source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/VariablesAndDPTs/AtaGeometry.asm@ 546

Last change on this file since 546 was 542, checked in by aitotat@…, 11 years ago

Changes to XTIDE Universal BIOS:

  • Fixed a bug that allowed EBIOS functions for user defined CHS.
  • Simplified user defined CHS and LBA setup a little.
File size: 11.1 KB
Line 
1; Project name : XTIDE Universal BIOS
2; Description : Functions for generating L-CHS parameters for
3; drives with more than 1024 cylinders.
4;
5; These algorithms are taken from: http://www.mossywell.com/boot-sequence
6; Take a look at it for more detailed information.
7;
8; This file is shared with BIOS Drive Information Tool.
9
10;
11; XTIDE Universal BIOS and Associated Tools
12; Copyright (C) 2009-2010 by Tomi Tilli, 2011-2013 by XTIDE Universal BIOS Team.
13;
14; This program is free software; you can redistribute it and/or modify
15; it under the terms of the GNU General Public License as published by
16; the Free Software Foundation; either version 2 of the License, or
17; (at your option) any later version.
18;
19; This program is distributed in the hope that it will be useful,
20; but WITHOUT ANY WARRANTY; without even the implied warranty of
21; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22; GNU General Public License for more details.
23; Visit http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
24;
25
26; Section containing code
27SECTION .text
28
29%ifdef MODULE_EBIOS
30;--------------------------------------------------------------------
31; AtaGeometry_GetLbaSectorCountToBXDXAXfromAtaInfoInESSI
32; Parameters:
33; ES:SI: Ptr to 512-byte ATA information read from the drive
34; Returns:
35; BX:DX:AX: 48-bit sector count
36; CL: FLGL_DPT_LBA48 if LBA48 supported
37; Zero if only LBA28 is supported
38; Corrupts registers:
39; Nothing
40;--------------------------------------------------------------------
41AtaGeometry_GetLbaSectorCountToBXDXAXfromAtaInfoInESSI:
42 mov bx, Registers_ExchangeDSSIwithESDI
43 call bx ; ATA info now in DS:DI
44 push bx ; We will return via Registers_ExchangeDSSIwithESDI
45
46 ; Check if LBA48 supported
47 test BYTE [di+ATA6.wSetSup83+1], A6_wSetSup83_LBA48>>8
48 jz SHORT .GetLba28SectorCount
49
50 ; Get LBA48 sector count
51 mov cl, FLGL_DPT_LBA48
52 mov ax, [di+ATA6.qwLBACnt]
53 mov dx, [di+ATA6.qwLBACnt+2]
54 mov bx, [di+ATA6.qwLBACnt+4]
55 ret
56
57.GetLba28SectorCount:
58 xor cl, cl
59 xor bx, bx
60 mov ax, [di+ATA1.dwLBACnt]
61 mov dx, [di+ATA1.dwLBACnt+2]
62 ret
63%endif ; MODULE_EBIOS
64
65
66;--------------------------------------------------------------------
67; AtaGeometry_GetLCHStoAXBLBHfromAtaInfoInESSIandTranslateModeInDX
68; Parameters:
69; DX: Wanted translate mode or TRANSLATEMODE_AUTO to autodetect
70; ES:SI: Ptr to 512-byte ATA information read from the drive
71; Returns:
72; AX: Number of L-CHS cylinders (1...1027, yes 1027)
73; BL: Number of L-CHS heads (1...255)
74; BH: Number of L-CHS sectors per track (1...63)
75; CX: Number of bits shifted (0...3)
76; DL: CHS Translate Mode
77; Corrupts registers:
78; DH
79;--------------------------------------------------------------------
80AtaGeometry_GetLCHStoAXBLBHfromAtaInfoInESSIandTranslateModeInDX:
81 call AtaGeometry_GetPCHStoAXBLBHfromAtaInfoInESSI
82
83 ; Check if user defined translate mode
84 dec dx ; Set ZF if TRANSLATEMODE_LARGE, SF if TRANSLATEMODE_NORMAL
85 jns SHORT .CheckIfLargeTranslationWanted
86 MIN_U ax, MAX_LCHS_CYLINDERS ; TRANSLATEMODE_NORMAL maximum cylinders
87 inc dx
88.CheckIfLargeTranslationWanted:
89 jz SHORT ConvertPCHfromAXBLtoRevisedEnhancedCHinAXBL
90 dec dx ; Set ZF if TRANSLATEMODE_ASSISTED_LBA
91 jz SHORT .UseAssistedLBA
92 ; TRANSLATEMODE_AUTO set
93
94 ; Generate L-CHS using simple bit shift algorithm (ECHS) if
95 ; 8192 or less cylinders.
96 cmp ax, 8192
97 jbe SHORT ConvertPCHfromAXBLtoEnhancedCHinAXBL
98
99 ; We have 8193 or more cylinders so two algorithms are available:
100 ; Revised ECHS or Assisted LBA. The Assisted LBA provides larger
101 ; capacity but requires LBA support from drive (drives this large
102 ; always support LBA but user might have unintentionally set LBA).
103.UseAssistedLBA:
104 test BYTE [es:si+ATA1.wCaps+1], A1_wCaps_LBA>>8
105 jz SHORT ConvertPCHfromAXBLtoRevisedEnhancedCHinAXBL
106
107 ; Drive supports LBA
108 call GetSectorCountToDXAXfromCHSinAXBLBH
109 call ConvertChsSectorCountFromDXAXtoLbaAssistedLCHSinAXBLBH
110 xor cx, cx ; No bits to shift
111 mov dl, TRANSLATEMODE_ASSISTED_LBA
112 ret
113
114
115;--------------------------------------------------------------------
116; AtaGeometry_GetPCHStoAXBLBHfromAtaInfoInESSI
117; Parameters:
118; ES:SI: Ptr to 512-byte ATA information read from the drive
119; Returns:
120; AX: Number of P-CHS cylinders (1...16383)
121; BL: Number of P-CHS heads (1...16)
122; BH: Number of P-CHS sectors per track (1...63)
123; Corrupts registers:
124; Nothing
125;--------------------------------------------------------------------
126AtaGeometry_GetPCHStoAXBLBHfromAtaInfoInESSI:
127 mov ax, [es:si+ATA1.wCylCnt] ; Cylinders (1...16383)
128 mov bl, [es:si+ATA1.wHeadCnt] ; Heads (1...16)
129 mov bh, [es:si+ATA1.wSPT] ; Sectors per Track (1...63)
130 ret
131
132
133;--------------------------------------------------------------------
134; GetSectorCountToDXAXfromCHSinAXBLBH
135; Parameters:
136; ES:SI: Ptr to 512-byte ATA information read from the drive
137; AX: Number of cylinders (1...16383)
138; BL: Number of heads (1...255)
139; BH: Number of sectors per track (1...63)
140; Returns:
141; DX:AX: Total number of CHS addressable sectors
142; Corrupts registers:
143; BX
144;--------------------------------------------------------------------
145GetSectorCountToDXAXfromCHSinAXBLBH:
146 xchg ax, bx
147 mul ah ; AX = Heads * Sectors per track
148 mul bx
149 ret
150
151
152;--------------------------------------------------------------------
153; Revised Enhanced CHS calculation (Revised ECHS)
154;
155; This algorithm translates P-CHS sector count to L-CHS sector count
156; with bit shift algorithm. Since 256 heads are not allowed
157; (DOS limit), this algorithm makes translations so that maximum of
158; 240 L-CHS heads can be used. This makes the maximum addressable capacity
159; to 7,927,234,560 bytes ~ 7.38 GiB. LBA addressing needs to be used to
160; get more capacity.
161;
162; L-CHS parameters generated here require the drive to use CHS addressing.
163;
164; Here is the algorithm:
165; If cylinders > 8192 and heads = 16
166; Heads = 15
167; Cylinders = cylinders * 16 / 15 (losing the fraction component)
168; Do a standard ECHS translation
169;
170; ConvertPCHfromAXBLtoRevisedEnhancedCHinAXBL:
171; Parameters:
172; AX: Number of P-CHS cylinders (8193...16383)
173; BL: Number of P-CHS heads (1...16)
174; Returns:
175; AX: Number of L-CHS cylinders (?...1024)
176; BL: Number of L-CHS heads (?...240)
177; CX: Number of bits shifted (0...3)
178; DL: ADDRESSING_MODE_NORMAL or ADDRESSING_MODE_LARGE
179; Corrupts registers:
180; Nothing
181;--------------------------------------------------------------------
182ConvertPCHfromAXBLtoRevisedEnhancedCHinAXBL:
183 ; Generate L-CHS using simple bit shift algorithm (ECHS) if
184 ; 8192 or less cylinders
185 cmp ax, 8192
186 jbe SHORT ConvertPCHfromAXBLtoEnhancedCHinAXBL
187 cmp bl, 16 ; Drives with 8193 or more cylinders can report 15 heads
188 jb SHORT ConvertPCHfromAXBLtoEnhancedCHinAXBL
189
190 eMOVZX cx, bl ; CX = 16
191 dec bx ; Heads = 15
192 mul cx ; DX:AX = Cylinders * 16
193 dec cx ; CX = 15
194 div cx ; AX = (Cylinders * 16) / 15
195 ; Fall to ConvertPCHfromAXBXtoEnhancedCHinAXBX
196
197
198;--------------------------------------------------------------------
199; Enhanced CHS calculation (ECHS)
200;
201; This algorithm translates P-CHS sector count to L-CHS sector count
202; with simple bit shift algorithm. Since 256 heads are not allowed
203; (DOS limit), this algorithm require that there are at most 8192
204; P-CHS cylinders. This makes the maximum addressable capacity
205; to 4,227,858,432 bytes ~ 3.94 GiB. Use Revised ECHS or Assisted LBA
206; algorithms if there are more than 8192 P-CHS cylinders.
207;
208; L-CHS parameters generated here require the drive to use CHS addressing.
209;
210; Here is the algorithm:
211; Multiplier = 1
212; Cylinder = Cylinder - 1
213; Is Cylinder < 1024? If not:
214; Do a right bitwise rotation on the cylinder (i.e., divide by 2)
215; Do a left bitwise rotation on the multiplier (i.e., multiply by 2)
216; Use the multiplier on the Cylinder and Head values to obtain the translated values.
217;
218; ConvertPCHfromAXBLtoEnhancedCHinAXBL:
219; Parameters:
220; AX: Number of P-CHS cylinders (1...8192)
221; BL: Number of P-CHS heads (1...16)
222; Returns:
223; AX: Number of L-CHS cylinders (?...1024)
224; BL: Number of L-CHS heads (?...128)
225; CX: Number of bits shifted (0...3)
226; DL: TRANSLATEMODE_NORMAL or TRANSLATEMODE_LARGE
227; Corrupts registers:
228; Nothing
229;--------------------------------------------------------------------
230ConvertPCHfromAXBLtoEnhancedCHinAXBL:
231 xor cx, cx ; No bits to shift initially
232 xor dl, dl ; Assume TRANSLATEMODE_NORMAL
233.ShiftIfMoreThan1024Cylinder:
234 cmp ax, MAX_LCHS_CYLINDERS
235 jbe SHORT ReturnLCHSinAXBLBH
236 shr ax, 1 ; Halve cylinders
237 eSHL_IM bl, 1 ; Double heads
238 inc cx ; Increment bit shift count
239 mov dl, TRANSLATEMODE_LARGE
240 jmp SHORT .ShiftIfMoreThan1024Cylinder
241
242
243;--------------------------------------------------------------------
244; LBA assist calculation (or Assisted LBA)
245;
246; This algorithm translates P-CHS sector count up to largest possible
247; L-CHS sector count (1024, 255, 63). Note that INT 13h interface allows
248; 256 heads but DOS supports up to 255 head. That is why BIOSes never
249; use 256 heads.
250;
251; L-CHS parameters generated here require the drive to use LBA addressing.
252;
253; Here is the algorithm:
254; If cylinders > 8192
255; Variable CH = Total CHS Sectors / 63
256; Divide (CH – 1) by 1024 and add 1
257; Round the result up to the nearest of 16, 32, 64, 128 and 255. This is the value to be used for the number of heads.
258; Divide CH by the number of heads. This is the value to be used for the number of cylinders.
259;
260; ConvertChsSectorCountFromDXAXtoLbaAssistedLCHSinAXBLBH:
261; Parameters:
262; DX:AX: Total number of P-CHS sectors for CHS addressing
263; (max = 16383 * 16 * 63 = 16,514,064)
264; Returns:
265; AX: Number of cylinders (?...1027)
266; BL: Number of heads (16, 32, 64, 128 or 255)
267; BH: Number of sectors per track (always 63)
268; Corrupts registers:
269; CX, DX
270;--------------------------------------------------------------------
271ConvertChsSectorCountFromDXAXtoLbaAssistedLCHSinAXBLBH:
272 ; Value CH = Total sector count / 63
273 ; Max = 16,514,064 / 63 = 262128
274 mov cx, LBA_ASSIST_SPT ; CX = 63
275 call Math_DivDXAXbyCX
276 push dx
277 push ax ; Value CH stored for later use
278
279 ; BX:DX:AX = Value CH - 1
280 ; Max = 262128 - 1 = 262127
281 xor bx, bx
282 sub ax, BYTE 1
283 sbb dx, bx
284
285 ; AX = Number of heads = ((Value CH - 1) / 1024) + 1
286 ; Max = (262127 / 1024) + 1 = 256
287 push si
288 call Size_DivideSizeInBXDXAXby1024andIncrementMagnitudeInCX
289 pop si
290 inc ax ; + 1
291
292 ; Heads must be 16, 32, 64, 128 or 255 (round up to the nearest)
293 ; Max = 255
294 mov cx, 16 ; Min number of heads
295.CompareNextValidNumberOfHeads:
296 cmp ax, cx
297 jbe SHORT .NumberOfHeadsNowInCX
298 eSHL_IM cl, 1 ; Double number of heads
299 jnz SHORT .CompareNextValidNumberOfHeads ; Reached 256 heads?
300 dec cl ; If so, limit heads to 255
301.NumberOfHeadsNowInCX:
302 mov bx, cx ; Number of heads are returned in BL
303 mov bh, LBA_ASSIST_SPT ; Sectors per Track
304
305 ; DX:AX = Number of cylinders = Value CH (without - 1) / number of heads
306 ; Max = 262128 / 255 = 1027
307 pop ax
308 pop dx ; Value CH back to DX:AX
309 div cx
310
311 ; Return L-CHS
312ReturnLCHSinAXBLBH:
313 ret
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