| 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 | TEMPORARY_VECTOR_FOR_SYSTEM_INT13h EQU 21h ; MS-DOS |
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| 25 | |
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| 26 | |
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| 27 | Int13hBiosInit_Handler: |
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| 28 | ; Ignore all but read command (assumed to read boot sector) |
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| 29 | cmp ah, READ_SECTORS_INTO_MEMORY |
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| 30 | jne SHORT .MainBiosStillInInitializationMode |
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| 31 | |
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| 32 | LOAD_BDA_SEGMENT_TO ds, ax |
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| 33 | |
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| 34 | ; Now install our handler and call 19h since non-standard motherboard BIOS did not |
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| 35 | ; do that or our INT 19h hander was replaced by other BIOS. |
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| 36 | mov WORD [BIOS_BOOT_LOADER_INTERRUPT_19h*4], Int19h_BootLoaderHandler |
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| 37 | mov [BIOS_BOOT_LOADER_INTERRUPT_19h*4+2], cs |
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| 38 | int BIOS_BOOT_LOADER_INTERRUPT_19h ; Does not return |
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| 39 | |
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| 40 | ; Main BIOS might reset floppy drives etc. so let's wait longer |
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| 41 | ; before installing our INT 19h handler. |
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| 42 | .MainBiosStillInInitializationMode: |
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| 43 | int TEMPORARY_VECTOR_FOR_SYSTEM_INT13h |
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| 44 | retf 2 |
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| 45 | |
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| 46 | |
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| 47 | ;-------------------------------------------------------------------- |
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| 48 | ; Int13hBiosInit_RestoreSystemHandler |
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| 49 | ; Parameters: |
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| 50 | ; Nothing |
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| 51 | ; Returns: |
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| 52 | ; Nothing |
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| 53 | ; Corrupts registers: |
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| 54 | ; AX, DS, ES |
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| 55 | ;-------------------------------------------------------------------- |
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| 56 | Int13hBiosInit_RestoreSystemHandler: |
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| 57 | LOAD_BDA_SEGMENT_TO ds, ax |
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| 58 | |
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| 59 | ; Is our very late init handler in place |
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| 60 | cmp WORD [BIOS_DISK_INTERRUPT_13h*4], Int13hBiosInit_Handler |
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| 61 | jne SHORT .SystemHandlerAlreadyInPlace |
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| 62 | |
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| 63 | les ax, [TEMPORARY_VECTOR_FOR_SYSTEM_INT13h*4] |
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| 64 | mov [BIOS_DISK_INTERRUPT_13h*4], ax |
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| 65 | mov [BIOS_DISK_INTERRUPT_13h*4+2], es |
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| 66 | .SystemHandlerAlreadyInPlace: |
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| 67 | ret |
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