Inline ASM in .c file is specific to MS tool-chain. Other tool-chain (such as Intel...

[mirror_edk2.git] / EdkCompatibilityPkg / Foundation / Library / EfiCommonLib / Ia32 / EfiZeroMem.asm

diff --git a/EdkCompatibilityPkg/Foundation/Library/EfiCommonLib/Ia32/EfiZeroMem.asm b/EdkCompatibilityPkg/Foundation/Library/EfiCommonLib/Ia32/EfiZeroMem.asm
new file mode 100644 (file)
index 0000000..ea8f1ab
--- /dev/null
+++ b/EdkCompatibilityPkg/Foundation/Library/EfiCommonLib/Ia32/EfiZeroMem.asm
@@ -0,0 +1,135 @@
+;/*++\r
+;\r
+;Copyright (c) 2006, Intel Corporation                                                         \r
+;All rights reserved. This program and the accompanying materials                          \r
+;are licensed and made available under the terms and conditions of the BSD License         \r
+;which accompanies this distribution.  The full text of the license may be found at        \r
+;http://opensource.org/licenses/bsd-license.php                                            \r
+;                                                                                          \r
+;THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,                     \r
+;WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.             \r
+;\r
+;Module Name:\r
+;\r
+;  EfiZeroMem.c\r
+;\r
+;Abstract:\r
+;\r
+;  This is the code that supports IA32-optimized ZeroMem service\r
+;\r
+;--*/\r
+;---------------------------------------------------------------------------\r
+    .686\r
+    .model  flat,C\r
+    .mmx\r
+    .code\r
+\r
+;---------------------------------------------------------------------------\r
+;VOID\r
+;EfiCommonLibZeroMem (\r
+;  IN VOID   *Buffer,\r
+;  IN UINTN  Count\r
+;  )\r
+;/*++\r
+;\r
+;Input:  VOID   *Buffer - Pointer to buffer to clear\r
+;        UINTN  Count  - Number of bytes to clear\r
+;\r
+;Output: None.\r
+;\r
+;Saves:\r
+;\r
+;Modifies:\r
+;\r
+;Description:  This function is an optimized zero-memory function.\r
+;\r
+;Notes:  This function tries to zero memory 8 bytes at a time. As a result, \r
+;        it first picks up any misaligned bytes, then words, before getting \r
+;        in the main loop that does the 8-byte clears.\r
+;\r
+;--*/\r
+EfiCommonLibZeroMem PROC\r
+;  UINT64 MmxSave;\r
+    push  ebp\r
+    mov   ebp, esp\r
+    push  ecx  ; Reserve space for local variable MmxSave\r
+    push  ecx\r
+    push  edi\r
+    \r
+    mov   ecx, [ebp + 0Ch] ; Count\r
+    mov   edi, [ebp + 8]; Buffer\r
+\r
+    ; Pick up misaligned start bytes (get pointer 4-byte aligned)\r
+_StartByteZero:\r
+    mov   eax, edi    \r
+    and   al, 3                       ; check lower 2 bits of address\r
+    test  al, al\r
+    je    _ZeroBlocks                 ; already aligned?\r
+    cmp   ecx, 0\r
+    je    _ZeroMemDone\r
+\r
+    ; Clear the byte memory location\r
+    mov   BYTE PTR [edi], 0           \r
+    inc    edi\r
+\r
+    ; Decrement our count\r
+    dec    ecx\r
+    jmp   _StartByteZero        ; back to top of loop\r
+\r
+_ZeroBlocks:\r
+\r
+    ; Compute how many 64-byte blocks we can clear \r
+    mov   edx, ecx\r
+    shr   ecx, 6                      ; convert to 64-byte count\r
+    shl   ecx, 6                      ; convert back to bytes\r
+    sub   edx, ecx                    ; subtract from the original count\r
+    shr   ecx, 6                      ; and this is how many 64-byte blocks\r
+\r
+    ; If no 64-byte blocks, then skip \r
+    cmp    ecx, 0\r
+    je    _ZeroRemaining\r
+\r
+    ; Save mm0\r
+    movq  [ebp - 8], mm0  ; Save mm0 to MmxSave\r
+\r
+    pxor  mm0, mm0          ; Clear mm0\r
+\r
+_B:\r
+    movq  QWORD PTR ds:[edi], mm0\r
+    movq  QWORD PTR ds:[edi+8], mm0\r
+    movq  QWORD PTR ds:[edi+16], mm0\r
+    movq  QWORD PTR ds:[edi+24], mm0\r
+    movq  QWORD PTR ds:[edi+32], mm0\r
+    movq  QWORD PTR ds:[edi+40], mm0\r
+    movq  QWORD PTR ds:[edi+48], mm0\r
+    movq  QWORD PTR ds:[edi+56], mm0\r
+   \r
+    add    edi, 64\r
+    dec    ecx\r
+    jnz    _B\r
+  \r
+; Restore mm0\r
+    movq  mm0, [ebp - 8] ; Restore mm0 from MmxSave\r
+    emms                                 ; Exit MMX Instruction\r
+\r
+_ZeroRemaining:\r
+    ; Zero out as many DWORDS as possible\r
+    mov   ecx, edx\r
+    shr   ecx, 2\r
+    xor   eax, eax\r
+\r
+    rep stosd\r
+\r
+    ; Zero out remaining as bytes\r
+    mov   ecx, edx\r
+    and   ecx, 03\r
+\r
+    rep   stosb\r
+ \r
+_ZeroMemDone:\r
+\r
+    pop    edi\r
+    leave\r
+    ret\r
+EfiCommonLibZeroMem ENDP       \r
+       END\r