[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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[526] | 12 | ; Copyright (C) 2009-2010 by Tomi Tilli, 2011-2013 by XTIDE Universal BIOS Team.
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[376] | 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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[549] | 67 | ; AtaGeometry_GetLCHStoAXBLBHfromAtaInfoInESSIwithTranslateModeInDX
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[421] | 68 | ; Parameters:
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[422] | 69 | ; DX: Wanted translate mode or TRANSLATEMODE_AUTO to autodetect
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[421] | 70 | ; ES:SI: Ptr to 512-byte ATA information read from the drive
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| 71 | ; Returns:
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| 72 | ; AX: Number of L-CHS cylinders (1...1027, yes 1027)
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| 73 | ; BL: Number of L-CHS heads (1...255)
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| 74 | ; BH: Number of L-CHS sectors per track (1...63)
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| 75 | ; CX: Number of bits shifted (0...3)
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[606] | 76 | ; DX: CHS Translate Mode
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[421] | 77 | ; Corrupts registers:
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[606] | 78 | ; Nothing
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[421] | 79 | ;--------------------------------------------------------------------
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[549] | 80 | AtaGeometry_GetLCHStoAXBLBHfromAtaInfoInESSIwithTranslateModeInDX:
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[421] | 81 | call AtaGeometry_GetPCHStoAXBLBHfromAtaInfoInESSI
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| 82 |
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[422] | 83 | ; Check if user defined translate mode
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[491] | 84 | dec dx ; Set ZF if TRANSLATEMODE_LARGE, SF if TRANSLATEMODE_NORMAL
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| 85 | jns SHORT .CheckIfLargeTranslationWanted
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[612] | 86 | call AtaGeometry_LimitAXtoMaximumLCylinders ; TRANSLATEMODE_NORMAL maximum cylinders
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[422] | 87 | inc dx
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| 88 | .CheckIfLargeTranslationWanted:
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| 89 | jz SHORT ConvertPCHfromAXBLtoRevisedEnhancedCHinAXBL
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| 90 | dec dx ; Set ZF if TRANSLATEMODE_ASSISTED_LBA
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| 91 | jz SHORT .UseAssistedLBA
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| 92 | ; TRANSLATEMODE_AUTO set
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| 93 |
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[549] | 94 | %ifndef MODULE_EBIOS
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| 95 | ; Since we do not have EBIOS functions, we might as well use the faster
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| 96 | ; LARGE mode for small drives. Assisted LBA provides more capacity for
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| 97 | ; larger drives.
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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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[606] | 102 | %else
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| 103 | ; Check if the drive is within the limits of NORMAL addressing.
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| 104 | ; If it is, then no CHS translation is necessary.
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| 105 | cmp ax, MAX_LCHS_CYLINDERS
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| 106 | jbe SHORT ConvertPCHfromAXBLtoEnhancedCHinAXBL
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[549] | 107 | %endif
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[421] | 108 |
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[549] | 109 | ; If we have EBIOS functions, we should always use Assisted LBA
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| 110 | ; for drives with LBA support. Otherwise the EBIOS functions are
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| 111 | ; useless since we never do LBA to P-CHS translation.
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| 112 | ; Even if we do not have EBIOS functions, we must do this check
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| 113 | ; since user might have forced LBA mode even though the drive does
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| 114 | ; not support LBA addressing.
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[421] | 115 | test BYTE [es:si+ATA1.wCaps+1], A1_wCaps_LBA>>8
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[422] | 116 | jz SHORT ConvertPCHfromAXBLtoRevisedEnhancedCHinAXBL
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[421] | 117 |
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[549] | 118 | ; Assisted LBA provides most capacity but translation algorithm is
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| 119 | ; slower. The speed difference doesn't matter on AT systems.
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| 120 | .UseAssistedLBA:
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[592] | 121 | ; Fall to GetSectorCountToDXAXfromCHSinAXBLBH
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| 122 |
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| 123 |
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| 124 | ;--------------------------------------------------------------------
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| 125 | ; GetSectorCountToDXAXfromCHSinAXBLBH
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| 126 | ; Parameters:
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| 127 | ; AX: Number of cylinders (1...16383)
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| 128 | ; BL: Number of heads (1...255)
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| 129 | ; BH: Number of sectors per track (1...63)
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| 130 | ; Returns:
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| 131 | ; DX:AX: Total number of CHS addressable sectors
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| 132 | ; Corrupts registers:
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| 133 | ; BX
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| 134 | ;--------------------------------------------------------------------
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| 135 | GetSectorCountToDXAXfromCHSinAXBLBH:
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| 136 | xchg ax, bx
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| 137 | mul ah ; AX = Heads * Sectors per track
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| 138 | mul bx
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| 139 | ; Fall to ConvertChsSectorCountFromDXAXtoLbaAssistedLCHSinAXBLBH
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| 140 |
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| 141 |
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| 142 | ;--------------------------------------------------------------------
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| 143 | ; LBA assist calculation (or Assisted LBA)
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| 144 | ;
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| 145 | ; This algorithm translates P-CHS sector count up to largest possible
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| 146 | ; L-CHS sector count (1024, 255, 63). Note that INT 13h interface allows
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| 147 | ; 256 heads but DOS supports up to 255 head. That is why BIOSes never
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| 148 | ; use 256 heads.
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| 149 | ;
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| 150 | ; L-CHS parameters generated here require the drive to use LBA addressing.
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| 151 | ;
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| 152 | ; Here is the algorithm:
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| 153 | ; If cylinders > 8192
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| 154 | ; Variable CH = Total CHS Sectors / 63
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| 155 | ; Divide (CH - 1) by 1024 and add 1
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| 156 | ; 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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| 157 | ; Divide CH by the number of heads. This is the value to be used for the number of cylinders.
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| 158 | ;
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| 159 | ; ConvertChsSectorCountFromDXAXtoLbaAssistedLCHSinAXBLBH:
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| 160 | ; Parameters:
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| 161 | ; DX:AX: Total number of P-CHS sectors for CHS addressing
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| 162 | ; (max = 16383 * 16 * 63 = 16,514,064)
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| 163 | ; Returns:
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| 164 | ; AX: Number of cylinders (?...1027)
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| 165 | ; BL: Number of heads (16, 32, 64, 128 or 255)
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| 166 | ; BH: Number of sectors per track (always 63)
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| 167 | ; CX: Number of bits shifted (0)
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[606] | 168 | ; DX: TRANSLATEMODE_ASSISTED_LBA
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[592] | 169 | ; Corrupts registers:
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[606] | 170 | ; Nothing
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[592] | 171 | ;--------------------------------------------------------------------
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| 172 | ConvertChsSectorCountFromDXAXtoLbaAssistedLCHSinAXBLBH:
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| 173 | ; Value CH = Total sector count / 63
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| 174 | ; Max = 16,514,064 / 63 = 262128
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| 175 | mov cx, LBA_ASSIST_SPT ; CX = 63
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| 176 |
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| 177 | ; --- Math_DivDXAXbyCX inlined (and slightly modified) since it's only used here
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| 178 | xor bx, bx
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| 179 | xchg bx, ax
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| 180 | xchg dx, ax
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| 181 | div cx
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| 182 | xchg ax, bx
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| 183 | div cx
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| 184 | mov dx, bx
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| 185 | ; ---
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| 186 |
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| 187 | push ax
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| 188 | push dx ; Value CH stored for later use
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| 189 |
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| 190 | ; BX:DX:AX = Value CH - 1
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| 191 | ; Max = 262128 - 1 = 262127
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| 192 | xor bx, bx
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| 193 | sub ax, BYTE 1
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| 194 | sbb dx, bx
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| 195 |
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| 196 | ; AX = Number of heads = ((Value CH - 1) / 1024) + 1
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| 197 | ; Max = (262127 / 1024) + 1 = 256
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| 198 | call Size_DivideSizeInBXDXAXby1024 ; Preserves CX and returns with BH cleared
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| 199 | pop dx
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| 200 | inc ax ; + 1
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| 201 |
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| 202 | ; Heads must be 16, 32, 64, 128 or 255 (round up to the nearest)
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| 203 | ; Max = 255
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| 204 | mov bl, 16 ; Min number of heads
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| 205 | .CompareNextValidNumberOfHeads:
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| 206 | cmp ax, bx
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| 207 | jbe SHORT .NumberOfHeadsNowInBX
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| 208 | eSHL_IM bx, 1 ; Double number of heads
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| 209 | jpo SHORT .CompareNextValidNumberOfHeads ; Reached 256 heads?
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| 210 | dec bx ; If so, limit heads to 255
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| 211 | .NumberOfHeadsNowInBX:
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| 212 |
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| 213 | ; DX:AX = Number of cylinders = Value CH (without - 1) / number of heads
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| 214 | ; Max = 262128 / 255 = 1027
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| 215 | pop ax ; Value CH back to DX:AX
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| 216 | div bx
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| 217 |
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| 218 | xchg bh, cl ; Sectors per Track to BH, zero to CL (CX)
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[422] | 219 | mov dl, TRANSLATEMODE_ASSISTED_LBA
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[606] | 220 | ; All combinations of value CH from 1 to 262128 divided by number of heads
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| 221 | ; (16/32/64/128/255) has been verified to return with DH cleared.
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[592] | 222 | ReturnLCHSinAXBLBH:
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[421] | 223 | ret
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| 224 |
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| 225 |
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| 226 | ;--------------------------------------------------------------------
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| 227 | ; AtaGeometry_GetPCHStoAXBLBHfromAtaInfoInESSI
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| 228 | ; Parameters:
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| 229 | ; ES:SI: Ptr to 512-byte ATA information read from the drive
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| 230 | ; Returns:
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| 231 | ; AX: Number of P-CHS cylinders (1...16383)
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| 232 | ; BL: Number of P-CHS heads (1...16)
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| 233 | ; BH: Number of P-CHS sectors per track (1...63)
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| 234 | ; Corrupts registers:
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| 235 | ; Nothing
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| 236 | ;--------------------------------------------------------------------
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| 237 | AtaGeometry_GetPCHStoAXBLBHfromAtaInfoInESSI:
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| 238 | mov ax, [es:si+ATA1.wCylCnt] ; Cylinders (1...16383)
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| 239 | mov bl, [es:si+ATA1.wHeadCnt] ; Heads (1...16)
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| 240 | mov bh, [es:si+ATA1.wSPT] ; Sectors per Track (1...63)
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| 241 | ret
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| 242 |
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| 243 |
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| 244 | ;--------------------------------------------------------------------
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| 245 | ; Revised Enhanced CHS calculation (Revised ECHS)
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[358] | 246 | ;
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[421] | 247 | ; This algorithm translates P-CHS sector count to L-CHS sector count
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| 248 | ; with bit shift algorithm. Since 256 heads are not allowed
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| 249 | ; (DOS limit), this algorithm makes translations so that maximum of
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| 250 | ; 240 L-CHS heads can be used. This makes the maximum addressable capacity
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| 251 | ; to 7,927,234,560 bytes ~ 7.38 GiB. LBA addressing needs to be used to
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| 252 | ; get more capacity.
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| 253 | ;
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| 254 | ; L-CHS parameters generated here require the drive to use CHS addressing.
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| 255 | ;
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| 256 | ; Here is the algorithm:
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| 257 | ; If cylinders > 8192 and heads = 16
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| 258 | ; Heads = 15
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| 259 | ; Cylinders = cylinders * 16 / 15 (losing the fraction component)
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| 260 | ; Do a standard ECHS translation
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| 261 | ;
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[592] | 262 | ; *FIXME* The above algorithm seems to be conflicting with info found here
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| 263 | ; https://web.archive.org/web/20000817071418/http://www.firmware.com:80/support/bios/over4gb.htm
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| 264 | ; which says that Revised ECHS is used when the cylinder count is > 8191.
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| 265 | ;
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[422] | 266 | ; ConvertPCHfromAXBLtoRevisedEnhancedCHinAXBL:
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[421] | 267 | ; Parameters:
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| 268 | ; AX: Number of P-CHS cylinders (8193...16383)
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| 269 | ; BL: Number of P-CHS heads (1...16)
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| 270 | ; Returns:
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| 271 | ; AX: Number of L-CHS cylinders (?...1024)
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| 272 | ; BL: Number of L-CHS heads (?...240)
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| 273 | ; CX: Number of bits shifted (0...3)
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[592] | 274 | ; DX: TRANSLATEMODE_NORMAL or TRANSLATEMODE_LARGE
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[421] | 275 | ; Corrupts registers:
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| 276 | ; Nothing
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| 277 | ;--------------------------------------------------------------------
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[422] | 278 | ConvertPCHfromAXBLtoRevisedEnhancedCHinAXBL:
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| 279 | ; Generate L-CHS using simple bit shift algorithm (ECHS) if
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| 280 | ; 8192 or less cylinders
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[549] | 281 | call AtaGeometry_IsDriveSmallEnoughForECHS
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| 282 | jc SHORT ConvertPCHfromAXBLtoEnhancedCHinAXBL
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[421] | 283 |
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| 284 | eMOVZX cx, bl ; CX = 16
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| 285 | dec bx ; Heads = 15
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| 286 | mul cx ; DX:AX = Cylinders * 16
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| 287 | dec cx ; CX = 15
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| 288 | div cx ; AX = (Cylinders * 16) / 15
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[567] | 289 | ; Fall to ConvertPCHfromAXBLtoEnhancedCHinAXBL
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[421] | 290 |
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| 291 |
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| 292 | ;--------------------------------------------------------------------
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| 293 | ; Enhanced CHS calculation (ECHS)
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| 294 | ;
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| 295 | ; This algorithm translates P-CHS sector count to L-CHS sector count
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| 296 | ; with simple bit shift algorithm. Since 256 heads are not allowed
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| 297 | ; (DOS limit), this algorithm require that there are at most 8192
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| 298 | ; P-CHS cylinders. This makes the maximum addressable capacity
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| 299 | ; to 4,227,858,432 bytes ~ 3.94 GiB. Use Revised ECHS or Assisted LBA
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| 300 | ; algorithms if there are more than 8192 P-CHS cylinders.
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| 301 | ;
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| 302 | ; L-CHS parameters generated here require the drive to use CHS addressing.
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| 303 | ;
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| 304 | ; Here is the algorithm:
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| 305 | ; Multiplier = 1
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| 306 | ; Cylinder = Cylinder - 1
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| 307 | ; Is Cylinder < 1024? If not:
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| 308 | ; Do a right bitwise rotation on the cylinder (i.e., divide by 2)
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| 309 | ; Do a left bitwise rotation on the multiplier (i.e., multiply by 2)
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| 310 | ; Use the multiplier on the Cylinder and Head values to obtain the translated values.
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| 311 | ;
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[422] | 312 | ; ConvertPCHfromAXBLtoEnhancedCHinAXBL:
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[421] | 313 | ; Parameters:
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[547] | 314 | ; AX: Number of P-CHS cylinders (1...8192, or up to 17475 if fell from above)
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[421] | 315 | ; BL: Number of P-CHS heads (1...16)
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| 316 | ; Returns:
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| 317 | ; AX: Number of L-CHS cylinders (?...1024)
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[547] | 318 | ; BL: Number of L-CHS heads (?...128, or up to 240 if fell from above)
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[421] | 319 | ; CX: Number of bits shifted (0...3)
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[547] | 320 | ; DX: TRANSLATEMODE_NORMAL or TRANSLATEMODE_LARGE
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[421] | 321 | ; Corrupts registers:
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| 322 | ; Nothing
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| 323 | ;--------------------------------------------------------------------
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[422] | 324 | ConvertPCHfromAXBLtoEnhancedCHinAXBL:
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[547] | 325 | cwd ; Assume TRANSLATEMODE_NORMAL
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[421] | 326 | xor cx, cx ; No bits to shift initially
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| 327 | .ShiftIfMoreThan1024Cylinder:
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| 328 | cmp ax, MAX_LCHS_CYLINDERS
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| 329 | jbe SHORT ReturnLCHSinAXBLBH
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[422] | 330 | shr ax, 1 ; Halve cylinders
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[445] | 331 | eSHL_IM bl, 1 ; Double heads
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[421] | 332 | inc cx ; Increment bit shift count
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[422] | 333 | mov dl, TRANSLATEMODE_LARGE
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[421] | 334 | jmp SHORT .ShiftIfMoreThan1024Cylinder
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| 335 |
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| 336 |
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| 337 | ;--------------------------------------------------------------------
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[549] | 338 | ; Checks should LARGE mode L-CHS be calculated with ECHS or Revised ECHS
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| 339 | ; algorithm. Revised ECHS is needed for drives with 8193 or more cylinders
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| 340 | ; AND 16 heads.
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| 341 | ;
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| 342 | ; AtaGeometry_IsDriveSmallEnoughForECHS:
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| 343 | ; Parameters:
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| 344 | ; AX: Number of P-Cylinders
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| 345 | ; BL: Number of P-Heads
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| 346 | ; Returns:
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| 347 | ; CF: Clear if Reviced ECHS is necessary
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| 348 | ; Set if ECHS is enough
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| 349 | ; Corrupts registers:
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| 350 | ; Nothing
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| 351 | ;--------------------------------------------------------------------
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| 352 | AtaGeometry_IsDriveSmallEnoughForECHS:
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| 353 | ; Generate L-CHS using simple bit shift algorithm (ECHS) if
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| 354 | ; 8192 or less cylinders. Use Revised ECHS if 8193 or more cylinders
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| 355 | ; AND 16 heads.
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| 356 | cmp ax, 8193
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| 357 | jb SHORT .RevisedECHSisNotNeeded
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| 358 | cmp bl, 16 ; Drives with 8193 or more cylinders can report 15 heads
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| 359 | .RevisedECHSisNotNeeded:
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| 360 | ret
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| 361 |
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[612] | 362 |
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| 363 | ;--------------------------------------------------------------------
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| 364 | ; AtaGeometry_LimitAXtoMaximumLCylinders
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| 365 | ; Parameters:
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| 366 | ; AX: Number of total L-CHS cylinders (1...1027)
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| 367 | ; Returns:
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| 368 | ; AX: Number of usable L-CHS cylinders (1...1024)
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| 369 | ; Corrupts registers:
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| 370 | ; Nothing
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| 371 | ;--------------------------------------------------------------------
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| 372 | AtaGeometry_LimitAXtoMaximumLCylinders:
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| 373 | MIN_U ax, MAX_LCHS_CYLINDERS
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| 374 | ret
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| 375 |
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