1 | ; Project name : XTIDE Universal BIOS |
---|
2 | ; Description : Functions for address translations. |
---|
3 | |
---|
4 | ; Section containing code |
---|
5 | SECTION .text |
---|
6 | |
---|
7 | ; Jump table for conversion functions |
---|
8 | ALIGN WORD_ALIGN |
---|
9 | g_rgfnAddressTranslation: |
---|
10 | dw DoNotConvertLCHS ; 0, ADDR_DPT_LCHS |
---|
11 | dw ConvertLCHStoPCHS ; 1, ADDR_DPT_PCHS |
---|
12 | dw ConvertLCHStoLBARegisterValues ; 2, ADDR_DPT_LBA28 |
---|
13 | dw ConvertLCHStoLBARegisterValues ; 3, ADDR_DPT_LBA48 |
---|
14 | |
---|
15 | |
---|
16 | ;-------------------------------------------------------------------- |
---|
17 | ; HAddress_OldInt13hAddressToIdeAddress |
---|
18 | ; Parameters: |
---|
19 | ; CH: Cylinder number, bits 7...0 |
---|
20 | ; CL: Bits 7...6: Cylinder number bits 9 and 8 |
---|
21 | ; Bits 5...0: Starting sector number (1...63) |
---|
22 | ; DH: Starting head number (0...255) |
---|
23 | ; DS:DI: Ptr to DPT |
---|
24 | ; Returns: |
---|
25 | ; BL: LBA Low Register / Sector Number Register (LBA 7...0) |
---|
26 | ; CL: LBA Mid Register / Low Cylinder Register (LBA 15...8) |
---|
27 | ; CH: LBA High Register / High Cylinder Register (LBA 23...16) |
---|
28 | ; BH: Drive and Head Register (LBA 27...24) |
---|
29 | ; Corrupts registers: |
---|
30 | ; AX, DX |
---|
31 | ;-------------------------------------------------------------------- |
---|
32 | ALIGN JUMP_ALIGN |
---|
33 | HAddress_OldInt13hAddressToIdeAddress: |
---|
34 | call AccessDPT_GetAddressingModeForWordLookToBX |
---|
35 | push WORD [cs:bx+g_rgfnAddressTranslation] ; Push return address |
---|
36 | ; Fall to HAddress_ExtractLCHSparametersFromOldInt13hAddress |
---|
37 | |
---|
38 | ;--------------------------------------------------------------------- |
---|
39 | ; HAddress_ExtractLCHSparametersFromOldInt13hAddress |
---|
40 | ; Parameters: |
---|
41 | ; CH: Cylinder number, bits 7...0 |
---|
42 | ; CL: Bits 7...6: Cylinder number bits 9 and 8 |
---|
43 | ; Bits 5...0: Sector number |
---|
44 | ; DH: Head number |
---|
45 | ; Returns: |
---|
46 | ; BL: Sector number (1...63) |
---|
47 | ; BH: Head number (0...255) |
---|
48 | ; CX: Cylinder number (0...1023) |
---|
49 | ; Corrupts registers: |
---|
50 | ; Nothing |
---|
51 | ;-------------------------------------------------------------------- |
---|
52 | HAddress_ExtractLCHSparametersFromOldInt13hAddress: |
---|
53 | mov bl, cl ; Copy sector number... |
---|
54 | and bl, 3Fh ; ...and limit to 1...63 |
---|
55 | sub cl, bl ; Remove from cylinder number high |
---|
56 | eROL_IM cl, 2 ; High bits to beginning |
---|
57 | mov bh, dh ; Copy Head number |
---|
58 | xchg cl, ch ; Cylinder number now in CX |
---|
59 | ret |
---|
60 | |
---|
61 | |
---|
62 | ;--------------------------------------------------------------------- |
---|
63 | ; Converts LCHS parameters to IDE P-CHS parameters. |
---|
64 | ; PCylinder = (LCylinder << n) + (LHead / PHeadCount) |
---|
65 | ; PHead = LHead % PHeadCount |
---|
66 | ; PSector = LSector |
---|
67 | ; |
---|
68 | ; HAddress_ConvertLCHStoPCHS: |
---|
69 | ; Parameters: |
---|
70 | ; BL: Sector number (1...63) |
---|
71 | ; BH: Head number (0...255) |
---|
72 | ; CX: Cylinder number (0...1023) |
---|
73 | ; DS:DI: Ptr to Disk Parameter Table |
---|
74 | ; Returns: |
---|
75 | ; BL: Sector number (1...63) |
---|
76 | ; BH: Head number (0...15) |
---|
77 | ; CX: Cylinder number (0...16382) |
---|
78 | ; Corrupts registers: |
---|
79 | ; AX, DX |
---|
80 | ;-------------------------------------------------------------------- |
---|
81 | ALIGN JUMP_ALIGN |
---|
82 | ConvertLCHStoPCHS: |
---|
83 | ; LHead / PHeadCount and LHead % PHeadCount |
---|
84 | eMOVZX ax, bh ; Copy L-CHS Head number to AX |
---|
85 | div BYTE [di+DPT.bPchsHeads]; AL = LHead / PHeadCount, AH = LHead % PHeadCount |
---|
86 | mov bh, ah ; Copy P-CHS Head number to BH |
---|
87 | xor ah, ah ; AX = LHead / PHeadCount |
---|
88 | |
---|
89 | ; (LCylinder << n) + (LHead / PHeadCount) |
---|
90 | mov dx, cx ; Copy L-CHS Cylinder number to DX |
---|
91 | mov cl, [di+DPT.wFlags] ; Load shift count |
---|
92 | and cl, MASK_DPT_CHS_SHIFT_COUNT |
---|
93 | shl dx, cl ; DX = LCylinder << n |
---|
94 | add ax, dx ; AX = P-CHS Cylinder number |
---|
95 | mov cx, ax ; Copy P-CHS Cylinder number to CX |
---|
96 | DoNotConvertLCHS: |
---|
97 | ret |
---|
98 | |
---|
99 | |
---|
100 | ;--------------------------------------------------------------------- |
---|
101 | ; Converts LCHS parameters to 28-bit LBA address. |
---|
102 | ; Only 24-bits are used since LHCS to LBA28 conversion has 8.4GB limit. |
---|
103 | ; LBA = ((cylToSeek*headsPerCyl+headToSeek)*sectPerTrack)+sectToSeek-1 |
---|
104 | ; |
---|
105 | ; Returned address is in same registers that |
---|
106 | ; HAddress_DoNotConvertLCHS and HAddress_ConvertLCHStoPCHS returns. |
---|
107 | ; |
---|
108 | ; ConvertLCHStoLBARegisterValues: |
---|
109 | ; Parameters: |
---|
110 | ; BL: Sector number (1...63) |
---|
111 | ; BH: Head number (0...255) |
---|
112 | ; CX: Cylinder number (0...1023) |
---|
113 | ; DS:DI: Ptr to Disk Parameter Table |
---|
114 | ; Returns: |
---|
115 | ; BL: LBA Low Register / Sector Number Register (LBA 7...0) |
---|
116 | ; CL: LBA Mid Register / Low Cylinder Register (LBA 15...8) |
---|
117 | ; CH: LBA High Register / High Cylinder Register (LBA 23...16) |
---|
118 | ; BH: Drive and Head Register (LBA 27...24) |
---|
119 | ; Corrupts registers: |
---|
120 | ; AX, DX |
---|
121 | ;-------------------------------------------------------------------- |
---|
122 | ALIGN JUMP_ALIGN |
---|
123 | ConvertLCHStoLBARegisterValues: |
---|
124 | ; cylToSeek*headsPerCyl (18-bit result) |
---|
125 | mov ax, cx ; Copy Cylinder number to AX |
---|
126 | eMOVZX dx, BYTE [di+DPT.bLchsHeads] |
---|
127 | mul dx ; DX:AX = cylToSeek*headsPerCyl |
---|
128 | |
---|
129 | ; +=headToSeek (18-bit result) |
---|
130 | add al, bh ; Add Head number to DX:AX |
---|
131 | adc ah, dh ; DH = Zero after previous multiplication |
---|
132 | adc dl, dh |
---|
133 | |
---|
134 | ; *=sectPerTrack (18-bit by 6-bit multiplication with 24-bit result) |
---|
135 | eMOVZX cx, BYTE [di+DPT.bPchsSectors] ; Load Sectors per Track |
---|
136 | xchg ax, dx ; Hiword to AX, loword to DX |
---|
137 | mul cl ; AX = hiword * Sectors per Track |
---|
138 | mov bh, al ; Backup hiword * Sectors per Track |
---|
139 | xchg ax, dx ; Loword back to AX |
---|
140 | mul cx ; DX:AX = loword * Sectors per Track |
---|
141 | add dl, bh ; DX:AX = (cylToSeek*headsPerCyl+headToSeek)*sectPerTrack |
---|
142 | |
---|
143 | ; +=sectToSeek-1 (24-bit result) |
---|
144 | xor bh, bh ; Sector number now in BX |
---|
145 | dec bx ; sectToSeek-=1 |
---|
146 | add ax, bx ; Add to loword |
---|
147 | adc dl, bh ; Add possible carry to byte2, BH=zero |
---|
148 | |
---|
149 | ; Copy DX:AX to proper return registers |
---|
150 | xchg bx, ax ; BL = Sector Number Register (LBA 7...0) |
---|
151 | mov cl, bh ; Low Cylinder Register (LBA 15...8) |
---|
152 | mov ch, dl ; High Cylinder Register (LBA 23...16) |
---|
153 | mov bh, dh ; Drive and Head Register (LBA 27...24) |
---|
154 | ret |
---|