source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/VariablesAndDPTs/RamVars.asm@ 102

Last change on this file since 102 was 99, checked in by Tomi Tilli, 14 years ago

Changes to XTIDE Universal BIOS:

  • Even more initialization code inlining.
File size: 6.8 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 [FULLRAMVARS.wSign], W_SIGN_FULLRAMVARS
43 ; Fall to .InitializeRamvarsFromDS
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 ; Fall to .InitializeDriveTranslationAndReturn
62
63;--------------------------------------------------------------------
64; .InitializeDriveTranslationAndReturn
65; Parameters:
66; DS: RAMVARS segment
67; Returns:
68; Nothing
69; Corrupts registers:
70; AX
71;--------------------------------------------------------------------
72.InitializeDriveTranslationAndReturn:
73 pop es
74 jmp DriveXlate_Reset
75
76
77;--------------------------------------------------------------------
78; Returns segment to RAMVARS.
79; RAMVARS might be located at the top of interrupt vectors (0030:0000h)
80; or at the top of system base RAM.
81;
82; RamVars_GetSegmentToDS
83; Parameters:
84; Nothing
85; Returns:
86; DS: RAMVARS segment
87; Corrupts registers:
88; DI
89;--------------------------------------------------------------------
90ALIGN JUMP_ALIGN
91RamVars_GetSegmentToDS:
92 test BYTE [cs:ROMVARS.wFlags], FLG_ROMVARS_FULLMODE
93 jnz SHORT .GetStolenSegmentToDS
94 mov di, SEGMENT_RAMVARS_TOP_OF_INTERRUPT_VECTORS
95 mov ds, di
96 ret
97
98ALIGN JUMP_ALIGN
99.GetStolenSegmentToDS:
100 LOAD_BDA_SEGMENT_TO ds, di
101 mov di, [BDA.wBaseMem] ; Load available base memory size in kB
102 eSHL_IM di, 6 ; Segment to first stolen kB (*=40h)
103ALIGN JUMP_ALIGN
104.LoopStolenKBs:
105 mov ds, di ; EBDA segment to DS
106 add di, BYTE 64 ; DI to next stolen kB
107 cmp WORD [FULLRAMVARS.wSign], W_SIGN_FULLRAMVARS
108 jne SHORT .LoopStolenKBs ; Loop until sign found (always found eventually)
109 ret
110
111
112;--------------------------------------------------------------------
113; Checks if INT 13h function is handled by this BIOS.
114;
115; RamVars_IsFunctionHandledByThisBIOS
116; Parameters:
117; AH: INT 13h function number
118; DL: Drive number
119; DS: RAMVARS segment
120; Returns:
121; CF: Set if function is handled by this BIOS
122; Cleared if function belongs to some other BIOS
123; Corrupts registers:
124; DI
125;--------------------------------------------------------------------
126ALIGN JUMP_ALIGN
127RamVars_IsFunctionHandledByThisBIOS:
128 test ah, ah ; Reset for all floppy and hard disk drives?
129 jz SHORT .FunctionIsHandledByOurBIOS
130 cmp ah, 08h ; Read Disk Drive Parameters?
131 jne SHORT RamVars_IsDriveHandledByThisBIOS
132 test dl, 80h ; We dot not handle floppy drives
133 jz SHORT .FunctionIsNotHandledByOurBIOS
134ALIGN JUMP_ALIGN
135.FunctionIsHandledByOurBIOS:
136 stc
137.FunctionIsNotHandledByOurBIOS:
138 ret
139
140;--------------------------------------------------------------------
141; Checks if drive is handled by this BIOS.
142;
143; RamVars_IsDriveHandledByThisBIOS
144; Parameters:
145; DL: Drive number
146; DS: RAMVARS segment
147; Returns:
148; CF: Set if drive is handled by this BIOS
149; Cleared if drive belongs to some other BIOS
150; Corrupts registers:
151; DI
152;--------------------------------------------------------------------
153ALIGN JUMP_ALIGN
154RamVars_IsDriveHandledByThisBIOS:
155 xchg di, ax ; Backup AX
156 mov ax, [RAMVARS.wDrvCntAndFirst] ; Drive count to AL, First number to AH
157 add al, ah ; One past last drive to AL
158 cmp dl, al ; Above last supported?
159 jae SHORT .DriveNotHandledByThisBIOS
160 cmp dl, ah ; Below first supported?
161 jb SHORT .DriveNotHandledByThisBIOS
162 xchg ax, di
163 stc
164 ret
165ALIGN JUMP_ALIGN
166.DriveNotHandledByThisBIOS:
167 xchg ax, di
168 clc
169 ret
170
171
172;--------------------------------------------------------------------
173; RamVars_IncrementHardDiskCount
174; Parameters:
175; DL: Drive number for new drive
176; DS: RAMVARS segment
177; Returns:
178; Nothing
179; Corrupts registers:
180; Nothing
181;--------------------------------------------------------------------
182RamVars_IncrementHardDiskCount:
183 inc BYTE [RAMVARS.bDrvCnt] ; Increment drive count to RAMVARS
184 cmp BYTE [RAMVARS.bFirstDrv], 0 ; First drive set?
185 ja SHORT .Return ; If so, return
186 mov [RAMVARS.bFirstDrv], dl ; Store first drive number
187.Return:
188 ret
189
190
191;--------------------------------------------------------------------
192; RamVars_GetHardDiskCountFromBDAtoCX
193; Parameters:
194; DS: RAMVARS segment
195; Returns:
196; CX: Total hard disk count
197; Corrupts registers:
198; Nothing
199;--------------------------------------------------------------------
200ALIGN JUMP_ALIGN
201RamVars_GetHardDiskCountFromBDAtoCX:
202 push es
203 push dx
204
205 LOAD_BDA_SEGMENT_TO es, cx ; Zero CX
206 call RamVars_GetCountOfKnownDrivesToDL
207 MAX_U dl, [es:BDA.bHDCount]
208 mov cl, dl
209
210 pop dx
211 pop es
212 ret
213
214;--------------------------------------------------------------------
215; RamVars_GetCountOfKnownDrivesToDL
216; Parameters:
217; DS: RAMVARS segment
218; Returns:
219; DL: Total hard disk count
220; Corrupts registers:
221; Nothing
222;--------------------------------------------------------------------
223ALIGN JUMP_ALIGN
224RamVars_GetCountOfKnownDrivesToDL:
225 mov dl, [RAMVARS.bFirstDrv] ; Number for our first drive
226 add dl, [RAMVARS.bDrvCnt] ; Our drives
227 and dl, 7Fh ; Clear HD bit for drive count
228 ret
229
230
231;--------------------------------------------------------------------
232; RamVars_GetIdeControllerCountToCX
233; Parameters:
234; Nothing
235; Returns:
236; CX: Number of IDE controllers to handle
237; Corrupts registers:
238; Nothing
239;--------------------------------------------------------------------
240RamVars_GetIdeControllerCountToCX:
241 eMOVZX cx, BYTE [cs:ROMVARS.bIdeCnt]
242 ret
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