projects / mirror_edk2.git / blame
| Commit | Line | Data |
|---|---|---|
| b341712e | 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 | |
| b341712e | 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 | #include "EfiBind.h" //For ASM_PFX\r | |
| 24 | #---------------------------------------------------------------------------\r | |
| 25 | \r | |
| 26 | .globl ASM_PFX(Log2)\r | |
| 27 | \r | |
| 28 | #UINT8\r | |
| 29 | #Log2 (\r | |
| 30 | # IN UINT64 Operand\r | |
| 31 | # )\r | |
| 32 | #/*++\r | |
| 33 | #\r | |
| 34 | #Routine Description:\r | |
| 35 | # \r | |
| 36 | # Calculates and floors logarithms based on 2\r | |
| 37 | #\r | |
| 38 | #Arguments:\r | |
| 39 | #\r | |
| 40 | # Operand - value to calculate logarithm\r | |
| 41 | # \r | |
| 42 | #Returns:\r | |
| 43 | #\r | |
| 44 | # The largest integer that is less than or equal\r | |
| 45 | # to the logarithm of Operand based on 2 \r | |
| 46 | #\r | |
| 47 | #--*/\r | |
| 48 | ASM_PFX(Log2):\r | |
| 49 | movl $64, %ecx\r | |
| 50 | \r | |
| 51 | cmpl $0, 4(%esp) # (UINT32 *(&Operand))\r | |
| 52 | jne _Log2_Wend\r | |
| 53 | cmpl $0, 8(%esp) # (UINT32 *(&Operand)) + 1\r | |
| 54 | jne _Log2_Wend\r | |
| 55 | movb $0xFF, %cl\r | |
| 56 | jmp _Log2_Done\r | |
| 57 | \r | |
| 58 | _Log2_Wend: \r | |
| 59 | decl %ecx\r | |
| 60 | cmpl $32, %ecx\r | |
| 61 | jae _Log2_Higher\r | |
| 62 | btl %ecx, 4(%esp) # (UINT32 *(&Operand))\r | |
| 63 | jmp _Log2_Bit\r | |
| 64 | \r | |
| 65 | _Log2_Higher: \r | |
| 66 | movl %ecx, %eax\r | |
| 67 | subl $32, %eax\r | |
| 68 | btl %eax, 8(%esp) # (UINT32 *(&Operand)) + 1\r | |
| 69 | \r | |
| 70 | _Log2_Bit: \r | |
| 71 | jc _Log2_Done\r | |
| 72 | jmp _Log2_Wend\r | |
| 73 | \r | |
| 74 | _Log2_Done: \r | |
| 75 | movb %cl, %al\r | |
| 76 | \r | |
| 77 | ret\r | |
| 78 | \r |