source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/VariablesAndDPTs/RamVars.asm@ 292

Last change on this file since 292 was 270, checked in by gregli@…, 13 years ago

Fixed a bug with the number of floppy drives reported, if there were no floppy drives emulated.
File size: 5.0 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 mov ax, LITE_MODE_RAMVARS_SEGMENT
34 test BYTE [cs:ROMVARS.wFlags], FLG_ROMVARS_FULLMODE
35 jz SHORT .InitializeRamvars ; No need to steal RAM
36
37 LOAD_BDA_SEGMENT_TO ds, ax, ! ; Zero AX
38 mov al, [cs:ROMVARS.bStealSize]
39 sub [BDA.wBaseMem], ax
40 mov ax, [BDA.wBaseMem]
41 eSHL_IM ax, 6 ; Segment to first stolen kB (*=40h)
42 ; Fall to .InitializeRamvars
43
44;--------------------------------------------------------------------
45; .InitializeRamvars
46; Parameters:
47; AX: RAMVARS segment
48; Returns:
49; DS: RAMVARS segment
50; Corrupts registers:
51; AX, CX, DI, ES
52;--------------------------------------------------------------------
53.InitializeRamvars:
54 mov ds, ax
55 mov es, ax
56 mov cx, RAMVARS_size
57 xor di, di
58 call Memory_ZeroESDIwithSizeInCX
59 mov WORD [RAMVARS.wSignature], RAMVARS_SIGNATURE
60 ; Fall to .InitializeDriveTranslationAndReturn
61
62;--------------------------------------------------------------------
63; .InitializeDriveTranslationAndReturn
64; Parameters:
65; DS: RAMVARS segment
66; Returns:
67; Nothing
68; Corrupts registers:
69; AX
70;--------------------------------------------------------------------
71.InitializeDriveTranslationAndReturn:
72 pop es
73 jmp DriveXlate_Reset
74
75
76;--------------------------------------------------------------------
77; Returns segment to RAMVARS.
78; RAMVARS might be located at the top of interrupt vectors (0030:0000h)
79; or at the top of system base RAM.
80;
81; RamVars_GetSegmentToDS
82; Parameters:
83; Nothing
84; Returns:
85; DS: RAMVARS segment
86; Corrupts registers:
87; DI
88;--------------------------------------------------------------------
89ALIGN JUMP_ALIGN
90RamVars_GetSegmentToDS:
91 test BYTE [cs:ROMVARS.wFlags], FLG_ROMVARS_FULLMODE
92 jnz SHORT .GetStolenSegmentToDS
93%ifndef USE_186
94 mov di, LITE_MODE_RAMVARS_SEGMENT
95 mov ds, di
96%else
97 push LITE_MODE_RAMVARS_SEGMENT
98 pop ds
99%endif
100 ret
101
102ALIGN JUMP_ALIGN
103.GetStolenSegmentToDS:
104 LOAD_BDA_SEGMENT_TO ds, di
105 mov di, [BDA.wBaseMem] ; Load available base memory size in kB
106 eSHL_IM di, 6 ; Segment to first stolen kB (*=40h)
107ALIGN JUMP_ALIGN
108.LoopStolenKBs:
109 mov ds, di ; EBDA segment to DS
110 add di, BYTE 64 ; DI to next stolen kB
111 cmp WORD [RAMVARS.wSignature], RAMVARS_SIGNATURE
112 jne SHORT .LoopStolenKBs ; Loop until sign found (always found eventually)
113 ret
114
115
116;--------------------------------------------------------------------
117; RamVars_GetHardDiskCountFromBDAtoAX
118; Parameters:
119; DS: RAMVARS segment
120; Returns:
121; AX: Total hard disk count
122; Corrupts registers:
123; CX
124;--------------------------------------------------------------------
125ALIGN JUMP_ALIGN
126RamVars_GetHardDiskCountFromBDAtoAX:
127 push es
128
129 LOAD_BDA_SEGMENT_TO es, ax
130 call RamVars_GetCountOfKnownDrivesToAX
131 mov cl, [es:BDA.bHDCount]
132 MAX_U al, cl
133
134 pop es
135 ret
136
137;--------------------------------------------------------------------
138; RamVars_GetCountOfKnownDrivesToAX
139; Parameters:
140; DS: RAMVARS segment
141; Returns:
142; AX: Total hard disk count
143; Corrupts registers:
144; None
145;--------------------------------------------------------------------
146ALIGN JUMP_ALIGN
147RamVars_GetCountOfKnownDrivesToAX:
148 mov ax, [RAMVARS.wDrvCntAndFirst]
149 add al, ah
150 and al, 7fh
151 cbw
152 ret
153
154;--------------------------------------------------------------------
155; RamVars_GetIdeControllerCountToCX
156; Parameters:
157; Nothing
158; Returns:
159; CX: Number of IDE controllers to handle
160; Corrupts registers:
161; Nothing
162;--------------------------------------------------------------------
163ALIGN JUMP_ALIGN
164RamVars_GetIdeControllerCountToCX:
165 eMOVZX cx, BYTE [cs:ROMVARS.bIdeCnt]
166 ret
167
168%ifdef MODULE_SERIAL_FLOPPY
169;--------------------------------------------------------------------
170; RamVars_UnpackFlopCntAndFirstToAL
171; Parameters:
172; Nothing
173; Returns:
174; AL: First floppy drive number supported
175; CF: Number of floppy drives supported (clear = 1, set = 2)
176; SF: Emulating drives (clear = yes, set = no)
177; Corrupts registers:
178; Nothing
179;--------------------------------------------------------------------
180ALIGN JUMP_ALIGN
181RamVars_UnpackFlopCntAndFirstToAL:
182 mov al, [RAMVARS.xlateVars+XLATEVARS.bFlopCntAndFirst]
183 sar al, 1
184 ret
185%endif
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