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