source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/Initialization/FloppyDrive.asm@ 556

Last change on this file since 556 was 551, checked in by aitotat@…, 11 years ago

Changes to XTIDE Universal BIOS:

  • DMA fixes by James Pearce.
  • Interrupt handlers are now installed before starting to detect drives (HotkeyBar require INT 40h handler for correct drive letters).
File size: 5.5 KB
Line 
1; Project name : XTIDE Universal BIOS
2; Description : Various floppy drive related functions that
3; Boot Menu uses.
4
5;
6; XTIDE Universal BIOS and Associated Tools
7; Copyright (C) 2009-2010 by Tomi Tilli, 2011-2013 by XTIDE Universal BIOS Team.
8;
9; This program is free software; you can redistribute it and/or modify
10; it under the terms of the GNU General Public License as published by
11; the Free Software Foundation; either version 2 of the License, or
12; (at your option) any later version.
13;
14; This program is distributed in the hope that it will be useful,
15; but WITHOUT ANY WARRANTY; without even the implied warranty of
16; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17; GNU General Public License for more details.
18; Visit http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
19;
20
21; Section containing code
22SECTION .text
23
24;--------------------------------------------------------------------
25; Checks is floppy drive handler installed to interrupt vector 40h.
26;
27; FloppyDrive_IsInt40hInstalled
28; Parameters:
29; ES: BDA and Interrupt Vector segment (zero)
30; Returns:
31; CF: Set if INT 40h is installed
32; Cleared if INT 40h is not installed
33; Corrupts registers:
34; BX, CX, DI
35;--------------------------------------------------------------------
36FloppyDrive_IsInt40hInstalled:
37%ifdef USE_AT
38 push es
39 push dx
40 push ax
41
42 call LoadInt40hVerifyParameters
43 int BIOS_DISK_INTERRUPT_13h
44 jc SHORT .Int40hIsInstalled ; Maybe there are not any floppy drives at all
45 push es ; Drive Parameter Table segment
46 push di ; Drive Parameter Table offset
47
48 call LoadInt40hVerifyParameters
49 int BIOS_DISKETTE_INTERRUPT_40h
50
51 pop dx
52 pop cx
53 cmp dx, di ; Difference in offsets?
54 jne SHORT .Int40hNotInstalled
55 mov dx, es
56 cmp cx, dx ; Difference in segments?
57 je SHORT .Int40hIsInstalled
58.Int40hNotInstalled:
59 stc
60.Int40hIsInstalled:
61 pop ax
62 pop dx
63 pop es
64
65%else ; if XT build
66 cmp BYTE [es:BIOS_DISKETTE_INTERRUPT_40h*4+3], 0C0h ; Any ROM segment? (set CF if not)
67%endif ; USE_AT
68 cmc
69 ret
70
71;--------------------------------------------------------------------
72; LoadInt40hVerifyParameters
73; Parameters:
74; Nothing
75; Returns:
76; AH: 08h (Get Drive Parameters)
77; DL: 00h (floppy drive)
78; ES:DI: 0:0h (to guard against BIOS bugs)
79; Corrupts registers:
80; DH
81;--------------------------------------------------------------------
82%ifdef USE_AT
83LoadInt40hVerifyParameters:
84 mov ah, GET_DRIVE_PARAMETERS
85 cwd ; Floppy drive 0
86 mov di, dx
87 mov es, dx ; ES:DI = 0000:0000h to guard against BIOS bugs
88 ret
89%endif
90
91
92;--------------------------------------------------------------------
93; Returns floppy drive type.
94; PC/XT system do not support AH=08h but FLOPPY_TYPE_525_OR_35_DD
95; is still returned for them.
96;
97; FloppyDrive_GetType
98; Parameters:
99; DL: Floppy Drive number
100; Returns:
101; BX: Floppy Drive Type:
102; FLOPPY_TYPE_525_OR_35_DD
103; FLOPPY_TYPE_525_DD
104; FLOPPY_TYPE_525_HD
105; FLOPPY_TYPE_35_DD
106; FLOPPY_TYPE_35_HD
107; FLOPPY_TYPE_35_ED
108; CF: Set if AH=08h not supported (XT systems) or error
109; Cleared if type read correctly (AT systems)
110; Corrupts registers:
111; AX, CX, DX, DI, ES
112;--------------------------------------------------------------------
113%ifdef MODULE_BOOT_MENU
114FloppyDrive_GetType:
115 mov ah, GET_DRIVE_PARAMETERS
116 xor bx, bx ; FLOPPY_TYPE_525_OR_35_DD when function not supported
117 int BIOS_DISKETTE_INTERRUPT_40h
118 ret
119%endif
120
121
122;--------------------------------------------------------------------
123; Returns number of Floppy Drives in system.
124;
125; FloppyDrive_GetCountToAX
126; Parameters:
127; DS: RAMVARS Segment
128; Returns:
129; AX: Number of Floppy Drives
130;--------------------------------------------------------------------
131FloppyDrive_GetCountToAX:
132%ifdef MODULE_SERIAL_FLOPPY
133 call RamVars_UnpackFlopCntAndFirstToAL
134 js .UseBIOSorBDA ; We didn't add in any drives, counts here are not valid
135
136 adc al, 1 ; adds in the drive count bit, and adds 1 for count vs. 0-index,
137 jmp .FinishCalc ; need to clear AH on the way out, and add in minimum drive numbers
138
139.UseBIOSorBDA:
140%endif
141 call FloppyDrive_GetCountFromBIOS_or_BDA
142
143.FinishCalc:
144 mov ah, [cs:ROMVARS.bMinFddCnt]
145 MAX_U al, ah
146 cbw
147
148 ret
149
150
151;--------------------------------------------------------------------
152; FloppyDrive_GetCountFromBIOS_or_BDA
153; Parameters:
154; Nothing
155; Returns:
156; AL: Number of Floppy Drives
157; CF: Cleared if successful
158; Set if BIOS function not supported
159; Corrupts registers:
160; AH
161;--------------------------------------------------------------------
162FloppyDrive_GetCountFromBIOS_or_BDA:
163 push es
164
165; Reads Floppy Drive Count from BIOS.
166; Does not work on most XT systems. Call .GetCountFromBDA
167; if this function fails.
168%ifdef USE_AT
169 push di
170 push bx
171 push cx
172 push dx
173
174 mov ah, GET_DRIVE_PARAMETERS
175 cwd ; Floppy Drive 00h
176 int BIOS_DISKETTE_INTERRUPT_40h
177 xchg ax, dx ; Number of Floppy Drives to AL
178
179 pop dx
180 pop cx
181 pop bx
182 pop di
183
184; Reads Floppy Drive Count (0...4) from BIOS Data Area.
185; This function should be used only if .GetCountFromBIOS fails.
186%else ; ifndef USE_AT
187 LOAD_BDA_SEGMENT_TO es, ax
188 mov al, [es:BDA.wEquipment] ; Load Equipment WORD low byte
189
190%ifdef USE_UNDOC_INTEL
191 and al, 0C1h
192 eAAM 64
193%else
194 mov ah, al ; Copy it to AH
195 and ax, 0C001h ; Leave bits 15..14 and 0
196 eROL_IM ah, 2 ; EW low byte bits 7..6 to 1..0
197%endif ; USE_UNDOC_INTEL
198
199 add al, ah ; AL = Floppy Drive count
200%endif ; USE_AT
201
202 pop es
203 ret
Note: See TracBrowser for help on using the repository browser.