[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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[392] | 6 | ; Copyright (C) 2009-2010 by Tomi Tilli, 2011-2012 by XTIDE Universal BIOS Team. |
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| 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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| 37 | call LoadFirstSectorFromDriveDL |
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[505] | 38 | %ifndef USE_386 |
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[392] | 39 | jc SHORT .FailedToLoadFirstSector |
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[505] | 40 | %else |
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| 41 | jc DetectPrint_FailedToLoadFirstSector |
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| 42 | %endif |
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[392] | 43 | |
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| 44 | test dl, dl |
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| 45 | jns SHORT .AlwaysBootFromFloppyDriveForBooterGames |
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| 46 | cmp WORD [es:bx+510], 0AA55h ; Valid boot sector? |
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| 47 | jne SHORT .FirstHardDiskSectorNotBootable |
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| 48 | .AlwaysBootFromFloppyDriveForBooterGames: |
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| 49 | stc |
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[505] | 50 | jmp SHORT JumpToBootSector_or_RomBoot |
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| 51 | |
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| 52 | %ifndef USE_386 |
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[392] | 53 | .FailedToLoadFirstSector: |
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[505] | 54 | jmp DetectPrint_FailedToLoadFirstSector |
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| 55 | %endif |
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| 56 | |
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[392] | 57 | .FirstHardDiskSectorNotBootable: |
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| 58 | mov si, g_szBootSectorNotFound |
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[505] | 59 | jmp DetectPrint_NullTerminatedStringFromCSSIandSetCF |
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[392] | 60 | |
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[505] | 61 | %ifndef CHECK_FOR_UNUSED_ENTRYPOINTS |
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[492] | 62 | %ifdef MODULE_DRIVEXLATE |
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| 63 | %if TryToBoot_FallThroughTo_BootSector_TryToLoadFromDriveDL_AndBoot <> BootSector_TryToLoadFromDriveDL_AndBoot |
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| 64 | %error "TryToBoot_FallThroughTo_BootSector_TryToLoadFromDriveDL_AndBoot <> BootSector_TryToLoadFromDriveDL_AndBoot, BootSector must come immediately after int19h.asm" |
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| 65 | %endif |
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| 66 | %endif |
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| 67 | %endif |
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| 68 | |
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[392] | 69 | ;-------------------------------------------------------------------- |
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| 70 | ; LoadFirstSectorFromDriveDL |
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| 71 | ; Parameters: |
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| 72 | ; DL: Drive to boot from (translated, 00h or 80h) |
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| 73 | ; Returns: |
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| 74 | ; AH: INT 13h error code |
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| 75 | ; ES:BX: Ptr to boot sector (if successful) |
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| 76 | ; CF: Cleared if read successful |
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| 77 | ; Set if any error |
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| 78 | ; Corrupts registers: |
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| 79 | ; AL, CX, DH, DI |
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| 80 | ;-------------------------------------------------------------------- |
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| 81 | LoadFirstSectorFromDriveDL: |
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| 82 | LOAD_BDA_SEGMENT_TO es, bx ; ES:BX now points to... |
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| 83 | mov bx, BOOTVARS.rgbBootSect ; ...boot sector location |
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| 84 | mov di, BOOT_READ_RETRY_TIMES ; Initialize retry counter |
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| 85 | |
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| 86 | .ReadRetryLoop: |
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[505] | 87 | mov ax, 0201h ; Read 1 sector |
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| 88 | mov cx, 1 ; Cylinder 0, Sector 1 |
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| 89 | xor dh, dh ; Head 0 |
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| 90 | int BIOS_DISK_INTERRUPT_13h |
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| 91 | jc SHORT .FailedToLoadFirstSector |
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| 92 | .Return: |
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| 93 | ret |
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| 94 | |
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| 95 | .FailedToLoadFirstSector: |
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[428] | 96 | dec di ; Decrement retry counter (preserve CF) |
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| 97 | jz SHORT .Return ; Loop while retries left |
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[392] | 98 | |
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[428] | 99 | ; Reset drive and retry |
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[505] | 100 | xor ax, ax ; AH=00h, Disk Controller Reset |
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[392] | 101 | test dl, dl ; Floppy drive? |
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[505] | 102 | eCMOVS ah, RESET_HARD_DISK ; AH=0Dh, Reset Hard Disk (Alternate reset) |
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[392] | 103 | int BIOS_DISK_INTERRUPT_13h |
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[428] | 104 | jmp SHORT .ReadRetryLoop |
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[392] | 105 | |
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