1 | ; Project name : XTIDE Universal BIOS |
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2 | ; Description : Functions for generating L-CHS parameters for |
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3 | ; drives with more than 1024 cylinders. |
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4 | ; |
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5 | ; These algorithms are taken from: http://www.mossywell.com/boot-sequence |
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6 | ; Take a look at it for more detailed information. |
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7 | ; |
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8 | ; This file is shared with BIOS Drive Information Tool. |
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9 | |
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10 | ; |
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11 | ; XTIDE Universal BIOS and Associated Tools |
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12 | ; Copyright (C) 2009-2010 by Tomi Tilli, 2011-2013 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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18 | ; |
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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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22 | ; GNU General Public License for more details. |
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23 | ; Visit http://www.gnu.org/licenses/old-licenses/gpl-2.0.html |
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24 | ; |
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25 | |
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26 | ; Section containing code |
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27 | SECTION .text |
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28 | |
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29 | %ifdef MODULE_EBIOS |
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30 | ;-------------------------------------------------------------------- |
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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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35 | ; BX:DX:AX: 48-bit sector count |
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36 | ; CL: FLGL_DPT_LBA48 if LBA48 supported |
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37 | ; Zero if only LBA28 is supported |
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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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67 | ; AtaGeometry_GetLCHStoAXBLBHfromAtaInfoInESSIwithTranslateModeInDX |
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68 | ; Parameters: |
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69 | ; DX: Wanted translate mode or TRANSLATEMODE_AUTO to autodetect |
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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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76 | ; DX: CHS Translate Mode |
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77 | ; Corrupts registers: |
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78 | ; Nothing |
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79 | ;-------------------------------------------------------------------- |
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80 | AtaGeometry_GetLCHStoAXBLBHfromAtaInfoInESSIwithTranslateModeInDX: |
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81 | call AtaGeometry_GetPCHStoAXBLBHfromAtaInfoInESSI |
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82 | |
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83 | ; Check if user defined translate mode |
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84 | dec dx ; Set ZF if TRANSLATEMODE_LARGE, SF if TRANSLATEMODE_NORMAL |
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85 | jns SHORT .CheckIfLargeTranslationWanted |
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86 | call AtaGeometry_LimitAXtoMaximumLCylinders ; TRANSLATEMODE_NORMAL maximum cylinders |
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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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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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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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101 | jbe SHORT ConvertPCHfromAXBLtoEnhancedCHinAXBL |
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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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107 | %endif |
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108 | |
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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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115 | test BYTE [es:si+ATA1.wCaps+1], A1_wCaps_LBA>>8 |
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116 | jz SHORT ConvertPCHfromAXBLtoRevisedEnhancedCHinAXBL |
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117 | |
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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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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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168 | ; DX: TRANSLATEMODE_ASSISTED_LBA |
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169 | ; Corrupts registers: |
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170 | ; Nothing |
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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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219 | mov dl, TRANSLATEMODE_ASSISTED_LBA |
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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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222 | ReturnLCHSinAXBLBH: |
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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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246 | ; |
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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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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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266 | ; ConvertPCHfromAXBLtoRevisedEnhancedCHinAXBL: |
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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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274 | ; DX: TRANSLATEMODE_NORMAL or TRANSLATEMODE_LARGE |
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275 | ; Corrupts registers: |
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276 | ; Nothing |
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277 | ;-------------------------------------------------------------------- |
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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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281 | call AtaGeometry_IsDriveSmallEnoughForECHS |
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282 | jc SHORT ConvertPCHfromAXBLtoEnhancedCHinAXBL |
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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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289 | ; Fall to ConvertPCHfromAXBLtoEnhancedCHinAXBL |
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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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312 | ; ConvertPCHfromAXBLtoEnhancedCHinAXBL: |
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313 | ; Parameters: |
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314 | ; AX: Number of P-CHS cylinders (1...8192, or up to 17475 if fell from above) |
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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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318 | ; BL: Number of L-CHS heads (?...128, or up to 240 if fell from above) |
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319 | ; CX: Number of bits shifted (0...3) |
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320 | ; DX: TRANSLATEMODE_NORMAL or TRANSLATEMODE_LARGE |
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321 | ; Corrupts registers: |
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322 | ; Nothing |
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323 | ;-------------------------------------------------------------------- |
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324 | ConvertPCHfromAXBLtoEnhancedCHinAXBL: |
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325 | cwd ; Assume TRANSLATEMODE_NORMAL |
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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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330 | shr ax, 1 ; Halve cylinders |
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331 | eSHL_IM bl, 1 ; Double heads |
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332 | inc cx ; Increment bit shift count |
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333 | mov dl, TRANSLATEMODE_LARGE |
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334 | jmp SHORT .ShiftIfMoreThan1024Cylinder |
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335 | |
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336 | |
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337 | ;-------------------------------------------------------------------- |
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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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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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