source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/Handlers/Int13h/Tools/Address.asm@ 221

Last change on this file since 221 was 200, checked in by gregli@…, 13 years ago

Added logic to skip scanning COM ports if a COM port was already found during the normal detection process, to avoid finding the same serial drive twice and preseting the OS with two drives which in reality point to the same physical file on the server. Also added logic to skip scanning for the slave serial drive if the master was not found. And various small optimizations.
File size: 5.6 KB
Line 
1; Project name : XTIDE Universal BIOS
2; Description : Functions for address translations.
3
4; Section containing code
5SECTION .text
6
7;---------------------------------------------------------------------
8; Address_ExtractLCHSparametersFromOldInt13hAddress
9; Parameters:
10; CH: Cylinder number, bits 7...0
11; CL: Bits 7...6: Cylinder number bits 9 and 8
12; Bits 5...0: Sector number
13; DH: Head number
14; Returns:
15; BL: Sector number (1...63)
16; BH: Head number (0...255)
17; CX: Cylinder number (0...1023)
18; Corrupts registers:
19; Nothing
20;--------------------------------------------------------------------
21ALIGN JUMP_ALIGN
22Address_ExtractLCHSparametersFromOldInt13hAddress:
23 mov bl, cl ; Copy sector number...
24 and bl, 3Fh ; ...and limit to 1...63
25 sub cl, bl ; Remove from cylinder number high
26 eROL_IM cl, 2 ; High bits to beginning
27 mov bh, dh ; Copy Head number
28 xchg cl, ch ; Cylinder number now in CX
29 ret
30
31
32;---------------------------------------------------------------------
33; Converts LCHS parameters to IDE P-CHS parameters.
34; PCylinder = (LCylinder << n) + (LHead / PHeadCount)
35; PHead = LHead % PHeadCount
36; PSector = LSector
37;
38; Address_ConvertLCHStoPCHS:
39; Parameters:
40; BL: Sector number (1...63)
41; BH: Head number (0...255)
42; CX: Cylinder number (0...1023)
43; DS:DI: Ptr to Disk Parameter Table
44; Returns:
45; BL: Sector number (1...63)
46; BH: Head number (0...15)
47; CX: Cylinder number (0...16382)
48; Corrupts registers:
49; AX, DX
50;--------------------------------------------------------------------
51ALIGN JUMP_ALIGN
52ConvertLCHStoPCHS:
53 ; LHead / PHeadCount and LHead % PHeadCount
54 eMOVZX ax, bh ; Copy L-CHS Head number to AX
55 div BYTE [di+DPT.bHeads] ; AL = LHead / PHeadCount, AH = LHead % PHeadCount
56 mov bh, ah ; Copy P-CHS Head number to BH
57 xor ah, ah ; AX = LHead / PHeadCount
58
59 ; (LCylinder << n) + (LHead / PHeadCount)
60 mov dx, cx ; Copy L-CHS Cylinder number to DX
61 mov cl, [di+DPT.bFlagsLow] ; Load shift count
62 and cl, MASKL_DPT_CHS_SHIFT_COUNT
63 shl dx, cl ; DX = LCylinder << n
64 add ax, dx ; AX = P-CHS Cylinder number
65 xchg cx, ax ; Move P-CHS Cylinder number to CX
66DoNotConvertLCHS:
67 ret
68
69;--------------------------------------------------------------------
70; Address_OldInt13hAddressToIdeAddress
71; Parameters:
72; CH: Cylinder number, bits 7...0
73; CL: Bits 7...6: Cylinder number bits 9 and 8
74; Bits 5...0: Starting sector number (1...63)
75; DH: Starting head number (0...255)
76; DS:DI: Ptr to DPT
77; Returns:
78; BL: LBA Low Register / Sector Number Register (LBA 7...0)
79; CL: LBA Mid Register / Low Cylinder Register (LBA 15...8)
80; CH: LBA High Register / High Cylinder Register (LBA 23...16)
81; BH: Drive and Head Register (LBA 27...24)
82; Corrupts registers:
83; AX, DX
84;--------------------------------------------------------------------
85ALIGN JUMP_ALIGN
86Address_OldInt13hAddressToIdeAddress:
87 call Address_ExtractLCHSparametersFromOldInt13hAddress
88
89 AccessDPT_GetUnshiftedAddressModeToALZF
90
91;;; 0: ADDR_DPT_LCHS
92 jz DoNotConvertLCHS
93
94;;; 1: ADDR_DPT_PCHS
95 ;
96 ; Since we are only checking for zero, we can do our math in the high order bits,
97 ; in this case effectively subtracting 1 from the address mode.
98 ;
99 sub al,(1<<ADDRESSING_MODE_FIELD_POSITION)
100 jz ConvertLCHStoPCHS
101
102;;; 2: ADDR_DPT_LBA28 and 3: ADDR_DPT_LBA48
103 ; Fall through to ConvertLCHStoLBARegisterValues
104
105;---------------------------------------------------------------------
106; Converts LCHS parameters to 28-bit LBA address.
107; Only 24-bits are used since LHCS to LBA28 conversion has 8.4GB limit.
108; LBA = ((cylToSeek*headsPerCyl+headToSeek)*sectPerTrack)+sectToSeek-1
109;
110; Returned address is in same registers that
111; Address_DoNotConvertLCHS and Address_ConvertLCHStoPCHS returns.
112;
113; ConvertLCHStoLBARegisterValues:
114; Parameters:
115; BL: Sector number (1...63)
116; BH: Head number (0...255)
117; CX: Cylinder number (0...1023)
118; DS:DI: Ptr to Disk Parameter Table
119; Returns:
120; BL: LBA Low Register / Sector Number Register (LBA 7...0)
121; CL: LBA Mid Register / Low Cylinder Register (LBA 15...8)
122; CH: LBA High Register / High Cylinder Register (LBA 23...16)
123; BH: Drive and Head Register (LBA 27...24)
124; Corrupts registers:
125; AX, DX
126;--------------------------------------------------------------------
127ALIGN JUMP_ALIGN
128ConvertLCHStoLBARegisterValues:
129 ; cylToSeek*headsPerCyl (18-bit result)
130 mov ax, cx ; Copy Cylinder number to AX
131 eMOVZX dx, BYTE [di+DPT.bHeads]
132 mul dx ; DX:AX = cylToSeek*headsPerCyl
133
134 ; +=headToSeek (18-bit result)
135 add al, bh ; Add Head number to DX:AX
136 adc ah, dh ; DH = Zero after previous multiplication
137 adc dl, dh
138
139 ; *=sectPerTrack (18-bit by 6-bit multiplication with 24-bit result)
140 mov cx, LBA_ASSIST_SPT ; Load Sectors per Track
141 xchg ax, dx ; Hiword to AX, loword to DX
142 mul cl ; AX = hiword * Sectors per Track
143 mov bh, al ; Backup hiword * Sectors per Track
144 xchg ax, dx ; Loword back to AX
145 mul cx ; DX:AX = loword * Sectors per Track
146 add dl, bh ; DX:AX = (cylToSeek*headsPerCyl+headToSeek)*sectPerTrack
147
148 ; +=sectToSeek-1 (24-bit result)
149 xor bh, bh ; Sector number now in BX
150 dec bx ; sectToSeek-=1
151 add ax, bx ; Add to loword
152 adc dl, bh ; Add possible carry to byte2, BH=zero
153
154 ; Copy DX:AX to proper return registers
155 xchg bx, ax ; BL = Sector Number Register (LBA 7...0)
156 mov cl, bh ; Low Cylinder Register (LBA 15...8)
157 mov ch, dl ; High Cylinder Register (LBA 23...16)
158 mov bh, dh ; Drive and Head Register (LBA 27...24)
159 ret
Note: See TracBrowser for help on using the repository browser.