source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/VariablesAndDPTs/RamVars.asm@ 176

Last change on this file since 176 was 155, checked in by Tomi Tilli, 14 years ago

Changes to XTIDE Universal BIOS:

  • AH=4h again uses VERIFY command (copy-pasting had changed it to WRITE).
  • Timeout should now work on all overflow situations.
  • Cleaned code a bit.
File size: 6.2 KB
Line 
1; Project name : XTIDE Universal BIOS
2; Description : Functions for accessings RAMVARS.
3
4; Section containing code
5SECTION .text
6
7;--------------------------------------------------------------------
8; Initializes RAMVARS.
9; Drive detection can be started after this function returns.
10;
11; RamVars_Initialize
12; Parameters:
13; Nothing
14; Returns:
15; DS: RAMVARS segment
16; Corrupts registers:
17; AX, CX, DI
18;--------------------------------------------------------------------
19RamVars_Initialize:
20 push es
21 ; Fall to .StealMemoryForRAMVARS
22
23;--------------------------------------------------------------------
24; .StealMemoryForRAMVARS
25; Parameters:
26; Nothing
27; Returns:
28; DS: RAMVARS segment
29; Corrupts registers:
30; AX
31;--------------------------------------------------------------------
32.StealMemoryForRAMVARS:
33 test BYTE [cs:ROMVARS.wFlags], FLG_ROMVARS_FULLMODE
34 jz SHORT .InitializeRamvars ; No need to steal RAM
35
36 LOAD_BDA_SEGMENT_TO ds, ax, ! ; Zero AX
37 mov al, [cs:ROMVARS.bStealSize]
38 sub [BDA.wBaseMem], ax
39 mov ax, [BDA.wBaseMem]
40 eSHL_IM ax, 6 ; Segment to first stolen kB (*=40h)
41 mov ds, ax
42 mov WORD [RAMVARS.wSignature], RAMVARS_SIGNATURE
43 ; Fall to .InitializeRamvars
44
45;--------------------------------------------------------------------
46; .InitializeRamvars
47; Parameters:
48; Nothing
49; Returns:
50; DS: RAMVARS segment
51; Corrupts registers:
52; AX, CX, DI, ES
53;--------------------------------------------------------------------
54.InitializeRamvars:
55 call RamVars_GetSegmentToDS
56 mov cx, RAMVARS_size
57 xor di, di
58 push ds
59 pop es
60 call Memory_ZeroESDIwithSizeInCX
61 mov WORD [RAMVARS.wSignature], RAMVARS_SIGNATURE
62 ; Fall to .InitializeDriveTranslationAndReturn
63
64;--------------------------------------------------------------------
65; .InitializeDriveTranslationAndReturn
66; Parameters:
67; DS: RAMVARS segment
68; Returns:
69; Nothing
70; Corrupts registers:
71; AX
72;--------------------------------------------------------------------
73.InitializeDriveTranslationAndReturn:
74 pop es
75 jmp DriveXlate_Reset
76
77
78;--------------------------------------------------------------------
79; Returns segment to RAMVARS.
80; RAMVARS might be located at the top of interrupt vectors (0030:0000h)
81; or at the top of system base RAM.
82;
83; RamVars_GetSegmentToDS
84; Parameters:
85; Nothing
86; Returns:
87; DS: RAMVARS segment
88; Corrupts registers:
89; DI
90;--------------------------------------------------------------------
91ALIGN JUMP_ALIGN
92RamVars_GetSegmentToDS:
93 test BYTE [cs:ROMVARS.wFlags], FLG_ROMVARS_FULLMODE
94 jnz SHORT .GetStolenSegmentToDS
95 mov di, LITE_MODE_RAMVARS_SEGMENT
96 mov ds, di
97 ret
98
99ALIGN JUMP_ALIGN
100.GetStolenSegmentToDS:
101 LOAD_BDA_SEGMENT_TO ds, di
102 mov di, [BDA.wBaseMem] ; Load available base memory size in kB
103 eSHL_IM di, 6 ; Segment to first stolen kB (*=40h)
104ALIGN JUMP_ALIGN
105.LoopStolenKBs:
106 mov ds, di ; EBDA segment to DS
107 add di, BYTE 64 ; DI to next stolen kB
108 cmp WORD [RAMVARS.wSignature], RAMVARS_SIGNATURE
109 jne SHORT .LoopStolenKBs ; Loop until sign found (always found eventually)
110 ret
111
112
113;--------------------------------------------------------------------
114; Checks if INT 13h function is handled by this BIOS.
115;
116; RamVars_IsFunctionHandledByThisBIOS
117; Parameters:
118; AH: INT 13h function number
119; DL: Drive number
120; DS: RAMVARS segment
121; Returns:
122; CF: Set if function is handled by this BIOS
123; Cleared if function belongs to some other BIOS
124; Corrupts registers:
125; Nothing
126;--------------------------------------------------------------------
127ALIGN JUMP_ALIGN
128RamVars_IsFunctionHandledByThisBIOS:
129 test ah, ah ; Reset for all floppy and hard disk drives?
130 jz SHORT .FunctionIsHandledByOurBIOS
131 cmp ah, 08h ; Read Disk Drive Parameters?
132 jne SHORT RamVars_IsDriveHandledByThisBIOS
133 test dl, dl ; We do not handle floppy drives
134 jns SHORT .FunctionIsNotHandledByOurBIOS
135ALIGN JUMP_ALIGN
136.FunctionIsHandledByOurBIOS:
137 stc
138.FunctionIsNotHandledByOurBIOS:
139 ret
140
141;--------------------------------------------------------------------
142; Checks if drive is handled by this BIOS.
143;
144; RamVars_IsDriveHandledByThisBIOS
145; Parameters:
146; DL: Drive number
147; DS: RAMVARS segment
148; Returns:
149; CF: Set if drive is handled by this BIOS
150; Cleared if drive belongs to some other BIOS
151; Corrupts registers:
152; Nothing
153;--------------------------------------------------------------------
154ALIGN JUMP_ALIGN
155RamVars_IsDriveHandledByThisBIOS:
156 push ax
157 mov ax, [RAMVARS.wDrvCntAndFirst] ; Drive count to AL, First number to AH
158 add al, ah ; One past last drive to AL
159 cmp dl, al ; Above last supported?
160 jae SHORT .DriveNotHandledByThisBIOS
161 cmp ah, dl ; Below first supported?
162 ja SHORT .DriveNotHandledByThisBIOS
163 stc
164.DriveNotHandledByThisBIOS:
165 pop ax
166 ret
167
168
169;--------------------------------------------------------------------
170; RamVars_GetHardDiskCountFromBDAtoCX
171; Parameters:
172; DS: RAMVARS segment
173; Returns:
174; CX: Total hard disk count
175; Corrupts registers:
176; Nothing
177;--------------------------------------------------------------------
178ALIGN JUMP_ALIGN
179RamVars_GetHardDiskCountFromBDAtoCX:
180 push es
181 push dx
182
183 LOAD_BDA_SEGMENT_TO es, cx, ! ; Zero CX
184 call RamVars_GetCountOfKnownDrivesToDL
185 MAX_U dl, [es:BDA.bHDCount]
186 mov cl, dl
187
188 pop dx
189 pop es
190 ret
191
192;--------------------------------------------------------------------
193; RamVars_GetCountOfKnownDrivesToDL
194; Parameters:
195; DS: RAMVARS segment
196; Returns:
197; DL: Total hard disk count
198; Corrupts registers:
199; Nothing
200;--------------------------------------------------------------------
201ALIGN JUMP_ALIGN
202RamVars_GetCountOfKnownDrivesToDL:
203 mov dl, [RAMVARS.bFirstDrv] ; Number for our first drive
204 add dl, [RAMVARS.bDrvCnt] ; Our drives
205 and dl, 7Fh ; Clear HD bit for drive count
206 ret
207
208
209;--------------------------------------------------------------------
210; RamVars_GetIdeControllerCountToCX
211; Parameters:
212; Nothing
213; Returns:
214; CX: Number of IDE controllers to handle
215; Corrupts registers:
216; Nothing
217;--------------------------------------------------------------------
218RamVars_GetIdeControllerCountToCX:
219 eMOVZX cx, BYTE [cs:ROMVARS.bIdeCnt]
220 ret
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