsbKeyboardDevice->KeyState.KeyShiftState |= EFI_LEFT_LOGO_PRESSED;\r
   }\r
-  if (UsbKeyboardDevice->RightLogoOn == 1) {\r
+  if (UsbKeyboardDevice->RightLogoOn) {\r
     UsbKeyboardDevice->KeyState.KeyShiftState |= EFI_RIGHT_LOGO_PRESSED;\r
   }\r
-  if (UsbKeyboardDevice->MenuKeyOn == 1) {\r
+  if (UsbKeyboardDevice->MenuKeyOn) {\r
     UsbKeyboardDevice->KeyState.KeyShiftState |= EFI_MENU_KEY_PRESSED;\r
   }\r
-  if (UsbKeyboardDevice->SysReqOn == 1) {\r
+  if (UsbKeyboardDevice->SysReqOn) {\r
     UsbKeyboardDevice->KeyState.KeyShiftState |= EFI_SYS_REQ_PRESSED;\r
   }\r
 \r
-  if (UsbKeyboardDevice->ScrollOn == 1) {\r
+  if (UsbKeyboardDevice->ScrollOn) {\r
     UsbKeyboardDevice->KeyState.KeyToggleState |= EFI_SCROLL_LOCK_ACTIVE;\r
   }\r
-  if (UsbKeyboardDevice->NumLockOn == 1) {\r
+  if (UsbKeyboardDevice->NumLockOn) {\r
     UsbKeyboardDevice->KeyState.KeyToggleState |= EFI_NUM_LOCK_ACTIVE;\r
   }\r
-  if (UsbKeyboardDevice->CapsOn == 1) {\r
+  if (UsbKeyboardDevice->CapsOn) {\r
     UsbKeyboardDevice->KeyState.KeyToggleState |= EFI_CAPS_LOCK_ACTIVE;\r
   }\r
 \r
@@ -1662,34 +1764,30 @@ USBKeyCodeToEFIScanCode (
 \r
 \r
 /**\r
-  Resets USB Keyboard Buffer.\r
-\r
-  @param  KeyboardBuffer     Points to the USB Keyboard Buffer.\r
+  Resets USB keyboard buffer.\r
 \r
-  @retval EFI_SUCCESS        Init key buffer successfully.\r
+  @param  KeyboardBuffer     Points to the USB keyboard buffer.\r
 \r
 **/\r
-EFI_STATUS\r
+VOID\r
 EFIAPI\r
 InitUSBKeyBuffer (\r
-  IN OUT  USB_KB_BUFFER   *KeyboardBuffer\r
+  OUT  USB_KB_BUFFER   *KeyboardBuffer\r
   )\r
 {\r
   ZeroMem (KeyboardBuffer, sizeof (USB_KB_BUFFER));\r
 \r
-  KeyboardBuffer->bHead = KeyboardBuffer->bTail;\r
-\r
-  return EFI_SUCCESS;\r
+  KeyboardBuffer->BufferHead = KeyboardBuffer->BufferTail;\r
 }\r
 \r
 \r
 /**\r
-  Check whether USB Keyboard buffer is empty.\r
+  Check whether USB keyboard buffer is empty.\r
 \r
-  @param  KeyboardBuffer     USB Keyboard Buffer.\r
+  @param  KeyboardBuffer     USB keyboard buffer\r
 \r
-  @retval TRUE               Key buffer is empty.\r
-  @retval FALSE              Key buffer is not empty.\r
+  @retval TRUE               Keyboard buffer is empty.\r
+  @retval FALSE              Keyboard buffer is not empty.\r
 \r
 **/\r
 BOOLEAN\r
@@ -1699,19 +1797,19 @@ IsUSBKeyboardBufferEmpty (
   )\r
 {\r
   //\r
-  // meet FIFO empty condition\r
+  // Meet FIFO empty condition\r
   //\r
-  return (BOOLEAN) (KeyboardBuffer->bHead == KeyboardBuffer->bTail);\r
+  return (BOOLEAN) (KeyboardBuffer->BufferHead == KeyboardBuffer->BufferTail);\r
 }\r
 \r
 \r
 /**\r
-  Check whether USB Keyboard buffer is full.\r
+  Check whether USB keyboard buffer is full.\r
 \r
-  @param  KeyboardBuffer     USB Keyboard Buffer.\r
+  @param  KeyboardBuffer     USB keyboard buffer\r
 \r
-  @retval TRUE               Key buffer is full.\r
-  @retval FALSE              Key buffer is not full.\r
+  @retval TRUE               Keyboard buffer is full.\r
+  @retval FALSE              Keyboard buffer is not full.\r
 \r
 **/\r
 BOOLEAN\r
@@ -1720,93 +1818,91 @@ IsUSBKeyboardBufferFull (
   IN  USB_KB_BUFFER   *KeyboardBuffer\r
   )\r
 {\r
-  return (BOOLEAN)(((KeyboardBuffer->bTail + 1) % (MAX_KEY_ALLOWED + 1)) ==\r
-                                                        KeyboardBuffer->bHead);\r
+  return (BOOLEAN)(((KeyboardBuffer->BufferTail + 1) % (MAX_KEY_ALLOWED + 1)) == KeyboardBuffer->BufferHead);\r
 }\r
 \r
 \r
 /**\r
-  Inserts a key code into keyboard buffer.\r
+  Inserts a keycode into keyboard buffer.\r
 \r
-  @param  KeyboardBuffer     Points to the USB Keyboard Buffer.\r
-  @param  Key                Key code\r
-  @param  Down               Special key\r
-\r
-  @retval EFI_SUCCESS        Success\r
+  @param  KeyboardBuffer     Points to the USB keyboard buffer.\r
+  @param  Key                Keycode to insert.\r
+  @param  Down               TRUE means key is pressed.\r
+                             FALSE means key is released.\r
 \r
 **/\r
-EFI_STATUS\r
+VOID\r
 EFIAPI\r
 InsertKeyCode (\r
   IN OUT  USB_KB_BUFFER *KeyboardBuffer,\r
   IN      UINT8         Key,\r
-  IN      UINT8         Down\r
+  IN      BOOLEAN       Down\r
   )\r
 {\r
   USB_KEY UsbKey;\r
 \r
   //\r
-  // if keyboard buffer is full, throw the\r
+  // If keyboard buffer is full, throw the\r
   // first key out of the keyboard buffer.\r
   //\r
   if (IsUSBKeyboardBufferFull (KeyboardBuffer)) {\r
     RemoveKeyCode (KeyboardBuffer, &UsbKey);\r
   }\r
 \r
-  KeyboardBuffer->buffer[KeyboardBuffer->bTail].KeyCode = Key;\r
-  KeyboardBuffer->buffer[KeyboardBuffer->bTail].Down    = Down;\r
+  ASSERT (KeyboardBuffer->BufferTail <= MAX_KEY_ALLOWED);\r
+\r
+  KeyboardBuffer->Buffer[KeyboardBuffer->BufferTail].KeyCode = Key;\r
+  KeyboardBuffer->Buffer[KeyboardBuffer->BufferTail].Down    = Down;\r
 \r
   //\r
-  // adjust the tail pointer of the FIFO keyboard buffer.\r
+  // Adjust the tail pointer of the FIFO keyboard buffer.\r
   //\r
-  KeyboardBuffer->bTail = (UINT8) ((KeyboardBuffer->bTail + 1) % (MAX_KEY_ALLOWED + 1));\r
-\r
-  return EFI_SUCCESS;\r
+  KeyboardBuffer->BufferTail = (UINT8) ((KeyboardBuffer->BufferTail + 1) % (MAX_KEY_ALLOWED + 1));\r
 }\r
 \r
 \r
 /**\r
-  Pops a key code off from keyboard buffer.\r
+  Remove a keycode from keyboard buffer and return it.\r
 \r
-  @param  KeyboardBuffer     Points to the USB Keyboard Buffer.\r
-  @param  UsbKey             Points to the buffer that contains a usb key code.\r
+  @param  KeyboardBuffer     Points to the USB keyboard buffer.\r
+  @param  UsbKey             Points to the buffer that contains keycode for output.\r
 \r
-  @retval EFI_SUCCESS        Success\r
-  @retval EFI_DEVICE_ERROR   Hardware Error\r
+  @retval EFI_SUCCESS        Keycode successfully removed from keyboard buffer.\r
+  @retval EFI_DEVICE_ERROR   Keyboard buffer is empty.\r
 \r
 **/\r
 EFI_STATUS\r
 EFIAPI\r
 RemoveKeyCode (\r
   IN OUT  USB_KB_BUFFER *KeyboardBuffer,\r
-  OUT     USB_KEY       *UsbKey\r
+     OUT  USB_KEY       *UsbKey\r
   )\r
 {\r
   if (IsUSBKeyboardBufferEmpty (KeyboardBuffer)) {\r
     return EFI_DEVICE_ERROR;\r
   }\r
 \r
-  UsbKey->KeyCode = KeyboardBuffer->buffer[KeyboardBuffer->bHead].KeyCode;\r
-  UsbKey->Down    = KeyboardBuffer->buffer[KeyboardBuffer->bHead].Down;\r
+  ASSERT (KeyboardBuffer->BufferHead <= MAX_KEY_ALLOWED);\r
+\r
+  UsbKey->KeyCode = KeyboardBuffer->Buffer[KeyboardBuffer->BufferHead].KeyCode;\r
+  UsbKey->Down    = KeyboardBuffer->Buffer[KeyboardBuffer->BufferHead].Down;\r
 \r
   //\r
-  // adjust the head pointer of the FIFO keyboard buffer.\r
+  // Adjust the head pointer of the FIFO keyboard buffer.\r
   //\r
-  KeyboardBuffer->bHead = (UINT8) ((KeyboardBuffer->bHead + 1) % (MAX_KEY_ALLOWED + 1));\r
+  KeyboardBuffer->BufferHead = (UINT8) ((KeyboardBuffer->BufferHead + 1) % (MAX_KEY_ALLOWED + 1));\r
 \r
   return EFI_SUCCESS;\r
 }\r
 \r
 \r
 /**\r
-  Sets USB Keyboard LED state.\r
+  Sets USB keyboard LED state.\r
 \r
   @param  UsbKeyboardDevice  The USB_KB_DEV instance.\r
 \r
-  @retval EFI_SUCCESS        Success\r
-\r
 **/\r
-EFI_STATUS\r
+VOID\r
 EFIAPI\r
 SetKeyLED (\r
   IN  USB_KB_DEV    *UsbKeyboardDevice\r
@@ -1818,14 +1914,14 @@ SetKeyLED (
   //\r
   // Set each field in Led map.\r
   //\r
-  Led.NumLock    = (UINT8) UsbKeyboardDevice->NumLockOn;\r
-  Led.CapsLock   = (UINT8) UsbKeyboardDevice->CapsOn;\r
-  Led.ScrollLock = (UINT8) UsbKeyboardDevice->ScrollOn;\r
+  Led.NumLock    = (UINT8) ((UsbKeyboardDevice->NumLockOn) ? 1 : 0);\r
+  Led.CapsLock   = (UINT8) ((UsbKeyboardDevice->CapsOn) ? 1 : 0);\r
+  Led.ScrollLock = (UINT8) ((UsbKeyboardDevice->ScrollOn) ? 1 : 0);\r
   Led.Resrvd     = 0;\r
 \r
   ReportId       = 0;\r
   //\r
-  // call Set Report Request to lighten the LED.\r
+  // Call Set_Report Request to lighten the LED.\r
   //\r
   UsbSetReportRequest (\r
     UsbKeyboardDevice->UsbIo,\r
@@ -1835,18 +1931,21 @@ SetKeyLED (
     1,\r
     (UINT8 *) &Led\r
     );\r
-\r
-  return EFI_SUCCESS;\r
 }\r
 \r
 \r
 /**\r
-  Timer handler for Repeat Key timer.\r
+  Handler for Repeat Key event.\r
+\r
+  This function is the handler for Repeat Key event triggered\r
+  by timer.\r
+  After a repeatable key is pressed, the event would be triggered\r
+  with interval of USBKBD_REPEAT_DELAY. Once the event is triggered,\r
+  following trigger will come with interval of USBKBD_REPEAT_RATE.\r
 \r
   @param  Event              The Repeat Key event.\r
   @param  Context            Points to the USB_KB_DEV instance.\r
 \r
-\r
 **/\r
 VOID\r
 EFIAPI\r
@@ -1864,34 +1963,38 @@ USBKeyboardRepeatHandler (
   //\r
   if (UsbKeyboardDevice->RepeatKey != 0) {\r
     //\r
-    // Inserts one Repeat key into keyboard buffer,\r
+    // Inserts the repeat key into keyboard buffer,\r
     //\r
     InsertKeyCode (\r
       &(UsbKeyboardDevice->KeyboardBuffer),\r
       UsbKeyboardDevice->RepeatKey,\r
-      1\r
+      TRUE\r
       );\r
 \r
     //\r
-    // set repeate rate for repeat key generation.\r
+    // Set repeat rate for next repeat key generation.\r
     //\r
     gBS->SetTimer (\r
-          UsbKeyboardDevice->RepeatTimer,\r
-          TimerRelative,\r
-          USBKBD_REPEAT_RATE\r
-          );\r
-\r
+           UsbKeyboardDevice->RepeatTimer,\r
+           TimerRelative,\r
+           USBKBD_REPEAT_RATE\r
+           );\r
   }\r
 }\r
 \r
 \r
 /**\r
-  Timer handler for Delayed Recovery timer.\r
+  Handler for Delayed Recovery event.\r
+\r
+  This function is the handler for Delayed Recovery event triggered\r
+  by timer.\r
+  After a device error occurs, the event would be triggered\r
+  with interval of EFI_USB_INTERRUPT_DELAY. EFI_USB_INTERRUPT_DELAY\r
+  is defined in USB standard for error handling.\r
 \r
   @param  Event              The Delayed Recovery event.\r
   @param  Context            Points to the USB_KB_DEV instance.\r
 \r
-\r
 **/\r
 VOID\r
 EFIAPI\r
@@ -1911,13 +2014,16 @@ USBKeyboardRecoveryHandler (
 \r
   PacketSize        = (UINT8) (UsbKeyboardDevice->IntEndpointDescriptor.MaxPacketSize);\r
 \r
+  //\r
+  // Re-submit Asynchronous Interrupt Transfer for recovery.\r
+  //\r
   UsbIo->UsbAsyncInterruptTransfer (\r
-          UsbIo,\r
-          UsbKeyboardDevice->IntEndpointDescriptor.EndpointAddress,\r
-          TRUE,\r
-          UsbKeyboardDevice->IntEndpointDescriptor.Interval,\r
-          PacketSize,\r
-          KeyboardHandler,\r
-          UsbKeyboardDevice\r
-          );\r
+           UsbIo,\r
+           UsbKeyboardDevice->IntEndpointDescriptor.EndpointAddress,\r
+           TRUE,\r
+           UsbKeyboardDevice->IntEndpointDescriptor.Interval,\r
+           PacketSize,\r
+           KeyboardHandler,\r
+           UsbKeyboardDevice\r
+           );\r
 }\r