| 478db76b |
1 | ;/*++\r |
| 2 | ;\r |
| 3 | ;Copyright (c) 2006, Intel Corporation \r |
| 4 | ;All rights reserved. This program and the accompanying materials \r |
| 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 | ;---------------------------------------------------------------------------\r |
| 25 | .686\r |
| 26 | .model flat,C\r |
| 27 | .code\r |
| 28 | \r |
| 29 | ;---------------------------------------------------------------------------\r |
| 30 | ;UINT64\r |
| 31 | ;RShiftU64 (\r |
| 32 | ; IN UINT64 Operand,\r |
| 33 | ; IN UINTN Count\r |
| 34 | ; )\r |
| 35 | ;/*++\r |
| 36 | ;\r |
| 37 | ;Routine Description:\r |
| 38 | ; This routine allows a 64 bit value to be right shifted by 32 bits and returns the \r |
| 39 | ; shifted value.\r |
| 40 | ; Count is valid up 63. (Only Bits 0-5 is valid for Count)\r |
| 41 | ;Arguments:\r |
| 42 | ; Operand - Value to be shifted\r |
| 43 | ; Count - Number of times to shift right.\r |
| 44 | ; \r |
| 45 | ;Returns:\r |
| 46 | ;\r |
| 47 | ; Value shifted right identified by the Count.\r |
| 48 | ;\r |
| 49 | ;--*/\r |
| 50 | RShiftU64 PROC\r |
| 51 | \r |
| 52 | mov eax, [esp + 4]; dword ptr Operand[0]\r |
| 53 | mov edx, [esp + 8]; dword ptr Operand[4]\r |
| 54 | \r |
| 55 | ;\r |
| 56 | ; CL is valid from 0 - 31. shld will move EDX:EAX by CL times but EDX is not touched\r |
| 57 | ; For CL of 32 - 63, it will be shifted 0 - 31 so we will move edx to eax later. \r |
| 58 | ;\r |
| 59 | mov ecx, [esp + 0Ch] ; Count\r |
| 60 | and ecx, 63\r |
| 61 | shrd eax, edx, cl\r |
| 62 | shr edx, cl\r |
| 63 | \r |
| 64 | cmp ecx, 32\r |
| 65 | jc short _RShiftU64_Done\r |
| 66 | \r |
| 67 | ;\r |
| 68 | ; Since Count is 32 - 63, edx will have been shifted by 0 - 31 \r |
| 69 | ; If shifted by 32 or more, set upper 32 bits to zero.\r |
| 70 | ;\r |
| 71 | mov eax, edx\r |
| 72 | xor edx, edx\r |
| 73 | \r |
| 74 | _RShiftU64_Done:\r |
| 75 | \r |
| 76 | ret\r |
| 77 | RShiftU64 ENDP \r |
| 78 | END\r |
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