source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/VariablesAndDPTs/FindDPT.asm@ 420

Last change on this file since 420 was 376, checked in by gregli@…, 13 years ago

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1; Project name : XTIDE Universal BIOS
2; Description : Functions for finding Disk Parameter Table.
3
4;
5; XTIDE Universal BIOS and Associated Tools
6; Copyright (C) 2009-2010 by Tomi Tilli, 2011-2012 by XTIDE Universal BIOS Team.
7;
8; This program is free software; you can redistribute it and/or modify
9; it under the terms of the GNU General Public License as published by
10; the Free Software Foundation; either version 2 of the License, or
11; (at your option) any later version.
12;
13; This program is distributed in the hope that it will be useful,
14; but WITHOUT ANY WARRANTY; without even the implied warranty of
15; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16; GNU General Public License for more details.
17; Visit http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
18;
19
20; Section containing code
21SECTION .text
22
23;--------------------------------------------------------------------
24; Checks if drive is handled by this BIOS, and return DPT pointer.
25;
26; FindDPT_ForDriveNumberInDL
27; Parameters:
28; DL: Drive number
29; DS: RAMVARS segment
30; Returns:
31; CF: Cleared if drive is handled by this BIOS
32; Set if drive belongs to some other BIOS
33; DI: DPT Pointer if drive is handled by this BIOS
34; Zero if drive belongs to some other BIOS
35; Corrupts registers:
36; Nothing
37;--------------------------------------------------------------------
38ALIGN JUMP_ALIGN
39FindDPT_ForDriveNumberInDL:
40 xchg di, ax ; Save the contents of AX in DI
41
42;
43; Check Our Hard Disks
44;
45 mov ax, [RAMVARS.wDrvCntAndFirst] ; Drive count to AH, First number to AL
46 add ah, al ; One past last drive to AH
47
48%ifdef MODULE_SERIAL_FLOPPY
49 cmp dl, ah ; Above last supported?
50 jae SHORT .HardDiskNotHandledByThisBIOS
51
52 cmp dl, al ; Below first supported?
53 jae SHORT .CalcDPTForDriveNumber
54
55ALIGN JUMP_ALIGN
56.HardDiskNotHandledByThisBIOS:
57;
58; Check Our Floppy Disks
59;
60 call RamVars_UnpackFlopCntAndFirstToAL
61 js SHORT .DiskIsNotHandledByThisBIOS
62
63 cbw ; Always 0h (no floppy drive covered above)
64 adc ah, al ; Add in first drive number and number of drives
65
66 cmp ah, dl ; Check second drive if two, first drive if only one
67 jz SHORT .CalcDPTForDriveNumber
68 cmp al, dl ; Check first drive in all cases, redundant but OK to repeat
69 jnz SHORT .DiskIsNotHandledByThisBIOS
70%else
71 cmp dl, ah ; Above last supported?
72 jae SHORT .DiskIsNotHandledByThisBIOS
73
74 cmp dl, al ; Below first supported?
75 jb SHORT .DiskIsNotHandledByThisBIOS
76%endif
77 ; fall-through to CalcDPTForDriveNumber
78
79;--------------------------------------------------------------------
80; Finds Disk Parameter Table for drive number.
81; Not intended to be called except by FindDPT_ForDriveNumberInDL
82;
83; CalcDPTForDriveNumber
84; Parameters:
85; DL: Drive number
86; DS: RAMVARS segment
87; DI: Saved copy of AX from entry at FindDPT_ForDriveNumberInDL
88; Returns:
89; DS:DI: Ptr to DPT
90; CF: Clear
91; Corrupts registers:
92; Nothing
93;--------------------------------------------------------------------
94ALIGN JUMP_ALIGN
95.CalcDPTForDriveNumber:
96 push dx
97
98%ifdef MODULE_SERIAL_FLOPPY
99 mov ax, [RAMVARS.wDrvCntAndFirst]
100
101 test dl, dl
102 js .harddisk
103
104 call RamVars_UnpackFlopCntAndFirstToAL
105 add dl, ah ; add in end of hard disk DPT list, floppies start immediately after
106
107ALIGN JUMP_ALIGN
108.harddisk:
109 sub dl, al ; subtract off beginning of either hard disk or floppy list (as appropriate)
110%else
111 sub dl, [RAMVARS.bFirstDrv] ; subtract off beginning of hard disk list
112%endif
113
114.CalcDPTForNewDrive:
115 mov al, LARGEST_DPT_SIZE
116
117 mul dl
118 add ax, BYTE RAMVARS_size ; Clears CF (will not overflow)
119
120 pop dx
121
122 xchg di, ax ; Restore AX from entry at FindDPT_ForDriveNumber, put DPT pointer in DI
123 ret
124
125ALIGN JUMP_ALIGN
126.DiskIsNotHandledByThisBIOS:
127;
128; Drive not found...
129;
130 xor ax, ax ; Clear DPT pointer
131 stc ; Is not supported by our BIOS
132
133 xchg di, ax ; Restore AX from save at top
134 ret
135
136
137;--------------------------------------------------------------------
138; FindDPT_ForIdevarsOffsetInDL
139; Parameters:
140; DL: Offset to IDEVARS to search for
141; DS: RAMVARS segment
142; Returns:
143; DS:DI: Ptr to first DPT with same IDEVARS as in DL
144; CF: Clear if wanted DPT found
145; Set if DPT not found, or no DPTs present
146; Corrupts registers:
147; SI
148;--------------------------------------------------------------------
149FindDPT_ForIdevarsOffsetInDL:
150 mov si, IterateFindFirstDPTforIdevars ; iteration routine (see below)
151 jmp SHORT FindDPT_IterateAllDPTs ; look for the first drive on this controller, if any
152
153;--------------------------------------------------------------------
154; Iteration routine for FindDPT_ForIdevarsOffsetInDL,
155; for use with IterateAllDPTs
156;
157; Returns when DPT is found on the controller with Idevars offset in DL
158;
159; IterateFindFirstDPTforIdevars
160; DL: Offset to IDEVARS to search from DPTs
161; DS:DI: Ptr to DPT to examine
162; Returns:
163; CF: Clear if wanted DPT found
164; Set if wrong DPT
165;--------------------------------------------------------------------
166IterateFindFirstDPTforIdevars:
167 cmp dl, [di+DPT.bIdevarsOffset] ; Clears CF if matched
168 je .done
169 stc ; Set CF for not found
170.done:
171 ret
172
173
174;--------------------------------------------------------------------
175; Finds pointer to first unused Disk Parameter Table.
176; Should only be used before DetectDrives is complete (not valid after this time).
177;
178; FindDPT_ForNewDriveToDSDI
179; Parameters:
180; DS: RAMVARS segment
181; Returns:
182; DS:DI: Ptr to first unused DPT
183; Corrupts registers:
184; AX
185;--------------------------------------------------------------------
186ALIGN JUMP_ALIGN
187FindDPT_ForNewDriveToDSDI:
188 push dx
189
190%ifdef MODULE_SERIAL_FLOPPY
191 mov dx, [RAMVARS.wDrvCntAndFlopCnt]
192 add dl, dh
193%else
194 mov dl, [RAMVARS.bDrvCnt]
195%endif
196
197 jmp short FindDPT_ForDriveNumberInDL.CalcDPTForNewDrive
198
199;--------------------------------------------------------------------
200; IterateToDptWithFlagsHighInBL
201; Parameters:
202; DS:DI: Ptr to DPT to examine
203; BL: Bit(s) to test in DPT.bFlagsHigh
204; Returns:
205; CF: Clear if wanted DPT found
206; Set if wrong DPT
207; Corrupts registers:
208; Nothing
209;--------------------------------------------------------------------
210ALIGN JUMP_ALIGN
211IterateToDptWithFlagsHighInBL:
212 test [di+DPT.bFlagsHigh], bl ; Clears CF
213 jnz SHORT .ReturnRightDPT
214 stc
215.ReturnRightDPT:
216 ret
217
218;--------------------------------------------------------------------
219; FindDPT_ToDSDIforSerialDevice
220; Parameters:
221; DS: RAMVARS segment
222; Returns:
223; DS:DI: Ptr to DPT
224; CF: Set if wanted DPT found
225; Cleared if DPT not found
226; Corrupts registers:
227; SI
228;--------------------------------------------------------------------
229%ifdef MODULE_SERIAL
230ALIGN JUMP_ALIGN
231FindDPT_ToDSDIforSerialDevice:
232 mov bl, FLGH_DPT_SERIAL_DEVICE
233; fall-through
234%endif
235
236;--------------------------------------------------------------------
237; FindDPT_ToDSDIforFlagsHigh
238; Parameters:
239; DS: RAMVARS segment
240; BL: Bit(s) to test in DPT.bFlagsHigh
241; Returns:
242; DS:DI: Ptr to DPT
243; CF: Set if wanted DPT found
244; Cleared if DPT not found
245; Corrupts registers:
246; SI
247;--------------------------------------------------------------------
248ALIGN JUMP_ALIGN
249FindDPT_ToDSDIforFlagsHighInBL:
250 mov si, IterateToDptWithFlagsHighInBL
251 ; Fall to IterateAllDPTs
252
253;--------------------------------------------------------------------
254; Iterates all Disk Parameter Tables.
255;
256; FindDPT_IterateAllDPTs
257; Parameters:
258; AX,BX,DX: Parameters to callback function
259; CS:SI: Ptr to callback function
260; Callback routine should return CF=clear if found
261; DS: RAMVARS segment
262; Returns:
263; DS:DI: Ptr to wanted DPT (if found)
264; If not found, points to first empty DPT
265; CF: Clear if wanted DPT found
266; Set if DPT not found, or no DPTs present
267; Corrupts registers:
268; Nothing unless corrupted by callback function
269;--------------------------------------------------------------------
270ALIGN JUMP_ALIGN
271FindDPT_IterateAllDPTs:
272 push cx
273
274 mov di, RAMVARS_size ; Point DS:DI to first DPT
275 eMOVZX cx, [RAMVARS.bDrvCnt]
276 jcxz .NotFound ; Return if no drives
277
278ALIGN JUMP_ALIGN
279.LoopWhileDPTsLeft:
280 call si ; Is wanted DPT?
281 jnc SHORT .Found ; If so, return
282 add di, BYTE LARGEST_DPT_SIZE ; Point to next DPT
283 loop .LoopWhileDPTsLeft
284
285ALIGN JUMP_ALIGN
286.NotFound:
287 stc
288
289ALIGN JUMP_ALIGN
290.Found:
291 pop cx
292 ret
293
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