projects / mirror_edk2.git / blame
| Commit | Line | Data |
|---|---|---|
| 478db76b | 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 | |
| 478db76b | 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 | ; Log2.c\r | |
| 15 | ;\r | |
| 16 | ;Abstract:\r | |
| 17 | ;\r | |
| 18 | ; 64-bit integer logarithm function for IA-32\r | |
| 19 | ;\r | |
| 20 | ;--*/\r | |
| 21 | ;\r | |
| 22 | ;---------------------------------------------------------------------------\r | |
| 23 | .686\r | |
| 24 | .model flat,C\r | |
| 25 | .code\r | |
| 26 | \r | |
| 27 | ;---------------------------------------------------------------------------\r | |
| 28 | \r | |
| 29 | ;UINT8\r | |
| 30 | ;Log2 (\r | |
| 31 | ; IN UINT64 Operand\r | |
| 32 | ; )\r | |
| 33 | ;/*++\r | |
| 34 | ;\r | |
| 35 | ;Routine Description:\r | |
| 36 | ; \r | |
| 37 | ; Calculates and floors logarithms based on 2\r | |
| 38 | ;\r | |
| 39 | ;Arguments:\r | |
| 40 | ;\r | |
| 41 | ; Operand - value to calculate logarithm\r | |
| 42 | ; \r | |
| 43 | ;Returns:\r | |
| 44 | ;\r | |
| 45 | ; The largest integer that is less than or equal\r | |
| 46 | ; to the logarithm of Operand based on 2 \r | |
| 47 | ;\r | |
| 48 | ;--*/\r | |
| 49 | Log2 PROC\r | |
| 50 | mov ecx, 64\r | |
| 51 | \r | |
| 52 | cmp dword ptr [esp + 4], 0 ; (UINT32 *(&Operand))\r | |
| 53 | jne _Log2_Wend \r | |
| 54 | cmp dword ptr [esp + 8], 0 ; (UINT32 *(&Operand)) + 1\r | |
| 55 | jne _Log2_Wend \r | |
| 56 | mov cl, 0FFH\r | |
| 57 | jmp _Log2_Done\r | |
| 58 | \r | |
| 59 | _Log2_Wend:\r | |
| 60 | dec ecx\r | |
| 61 | cmp ecx, 32\r | |
| 62 | jae _Log2_Higher\r | |
| 63 | bt [esp + 4], ecx ; (UINT32 *(&Operand))\r | |
| 64 | jmp _Log2_Bit\r | |
| 65 | \r | |
| 66 | _Log2_Higher:\r | |
| 67 | mov eax, ecx\r | |
| 68 | sub eax, 32\r | |
| 69 | bt [esp + 8], eax ; (UINT32 *(&Operand)) + 1\r | |
| 70 | \r | |
| 71 | _Log2_Bit:\r | |
| 72 | jc _Log2_Done\r | |
| 73 | jmp _Log2_Wend\r | |
| 74 | \r | |
| 75 | _Log2_Done:\r | |
| 76 | mov al, cl\r | |
| 77 | \r | |
| 78 | ret\r | |
| 79 | \r | |
| 80 | Log2 ENDP\r | |
| 81 | END\r |