[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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[50] | 4 | ; Last update : 8.10.2010 |
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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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| 30 | ret |
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| 31 | |
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| 32 | |
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| 33 | ;-------------------------------------------------------------------- |
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| 34 | ; FileIO_CloseUsingHandleFromBX |
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| 35 | ; Parameters: |
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| 36 | ; BX: File handle |
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| 37 | ; Returns: |
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| 38 | ; AX: DOS error code if CF set |
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| 39 | ; CF: Clear if file closed successfully |
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| 40 | ; Set if error |
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| 41 | ; Corrupts registers: |
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| 42 | ; AX |
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| 43 | ;-------------------------------------------------------------------- |
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| 44 | ALIGN JUMP_ALIGN |
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| 45 | FileIO_CloseUsingHandleFromBX: |
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| 46 | mov ah, CLOSE_FILE |
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| 47 | int DOS_INTERRUPT_21h |
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| 48 | ret |
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| 49 | |
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| 50 | |
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| 51 | ;-------------------------------------------------------------------- |
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| 52 | ; File position is updated so next read will start where |
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| 53 | ; previous read stopped. |
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| 54 | ; |
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| 55 | ; FileIO_ReadCXbytesToDSSIusingHandleFromBX |
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| 56 | ; Parameters: |
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| 57 | ; BX: File handle |
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| 58 | ; CX: Number of bytes to read |
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| 59 | ; DS:SI: Ptr to destination buffer |
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| 60 | ; Returns: |
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| 61 | ; AX: Number of bytes actually read if successfull (0 if at EOF before call) |
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| 62 | ; DOS error code if CF set |
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| 63 | ; CF: Clear if successfull |
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| 64 | ; Set if error |
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| 65 | ; Corrupts registers: |
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| 66 | ; Nothing |
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| 67 | ;-------------------------------------------------------------------- |
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| 68 | ALIGN JUMP_ALIGN |
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| 69 | FileIO_ReadCXbytesToDSSIusingHandleFromBX: |
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| 70 | xchg dx, si ; DS:DX now points to source buffer |
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| 71 | mov ah, READ_FROM_FILE_OR_DEVICE |
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| 72 | int DOS_INTERRUPT_21h |
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| 73 | xchg si, dx |
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| 74 | ret |
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| 75 | |
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| 76 | |
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| 77 | ;-------------------------------------------------------------------- |
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| 78 | ; File position is updated so next write will start where |
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| 79 | ; previous write stopped. |
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| 80 | ; |
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| 81 | ; FileIO_WriteCXbytesFromDSSIusingHandleFromBX: |
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| 82 | ; Parameters: |
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| 83 | ; BX: File handle |
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| 84 | ; CX: Number of bytes to write |
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| 85 | ; DS:SI: Ptr to source buffer |
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| 86 | ; Returns: |
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| 87 | ; AX: Number of bytes actually written if successfull (EOF check) |
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| 88 | ; DOS error code if CF set |
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| 89 | ; CF: Clear if successfull |
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| 90 | ; Set if error |
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| 91 | ; Corrupts registers: |
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| 92 | ; Nothing |
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| 93 | ;-------------------------------------------------------------------- |
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| 94 | ALIGN JUMP_ALIGN |
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| 95 | FileIO_WriteCXbytesFromDSSIusingHandleFromBX: |
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| 96 | xchg dx, si ; DS:DX now points to source buffer |
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| 97 | mov ah, WRITE_TO_FILE_OR_DEVICE |
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| 98 | int DOS_INTERRUPT_21h |
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| 99 | xchg si, dx |
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| 100 | ret |
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| 101 | |
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| 102 | |
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| 103 | ;-------------------------------------------------------------------- |
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| 104 | ; FileIO_SeekFromOriginInALtoOffsetInDXAXusingHandleFromBX: |
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| 105 | ; Parameters: |
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| 106 | ; AL: SEEK_FROM.(origin) |
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| 107 | ; BX: File handle |
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| 108 | ; DX:AX: Seek offset (signed) |
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| 109 | ; Returns: |
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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_SeekFromOriginInALtoOffsetInDXAXusingHandleFromBX: |
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| 118 | push dx |
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| 119 | push cx |
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| 120 | |
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| 121 | mov cx, dx ; DOS wants high word in CX |
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| 122 | xchg dx, ax ; DOS wants low word in DX |
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| 123 | mov ah, SET_CURRENT_FILE_POSITION |
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| 124 | int DOS_INTERRUPT_21h |
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| 125 | |
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| 126 | pop cx |
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| 127 | pop dx |
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| 128 | ret |
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