| 1 | ; Project name : XTIDE Universal BIOS |
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| 2 | ; Description : Int 13h handler that is used to initialize |
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| 3 | ; XTIDE Universal BIOS when our INT 19h was not called. |
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| 4 | |
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| 5 | ; |
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| 6 | ; XTIDE Universal BIOS and Associated Tools |
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| 7 | ; Copyright (C) 2009-2010 by Tomi Tilli, 2011-2013 by XTIDE Universal BIOS Team. |
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| 8 | ; |
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| 9 | ; This program is free software; you can redistribute it and/or modify |
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| 10 | ; it under the terms of the GNU General Public License as published by |
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| 11 | ; the Free Software Foundation; either version 2 of the License, or |
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| 12 | ; (at your option) any later version. |
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| 13 | ; |
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| 14 | ; This program is distributed in the hope that it will be useful, |
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| 15 | ; but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 16 | ; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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| 17 | ; GNU General Public License for more details. |
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| 18 | ; Visit http://www.gnu.org/licenses/old-licenses/gpl-2.0.html |
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| 19 | ; |
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| 20 | |
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| 21 | ; Section containing code |
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| 22 | SECTION .text |
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| 23 | |
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| 24 | |
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| 25 | ;-------------------------------------------------------------------- |
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| 26 | ; Int 13h software interrupt handler. |
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| 27 | ; This handler captures boot sector read from foreign drive when our |
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| 28 | ; INT 19h is not called. This way we can force XTIDE Universal BIOS |
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| 29 | ; initialization even without INT 19h being called. |
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| 30 | ; |
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| 31 | ; Int13hBiosInit_Handler |
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| 32 | ; Parameters: |
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| 33 | ; AH: Bios function |
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| 34 | ; READ_SECTORS_INTO_MEMORY will initialize XTIDE Universal BIOS |
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| 35 | ;-------------------------------------------------------------------- |
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| 36 | Int13hBiosInit_Handler: |
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| 37 | ; Initialize XTIDE Universal BIOS only if Int13hBiosInit_Handler is still at |
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| 38 | ; vector 13h. Otherwise some other BIOS has hooked us and our very late |
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| 39 | ; initialization is not possible. |
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| 40 | push ds |
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| 41 | push ax |
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| 42 | LOAD_BDA_SEGMENT_TO ds, ax |
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| 43 | pop ax |
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| 44 | cmp WORD [BIOS_DISK_INTERRUPT_13h*4], Int13hBiosInit_Handler |
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| 45 | pop ds |
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| 46 | jne SHORT .VeryLateInitFailed ; XTIDE Universal BIOS does not work |
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| 47 | |
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| 48 | ; Ignore all but read command (assumed to read boot sector) |
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| 49 | cmp ah, READ_SECTORS_INTO_MEMORY |
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| 50 | je SHORT Int19h_BootLoaderHandler |
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| 51 | |
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| 52 | ; Call system INT 13h since not trying to read boot sector |
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| 53 | int TEMPORARY_VECTOR_FOR_SYSTEM_INT13h |
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| 54 | retf 2 |
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| 55 | |
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| 56 | .VeryLateInitFailed: |
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| 57 | mov ah, RET_HD_INVALID |
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| 58 | stc |
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| 59 | retf 2 |
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