[41] | 1 | ; Project name : Assembly Library |
---|
| 2 | ; Description : Functions for bit handling. |
---|
| 3 | |
---|
[376] | 4 | ; |
---|
| 5 | ; XTIDE Universal BIOS and Associated Tools |
---|
| 6 | ; Copyright (C) 2009-2010 by Tomi Tilli, 2011-2012 by XTIDE Universal BIOS Team. |
---|
| 7 | ; |
---|
| 8 | ; This program is free software; you can redistribute it and/or modify |
---|
| 9 | ; it under the terms of the GNU General Public License as published by |
---|
| 10 | ; the Free Software Foundation; either version 2 of the License, or |
---|
| 11 | ; (at your option) any later version. |
---|
| 12 | ; |
---|
| 13 | ; This program is distributed in the hope that it will be useful, |
---|
| 14 | ; but WITHOUT ANY WARRANTY; without even the implied warranty of |
---|
| 15 | ; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
---|
| 16 | ; GNU General Public License for more details. |
---|
| 17 | ; Visit http://www.gnu.org/licenses/old-licenses/gpl-2.0.html |
---|
| 18 | ; |
---|
| 19 | |
---|
[41] | 20 | ; Section containing code |
---|
| 21 | SECTION .text |
---|
| 22 | |
---|
| 23 | ;-------------------------------------------------------------------- |
---|
| 24 | ; Bit_GetSetCountToCXfromDXAX |
---|
| 25 | ; Parameters |
---|
| 26 | ; DX:AX: Source DWORD |
---|
| 27 | ; Returns: |
---|
| 28 | ; CX: Number of bits set in DX:AX |
---|
| 29 | ; Corrupts registers: |
---|
| 30 | ; Nothing |
---|
| 31 | ;-------------------------------------------------------------------- |
---|
| 32 | ALIGN JUMP_ALIGN |
---|
| 33 | Bit_GetSetCountToCXfromDXAX: |
---|
| 34 | push bx |
---|
| 35 | |
---|
| 36 | call Bit_GetSetCountToCXfromAX |
---|
| 37 | mov bx, cx |
---|
| 38 | xchg ax, dx |
---|
| 39 | call Bit_GetSetCountToCXfromAX |
---|
| 40 | xchg ax, dx |
---|
| 41 | add cx, bx |
---|
| 42 | |
---|
| 43 | pop bx |
---|
| 44 | ret |
---|
| 45 | |
---|
| 46 | |
---|
| 47 | ;-------------------------------------------------------------------- |
---|
| 48 | ; Bit_GetSetCountToCXfromAX |
---|
| 49 | ; Parameters |
---|
| 50 | ; AX: Source WORD |
---|
| 51 | ; Returns: |
---|
| 52 | ; CX: Number of bits set in AX |
---|
| 53 | ; Corrupts registers: |
---|
| 54 | ; Nothing |
---|
| 55 | ;-------------------------------------------------------------------- |
---|
| 56 | ALIGN JUMP_ALIGN |
---|
| 57 | Bit_GetSetCountToCXfromAX: |
---|
| 58 | push ax |
---|
| 59 | |
---|
| 60 | xor cx, cx |
---|
| 61 | ALIGN JUMP_ALIGN |
---|
| 62 | .BitScanLoop: |
---|
| 63 | shr ax, 1 |
---|
| 64 | jz SHORT .LastBitInCF |
---|
[103] | 65 | adc cl, ch |
---|
[41] | 66 | jmp SHORT .BitScanLoop |
---|
| 67 | ALIGN JUMP_ALIGN |
---|
| 68 | .LastBitInCF: |
---|
[103] | 69 | adc cl, ch |
---|
[41] | 70 | |
---|
| 71 | pop ax |
---|
| 72 | ret |
---|
| 73 | |
---|
| 74 | |
---|
| 75 | ;-------------------------------------------------------------------- |
---|
| 76 | ; Bit_SetToDXAXfromIndexInCL |
---|
| 77 | ; Parameters: |
---|
| 78 | ; CL: Index of bit to set (0...31) |
---|
| 79 | ; DX:AX: Destination DWORD with flag to be set |
---|
| 80 | ; Returns: |
---|
| 81 | ; DX:AX: DWORD with wanted bit set |
---|
| 82 | ; Corrupts registers: |
---|
| 83 | ; Nothing |
---|
| 84 | ;-------------------------------------------------------------------- |
---|
| 85 | ALIGN JUMP_ALIGN |
---|
| 86 | Bit_SetToDXAXfromIndexInCL: |
---|
| 87 | cmp cl, 16 |
---|
| 88 | jb SHORT Bit_SetToAXfromIndexInCL |
---|
| 89 | |
---|
| 90 | sub cl, 16 |
---|
| 91 | xchg ax, dx |
---|
| 92 | call Bit_SetToAXfromIndexInCL |
---|
| 93 | xchg dx, ax |
---|
| 94 | add cl, 16 |
---|
| 95 | ret |
---|
| 96 | |
---|
| 97 | ;-------------------------------------------------------------------- |
---|
| 98 | ; Bit_SetToAXfromIndexInCL |
---|
| 99 | ; Parameters: |
---|
| 100 | ; CL: Index of bit to set (0...15) |
---|
| 101 | ; AX: Destination WORD with flag to be set |
---|
| 102 | ; Returns: |
---|
| 103 | ; AX: WORD with wanted bit set |
---|
| 104 | ; Corrupts registers: |
---|
| 105 | ; Nothing |
---|
| 106 | ;-------------------------------------------------------------------- |
---|
| 107 | ALIGN JUMP_ALIGN |
---|
| 108 | Bit_SetToAXfromIndexInCL: |
---|
| 109 | push dx |
---|
| 110 | |
---|
| 111 | mov dx, 1 |
---|
| 112 | shl dx, cl |
---|
| 113 | or ax, dx |
---|
| 114 | |
---|
| 115 | pop dx |
---|
| 116 | ret |
---|