[41] | 1 | ; Project name : Assembly Library |
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| 2 | ; Description : Functions for file access. |
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| 3 | |
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| 4 | ; Section containing code |
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| 5 | SECTION .text |
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| 6 | |
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| 7 | ;-------------------------------------------------------------------- |
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| 8 | ; FileIO_OpenWithPathInDSSIandFileAccessInAL |
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| 9 | ; Parameters: |
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| 10 | ; AL: FILE_ACCESS.(mode) |
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| 11 | ; DS:SI: Ptr to NULL terminated path or file name |
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| 12 | ; Returns: |
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| 13 | ; AX: DOS error code if CF set |
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| 14 | ; BX: File handle if CF cleared |
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| 15 | ; CF: Clear if file opened successfully |
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| 16 | ; Set if error |
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| 17 | ; Corrupts registers: |
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| 18 | ; AX, BX |
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| 19 | ;-------------------------------------------------------------------- |
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| 20 | ALIGN JUMP_ALIGN |
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| 21 | FileIO_OpenWithPathInDSSIandFileAccessInAL: |
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| 22 | xchg dx, si ; Path now in DS:DX |
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| 23 | mov ah, OPEN_EXISTING_FILE |
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| 24 | int DOS_INTERRUPT_21h |
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| 25 | xchg si, dx |
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[51] | 26 | mov bx, ax ; Copy file handle to BX |
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[41] | 27 | ret |
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| 28 | |
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| 29 | |
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| 30 | ;-------------------------------------------------------------------- |
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| 31 | ; FileIO_CloseUsingHandleFromBX |
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| 32 | ; Parameters: |
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| 33 | ; BX: File handle |
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| 34 | ; Returns: |
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| 35 | ; AX: DOS error code if CF set |
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| 36 | ; CF: Clear if file closed successfully |
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| 37 | ; Set if error |
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| 38 | ; Corrupts registers: |
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| 39 | ; AX |
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| 40 | ;-------------------------------------------------------------------- |
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| 41 | ALIGN JUMP_ALIGN |
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| 42 | FileIO_CloseUsingHandleFromBX: |
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| 43 | mov ah, CLOSE_FILE |
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| 44 | int DOS_INTERRUPT_21h |
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| 45 | ret |
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| 46 | |
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| 47 | |
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| 48 | ;-------------------------------------------------------------------- |
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[66] | 49 | ; FileIO_ReadDXCXbytesToDSSIusingHandleFromBX |
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| 50 | ; Parameters: |
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| 51 | ; BX: File handle |
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| 52 | ; DX:CX: Number of bytes to read |
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| 53 | ; DS:SI: Ptr to destination buffer |
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| 54 | ; Returns: |
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| 55 | ; AX: DOS error code if CF set |
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| 56 | ; CF: Clear if successfull |
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| 57 | ; Set if error |
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| 58 | ; Corrupts registers: |
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| 59 | ; AX |
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| 60 | ;-------------------------------------------------------------------- |
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| 61 | ALIGN JUMP_ALIGN |
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| 62 | FileIO_ReadDXCXbytesToDSSIusingHandleFromBX: |
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| 63 | push bp |
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| 64 | mov bp, FileIO_ReadCXbytesToDSSIusingHandleFromBX |
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| 65 | call SplitLargeReadOrWritesToSmallerBlocks |
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| 66 | pop bp |
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| 67 | ret |
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| 68 | |
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| 69 | ;-------------------------------------------------------------------- |
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[41] | 70 | ; File position is updated so next read will start where |
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| 71 | ; previous read stopped. |
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| 72 | ; |
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| 73 | ; FileIO_ReadCXbytesToDSSIusingHandleFromBX |
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| 74 | ; Parameters: |
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| 75 | ; BX: File handle |
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| 76 | ; CX: Number of bytes to read |
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| 77 | ; DS:SI: Ptr to destination buffer |
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| 78 | ; Returns: |
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| 79 | ; AX: Number of bytes actually read if successfull (0 if at EOF before call) |
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| 80 | ; DOS error code if CF set |
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| 81 | ; CF: Clear if successfull |
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| 82 | ; Set if error |
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| 83 | ; Corrupts registers: |
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| 84 | ; Nothing |
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| 85 | ;-------------------------------------------------------------------- |
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| 86 | ALIGN JUMP_ALIGN |
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| 87 | FileIO_ReadCXbytesToDSSIusingHandleFromBX: |
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[51] | 88 | xchg dx, si ; DS:DX now points to destination buffer |
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[41] | 89 | mov ah, READ_FROM_FILE_OR_DEVICE |
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| 90 | int DOS_INTERRUPT_21h |
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| 91 | xchg si, dx |
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| 92 | ret |
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| 93 | |
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| 94 | |
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| 95 | ;-------------------------------------------------------------------- |
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[66] | 96 | ; FileIO_WriteDXCXbytesFromDSSIusingHandleFromBX |
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| 97 | ; Parameters: |
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| 98 | ; BX: File handle |
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| 99 | ; DX:CX: Number of bytes to write |
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| 100 | ; DS:SI: Ptr to source buffer |
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| 101 | ; Returns: |
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| 102 | ; AX: DOS error code if CF set |
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| 103 | ; CF: Clear if successfull |
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| 104 | ; Set if error |
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| 105 | ; Corrupts registers: |
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| 106 | ; AX |
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| 107 | ;-------------------------------------------------------------------- |
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| 108 | ALIGN JUMP_ALIGN |
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| 109 | FileIO_WriteDXCXbytesFromDSSIusingHandleFromBX: |
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| 110 | push bp |
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| 111 | mov bp, FileIO_WriteCXbytesFromDSSIusingHandleFromBX |
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| 112 | call SplitLargeReadOrWritesToSmallerBlocks |
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| 113 | pop bp |
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| 114 | ret |
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| 115 | |
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| 116 | ;-------------------------------------------------------------------- |
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[41] | 117 | ; File position is updated so next write will start where |
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| 118 | ; previous write stopped. |
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| 119 | ; |
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| 120 | ; FileIO_WriteCXbytesFromDSSIusingHandleFromBX: |
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| 121 | ; Parameters: |
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| 122 | ; BX: File handle |
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| 123 | ; CX: Number of bytes to write |
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| 124 | ; DS:SI: Ptr to source buffer |
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| 125 | ; Returns: |
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| 126 | ; AX: Number of bytes actually written if successfull (EOF check) |
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| 127 | ; DOS error code if CF set |
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| 128 | ; CF: Clear if successfull |
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| 129 | ; Set if error |
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| 130 | ; Corrupts registers: |
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| 131 | ; Nothing |
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| 132 | ;-------------------------------------------------------------------- |
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| 133 | ALIGN JUMP_ALIGN |
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| 134 | FileIO_WriteCXbytesFromDSSIusingHandleFromBX: |
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| 135 | xchg dx, si ; DS:DX now points to source buffer |
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| 136 | mov ah, WRITE_TO_FILE_OR_DEVICE |
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| 137 | int DOS_INTERRUPT_21h |
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| 138 | xchg si, dx |
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| 139 | ret |
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| 140 | |
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| 141 | |
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| 142 | ;-------------------------------------------------------------------- |
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[66] | 143 | ; SplitLargeReadOrWritesToSmallerBlocks |
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| 144 | ; Parameters: |
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| 145 | ; BX: File handle |
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| 146 | ; BP: Ptr to transfer function |
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| 147 | ; DX:CX: Number of bytes to transfer |
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| 148 | ; DS:SI: Ptr to transfer buffer |
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| 149 | ; Returns: |
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| 150 | ; AX: DOS error code if CF set |
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| 151 | ; CF: Clear if successfull |
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| 152 | ; Set if error |
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| 153 | ; Corrupts registers: |
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| 154 | ; AX |
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| 155 | ;-------------------------------------------------------------------- |
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| 156 | ALIGN JUMP_ALIGN |
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| 157 | SplitLargeReadOrWritesToSmallerBlocks: |
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| 158 | push ds |
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| 159 | push si |
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| 160 | push dx |
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| 161 | push cx |
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| 162 | |
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| 163 | xchg ax, cx ; DX:AX now holds bytes to transfer |
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| 164 | mov cx, SPLIT_SIZE_FOR_LARGE_TRANSFERS |
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| 165 | div cx ; AX = Number of full transfers |
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| 166 | push dx ; Bytes for last transfer |
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| 167 | test ax, ax |
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| 168 | jz SHORT .TransferRemainingBytes |
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| 169 | xchg dx, ax ; DX = Number of full transfers |
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| 170 | |
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| 171 | ALIGN JUMP_ALIGN |
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| 172 | .TransferNextBytes: |
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[105] | 173 | call NormalizeDSSI |
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[66] | 174 | call bp ; Transfer function |
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| 175 | jc SHORT .ErrorOccurredDuringTransfer |
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[67] | 176 | add si, SPLIT_SIZE_FOR_LARGE_TRANSFERS |
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[66] | 177 | dec dx |
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| 178 | jnz SHORT .TransferNextBytes |
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| 179 | .TransferRemainingBytes: |
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| 180 | pop cx ; CX = Bytes for last transfer |
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| 181 | jcxz .ReturnErrorCodeInAX ; No remaining bytes |
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[105] | 182 | call NormalizeDSSI |
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[66] | 183 | call bp |
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| 184 | .ReturnErrorCodeInAX: |
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| 185 | pop cx |
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| 186 | pop dx |
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| 187 | pop si |
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| 188 | pop ds |
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| 189 | ret |
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| 190 | .ErrorOccurredDuringTransfer: |
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| 191 | pop cx ; Remove bytes for last transfer |
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| 192 | jmp SHORT .ReturnErrorCodeInAX |
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| 193 | |
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[105] | 194 | ;-------------------------------------------------------------------- |
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| 195 | ; NormalizeDSSI |
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| 196 | ; Parameters |
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| 197 | ; DS:SI: Ptr to normalize |
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| 198 | ; Returns: |
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| 199 | ; DS:SI: Normalized pointer |
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| 200 | ; Corrupts registers: |
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| 201 | ; Nothing |
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| 202 | ;-------------------------------------------------------------------- |
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| 203 | ALIGN JUMP_ALIGN |
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| 204 | NormalizeDSSI: |
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| 205 | push dx |
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| 206 | push ax |
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| 207 | NORMALIZE_FAR_POINTER ds, si, ax, dx |
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| 208 | pop ax |
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| 209 | pop dx |
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| 210 | ret |
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[66] | 211 | |
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[105] | 212 | |
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[66] | 213 | ;-------------------------------------------------------------------- |
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[51] | 214 | ; FileIO_GetFileSizeToDXAXusingHandleFromBXandResetFilePosition: |
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| 215 | ; Parameters: |
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| 216 | ; BX: File handle |
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| 217 | ; Returns: |
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| 218 | ; DX:AX: Signed file size (if CF cleared) |
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| 219 | ; AX: DOS error code (if CF set) |
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| 220 | ; CF: Clear if successfull |
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| 221 | ; Set if error |
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| 222 | ; Corrupts registers: |
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| 223 | ; Nothing |
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| 224 | ;-------------------------------------------------------------------- |
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| 225 | ALIGN JUMP_ALIGN |
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| 226 | FileIO_GetFileSizeToDXAXusingHandleFromBXandResetFilePosition: |
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| 227 | push cx |
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| 228 | |
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| 229 | ; Get file size to DX:AX |
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| 230 | xor cx, cx |
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| 231 | xor dx, dx |
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| 232 | mov al, SEEK_FROM.endOfFile |
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| 233 | call FileIO_SeekFromOriginInALtoOffsetInDXAXusingHandleFromBX |
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| 234 | jc SHORT .ReturnFileError |
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| 235 | push dx |
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| 236 | push ax |
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| 237 | |
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| 238 | ; Reset file position |
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| 239 | xor dx, dx |
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| 240 | mov al, SEEK_FROM.startOfFile |
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| 241 | call FileIO_SeekFromOriginInALtoOffsetInDXAXusingHandleFromBX |
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| 242 | pop ax |
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| 243 | pop dx |
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| 244 | |
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| 245 | .ReturnFileError: |
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| 246 | pop cx |
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| 247 | ret |
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| 248 | |
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| 249 | |
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| 250 | ;-------------------------------------------------------------------- |
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[41] | 251 | ; FileIO_SeekFromOriginInALtoOffsetInDXAXusingHandleFromBX: |
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| 252 | ; Parameters: |
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| 253 | ; AL: SEEK_FROM.(origin) |
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| 254 | ; BX: File handle |
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[51] | 255 | ; CX:DX: Signed offset to seek starting from AL |
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[41] | 256 | ; Returns: |
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[51] | 257 | ; DX:AX: New file position in bytes from start of file (if CF cleared) |
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| 258 | ; AX: DOS error code (if CF set) |
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[41] | 259 | ; CF: Clear if successfull |
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| 260 | ; Set if error |
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| 261 | ; Corrupts registers: |
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| 262 | ; Nothing |
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| 263 | ;-------------------------------------------------------------------- |
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| 264 | ALIGN JUMP_ALIGN |
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| 265 | FileIO_SeekFromOriginInALtoOffsetInDXAXusingHandleFromBX: |
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| 266 | mov ah, SET_CURRENT_FILE_POSITION |
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| 267 | int DOS_INTERRUPT_21h |
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| 268 | ret |
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