source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/Handlers/Int13h/AH8h_HParams.asm@ 3

Last change on this file since 3 was 3, checked in by Tomi Tilli, 14 years ago
File size: 3.7 KB
Line 
1; File name : AH8h_HParams.asm
2; Project name : IDE BIOS
3; Created date : 27.9.2007
4; Last update : 12.4.2010
5; Author : Tomi Tilli
6; Description : Int 13h function AH=8h, Read Disk Drive Parameters.
7
8; Section containing code
9SECTION .text
10
11;--------------------------------------------------------------------
12; Int 13h function AH=8h, Read Disk Drive Parameters.
13;
14; AH8h_HandlerForReadDiskDriveParameters
15; Parameters:
16; AH: Bios function 8h
17; DL: Drive number
18; Parameters loaded by Int13h_Jump:
19; DS: RAMVARS segment
20; Returns:
21; CH: Maximum cylinder number, bits 7...0
22; CL: Bits 7...6: Cylinder number bits 9...8
23; Bits 5...0: Maximum sector number (1...63)
24; DH: Maximum head number (0...255)
25; DL: Number of drives
26; AH: Int 13h/40h floppy return status
27; CF: 0 if successfull, 1 if error
28; IF: 1
29; Corrupts registers:
30; Flags
31;--------------------------------------------------------------------
32ALIGN JUMP_ALIGN
33AH8h_HandlerForReadDiskDriveParameters:
34 push bx
35 call AH8h_GetDriveParameters
36 pop bx
37 jmp Int13h_ReturnWithoutSwappingDrives
38
39
40;--------------------------------------------------------------------
41; Returns L-CHS parameters for drive and total hard disk count.
42;
43; AH8h_HParams
44; Parameters:
45; DL: Drive number
46; DS: RAMVARS segment
47; Returns:
48; CH: Maximum cylinder number, bits 7...0
49; CL: Bits 7...6: Cylinder number bits 9...8
50; Bits 5...0: Maximum sector number (1...63)
51; DH: Maximum head number (0...255)
52; DL: Number of drives
53; DS:DI: Ptr to DPT
54; AH: Int 13h/40h floppy return status
55; CF: 0 if successfull, 1 if error
56; Corrupts registers:
57; AL, BX
58;--------------------------------------------------------------------
59ALIGN JUMP_ALIGN
60AH8h_GetDriveParameters:
61 call FindDPT_ForDriveNumber
62 call AccessDPT_GetLCHSfromPCHS ; AX=sectors, BX=cylinders, DX=heads
63 call AH8h_ReserveCylinders
64 call AH8h_PackReturnValues
65 xor ax, ax ; Clear AH and CF
66 ret
67
68
69;--------------------------------------------------------------------
70; Reserves diagnostic cylinder if so configured.
71;
72; AH8h_ReserveCylinders
73; Parameters:
74; BX: Total number of L-CHS cylinders available
75; DS:DI: Ptr to DPT
76; Returns:
77; BX: Number of L-CHS cylinders available after reserving
78; Corrupts registers:
79; CX
80;--------------------------------------------------------------------
81ALIGN JUMP_ALIGN
82AH8h_ReserveCylinders:
83 test BYTE [cs:ROMVARS.wFlags], FLG_ROMVARS_MAXSIZE
84 jnz SHORT .Return
85 dec bx ; Reserve diagnostic cylinder
86ALIGN JUMP_ALIGN
87.Return:
88 ret
89
90
91;--------------------------------------------------------------------
92; Packs L-CHS values to INT 13h, AH=08h return values.
93;
94; AH8h_PackReturnValues
95; Parameters:
96; AX: Number of L-CHS sectors per track (1...63)
97; BX: Number of L-CHS cylinders available (1...1024)
98; DX: Number of L-CHS heads (1...256)
99; Returns:
100; CH: Maximum cylinder number, bits 7...0
101; CL: Bits 7...6: Cylinder number bits 9...8
102; Bits 5...0: Maximum sector number (1...63)
103; DH: Maximum head number (0...255)
104; DL: Number of drives
105; Corrupts registers:
106; AX, BX
107;--------------------------------------------------------------------
108ALIGN JUMP_ALIGN
109AH8h_PackReturnValues:
110 dec bx ; Cylinder count to last cylinder
111 dec dx ; Head count to max head number
112 mov dh, dl ; Max head number to DH
113 push ax
114 call RamVars_GetDriveCounts ; Hard disk count to CX
115 pop ax
116 mov dl, cl ; Hard disk count to DL
117 mov ch, bl ; Cylinder bits 7...0 to CH
118 mov cl, bh ; Cylinder bits 9...8 to CL
119 eROR_IM cl, 2 ; Cylinder bits 9...8 to CL bits 7...6
120 or cl, al ; Sectors per track to CL bits 5...0
121 ret
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