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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4 | ; Last update : 8.10.2010 |
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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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