projects / mirror_edk2.git / blame
| Commit | Line | Data |
|---|---|---|
| 3eb9473e | 1 | /*++\r |
| 2 | \r | |
| 4ea9375a HT |
3 | Copyright (c) 2006, Intel Corporation. All rights reserved.<BR>\r |
| 4 | This program and the accompanying materials \r | |
| 3eb9473e | 5 | are licensed and made available under the terms and conditions of the BSD License \r |
| 6 | which accompanies this distribution. The full text of the license may be found at \r | |
| 7 | http://opensource.org/licenses/bsd-license.php \r | |
| 8 | \r | |
| 9 | THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, \r | |
| 10 | WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED. \r | |
| 11 | \r | |
| 12 | Module Name:\r | |
| 13 | \r | |
| 14 | RShiftU64.c\r | |
| 15 | \r | |
| 16 | Abstract:\r | |
| 17 | \r | |
| 18 | 64-bit right shift function for IA-32\r | |
| 19 | \r | |
| 20 | --*/\r | |
| 21 | \r | |
| 22 | #include "Tiano.h"\r | |
| 23 | \r | |
| 24 | UINT64\r | |
| 25 | RShiftU64 (\r | |
| 26 | IN UINT64 Operand,\r | |
| 27 | IN UINTN Count\r | |
| 28 | )\r | |
| 29 | /*++\r | |
| 30 | \r | |
| 31 | Routine Description:\r | |
| 32 | This routine allows a 64 bit value to be right shifted by 32 bits and returns the \r | |
| 33 | shifted value.\r | |
| 34 | Count is valid up 63. (Only Bits 0-5 is valid for Count)\r | |
| 35 | Arguments:\r | |
| 36 | Operand - Value to be shifted\r | |
| 37 | Count - Number of times to shift right.\r | |
| 38 | \r | |
| 39 | Returns:\r | |
| 40 | \r | |
| 41 | Value shifted right identified by the Count.\r | |
| 42 | \r | |
| 43 | --*/\r | |
| 44 | {\r | |
| 45 | __asm {\r | |
| 46 | \r | |
| 47 | mov eax, dword ptr Operand[0]\r | |
| 48 | mov edx, dword ptr Operand[4]\r | |
| 49 | \r | |
| 50 | ;\r | |
| 51 | ; CL is valid from 0 - 31. shld will move EDX:EAX by CL times but EDX is not touched\r | |
| 52 | ; For CL of 32 - 63, it will be shifted 0 - 31 so we will move edx to eax later. \r | |
| 53 | ;\r | |
| 54 | mov ecx, Count\r | |
| 55 | and ecx, 63\r | |
| 56 | shrd eax, edx, cl\r | |
| 57 | shr edx, cl\r | |
| 58 | \r | |
| 59 | cmp ecx, 32\r | |
| 60 | jc short _RShiftU64_Done\r | |
| 61 | \r | |
| 62 | ;\r | |
| 63 | ; Since Count is 32 - 63, edx will have been shifted by 0 - 31 \r | |
| 64 | ; If shifted by 32 or more, set upper 32 bits to zero.\r | |
| 65 | ;\r | |
| 66 | mov eax, edx\r | |
| 67 | xor edx, edx\r | |
| 68 | \r | |
| 69 | _RShiftU64_Done:\r | |
| 70 | }\r | |
| 71 | }\r |