[41] | 1 | ; File name : FileIO.asm |
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| 2 | ; Project name : Assembly Library |
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| 3 | ; Created date : 1.9.2010 |
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[51] | 4 | ; Last update : 10.10.2010 |
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[41] | 5 | ; Author : Tomi Tilli |
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| 6 | ; Description : Functions for file access. |
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| 7 | |
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| 8 | ; Section containing code |
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| 9 | SECTION .text |
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| 10 | |
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| 11 | ;-------------------------------------------------------------------- |
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| 12 | ; FileIO_OpenWithPathInDSSIandFileAccessInAL |
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| 13 | ; Parameters: |
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| 14 | ; AL: FILE_ACCESS.(mode) |
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| 15 | ; DS:SI: Ptr to NULL terminated path or file name |
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| 16 | ; Returns: |
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| 17 | ; AX: DOS error code if CF set |
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| 18 | ; BX: File handle if CF cleared |
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| 19 | ; CF: Clear if file opened successfully |
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| 20 | ; Set if error |
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| 21 | ; Corrupts registers: |
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| 22 | ; AX, BX |
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| 23 | ;-------------------------------------------------------------------- |
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| 24 | ALIGN JUMP_ALIGN |
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| 25 | FileIO_OpenWithPathInDSSIandFileAccessInAL: |
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| 26 | xchg dx, si ; Path now in DS:DX |
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| 27 | mov ah, OPEN_EXISTING_FILE |
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| 28 | int DOS_INTERRUPT_21h |
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| 29 | xchg si, dx |
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[51] | 30 | mov bx, ax ; Copy file handle to BX |
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[41] | 31 | ret |
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| 32 | |
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| 33 | |
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| 34 | ;-------------------------------------------------------------------- |
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| 35 | ; FileIO_CloseUsingHandleFromBX |
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| 36 | ; Parameters: |
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| 37 | ; BX: File handle |
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| 38 | ; Returns: |
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| 39 | ; AX: DOS error code if CF set |
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| 40 | ; CF: Clear if file closed successfully |
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| 41 | ; Set if error |
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| 42 | ; Corrupts registers: |
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| 43 | ; AX |
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| 44 | ;-------------------------------------------------------------------- |
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| 45 | ALIGN JUMP_ALIGN |
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| 46 | FileIO_CloseUsingHandleFromBX: |
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| 47 | mov ah, CLOSE_FILE |
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| 48 | int DOS_INTERRUPT_21h |
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| 49 | ret |
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| 50 | |
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| 51 | |
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| 52 | ;-------------------------------------------------------------------- |
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| 53 | ; File position is updated so next read will start where |
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| 54 | ; previous read stopped. |
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| 55 | ; |
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| 56 | ; FileIO_ReadCXbytesToDSSIusingHandleFromBX |
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| 57 | ; Parameters: |
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| 58 | ; BX: File handle |
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| 59 | ; CX: Number of bytes to read |
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| 60 | ; DS:SI: Ptr to destination buffer |
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| 61 | ; Returns: |
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| 62 | ; AX: Number of bytes actually read if successfull (0 if at EOF before call) |
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| 63 | ; DOS error code if CF set |
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| 64 | ; CF: Clear if successfull |
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| 65 | ; Set if error |
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| 66 | ; Corrupts registers: |
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| 67 | ; Nothing |
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| 68 | ;-------------------------------------------------------------------- |
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| 69 | ALIGN JUMP_ALIGN |
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| 70 | FileIO_ReadCXbytesToDSSIusingHandleFromBX: |
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[51] | 71 | xchg dx, si ; DS:DX now points to destination buffer |
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[41] | 72 | mov ah, READ_FROM_FILE_OR_DEVICE |
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| 73 | int DOS_INTERRUPT_21h |
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| 74 | xchg si, dx |
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| 75 | ret |
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| 76 | |
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| 77 | |
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| 78 | ;-------------------------------------------------------------------- |
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| 79 | ; File position is updated so next write will start where |
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| 80 | ; previous write stopped. |
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| 81 | ; |
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| 82 | ; FileIO_WriteCXbytesFromDSSIusingHandleFromBX: |
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| 83 | ; Parameters: |
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| 84 | ; BX: File handle |
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| 85 | ; CX: Number of bytes to write |
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| 86 | ; DS:SI: Ptr to source buffer |
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| 87 | ; Returns: |
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| 88 | ; AX: Number of bytes actually written if successfull (EOF check) |
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| 89 | ; DOS error code if CF set |
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| 90 | ; CF: Clear if successfull |
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| 91 | ; Set if error |
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| 92 | ; Corrupts registers: |
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| 93 | ; Nothing |
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| 94 | ;-------------------------------------------------------------------- |
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| 95 | ALIGN JUMP_ALIGN |
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| 96 | FileIO_WriteCXbytesFromDSSIusingHandleFromBX: |
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| 97 | xchg dx, si ; DS:DX now points to source buffer |
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| 98 | mov ah, WRITE_TO_FILE_OR_DEVICE |
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| 99 | int DOS_INTERRUPT_21h |
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| 100 | xchg si, dx |
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| 101 | ret |
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| 102 | |
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| 103 | |
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| 104 | ;-------------------------------------------------------------------- |
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[51] | 105 | ; FileIO_GetFileSizeToDXAXusingHandleFromBXandResetFilePosition: |
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| 106 | ; Parameters: |
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| 107 | ; BX: File handle |
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| 108 | ; Returns: |
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| 109 | ; DX:AX: Signed file size (if CF cleared) |
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| 110 | ; AX: DOS error code (if CF set) |
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| 111 | ; CF: Clear if successfull |
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| 112 | ; Set if error |
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| 113 | ; Corrupts registers: |
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| 114 | ; Nothing |
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| 115 | ;-------------------------------------------------------------------- |
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| 116 | ALIGN JUMP_ALIGN |
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| 117 | FileIO_GetFileSizeToDXAXusingHandleFromBXandResetFilePosition: |
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| 118 | push cx |
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| 119 | |
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| 120 | ; Get file size to DX:AX |
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| 121 | xor cx, cx |
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| 122 | xor dx, dx |
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| 123 | mov al, SEEK_FROM.endOfFile |
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| 124 | call FileIO_SeekFromOriginInALtoOffsetInDXAXusingHandleFromBX |
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| 125 | jc SHORT .ReturnFileError |
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| 126 | push dx |
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| 127 | push ax |
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| 128 | |
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| 129 | ; Reset file position |
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| 130 | xor dx, dx |
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| 131 | mov al, SEEK_FROM.startOfFile |
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| 132 | call FileIO_SeekFromOriginInALtoOffsetInDXAXusingHandleFromBX |
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| 133 | pop ax |
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| 134 | pop dx |
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| 135 | |
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| 136 | .ReturnFileError: |
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| 137 | pop cx |
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| 138 | ret |
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| 139 | |
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| 140 | |
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| 141 | ;-------------------------------------------------------------------- |
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[41] | 142 | ; FileIO_SeekFromOriginInALtoOffsetInDXAXusingHandleFromBX: |
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| 143 | ; Parameters: |
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| 144 | ; AL: SEEK_FROM.(origin) |
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| 145 | ; BX: File handle |
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[51] | 146 | ; CX:DX: Signed offset to seek starting from AL |
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[41] | 147 | ; Returns: |
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[51] | 148 | ; DX:AX: New file position in bytes from start of file (if CF cleared) |
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| 149 | ; AX: DOS error code (if CF set) |
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[41] | 150 | ; CF: Clear if successfull |
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| 151 | ; Set if error |
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| 152 | ; Corrupts registers: |
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| 153 | ; Nothing |
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| 154 | ;-------------------------------------------------------------------- |
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| 155 | ALIGN JUMP_ALIGN |
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| 156 | FileIO_SeekFromOriginInALtoOffsetInDXAXusingHandleFromBX: |
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| 157 | mov ah, SET_CURRENT_FILE_POSITION |
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| 158 | int DOS_INTERRUPT_21h |
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| 159 | ret |
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