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 : 3.9.2010 |
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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 | |
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9 | ; File access and sharing modes |
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10 | struc FILE_ACCESS |
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11 | .ReadOnly resb 1 |
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12 | .WriteOnly resb 1 |
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13 | .ReadAndWrite resb 1 |
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14 | endstruc |
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15 | |
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16 | ; Origin of file seek |
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17 | struc SEEK_FROM |
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18 | .startOfFile resb 1 |
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19 | .currentFilePosition resb 1 |
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20 | .endOfFile resb 1 |
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21 | endstruc |
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22 | |
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23 | |
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24 | ; Section containing code |
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25 | SECTION .text |
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26 | |
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27 | ;-------------------------------------------------------------------- |
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28 | ; FileIO_OpenWithPathInDSSIandFileAccessInAL |
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29 | ; Parameters: |
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30 | ; AL: FILE_ACCESS.(mode) |
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31 | ; DS:SI: Ptr to NULL terminated path or file name |
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32 | ; Returns: |
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33 | ; AX: DOS error code if CF set |
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34 | ; BX: File handle if CF cleared |
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35 | ; CF: Clear if file opened successfully |
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36 | ; Set if error |
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37 | ; Corrupts registers: |
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38 | ; AX, BX |
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39 | ;-------------------------------------------------------------------- |
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40 | ALIGN JUMP_ALIGN |
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41 | FileIO_OpenWithPathInDSSIandFileAccessInAL: |
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42 | xchg dx, si ; Path now in DS:DX |
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43 | mov ah, OPEN_EXISTING_FILE |
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44 | int DOS_INTERRUPT_21h |
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45 | xchg si, dx |
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46 | ret |
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47 | |
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48 | |
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49 | ;-------------------------------------------------------------------- |
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50 | ; FileIO_CloseUsingHandleFromBX |
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51 | ; Parameters: |
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52 | ; BX: File handle |
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53 | ; Returns: |
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54 | ; AX: DOS error code if CF set |
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55 | ; CF: Clear if file closed successfully |
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56 | ; Set if error |
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57 | ; Corrupts registers: |
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58 | ; AX |
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59 | ;-------------------------------------------------------------------- |
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60 | ALIGN JUMP_ALIGN |
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61 | FileIO_CloseUsingHandleFromBX: |
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62 | mov ah, CLOSE_FILE |
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63 | int DOS_INTERRUPT_21h |
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64 | ret |
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65 | |
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66 | |
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67 | ;-------------------------------------------------------------------- |
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68 | ; File position is updated so next read will start where |
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69 | ; previous read stopped. |
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70 | ; |
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71 | ; FileIO_ReadCXbytesToDSSIusingHandleFromBX |
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72 | ; Parameters: |
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73 | ; BX: File handle |
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74 | ; CX: Number of bytes to read |
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75 | ; DS:SI: Ptr to destination buffer |
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76 | ; Returns: |
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77 | ; AX: Number of bytes actually read if successfull (0 if at EOF before call) |
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78 | ; DOS error code if CF set |
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79 | ; CF: Clear if successfull |
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80 | ; Set if error |
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81 | ; Corrupts registers: |
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82 | ; Nothing |
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83 | ;-------------------------------------------------------------------- |
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84 | ALIGN JUMP_ALIGN |
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85 | FileIO_ReadCXbytesToDSSIusingHandleFromBX: |
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86 | xchg dx, si ; DS:DX now points to source buffer |
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87 | mov ah, READ_FROM_FILE_OR_DEVICE |
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88 | int DOS_INTERRUPT_21h |
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89 | xchg si, dx |
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90 | ret |
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91 | |
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92 | |
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93 | ;-------------------------------------------------------------------- |
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94 | ; File position is updated so next write will start where |
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95 | ; previous write stopped. |
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96 | ; |
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97 | ; FileIO_WriteCXbytesFromDSSIusingHandleFromBX: |
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98 | ; Parameters: |
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99 | ; BX: File handle |
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100 | ; CX: Number of bytes to write |
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101 | ; DS:SI: Ptr to source buffer |
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102 | ; Returns: |
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103 | ; AX: Number of bytes actually written if successfull (EOF check) |
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104 | ; DOS error code if CF set |
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105 | ; CF: Clear if successfull |
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106 | ; Set if error |
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107 | ; Corrupts registers: |
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108 | ; Nothing |
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109 | ;-------------------------------------------------------------------- |
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110 | ALIGN JUMP_ALIGN |
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111 | FileIO_WriteCXbytesFromDSSIusingHandleFromBX: |
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112 | xchg dx, si ; DS:DX now points to source buffer |
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113 | mov ah, WRITE_TO_FILE_OR_DEVICE |
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114 | int DOS_INTERRUPT_21h |
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115 | xchg si, dx |
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116 | ret |
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117 | |
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118 | |
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119 | ;-------------------------------------------------------------------- |
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120 | ; FileIO_SeekFromOriginInALtoOffsetInDXAXusingHandleFromBX: |
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121 | ; Parameters: |
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122 | ; AL: SEEK_FROM.(origin) |
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123 | ; BX: File handle |
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124 | ; DX:AX: Seek offset (signed) |
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125 | ; Returns: |
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126 | ; AX: DOS error code if CF set |
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127 | ; CF: Clear if successfull |
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128 | ; Set if error |
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129 | ; Corrupts registers: |
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130 | ; Nothing |
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131 | ;-------------------------------------------------------------------- |
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132 | ALIGN JUMP_ALIGN |
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133 | FileIO_SeekFromOriginInALtoOffsetInDXAXusingHandleFromBX: |
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134 | push dx |
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135 | push cx |
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136 | |
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137 | mov cx, dx ; DOS wants high word in CX |
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138 | xchg dx, ax ; DOS wants low word in DX |
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139 | mov ah, SET_CURRENT_FILE_POSITION |
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140 | int DOS_INTERRUPT_21h |
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141 | |
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142 | pop cx |
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143 | pop dx |
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144 | ret |
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