| 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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