source: xtideuniversalbios/trunk/Assembly_Library/Src/File/FileIO.asm@ 439

Last change on this file since 439 was 376, checked in by gregli@…, 13 years ago

WIDE checkin... Added copyright and license information to sorce files, as per the GPL instructions for usage.
File size: 8.0 KB
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[41]1; Project name : Assembly Library
2; Description : Functions for file access.
3
[376]4;
5; XTIDE Universal BIOS and Associated Tools
6; Copyright (C) 2009-2010 by Tomi Tilli, 2011-2012 by XTIDE Universal BIOS Team.
7;
8; This program is free software; you can redistribute it and/or modify
9; it under the terms of the GNU General Public License as published by
10; the Free Software Foundation; either version 2 of the License, or
11; (at your option) any later version.
12;
13; This program is distributed in the hope that it will be useful,
14; but WITHOUT ANY WARRANTY; without even the implied warranty of
15; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16; GNU General Public License for more details.
17; Visit http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
18;
19
20
[41]21; Section containing code
22SECTION .text
23
24;--------------------------------------------------------------------
25; FileIO_OpenWithPathInDSSIandFileAccessInAL
26; Parameters:
27; AL: FILE_ACCESS.(mode)
28; DS:SI: Ptr to NULL terminated path or file name
29; Returns:
30; AX: DOS error code if CF set
31; BX: File handle if CF cleared
32; CF: Clear if file opened successfully
33; Set if error
34; Corrupts registers:
35; AX, BX
36;--------------------------------------------------------------------
37ALIGN JUMP_ALIGN
38FileIO_OpenWithPathInDSSIandFileAccessInAL:
39 xchg dx, si ; Path now in DS:DX
40 mov ah, OPEN_EXISTING_FILE
41 int DOS_INTERRUPT_21h
42 xchg si, dx
[51]43 mov bx, ax ; Copy file handle to BX
[41]44 ret
45
46
47;--------------------------------------------------------------------
[66]48; FileIO_ReadDXCXbytesToDSSIusingHandleFromBX
49; Parameters:
50; BX: File handle
51; DX:CX: Number of bytes to read
52; DS:SI: Ptr to destination buffer
53; Returns:
54; AX: DOS error code if CF set
[293]55; CF: Clear if successful
[66]56; Set if error
57; Corrupts registers:
58; AX
59;--------------------------------------------------------------------
60ALIGN JUMP_ALIGN
61FileIO_ReadDXCXbytesToDSSIusingHandleFromBX:
62 push bp
63 mov bp, FileIO_ReadCXbytesToDSSIusingHandleFromBX
64 call SplitLargeReadOrWritesToSmallerBlocks
65 pop bp
66 ret
67
68;--------------------------------------------------------------------
[41]69; File position is updated so next read will start where
70; previous read stopped.
[133]71;
[41]72; FileIO_ReadCXbytesToDSSIusingHandleFromBX
73; Parameters:
74; BX: File handle
75; CX: Number of bytes to read
76; DS:SI: Ptr to destination buffer
77; Returns:
[293]78; AX: Number of bytes actually read if successful (0 if at EOF before call)
[41]79; DOS error code if CF set
[293]80; CF: Clear if successful
[41]81; Set if error
82; Corrupts registers:
83; Nothing
84;--------------------------------------------------------------------
85ALIGN JUMP_ALIGN
86FileIO_ReadCXbytesToDSSIusingHandleFromBX:
[51]87 xchg dx, si ; DS:DX now points to destination buffer
[41]88 mov ah, READ_FROM_FILE_OR_DEVICE
89 int DOS_INTERRUPT_21h
90 xchg si, dx
91 ret
92
93
94;--------------------------------------------------------------------
[66]95; FileIO_WriteDXCXbytesFromDSSIusingHandleFromBX
96; Parameters:
97; BX: File handle
98; DX:CX: Number of bytes to write
99; DS:SI: Ptr to source buffer
100; Returns:
101; AX: DOS error code if CF set
[293]102; CF: Clear if successful
[66]103; Set if error
104; Corrupts registers:
105; AX
106;--------------------------------------------------------------------
107ALIGN JUMP_ALIGN
108FileIO_WriteDXCXbytesFromDSSIusingHandleFromBX:
109 push bp
110 mov bp, FileIO_WriteCXbytesFromDSSIusingHandleFromBX
111 call SplitLargeReadOrWritesToSmallerBlocks
112 pop bp
113 ret
114
115;--------------------------------------------------------------------
[41]116; File position is updated so next write will start where
117; previous write stopped.
[133]118;
[41]119; FileIO_WriteCXbytesFromDSSIusingHandleFromBX:
120; Parameters:
121; BX: File handle
122; CX: Number of bytes to write
123; DS:SI: Ptr to source buffer
124; Returns:
[293]125; AX: Number of bytes actually written if successful (EOF check)
[41]126; DOS error code if CF set
[293]127; CF: Clear if successful
[41]128; Set if error
129; Corrupts registers:
130; Nothing
131;--------------------------------------------------------------------
132ALIGN JUMP_ALIGN
133FileIO_WriteCXbytesFromDSSIusingHandleFromBX:
134 xchg dx, si ; DS:DX now points to source buffer
135 mov ah, WRITE_TO_FILE_OR_DEVICE
136 int DOS_INTERRUPT_21h
137 xchg si, dx
138 ret
139
140
141;--------------------------------------------------------------------
[66]142; SplitLargeReadOrWritesToSmallerBlocks
143; Parameters:
144; BX: File handle
145; BP: Ptr to transfer function
146; DX:CX: Number of bytes to transfer
147; DS:SI: Ptr to transfer buffer
148; Returns:
149; AX: DOS error code if CF set
[293]150; CF: Clear if successful
[66]151; Set if error
152; Corrupts registers:
153; AX
154;--------------------------------------------------------------------
155ALIGN JUMP_ALIGN
156SplitLargeReadOrWritesToSmallerBlocks:
157 push ds
158 push si
159 push dx
160 push cx
161
162 xchg ax, cx ; DX:AX now holds bytes to transfer
163 mov cx, SPLIT_SIZE_FOR_LARGE_TRANSFERS
164 div cx ; AX = Number of full transfers
165 push dx ; Bytes for last transfer
166 test ax, ax
167 jz SHORT .TransferRemainingBytes
168 xchg dx, ax ; DX = Number of full transfers
169
170ALIGN JUMP_ALIGN
171.TransferNextBytes:
[105]172 call NormalizeDSSI
[66]173 call bp ; Transfer function
174 jc SHORT .ErrorOccurredDuringTransfer
[67]175 add si, SPLIT_SIZE_FOR_LARGE_TRANSFERS
[66]176 dec dx
177 jnz SHORT .TransferNextBytes
178.TransferRemainingBytes:
179 pop cx ; CX = Bytes for last transfer
180 jcxz .ReturnErrorCodeInAX ; No remaining bytes
[105]181 call NormalizeDSSI
[66]182 call bp
183.ReturnErrorCodeInAX:
184 pop cx
185 pop dx
186 pop si
187 pop ds
188 ret
189.ErrorOccurredDuringTransfer:
190 pop cx ; Remove bytes for last transfer
191 jmp SHORT .ReturnErrorCodeInAX
192
[105]193;--------------------------------------------------------------------
194; NormalizeDSSI
195; Parameters
196; DS:SI: Ptr to normalize
197; Returns:
198; DS:SI: Normalized pointer
199; Corrupts registers:
200; Nothing
201;--------------------------------------------------------------------
202ALIGN JUMP_ALIGN
203NormalizeDSSI:
204 push dx
205 push ax
206 NORMALIZE_FAR_POINTER ds, si, ax, dx
207 pop ax
208 pop dx
209 ret
[66]210
[105]211
[66]212;--------------------------------------------------------------------
[51]213; FileIO_GetFileSizeToDXAXusingHandleFromBXandResetFilePosition:
214; Parameters:
215; BX: File handle
216; Returns:
217; DX:AX: Signed file size (if CF cleared)
218; AX: DOS error code (if CF set)
[293]219; CF: Clear if successful
[51]220; Set if error
221; Corrupts registers:
222; Nothing
223;--------------------------------------------------------------------
224ALIGN JUMP_ALIGN
225FileIO_GetFileSizeToDXAXusingHandleFromBXandResetFilePosition:
226 push cx
227
228 ; Get file size to DX:AX
229 xor cx, cx
230 xor dx, dx
231 mov al, SEEK_FROM.endOfFile
232 call FileIO_SeekFromOriginInALtoOffsetInDXAXusingHandleFromBX
233 jc SHORT .ReturnFileError
234 push dx
235 push ax
236
237 ; Reset file position
238 xor dx, dx
239 mov al, SEEK_FROM.startOfFile
240 call FileIO_SeekFromOriginInALtoOffsetInDXAXusingHandleFromBX
241 pop ax
242 pop dx
243
244.ReturnFileError:
245 pop cx
246 ret
247
248
249;--------------------------------------------------------------------
[133]250; FileIO_CloseUsingHandleFromBX
251; Parameters:
252; BX: File handle
253; Returns:
254; AX: DOS error code if CF set
255; CF: Clear if file closed successfully
256; Set if error
257; Corrupts registers:
258; AX
259;--------------------------------------------------------------------
260ALIGN JUMP_ALIGN
261FileIO_CloseUsingHandleFromBX:
262 mov ah, CLOSE_FILE
263 SKIP2B f ; cmp ax, <next instruction>
264 ; Fall to FileIO_SeekFromOriginInALtoOffsetInDXAXusingHandleFromBX
265
266
267;--------------------------------------------------------------------
[41]268; FileIO_SeekFromOriginInALtoOffsetInDXAXusingHandleFromBX:
269; Parameters:
270; AL: SEEK_FROM.(origin)
271; BX: File handle
[51]272; CX:DX: Signed offset to seek starting from AL
[41]273; Returns:
[51]274; DX:AX: New file position in bytes from start of file (if CF cleared)
275; AX: DOS error code (if CF set)
[293]276; CF: Clear if successful
[41]277; Set if error
278; Corrupts registers:
279; Nothing
280;--------------------------------------------------------------------
281FileIO_SeekFromOriginInALtoOffsetInDXAXusingHandleFromBX:
282 mov ah, SET_CURRENT_FILE_POSITION
283 int DOS_INTERRUPT_21h
284 ret
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