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Rev | Author | Line No. | Line |
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2288 | clevermous | 1 | ; Copyright (c) 2008-2009, diamond |
2 | ; All rights reserved. |
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3 | ; |
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4 | ; Redistribution and use in source and binary forms, with or without |
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5 | ; modification, are permitted provided that the following conditions are met: |
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6 | ; * Redistributions of source code must retain the above copyright |
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7 | ; notice, this list of conditions and the following disclaimer. |
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8 | ; * Redistributions in binary form must reproduce the above copyright |
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9 | ; notice, this list of conditions and the following disclaimer in the |
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10 | ; documentation and/or other materials provided with the distribution. |
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11 | ; * Neither the name of the |
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12 | ; names of its contributors may be used to endorse or promote products |
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13 | ; derived from this software without specific prior written permission. |
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14 | ; |
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15 | ; THIS SOFTWARE IS PROVIDED BY Alexey Teplov aka |
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16 | ; EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED |
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17 | ; WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE |
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18 | ; DISCLAIMED. IN NO EVENT SHALL |
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19 | ; DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES |
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20 | ; (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
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21 | ; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND |
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22 | ; ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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23 | ; (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS |
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24 | ; SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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25 | ;***************************************************************************** |
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26 | |||
8091 | dunkaist | 27 | use_lba = 1 |
2288 | clevermous | 28 | org 0x7C00 |
29 | jmp start |
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30 | nop |
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31 | ; FAT parameters, BPB |
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32 | ; they must be changed at install, replaced with real values |
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33 | rb 8 ; BS_OEMName, ignored |
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34 | dw 200h ; BPB_BytsPerSec |
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35 | BPB_SecsPerClus db ? |
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36 | BPB_RsvdSecCnt dw ? |
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37 | BPB_NumFATs db ? |
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38 | BPB_RootEntCnt dw ? |
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39 | dw ? ; BPB_TotSec16 |
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40 | db ? ; BPB_Media |
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41 | dw ? ; BPB_FATSz16 = 0 for FAT32 |
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42 | BPB_SecPerTrk dw ? |
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43 | BPB_NumHeads dw ? |
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44 | BPB_HiddSec dd ? |
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45 | dd ? ; BPB_TotSec32 |
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46 | BPB_FATSz32 dd ? |
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47 | BPB_ExtFlags dw ? |
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48 | dw ? ; BPB_FSVer |
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49 | BPB_RootClus dd ? |
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50 | dw ? ; BPB_FSInfo |
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51 | BPB_BkBootSec dw ? |
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52 | rb 12 ; BPB_Reserved |
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53 | BS_DrvNum db ? |
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54 | db ? ; BS_Reserved1 |
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55 | db ? ; BS_BootSig |
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56 | dd ? ; BS_VolID |
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57 | rb 11 ; BS_VolLab |
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58 | rb 8 ; |
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59 | |||
60 | curseg dw 0x8000 |
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61 | |||
62 | start: |
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63 | xor ax, ax |
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64 | mov ss, ax |
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65 | mov sp, 0x7C00 |
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66 | mov ds, ax |
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67 | mov bp, sp |
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68 | cld |
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69 | sti |
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70 | push dx ; byte [bp-2] = boot drive |
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71 | if use_lba |
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72 | mov ah, 41h |
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73 | mov bx, 55AAh |
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74 | int 13h |
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75 | mov si, aNoLBA |
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76 | jc err_ |
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77 | cmp bx, 0AA55h |
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78 | jnz err_ |
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79 | test cl, 1 |
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80 | jz err_ |
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81 | else |
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82 | mov ah, 8 |
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83 | int 13h |
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84 | jc @f |
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85 | movzx ax, dh |
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86 | inc ax |
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87 | mov [bp+BPB_NumHeads-0x7C00], ax |
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88 | and cx, 3Fh |
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89 | mov [bp+BPB_SecPerTrk-0x7C00], cx |
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90 | @@: |
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91 | end if |
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92 | ; get FAT parameters |
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93 | xor bx, bx |
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94 | movzx eax, [bp+BPB_NumFATs-0x7C00] |
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95 | mul [bp+BPB_FATSz32-0x7C00] |
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96 | movzx ecx, [bp+BPB_RsvdSecCnt-0x7C00] |
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97 | push ecx ; FAT start = dword [bp-6] |
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98 | add eax, ecx |
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99 | push eax ; data start = dword [bp-10] |
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100 | ;push dword -1 ; dword [bp-14] = current sector for FAT cache |
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101 | db 66h |
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102 | push -1 ; dword [bp-14] = current sector for FAT cache |
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103 | mov eax, [bp+BPB_RootClus-0x7C00] |
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104 | mov si, main_loader |
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105 | call lookup_in_dir |
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106 | jnc kordldr_ok |
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107 | noloader: |
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108 | mov si, aLoaderNotFound |
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109 | err_: |
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110 | call out_string |
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111 | mov si, aPressAnyKey |
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112 | call out_string |
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113 | xor ax, ax |
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114 | int 16h |
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115 | int 18h |
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116 | jmp $ |
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117 | kordldr_ok: |
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118 | mov eax, [es:di+20-2] ; hiword(eax) = hiword(cluster) |
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119 | mov ax, [es:di+26] ; loword(eax) = loword(cluster) |
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120 | mov es, bx ; es = 0 |
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121 | mov bx, 0x7E00 |
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122 | push bx ; save return address: bx = 7E00 |
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123 | ; fall through - 'ret' in read_cluster will return to 7E00 |
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124 | |||
125 | read_cluster: |
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126 | ; ss:bp = 0:7C00 |
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127 | ; es:bx = pointer to data |
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128 | ; eax = cluster |
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129 | sub eax, 2 |
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130 | movzx ecx, [bp+BPB_SecsPerClus-0x7C00] |
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131 | mul ecx |
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132 | |||
133 | read_sectors2: |
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134 | ; same as read_sectors32, but eax is relative to start of data |
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135 | add eax, [bp-10] |
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136 | read_sectors32: |
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137 | ; ss:bp = 0:7C00 |
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138 | ; es:bx = pointer to data |
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139 | ; eax = first sector |
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140 | ; cx = number of sectors |
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141 | ; some high words of 32-bit registers are destroyed! |
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142 | pusha |
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143 | add eax, [bp+BPB_HiddSec-0x7C00] |
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144 | if use_lba |
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145 | push ds |
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146 | do_read_sectors: |
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147 | push ax |
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148 | push cx |
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149 | cmp cx, 0x7F |
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150 | jbe @f |
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151 | mov cx, 0x7F |
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152 | @@: |
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153 | ; create disk address packet on the stack |
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154 | ; dq starting LBA |
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155 | push 0 |
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156 | push 0 |
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157 | push eax |
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158 | ; dd buffer |
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159 | push es |
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160 | push bx |
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161 | ; dw number of blocks to transfer (no more than 0x7F) |
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162 | push cx |
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163 | ; dw packet size in bytes |
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164 | push 10h |
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165 | ; issue BIOS call |
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166 | push ss |
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167 | pop ds |
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168 | mov si, sp |
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169 | mov dl, [bp-2] |
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170 | mov ah, 42h |
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171 | int 13h |
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172 | mov si, aReadError |
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173 | jc err_ |
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174 | ; restore stack |
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175 | add sp, 10h |
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176 | ; increase current sector & buffer; decrease number of sectors |
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177 | movzx esi, cx |
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178 | mov ax, es |
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179 | shl cx, 5 |
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180 | add ax, cx |
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181 | mov es, ax |
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182 | pop cx |
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183 | pop ax |
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184 | add eax, esi |
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185 | sub cx, si |
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186 | jnz do_read_sectors |
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187 | pop ds |
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188 | popa |
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189 | ret |
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190 | else |
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191 | do_read_sectors: |
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192 | pusha |
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193 | pop edi ; loword(edi) = di, hiword(edi) = si |
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194 | push bx |
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195 | |||
196 | ; eax / (SectorsPerTrack) -> eax, remainder bx |
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197 | movzx esi, [bp+BPB_SecPerTrk-0x7C00] |
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198 | xor edx, edx |
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199 | div esi |
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200 | mov bx, dx ; bx=sector-1 |
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201 | |||
202 | ; eax -> dx:ax |
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203 | push eax |
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204 | pop ax |
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205 | pop dx |
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206 | ; (dword in dx:ax) / (NumHeads) -> (word in ax), remainder dx |
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207 | div [bp+BPB_NumHeads-0x7C00] |
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208 | |||
209 | ; number of sectors: read no more than to end of track |
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210 | sub si, bx |
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211 | cmp cx, si |
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212 | jbe @f |
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213 | mov cx, si |
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214 | @@: |
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215 | |||
216 | inc bx |
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217 | ; now ax=track, dl=head, dh=0, cl=number of sectors, ch=0, bl=sector; convert to int13 format |
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218 | movzx edi, cx |
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219 | mov dh, dl |
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220 | mov dl, [bp-2] |
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221 | shl ah, 6 |
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222 | mov ch, al |
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223 | mov al, cl |
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224 | mov cl, bl |
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225 | or cl, ah |
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226 | pop bx |
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227 | mov si, 3 |
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228 | mov ah, 2 |
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229 | @@: |
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230 | push ax |
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231 | int 13h |
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232 | jnc @f |
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233 | xor ax, ax |
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234 | int 13h ; reset drive |
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235 | pop ax |
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236 | dec si |
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237 | jnz @b |
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238 | mov si, aReadError |
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239 | jmp err_ |
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240 | @@: |
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241 | pop ax |
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242 | mov ax, es |
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243 | mov cx, di |
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244 | shl cx, 5 |
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245 | add ax, cx |
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246 | mov es, ax |
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247 | push edi |
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248 | popa |
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249 | add eax, edi |
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250 | sub cx, di |
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251 | jnz do_read_sectors |
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252 | popa |
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253 | ret |
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254 | end if |
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255 | |||
256 | lookup_in_dir: |
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257 | ; in: ds:si -> 11-bytes FAT name |
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258 | ; in: eax = cluster |
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259 | ; in: bx = 0 |
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260 | ; out: if found: CF=0, es:di -> directory entry |
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261 | ; out: if not found: CF=1 |
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262 | ; push 0x8000 |
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263 | ; pop es |
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264 | ; read current cluster: first cluster goes to 8000:0000, others - to 8200:0000 |
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265 | mov es, [bp-7C00h + curseg] |
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266 | push es |
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267 | push eax |
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268 | call read_cluster |
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269 | mov ax, es |
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270 | cmp ah, 82h |
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271 | jb @f |
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272 | mov ax, 8200h |
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273 | @@: |
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274 | mov [bp-7C00h + curseg], ax |
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275 | pop eax |
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276 | pop es |
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277 | ; scan for filename |
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278 | shl cx, 4 |
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279 | xor di, di |
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280 | sloop: |
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281 | cmp byte [es:di], bl |
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282 | jz snotfound |
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283 | test byte [es:di+11], 8 ; volume label? |
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284 | jnz scont ; ignore volume labels |
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285 | pusha |
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286 | mov cx, 11 |
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287 | repz cmpsb |
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288 | popa |
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289 | jz sdone |
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290 | scont: |
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291 | add di, 0x20 |
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292 | loop sloop |
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293 | ; next cluster |
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294 | push 0x6000 |
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295 | pop es |
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296 | push es ax |
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297 | shr eax, 7 |
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298 | cmp eax, [bp-14] |
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299 | mov [bp-14], eax |
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300 | jz @f |
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301 | add eax, [bp-6] |
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302 | mov cx, 1 |
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303 | call read_sectors32 |
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304 | @@: |
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305 | pop di es |
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306 | and di, 0x7F |
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307 | shl di, 2 |
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308 | and byte [es:di+3], 0x0F |
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309 | mov eax, [es:di] |
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310 | ;and eax, 0x0FFFFFFF |
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311 | cmp eax, 0x0FFFFFF7 |
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312 | jb lookup_in_dir |
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313 | snotfound: |
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314 | stc |
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315 | sdone: |
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316 | ret |
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317 | |||
318 | out_string: |
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319 | ; in: ds:si -> ASCIIZ string |
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320 | lodsb |
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321 | test al, al |
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322 | jz sdone |
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323 | mov ah, 0Eh |
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324 | mov bx, 7 |
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325 | int 10h |
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326 | jmp out_string |
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327 | |||
328 | aReadError db 'Read error',0 |
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329 | if use_lba |
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330 | aNoLBA db 'The drive does not support LBA!',0 |
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331 | end if |
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332 | aLoaderNotFound db 'Loader not found',0 |
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333 | aPressAnyKey db 13,10,'Press any key...',13,10,0 |
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334 | main_loader db 'KORDLDR F32' |
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335 | |||
336 | db 56h |
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337 | ; just to make file 512 bytes long :) |
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338 | db 'd' xor 'i' xor 'a' xor 'm' xor 'o' xor 'n' xor 'd' |
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339 | |||
340 | ; bootsector signature |
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341 | dw 0xAA55 |
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342 | |||
343 | ; display offsets of all procedures used by kordldr.f12.asm |
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344 | macro show [procedure] |
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345 | { |
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346 | bits = 16 |
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347 | display `procedure,' = ' |
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348 | repeat bits/4 |
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349 | d = '0' + procedure shr (bits - %*4) and 0Fh |
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350 | if d > '9' |
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351 | d = d + 'A'-'9'-1 |
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352 | end if |
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353 | display d |
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354 | end repeat |
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355 | display 13,10 |
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356 | } |
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357 | |||
358 | show read_sectors32, read_sectors2, err_, noloader |