source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/Initialization/FloppyDrive.asm@ 170

Last change on this file since 170 was 152, checked in by Tomi Tilli, 14 years ago

Changes to XTIDE Universal BIOS:

  • XTIDE mod should now be supported (untested).
  • Interrupt Service Routine no longer requires variable from RAMVARS.
  • Some small improvements.
File size: 5.3 KB
Line 
1; Project name : XTIDE Universal BIOS
2; Description : Various floppy drive related functions that
3; Boot Menu uses.
4
5; Section containing code
6SECTION .text
7
8;--------------------------------------------------------------------
9; Checks is floppy drive handler installed to interrupt vector 40h.
10;
11; FloppyDrive_IsInt40hInstalled
12; Parameters:
13; ES: BDA and Interrupt Vector segment (zero)
14; Returns:
15; CF: Set if INT 40h is installed
16; Cleared if INT 40h is not installed
17; Corrupts registers:
18; BX, CX, DI
19;--------------------------------------------------------------------
20FloppyDrive_IsInt40hInstalled:
21 cmp WORD [es:BIOS_DISKETTE_INTERRUPT_40h*4+2], 0C000h ; Any ROM segment?
22%ifdef USE_AT ; No need to verify on XT systems.
23 jb SHORT .Int40hHandlerIsNotInstalled
24 call .VerifyInt40hHandlerSinceSomeBiosesSimplyReturnFromInt40h
25.Int40hHandlerIsNotInstalled:
26%endif
27 cmc
28 ret
29
30;--------------------------------------------------------------------
31; .VerifyInt40hHandlerSinceSomeBiosesSimplyReturnFromInt40h
32; Parameters:
33; Nothing
34; Returns:
35; CF: Cleared if INT 40h is installed
36; Set if INT 40h is not installed
37; Corrupts registers:
38; BX, CX, DI
39;--------------------------------------------------------------------
40%ifdef USE_AT
41.VerifyInt40hHandlerSinceSomeBiosesSimplyReturnFromInt40h:
42 push es
43 push dx
44 push ax
45
46 call .LoadInt40hVerifyParameters
47 int BIOS_DISK_INTERRUPT_13h
48 jc SHORT .Int40hIsInstalled ; Maybe there are not any floppy drives at all
49 push es
50 push di
51
52 call .LoadInt40hVerifyParameters
53 int BIOS_DISKETTE_INTERRUPT_40h
54
55 pop dx
56 pop cx
57 cmp dx, di ; Difference in offsets?
58 jne SHORT .Int40hNotInstalled
59 mov dx, es
60 cmp cx, dx ; Difference in segments?
61 je SHORT .Int40hIsInstalled
62.Int40hNotInstalled:
63 stc
64.Int40hIsInstalled:
65 pop ax
66 pop dx
67 pop es
68 ret
69
70;--------------------------------------------------------------------
71; .LoadInt40hVerifyParameters
72; Parameters:
73; Nothing
74; Returns:
75; AH: 08h (Get Drive Parameters)
76; DL: 00h (floppy drive)
77; ES:DI: 0:0h (to guard against BIOS bugs)
78; Corrupts registers:
79; DH
80;--------------------------------------------------------------------
81.LoadInt40hVerifyParameters:
82 mov ah, 08h ; Get Drive Parameters
83 cwd ; Floppy drive 0
84 mov di, dx
85 mov es, dx ; ES:DI = 0000:0000h to guard against BIOS bugs
86 ret
87%endif
88
89
90;--------------------------------------------------------------------
91; Returns floppy drive type.
92; PC/XT system do not support AH=08h but FLOPPY_TYPE_525_OR_35_DD
93; is still returned for them.
94;
95; FloppyDrive_GetType
96; Parameters:
97; DL: Floppy Drive number
98; Returns:
99; BX: Floppy Drive Type:
100; FLOPPY_TYPE_525_OR_35_DD
101; FLOPPY_TYPE_525_DD
102; FLOPPY_TYPE_525_HD
103; FLOPPY_TYPE_35_DD
104; FLOPPY_TYPE_35_HD
105; FLOPPY_TYPE_35_ED
106; CF: Set if AH=08h not supported (XT systems) or error
107; Cleared if type read correctly (AT systems)
108; Corrupts registers:
109; AX, CX, DX, DI, ES
110;--------------------------------------------------------------------
111ALIGN JUMP_ALIGN
112FloppyDrive_GetType:
113 mov ah, 08h ; Get Drive Parameters
114 xor bx, bx ; FLOPPY_TYPE_525_OR_35_DD when function not supported
115 int BIOS_DISKETTE_INTERRUPT_40h
116 ret
117
118
119;--------------------------------------------------------------------
120; Returns number of Floppy Drives in system.
121;
122; FloppyDrive_GetCountToCX
123; Parameters:
124; Nothing
125; Returns:
126; CX: Number of Floppy Drives
127; Corrupts registers:
128; Nothing
129;--------------------------------------------------------------------
130ALIGN JUMP_ALIGN
131FloppyDrive_GetCountToCX:
132 push es
133%ifdef USE_AT
134 call GetCountFromBIOS
135%else
136 call GetCountFromBDA
137%endif
138 MAX_U cl, [cs:ROMVARS.bMinFddCnt]
139 xor ch, ch
140 pop es
141 ret
142
143
144;--------------------------------------------------------------------
145; Reads Floppy Drive Count from BIOS.
146; Does not work on most XT systems. Call FloppyDrive_GetCountFromBDA
147; if this function fails.
148;
149; GetCountFromBIOS
150; Parameters:
151; Nothing
152; Returns:
153; CL: Number of Floppy Drives
154; CF: Cleared if successfull
155; Set if BIOS function not supported
156; Corrupts registers:
157; CH, ES
158;--------------------------------------------------------------------
159%ifdef USE_AT
160ALIGN JUMP_ALIGN
161GetCountFromBIOS:
162 push di
163 push dx
164 push bx
165 push ax
166
167 mov ah, 08h ; Get Drive Parameters
168 cwd ; Floppy Drive 00h
169 int BIOS_DISKETTE_INTERRUPT_40h
170 mov cl, dl ; Number of Floppy Drives to CL
171
172 pop ax
173 pop bx
174 pop dx
175 pop di
176 ret
177%endif
178
179
180;--------------------------------------------------------------------
181; Reads Floppy Drive Count (0...4) from BIOS Data Area.
182; This function should be used only if FloppyDrive_GetCountFromBIOS fails.
183;
184; GetCountFromBDA
185; Parameters:
186; Nothing
187; Returns:
188; CL: Number of Floppy Drives
189; Corrupts registers:
190; CH, ES
191;--------------------------------------------------------------------
192%ifndef USE_AT
193ALIGN JUMP_ALIGN
194GetCountFromBDA:
195 LOAD_BDA_SEGMENT_TO es, cx
196 mov cl, [es:BDA.wEquipment] ; Load Equipment WORD low byte
197 mov ch, cl ; Copy it to CH
198 and cx, 0C001h ; Leave bits 15..14 and 0
199 eROL_IM ch, 2 ; EW low byte bits 7..6 to 1..0
200 add cl, ch ; CL = Floppy Drive count
201 ret
202%endif
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