[392] | 1 | ; Project name : XTIDE Universal BIOS |
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| 2 | ; Description : Reading and jumping to boot sector. |
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| 3 | |
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| 4 | ; |
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[505] | 5 | ; XTIDE Universal BIOS and Associated Tools |
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[526] | 6 | ; Copyright (C) 2009-2010 by Tomi Tilli, 2011-2013 by XTIDE Universal BIOS Team. |
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[392] | 7 | ; |
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| 8 | ; This program is free software; you can redistribute it and/or modify |
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| 9 | ; it under the terms of the GNU General Public License as published by |
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| 10 | ; the Free Software Foundation; either version 2 of the License, or |
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| 11 | ; (at your option) any later version. |
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[505] | 12 | ; |
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[392] | 13 | ; This program is distributed in the hope that it will be useful, |
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| 14 | ; but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 15 | ; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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| 16 | ; GNU General Public License for more details. |
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[505] | 17 | ; Visit http://www.gnu.org/licenses/old-licenses/gpl-2.0.html |
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| 18 | ; |
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[392] | 19 | |
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| 20 | ; Section containing code |
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| 21 | SECTION .text |
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| 22 | |
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| 23 | ;-------------------------------------------------------------------- |
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[505] | 24 | ; BootSector_TryToLoadFromDriveDL_AndBoot |
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[392] | 25 | ; Parameters: |
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| 26 | ; DL: Drive to boot from (translated, 00h or 80h) |
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| 27 | ; DS: RAMVARS segment |
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| 28 | ; Returns: |
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| 29 | ; ES:BX: Ptr to boot sector (if successful) |
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| 30 | ; CF: Set if boot sector loaded successfully |
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| 31 | ; Cleared if failed to load boot sector |
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| 32 | ; Corrupts registers: |
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| 33 | ; AX, CX, DH, SI, DI, (DL if failed to read boot sector) |
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| 34 | ;-------------------------------------------------------------------- |
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[492] | 35 | BootSector_TryToLoadFromDriveDL_AndBoot: |
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[392] | 36 | call DetectPrint_TryToBootFromDL |
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[595] | 37 | call BootSector_LoadFirstSectorFromDriveDL |
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[521] | 38 | jnc SHORT .FirstSectorLoadedToESBX |
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| 39 | |
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| 40 | ; Do not display timeout error (80h) for floppy drives since |
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| 41 | ; it most likely mean no diskette in drive. This way we do not |
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| 42 | ; display error code every time user intends to boot from hard disk |
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| 43 | ; when A then C boot order is used. |
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[568] | 44 | test dl, dl |
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[521] | 45 | js SHORT .PrintFailedToLoadErrorCode ; Hard Drive |
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| 46 | cmp ah, RET_HD_TIMEOUT |
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| 47 | je SHORT .ReturnWithCFclearSinceFailedToLoadBootSector |
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| 48 | cmp ah, RET_HD_NOMEDIA |
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| 49 | je SHORT .ReturnWithCFclearSinceFailedToLoadBootSector |
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| 50 | .PrintFailedToLoadErrorCode: |
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| 51 | call DetectPrint_FailedToLoadFirstSector |
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[568] | 52 | jmp SHORT .ReturnWithCFclearSinceFailedToLoadBootSector |
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[392] | 53 | |
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[521] | 54 | |
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| 55 | .FirstSectorLoadedToESBX: |
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[392] | 56 | test dl, dl |
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| 57 | jns SHORT .AlwaysBootFromFloppyDriveForBooterGames |
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| 58 | cmp WORD [es:bx+510], 0AA55h ; Valid boot sector? |
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| 59 | jne SHORT .FirstHardDiskSectorNotBootable |
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| 60 | .AlwaysBootFromFloppyDriveForBooterGames: |
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[597] | 61 | clc ; Boot Sector loaded successfully |
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| 62 | jmp SHORT Int19h_JumpToBootSectorInESBXOrRomBoot |
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[505] | 63 | |
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[392] | 64 | .FirstHardDiskSectorNotBootable: |
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| 65 | mov si, g_szBootSectorNotFound |
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[521] | 66 | call DetectPrint_NullTerminatedStringFromCSSI |
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| 67 | .ReturnWithCFclearSinceFailedToLoadBootSector: |
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| 68 | clc |
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| 69 | ret |
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[392] | 70 | |
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[492] | 71 | |
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[392] | 72 | ;-------------------------------------------------------------------- |
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[595] | 73 | ; BootSector_LoadFirstSectorFromDriveDL |
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[392] | 74 | ; Parameters: |
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| 75 | ; DL: Drive to boot from (translated, 00h or 80h) |
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| 76 | ; Returns: |
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| 77 | ; AH: INT 13h error code |
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| 78 | ; ES:BX: Ptr to boot sector (if successful) |
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| 79 | ; CF: Cleared if read successful |
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| 80 | ; Set if any error |
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| 81 | ; Corrupts registers: |
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| 82 | ; AL, CX, DH, DI |
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| 83 | ;-------------------------------------------------------------------- |
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[595] | 84 | BootSector_LoadFirstSectorFromDriveDL: |
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[392] | 85 | LOAD_BDA_SEGMENT_TO es, bx ; ES:BX now points to... |
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| 86 | mov bx, BOOTVARS.rgbBootSect ; ...boot sector location |
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| 87 | mov di, BOOT_READ_RETRY_TIMES ; Initialize retry counter |
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| 88 | |
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| 89 | .ReadRetryLoop: |
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[505] | 90 | mov ax, 0201h ; Read 1 sector |
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| 91 | mov cx, 1 ; Cylinder 0, Sector 1 |
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| 92 | xor dh, dh ; Head 0 |
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| 93 | int BIOS_DISK_INTERRUPT_13h |
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| 94 | jc SHORT .FailedToLoadFirstSector |
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| 95 | .Return: |
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| 96 | ret |
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| 97 | |
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| 98 | .FailedToLoadFirstSector: |
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[428] | 99 | dec di ; Decrement retry counter (preserve CF) |
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| 100 | jz SHORT .Return ; Loop while retries left |
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[392] | 101 | |
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[428] | 102 | ; Reset drive and retry |
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[505] | 103 | xor ax, ax ; AH=00h, Disk Controller Reset |
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[392] | 104 | test dl, dl ; Floppy drive? |
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[505] | 105 | eCMOVS ah, RESET_HARD_DISK ; AH=0Dh, Reset Hard Disk (Alternate reset) |
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[392] | 106 | int BIOS_DISK_INTERRUPT_13h |
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[428] | 107 | jmp SHORT .ReadRetryLoop |
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[392] | 108 | |
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