source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/Initialization/FloppyDrive.asm@ 223

Last change on this file since 223 was 181, checked in by krille_n_@…, 13 years ago

Changes to all parts of the project:

  • Size optimizations.
  • Added a define (EXCLUDE_FROM_XTIDECFG) to exclude unused library code from XTIDECFG.
  • Tried to minimize time spent with interrupts disabled.
  • Some minor attempts to improve speed (reordering instructions etc).
  • Tried to improve readability, did some cleanup and fixed some errors in comments.
File size: 5.3 KB
RevLine 
[102]1; Project name : XTIDE Universal BIOS
[3]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
[86]19;--------------------------------------------------------------------
[3]20FloppyDrive_IsInt40hInstalled:
[152]21 cmp WORD [es:BIOS_DISKETTE_INTERRUPT_40h*4+2], 0C000h ; Any ROM segment?
[102]22%ifdef USE_AT ; No need to verify on XT systems.
[39]23 jb SHORT .Int40hHandlerIsNotInstalled
24 call .VerifyInt40hHandlerSinceSomeBiosesSimplyReturnFromInt40h
[102]25.Int40hHandlerIsNotInstalled:
[99]26%endif
[27]27 cmc
[3]28 ret
29
[39]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
[86]39;--------------------------------------------------------------------
[99]40%ifdef USE_AT
[39]41.VerifyInt40hHandlerSinceSomeBiosesSimplyReturnFromInt40h:
42 push es
43 push dx
44 push ax
[3]45
[39]46 call .LoadInt40hVerifyParameters
[152]47 int BIOS_DISK_INTERRUPT_13h
[99]48 jc SHORT .Int40hIsInstalled ; Maybe there are not any floppy drives at all
49 push es
50 push di
[39]51
52 call .LoadInt40hVerifyParameters
[152]53 int BIOS_DISKETTE_INTERRUPT_40h
[39]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?
[99]61 je SHORT .Int40hIsInstalled
[39]62.Int40hNotInstalled:
63 stc
64.Int40hIsInstalled:
65 pop ax
66 pop dx
67 pop es
68 ret
69
[3]70;--------------------------------------------------------------------
[39]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
[86]80;--------------------------------------------------------------------
[39]81.LoadInt40hVerifyParameters:
[86]82 mov ah, 08h ; Get Drive Parameters
83 cwd ; Floppy drive 0
[39]84 mov di, dx
85 mov es, dx ; ES:DI = 0000:0000h to guard against BIOS bugs
86 ret
[99]87%endif
[39]88
89
90;--------------------------------------------------------------------
[3]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
[152]115 int BIOS_DISKETTE_INTERRUPT_40h
[3]116 ret
117
118
119;--------------------------------------------------------------------
120; Returns number of Floppy Drives in system.
121;
[124]122; FloppyDrive_GetCountToCX
[3]123; Parameters:
124; Nothing
125; Returns:
126; CX: Number of Floppy Drives
127; Corrupts registers:
128; Nothing
129;--------------------------------------------------------------------
130ALIGN JUMP_ALIGN
[124]131FloppyDrive_GetCountToCX:
[3]132 push es
[99]133%ifdef USE_AT
[124]134 call GetCountFromBIOS
[99]135%else
[124]136 call GetCountFromBDA
[99]137%endif
[181]138 mov ch, [cs:ROMVARS.bMinFddCnt]
139 MAX_U cl, ch
140 pop es
[3]141 xor ch, ch
142 ret
143
144
145;--------------------------------------------------------------------
146; Reads Floppy Drive Count from BIOS.
147; Does not work on most XT systems. Call FloppyDrive_GetCountFromBDA
148; if this function fails.
149;
[124]150; GetCountFromBIOS
[3]151; Parameters:
152; Nothing
153; Returns:
154; CL: Number of Floppy Drives
155; CF: Cleared if successfull
156; Set if BIOS function not supported
157; Corrupts registers:
158; CH, ES
159;--------------------------------------------------------------------
[99]160%ifdef USE_AT
[3]161ALIGN JUMP_ALIGN
[124]162GetCountFromBIOS:
[3]163 push di
164 push dx
165 push bx
166 push ax
167
168 mov ah, 08h ; Get Drive Parameters
[86]169 cwd ; Floppy Drive 00h
[152]170 int BIOS_DISKETTE_INTERRUPT_40h
[3]171 mov cl, dl ; Number of Floppy Drives to CL
172
173 pop ax
174 pop bx
175 pop dx
176 pop di
177 ret
[99]178%endif
[3]179
180
181;--------------------------------------------------------------------
182; Reads Floppy Drive Count (0...4) from BIOS Data Area.
183; This function should be used only if FloppyDrive_GetCountFromBIOS fails.
184;
[124]185; GetCountFromBDA
[3]186; Parameters:
187; Nothing
188; Returns:
189; CL: Number of Floppy Drives
190; Corrupts registers:
191; CH, ES
192;--------------------------------------------------------------------
[99]193%ifndef USE_AT
[3]194ALIGN JUMP_ALIGN
[124]195GetCountFromBDA:
[3]196 LOAD_BDA_SEGMENT_TO es, cx
197 mov cl, [es:BDA.wEquipment] ; Load Equipment WORD low byte
198 mov ch, cl ; Copy it to CH
199 and cx, 0C001h ; Leave bits 15..14 and 0
200 eROL_IM ch, 2 ; EW low byte bits 7..6 to 1..0
201 add cl, ch ; CL = Floppy Drive count
202 ret
[99]203%endif
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