[358] | 1 | ; Project name : XTIDE Universal BIOS
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| 2 | ; Description : Functions for generating L-CHS parameters for
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[421] | 3 | ; drives with more than 1024 cylinders.
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[358] | 4 | ;
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[421] | 5 | ; These algorithms are taken from: http://www.mossywell.com/boot-sequence
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[445] | 6 | ; Take a look at it for more detailed information.
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[421] | 7 | ;
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[358] | 8 | ; This file is shared with BIOS Drive Information Tool.
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| 9 |
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[376] | 10 | ;
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[445] | 11 | ; XTIDE Universal BIOS and Associated Tools
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[376] | 12 | ; Copyright (C) 2009-2010 by Tomi Tilli, 2011-2012 by XTIDE Universal BIOS Team.
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| 13 | ;
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| 14 | ; This program is free software; you can redistribute it and/or modify
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| 15 | ; it under the terms of the GNU General Public License as published by
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| 16 | ; the Free Software Foundation; either version 2 of the License, or
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| 17 | ; (at your option) any later version.
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[445] | 18 | ;
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[376] | 19 | ; This program is distributed in the hope that it will be useful,
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| 20 | ; but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 21 | ; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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[445] | 22 | ; GNU General Public License for more details.
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[376] | 23 | ; Visit http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
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| 24 | ;
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[445] | 25 |
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[358] | 26 | ; Section containing code
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| 27 | SECTION .text
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| 28 |
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[421] | 29 | %ifdef MODULE_EBIOS
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[358] | 30 | ;--------------------------------------------------------------------
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[421] | 31 | ; AtaGeometry_GetLbaSectorCountToBXDXAXfromAtaInfoInESSI
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| 32 | ; Parameters:
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| 33 | ; ES:SI: Ptr to 512-byte ATA information read from the drive
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| 34 | ; Returns:
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[445] | 35 | ; BX:DX:AX: 48-bit sector count
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[422] | 36 | ; CL: FLGL_DPT_LBA48 if LBA48 supported
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| 37 | ; Zero if only LBA28 is supported
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[421] | 38 | ; Corrupts registers:
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| 39 | ; Nothing
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| 40 | ;--------------------------------------------------------------------
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| 41 | AtaGeometry_GetLbaSectorCountToBXDXAXfromAtaInfoInESSI:
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| 42 | mov bx, Registers_ExchangeDSSIwithESDI
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| 43 | call bx ; ATA info now in DS:DI
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| 44 | push bx ; We will return via Registers_ExchangeDSSIwithESDI
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| 45 |
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| 46 | ; Check if LBA48 supported
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| 47 | test BYTE [di+ATA6.wSetSup83+1], A6_wSetSup83_LBA48>>8
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| 48 | jz SHORT .GetLba28SectorCount
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| 49 |
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| 50 | ; Get LBA48 sector count
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| 51 | mov cl, FLGL_DPT_LBA48
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| 52 | mov ax, [di+ATA6.qwLBACnt]
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| 53 | mov dx, [di+ATA6.qwLBACnt+2]
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| 54 | mov bx, [di+ATA6.qwLBACnt+4]
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| 55 | ret
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| 56 |
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| 57 | .GetLba28SectorCount:
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| 58 | xor cl, cl
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| 59 | xor bx, bx
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| 60 | mov ax, [di+ATA1.dwLBACnt]
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| 61 | mov dx, [di+ATA1.dwLBACnt+2]
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| 62 | ret
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| 63 | %endif ; MODULE_EBIOS
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| 64 |
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| 65 |
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| 66 | ;--------------------------------------------------------------------
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[422] | 67 | ; AtaGeometry_GetLCHStoAXBLBHfromAtaInfoInESSIandTranslateModeInDX
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| 68 | ; AtaGeometry_GetLCHStoAXBLBHfromPCHSinAXBLBHandTranslateModeInDX
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[421] | 69 | ; Parameters:
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[422] | 70 | ; DX: Wanted translate mode or TRANSLATEMODE_AUTO to autodetect
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[421] | 71 | ; ES:SI: Ptr to 512-byte ATA information read from the drive
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| 72 | ; Returns:
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| 73 | ; AX: Number of L-CHS cylinders (1...1027, yes 1027)
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| 74 | ; BL: Number of L-CHS heads (1...255)
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| 75 | ; BH: Number of L-CHS sectors per track (1...63)
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| 76 | ; CX: Number of bits shifted (0...3)
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[422] | 77 | ; DL: CHS Translate Mode
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[421] | 78 | ; Corrupts registers:
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| 79 | ; DH
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| 80 | ;--------------------------------------------------------------------
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[422] | 81 | AtaGeometry_GetLCHStoAXBLBHfromAtaInfoInESSIandTranslateModeInDX:
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[421] | 82 | call AtaGeometry_GetPCHStoAXBLBHfromAtaInfoInESSI
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| 83 | ; Fall to AtaGeometry_GetLCHStoAXBLBHfromPCHSinAXBLBH
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| 84 |
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[422] | 85 | AtaGeometry_GetLCHStoAXBLBHfromPCHSinAXBLBHandTranslateModeInDX:
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| 86 | ; Check if user defined translate mode
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| 87 | test dx, dx
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| 88 | jnz SHORT .CheckIfLargeTranslationWanted
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| 89 | MIN_U ax, MAX_LCHS_CYLINDERS ; TRANSLATEMODE_NORMAL maximum cylinders
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| 90 | inc dx
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| 91 | .CheckIfLargeTranslationWanted:
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| 92 | dec dx ; Set ZF if TRANSLATEMODE_LARGE
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| 93 | jz SHORT ConvertPCHfromAXBLtoRevisedEnhancedCHinAXBL
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| 94 | dec dx ; Set ZF if TRANSLATEMODE_ASSISTED_LBA
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| 95 | jz SHORT .UseAssistedLBA
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| 96 | ; TRANSLATEMODE_AUTO set
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| 97 |
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[421] | 98 | ; Generate L-CHS using simple bit shift algorithm (ECHS) if
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| 99 | ; 8192 or less cylinders.
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| 100 | cmp ax, 8192
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[422] | 101 | jbe SHORT ConvertPCHfromAXBLtoEnhancedCHinAXBL
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[421] | 102 |
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| 103 | ; We have 8193 or more cylinders so two algorithms are available:
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| 104 | ; Revised ECHS or Assisted LBA. The Assisted LBA provides larger
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| 105 | ; capacity but requires LBA support from drive (drives this large
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[422] | 106 | ; always support LBA but user might have unintentionally set LBA).
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| 107 | .UseAssistedLBA:
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[421] | 108 | test BYTE [es:si+ATA1.wCaps+1], A1_wCaps_LBA>>8
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[422] | 109 | jz SHORT ConvertPCHfromAXBLtoRevisedEnhancedCHinAXBL
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[421] | 110 |
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| 111 | ; Drive supports LBA
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[422] | 112 | call GetSectorCountToDXAXfromCHSinAXBLBH
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[421] | 113 | call ConvertChsSectorCountFromDXAXtoLbaAssistedLCHSinAXBLBH
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| 114 | xor cx, cx ; No bits to shift
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[422] | 115 | mov dl, TRANSLATEMODE_ASSISTED_LBA
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[421] | 116 | ret
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| 117 |
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| 118 |
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| 119 | ;--------------------------------------------------------------------
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| 120 | ; AtaGeometry_GetPCHStoAXBLBHfromAtaInfoInESSI
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| 121 | ; Parameters:
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| 122 | ; ES:SI: Ptr to 512-byte ATA information read from the drive
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| 123 | ; Returns:
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| 124 | ; AX: Number of P-CHS cylinders (1...16383)
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| 125 | ; BL: Number of P-CHS heads (1...16)
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| 126 | ; BH: Number of P-CHS sectors per track (1...63)
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| 127 | ; Corrupts registers:
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| 128 | ; Nothing
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| 129 | ;--------------------------------------------------------------------
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| 130 | AtaGeometry_GetPCHStoAXBLBHfromAtaInfoInESSI:
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| 131 | mov ax, [es:si+ATA1.wCylCnt] ; Cylinders (1...16383)
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| 132 | mov bl, [es:si+ATA1.wHeadCnt] ; Heads (1...16)
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| 133 | mov bh, [es:si+ATA1.wSPT] ; Sectors per Track (1...63)
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| 134 | ret
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| 135 |
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| 136 |
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| 137 | ;--------------------------------------------------------------------
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[422] | 138 | ; GetSectorCountToDXAXfromCHSinAXBLBH
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[421] | 139 | ; Parameters:
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| 140 | ; ES:SI: Ptr to 512-byte ATA information read from the drive
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| 141 | ; AX: Number of cylinders (1...16383)
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| 142 | ; BL: Number of heads (1...255)
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| 143 | ; BH: Number of sectors per track (1...63)
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| 144 | ; Returns:
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| 145 | ; DX:AX: Total number of CHS addressable sectors
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| 146 | ; Corrupts registers:
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| 147 | ; BX
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| 148 | ;--------------------------------------------------------------------
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[422] | 149 | GetSectorCountToDXAXfromCHSinAXBLBH:
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[421] | 150 | xchg ax, bx
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| 151 | mul ah ; AX = Heads * Sectors per track
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| 152 | mul bx
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| 153 | ret
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| 154 |
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| 155 |
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| 156 | ;--------------------------------------------------------------------
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| 157 | ; Revised Enhanced CHS calculation (Revised ECHS)
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[358] | 158 | ;
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[421] | 159 | ; This algorithm translates P-CHS sector count to L-CHS sector count
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| 160 | ; with bit shift algorithm. Since 256 heads are not allowed
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| 161 | ; (DOS limit), this algorithm makes translations so that maximum of
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| 162 | ; 240 L-CHS heads can be used. This makes the maximum addressable capacity
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| 163 | ; to 7,927,234,560 bytes ~ 7.38 GiB. LBA addressing needs to be used to
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| 164 | ; get more capacity.
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| 165 | ;
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| 166 | ; L-CHS parameters generated here require the drive to use CHS addressing.
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| 167 | ;
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| 168 | ; Here is the algorithm:
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| 169 | ; If cylinders > 8192 and heads = 16
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| 170 | ; Heads = 15
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| 171 | ; Cylinders = cylinders * 16 / 15 (losing the fraction component)
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| 172 | ; Do a standard ECHS translation
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| 173 | ;
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[422] | 174 | ; ConvertPCHfromAXBLtoRevisedEnhancedCHinAXBL:
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[421] | 175 | ; Parameters:
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| 176 | ; AX: Number of P-CHS cylinders (8193...16383)
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| 177 | ; BL: Number of P-CHS heads (1...16)
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| 178 | ; Returns:
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| 179 | ; AX: Number of L-CHS cylinders (?...1024)
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| 180 | ; BL: Number of L-CHS heads (?...240)
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| 181 | ; CX: Number of bits shifted (0...3)
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| 182 | ; DL: ADDRESSING_MODE_NORMAL or ADDRESSING_MODE_LARGE
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| 183 | ; Corrupts registers:
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| 184 | ; Nothing
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| 185 | ;--------------------------------------------------------------------
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[422] | 186 | ConvertPCHfromAXBLtoRevisedEnhancedCHinAXBL:
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| 187 | ; Generate L-CHS using simple bit shift algorithm (ECHS) if
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| 188 | ; 8192 or less cylinders
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| 189 | cmp ax, 8192
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| 190 | jbe SHORT ConvertPCHfromAXBLtoEnhancedCHinAXBL
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[421] | 191 | cmp bl, 16 ; Drives with 8193 or more cylinders can report 15 heads
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[422] | 192 | jb SHORT ConvertPCHfromAXBLtoEnhancedCHinAXBL
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[421] | 193 |
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| 194 | eMOVZX cx, bl ; CX = 16
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| 195 | dec bx ; Heads = 15
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| 196 | mul cx ; DX:AX = Cylinders * 16
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| 197 | dec cx ; CX = 15
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| 198 | div cx ; AX = (Cylinders * 16) / 15
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| 199 | ; Fall to ConvertPCHfromAXBXtoEnhancedCHinAXBX
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| 200 |
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| 201 |
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| 202 | ;--------------------------------------------------------------------
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| 203 | ; Enhanced CHS calculation (ECHS)
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| 204 | ;
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| 205 | ; This algorithm translates P-CHS sector count to L-CHS sector count
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| 206 | ; with simple bit shift algorithm. Since 256 heads are not allowed
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| 207 | ; (DOS limit), this algorithm require that there are at most 8192
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| 208 | ; P-CHS cylinders. This makes the maximum addressable capacity
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| 209 | ; to 4,227,858,432 bytes ~ 3.94 GiB. Use Revised ECHS or Assisted LBA
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| 210 | ; algorithms if there are more than 8192 P-CHS cylinders.
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| 211 | ;
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| 212 | ; L-CHS parameters generated here require the drive to use CHS addressing.
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| 213 | ;
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| 214 | ; Here is the algorithm:
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| 215 | ; Multiplier = 1
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| 216 | ; Cylinder = Cylinder - 1
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| 217 | ; Is Cylinder < 1024? If not:
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| 218 | ; Do a right bitwise rotation on the cylinder (i.e., divide by 2)
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| 219 | ; Do a left bitwise rotation on the multiplier (i.e., multiply by 2)
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| 220 | ; Use the multiplier on the Cylinder and Head values to obtain the translated values.
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| 221 | ;
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[422] | 222 | ; ConvertPCHfromAXBLtoEnhancedCHinAXBL:
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[421] | 223 | ; Parameters:
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| 224 | ; AX: Number of P-CHS cylinders (1...8192)
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| 225 | ; BL: Number of P-CHS heads (1...16)
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| 226 | ; Returns:
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| 227 | ; AX: Number of L-CHS cylinders (?...1024)
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| 228 | ; BL: Number of L-CHS heads (?...128)
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| 229 | ; CX: Number of bits shifted (0...3)
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[422] | 230 | ; DL: TRANSLATEMODE_NORMAL or TRANSLATEMODE_LARGE
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[421] | 231 | ; Corrupts registers:
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| 232 | ; Nothing
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| 233 | ;--------------------------------------------------------------------
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[422] | 234 | ConvertPCHfromAXBLtoEnhancedCHinAXBL:
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[421] | 235 | xor cx, cx ; No bits to shift initially
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[422] | 236 | xor dl, dl ; Assume TRANSLATEMODE_NORMAL
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[421] | 237 | .ShiftIfMoreThan1024Cylinder:
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| 238 | cmp ax, MAX_LCHS_CYLINDERS
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| 239 | jbe SHORT ReturnLCHSinAXBLBH
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[422] | 240 | shr ax, 1 ; Halve cylinders
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[445] | 241 | eSHL_IM bl, 1 ; Double heads
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[421] | 242 | inc cx ; Increment bit shift count
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[422] | 243 | mov dl, TRANSLATEMODE_LARGE
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[421] | 244 | jmp SHORT .ShiftIfMoreThan1024Cylinder
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| 245 |
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| 246 |
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| 247 | ;--------------------------------------------------------------------
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| 248 | ; LBA assist calculation (or Assisted LBA)
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| 249 | ;
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| 250 | ; This algorithm translates P-CHS sector count up to largest possible
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| 251 | ; L-CHS sector count (1024, 255, 63). Note that INT 13h interface allows
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| 252 | ; 256 heads but DOS supports up to 255 head. That is why BIOSes never
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| 253 | ; use 256 heads.
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| 254 | ;
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| 255 | ; L-CHS parameters generated here require the drive to use LBA addressing.
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| 256 | ;
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| 257 | ; Here is the algorithm:
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[419] | 258 | ; If cylinders > 8192
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[421] | 259 | ; Variable CH = Total CHS Sectors / 63
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| 260 | ; Divide (CH 1) by 1024 and add 1
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[419] | 261 | ; 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.
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| 262 | ; Divide CH by the number of heads. This is the value to be used for the number of cylinders.
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[358] | 263 | ;
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[421] | 264 | ; ConvertChsSectorCountFromDXAXtoLbaAssistedLCHSinAXBLBH:
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[358] | 265 | ; Parameters:
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[421] | 266 | ; DX:AX: Total number of P-CHS sectors for CHS addressing
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| 267 | ; (max = 16383 * 16 * 63 = 16,514,064)
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[358] | 268 | ; Returns:
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[421] | 269 | ; AX: Number of cylinders (?...1027)
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| 270 | ; BL: Number of heads (16, 32, 64, 128 or 255)
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[358] | 271 | ; BH: Number of sectors per track (always 63)
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| 272 | ; Corrupts registers:
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[421] | 273 | ; CX, DX
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[358] | 274 | ;--------------------------------------------------------------------
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[421] | 275 | ConvertChsSectorCountFromDXAXtoLbaAssistedLCHSinAXBLBH:
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[419] | 276 | ; Value CH = Total sector count / 63
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[421] | 277 | ; Max = 16,514,064 / 63 = 262128
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| 278 | mov cx, LBA_ASSIST_SPT ; CX = 63
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| 279 | call Math_DivDXAXbyCX
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[358] | 280 | push dx
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[421] | 281 | push ax ; Value CH stored for later use
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[358] | 282 |
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[419] | 283 | ; BX:DX:AX = Value CH - 1
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[421] | 284 | ; Max = 262128 - 1 = 262127
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| 285 | xor bx, bx
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| 286 | sub ax, BYTE 1
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| 287 | sbb dx, bx
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[419] | 288 |
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[421] | 289 | ; AX = Number of heads = ((Value CH - 1) / 1024) + 1
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| 290 | ; Max = (262127 / 1024) + 1 = 256
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| 291 | push si
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[358] | 292 | call Size_DivideSizeInBXDXAXby1024andIncrementMagnitudeInCX
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[421] | 293 | pop si
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| 294 | inc ax ; + 1
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[358] | 295 |
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[419] | 296 | ; Heads must be 16, 32, 64, 128 or 255 (round up to the nearest)
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[421] | 297 | ; Max = 255
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[419] | 298 | mov cx, 16 ; Min number of heads
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| 299 | .CompareNextValidNumberOfHeads:
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[358] | 300 | cmp ax, cx
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[419] | 301 | jbe SHORT .NumberOfHeadsNowInCX
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[445] | 302 | eSHL_IM cl, 1 ; Double number of heads
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| 303 | jnz SHORT .CompareNextValidNumberOfHeads ; Reached 256 heads?
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| 304 | dec cl ; If so, limit heads to 255
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[419] | 305 | .NumberOfHeadsNowInCX:
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| 306 | mov bx, cx ; Number of heads are returned in BL
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| 307 | mov bh, LBA_ASSIST_SPT ; Sectors per Track
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[358] | 308 |
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[419] | 309 | ; DX:AX = Number of cylinders = Value CH (without - 1) / number of heads
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[421] | 310 | ; Max = 262128 / 255 = 1027
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| 311 | pop ax
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| 312 | pop dx ; Value CH back to DX:AX
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| 313 | div cx
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[358] | 314 |
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[421] | 315 | ; Return L-CHS
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| 316 | ReturnLCHSinAXBLBH:
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[358] | 317 | ret
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