source: xtideuniversalbios/trunk/Assembly_Library/Src/File/FileIO.asm@ 50

Last change on this file since 50 was 50, checked in by Tomi Tilli, 14 years ago

Changes to Assembly Library:
Removed Memory_ExchangeSSBPwithESDI since it obviously corrupted stack.
CGA detection is now only done once when initializing Display Context.
Moved File Library defines to File.inc.
File size: 3.5 KB
Line 
1; File name : FileIO.asm
2; Project name : Assembly Library
3; Created date : 1.9.2010
4; Last update : 8.10.2010
5; Author : Tomi Tilli
6; Description : Functions for file access.
7
8; Section containing code
9SECTION .text
10
11;--------------------------------------------------------------------
12; FileIO_OpenWithPathInDSSIandFileAccessInAL
13; Parameters:
14; AL: FILE_ACCESS.(mode)
15; DS:SI: Ptr to NULL terminated path or file name
16; Returns:
17; AX: DOS error code if CF set
18; BX: File handle if CF cleared
19; CF: Clear if file opened successfully
20; Set if error
21; Corrupts registers:
22; AX, BX
23;--------------------------------------------------------------------
24ALIGN JUMP_ALIGN
25FileIO_OpenWithPathInDSSIandFileAccessInAL:
26 xchg dx, si ; Path now in DS:DX
27 mov ah, OPEN_EXISTING_FILE
28 int DOS_INTERRUPT_21h
29 xchg si, dx
30 ret
31
32
33;--------------------------------------------------------------------
34; FileIO_CloseUsingHandleFromBX
35; Parameters:
36; BX: File handle
37; Returns:
38; AX: DOS error code if CF set
39; CF: Clear if file closed successfully
40; Set if error
41; Corrupts registers:
42; AX
43;--------------------------------------------------------------------
44ALIGN JUMP_ALIGN
45FileIO_CloseUsingHandleFromBX:
46 mov ah, CLOSE_FILE
47 int DOS_INTERRUPT_21h
48 ret
49
50
51;--------------------------------------------------------------------
52; File position is updated so next read will start where
53; previous read stopped.
54;
55; FileIO_ReadCXbytesToDSSIusingHandleFromBX
56; Parameters:
57; BX: File handle
58; CX: Number of bytes to read
59; DS:SI: Ptr to destination buffer
60; Returns:
61; AX: Number of bytes actually read if successfull (0 if at EOF before call)
62; DOS error code if CF set
63; CF: Clear if successfull
64; Set if error
65; Corrupts registers:
66; Nothing
67;--------------------------------------------------------------------
68ALIGN JUMP_ALIGN
69FileIO_ReadCXbytesToDSSIusingHandleFromBX:
70 xchg dx, si ; DS:DX now points to source buffer
71 mov ah, READ_FROM_FILE_OR_DEVICE
72 int DOS_INTERRUPT_21h
73 xchg si, dx
74 ret
75
76
77;--------------------------------------------------------------------
78; File position is updated so next write will start where
79; previous write stopped.
80;
81; FileIO_WriteCXbytesFromDSSIusingHandleFromBX:
82; Parameters:
83; BX: File handle
84; CX: Number of bytes to write
85; DS:SI: Ptr to source buffer
86; Returns:
87; AX: Number of bytes actually written if successfull (EOF check)
88; DOS error code if CF set
89; CF: Clear if successfull
90; Set if error
91; Corrupts registers:
92; Nothing
93;--------------------------------------------------------------------
94ALIGN JUMP_ALIGN
95FileIO_WriteCXbytesFromDSSIusingHandleFromBX:
96 xchg dx, si ; DS:DX now points to source buffer
97 mov ah, WRITE_TO_FILE_OR_DEVICE
98 int DOS_INTERRUPT_21h
99 xchg si, dx
100 ret
101
102
103;--------------------------------------------------------------------
104; FileIO_SeekFromOriginInALtoOffsetInDXAXusingHandleFromBX:
105; Parameters:
106; AL: SEEK_FROM.(origin)
107; BX: File handle
108; DX:AX: Seek offset (signed)
109; Returns:
110; AX: DOS error code if CF set
111; CF: Clear if successfull
112; Set if error
113; Corrupts registers:
114; Nothing
115;--------------------------------------------------------------------
116ALIGN JUMP_ALIGN
117FileIO_SeekFromOriginInALtoOffsetInDXAXusingHandleFromBX:
118 push dx
119 push cx
120
121 mov cx, dx ; DOS wants high word in CX
122 xchg dx, ax ; DOS wants low word in DX
123 mov ah, SET_CURRENT_FILE_POSITION
124 int DOS_INTERRUPT_21h
125
126 pop cx
127 pop dx
128 ret
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