source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/VariablesAndDPTs/FindDPT.asm@ 266

Last change on this file since 266 was 265, checked in by aitotat@…, 12 years ago

Changes to XTIDE Universal BIOS:

  • Now builds without serial module.
File size: 6.6 KB
RevLine 
[150]1; Project name : XTIDE Universal BIOS
[3]2; Description : Functions for finding Disk Parameter Table.
3
4; Section containing code
5SECTION .text
6
7;--------------------------------------------------------------------
[262]8; Checks if drive is handled by this BIOS, and return DPT pointer.
[3]9;
[262]10; FindDPT_ForDriveNumberInDL
[3]11; Parameters:
[262]12; DL: Drive number
[3]13; DS: RAMVARS segment
14; Returns:
[262]15; CF: Cleared if drive is handled by this BIOS
16; Set if drive belongs to some other BIOS
17; DI: DPT Pointer if drive is handled by this BIOS
18; Zero if drive belongs to some other BIOS
[3]19; Corrupts registers:
[262]20; Nothing
[150]21;--------------------------------------------------------------------
22ALIGN JUMP_ALIGN
[262]23FindDPT_ForDriveNumberInDL:
24 xchg di, ax ; Save the contents of AX in DI
25
26;
27; Check Our Hard Disks
28;
29 mov ax, [RAMVARS.wDrvCntAndFirst] ; Drive count to AH, First number to AL
30 add ah, al ; One past last drive to AH
31
[258]32%ifdef MODULE_SERIAL_FLOPPY
[262]33 cmp dl, ah ; Above last supported?
34 jae SHORT .HardDiskNotHandledByThisBIOS
35
36 cmp dl, al ; Below first supported?
37 jae SHORT .CalcDPTForDriveNumber
38
39ALIGN JUMP_ALIGN
40.HardDiskNotHandledByThisBIOS:
41;
42; Check Our Floppy Disks
43;
44 call RamVars_UnpackFlopCntAndFirstToAL
45 cbw ; normally 0h, could be ffh if no drives present
46 adc ah, al ; if no drives present, still ffh (ffh + ffh + 1 = ffh)
47 js SHORT .DiskIsNotHandledByThisBIOS
48 cmp ah, dl ; Check second drive if two, first drive if only one
49 jz SHORT .CalcDPTForDriveNumber
50 cmp al, dl ; Check first drive in all cases, redundant but OK to repeat
51 jnz SHORT .DiskIsNotHandledByThisBIOS
52%else
53 cmp dl, ah ; Above last supported?
54 jae SHORT .DiskIsNotHandledByThisBIOS
55
56 cmp dl, al ; Below first supported?
57 jb SHORT .DiskIsNotHandledByThisBIOS
[258]58%endif
[262]59 ; fall-through to CalcDPTForDriveNumber
[150]60
61;--------------------------------------------------------------------
62; Finds Disk Parameter Table for drive number.
[262]63; Note intended to be called except by FindDPT_ForDriveNumber
[150]64;
[262]65; CalcDPTForDriveNumber
[150]66; Parameters:
67; DL: Drive number
68; DS: RAMVARS segment
[262]69; DI: Saved copy of AX from entry at FindDPT_ForDriveNumber
[150]70; Returns:
71; DS:DI: Ptr to DPT
[262]72; CF: Clear
[150]73; Corrupts registers:
[3]74; Nothing
75;--------------------------------------------------------------------
76ALIGN JUMP_ALIGN
[262]77.CalcDPTForDriveNumber:
[150]78 push dx
[3]79
[258]80%ifdef MODULE_SERIAL_FLOPPY
81 mov ax, [RAMVARS.wDrvCntAndFirst]
82
83 test dl, dl
84 js .harddisk
85
86 call RamVars_UnpackFlopCntAndFirstToAL
87 add dl, ah ; add in end of hard disk DPT list, floppies start immediately after
[262]88
89ALIGN JUMP_ALIGN
[258]90.harddisk:
91 sub dl, al ; subtract off beginning of either hard disk or floppy list (as appropriate)
92%else
93 sub dl, [RAMVARS.bFirstDrv] ; subtract off beginning of hard disk list
94%endif
[262]95
96.CalcDPTForNewDrive:
[150]97 mov al, LARGEST_DPT_SIZE
[258]98
[150]99 mul dl
[262]100 add ax, BYTE RAMVARS_size ; Clears CF (will not oveflow)
[3]101
[150]102 pop dx
[262]103
104 xchg di, ax ; Restore AX from entry at FindDPT_ForDriveNumber, put DPT pointer in DI
[150]105 ret
106
[262]107ALIGN JUMP_ALIGN
108.DiskIsNotHandledByThisBIOS:
[259]109;
[262]110; Drive not found...
111;
112 xor ax, ax ; Clear DPT pointer
113 stc ; Is not supported by our BIOS
114
115 xchg di, ax ; Restore AX from save at top
[259]116 ret
117
118;--------------------------------------------------------------------
[262]119; Finds pointer to first unused Disk Parameter Table.
120; Should only be used before DetectDrives is complete (not valid after this time).
[3]121;
[262]122; FindDPT_ForNewDriveToDSDI
[3]123; Parameters:
124; DS: RAMVARS segment
125; Returns:
[262]126; DS:DI: Ptr to first unused DPT
[3]127; Corrupts registers:
[262]128; AX
[3]129;--------------------------------------------------------------------
[262]130ALIGN JUMP_ALIGN
131FindDPT_ForNewDriveToDSDI:
132 push dx
[200]133
[262]134%ifdef MODULE_SERIAL_FLOPPY
135 mov dx, [RAMVARS.wDrvCntAndFlopCnt]
136 add dl, dh
137%else
138 mov dl, [RAMVARS.bDrvCnt]
139%endif
140
141 jmp short FindDPT_ForDriveNumberInDL.CalcDPTForNewDrive
[3]142
[152]143;--------------------------------------------------------------------
[233]144; IterateToDptWithFlagsHighInBL
[152]145; Parameters:
146; DS:DI: Ptr to DPT to examine
[233]147; BL: Bit(s) to test in DPT.bFlagsHigh
[152]148; Returns:
[262]149; CF: Clear if wanted DPT found
150; Set if wrong DPT
[152]151; Corrupts registers:
152; Nothing
153;--------------------------------------------------------------------
154ALIGN JUMP_ALIGN
[233]155IterateToDptWithFlagsHighInBL:
[262]156 test BYTE [di+DPT.bFlagsHigh], bl ; Clears CF
157 jnz SHORT .ReturnRightDPT
158 stc
159.ReturnRightDPT:
[3]160 ret
161
162;--------------------------------------------------------------------
[233]163; FindDPT_ToDSDIforSerialDevice
[161]164; Parameters:
165; DS: RAMVARS segment
166; Returns:
167; DS:DI: Ptr to DPT
168; CF: Set if wanted DPT found
169; Cleared if DPT not found
170; Corrupts registers:
[203]171; SI
[161]172;--------------------------------------------------------------------
[265]173%ifdef MODULE_SERIAL
[233]174ALIGN JUMP_ALIGN
175FindDPT_ToDSDIforSerialDevice:
176 mov bl, FLGH_DPT_SERIAL_DEVICE
177; fall-through
[265]178%endif
[233]179
180;--------------------------------------------------------------------
181; FindDPT_ToDSDIforFlagsHigh
182; Parameters:
183; DS: RAMVARS segment
184; BL: Bit(s) to test in DPT.bFlagsHigh
185; Returns:
186; DS:DI: Ptr to DPT
187; CF: Set if wanted DPT found
188; Cleared if DPT not found
189; Corrupts registers:
190; SI
191;--------------------------------------------------------------------
[161]192ALIGN JUMP_ALIGN
[233]193FindDPT_ToDSDIforFlagsHighInBL:
194 mov si, IterateToDptWithFlagsHighInBL
[161]195 ; Fall to IterateAllDPTs
196
197;--------------------------------------------------------------------
[3]198; Iterates all Disk Parameter Tables.
199;
[150]200; IterateAllDPTs
[3]201; Parameters:
[152]202; AX,BX,DX: Parameters to callback function
203; CS:SI: Ptr to callback function
[262]204; Callback routine should return CF=clear if found
[152]205; DS: RAMVARS segment
[3]206; Returns:
[152]207; DS:DI: Ptr to wanted DPT (if found)
[258]208; If not found, points to first empty DPT
[262]209; CF: Clear if wanted DPT found
210; Set if DPT not found, or no DPTs present
[3]211; Corrupts registers:
[150]212; Nothing unless corrupted by callback function
[3]213;--------------------------------------------------------------------
214ALIGN JUMP_ALIGN
[150]215IterateAllDPTs:
[3]216 push cx
[258]217
218 mov di, RAMVARS_size ; Point DS:DI to first DPT
219
[259]220 mov cl, [RAMVARS.bDrvCnt]
221 xor ch, ch ; Clears CF
[258]222
[262]223 jcxz .NotFound ; Return if no drives
[259]224
[3]225ALIGN JUMP_ALIGN
226.LoopWhileDPTsLeft:
227 call si ; Is wanted DPT?
[262]228 jnc SHORT .Found ; If so, return
229 add di, BYTE LARGEST_DPT_SIZE ; Point to next DPT
[258]230 loop .LoopWhileDPTsLeft
[262]231
[3]232ALIGN JUMP_ALIGN
[262]233.NotFound:
234 stc
235
236ALIGN JUMP_ALIGN
237.Found:
[3]238 pop cx
239 ret
[259]240
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