source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/Handlers/Int13hBiosInit.asm@ 559

Last change on this file since 559 was 559, checked in by aitotat@…, 11 years ago

Changes to XTIDE Universal BIOS:

  • All XT builds now default to 1 controller.
  • Very late initialization handler now waits read command until installing and calling 19h.
File size: 2.3 KB
Line 
1; Project name : XTIDE Universal BIOS
2; Description : Int 13h handler that is used to initialize
3; XTIDE Universal BIOS when our INT 19h was not called.
4
5;
6; XTIDE Universal BIOS and Associated Tools
7; Copyright (C) 2009-2010 by Tomi Tilli, 2011-2013 by XTIDE Universal BIOS Team.
8;
9; This program is free software; you can redistribute it and/or modify
10; it under the terms of the GNU General Public License as published by
11; the Free Software Foundation; either version 2 of the License, or
12; (at your option) any later version.
13;
14; This program is distributed in the hope that it will be useful,
15; but WITHOUT ANY WARRANTY; without even the implied warranty of
16; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17; GNU General Public License for more details.
18; Visit http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
19;
20
21; Section containing code
22SECTION .text
23
24TEMPORARY_VECTOR_FOR_SYSTEM_INT13h EQU 21h ; MS-DOS
25
26
27Int13hBiosInit_Handler:
28 ; Ignore all but read command (assumed to read boot sector)
29 cmp ah, READ_SECTORS_INTO_MEMORY
30 jne SHORT .MainBiosStillInInitializationMode
31
32 LOAD_BDA_SEGMENT_TO ds, ax
33
34 ; Now install our handler and call 19h since non-standard motherboard BIOS did not
35 ; do that or our INT 19h hander was replaced by other BIOS.
36 mov WORD [BIOS_BOOT_LOADER_INTERRUPT_19h*4], Int19h_BootLoaderHandler
37 mov [BIOS_BOOT_LOADER_INTERRUPT_19h*4+2], cs
38 int BIOS_BOOT_LOADER_INTERRUPT_19h ; Does not return
39
40 ; Main BIOS might reset floppy drives etc. so let's wait longer
41 ; before installing our INT 19h handler.
42.MainBiosStillInInitializationMode:
43 int TEMPORARY_VECTOR_FOR_SYSTEM_INT13h
44 retf 2
45
46
47;--------------------------------------------------------------------
48; Int13hBiosInit_RestoreSystemHandler
49; Parameters:
50; Nothing
51; Returns:
52; Nothing
53; Corrupts registers:
54; AX, DS, ES
55;--------------------------------------------------------------------
56Int13hBiosInit_RestoreSystemHandler:
57 LOAD_BDA_SEGMENT_TO ds, ax
58
59 ; Is our very late init handler in place
60 cmp WORD [BIOS_DISK_INTERRUPT_13h*4], Int13hBiosInit_Handler
61 jne SHORT .SystemHandlerAlreadyInPlace
62
63 les ax, [TEMPORARY_VECTOR_FOR_SYSTEM_INT13h*4]
64 mov [BIOS_DISK_INTERRUPT_13h*4], ax
65 mov [BIOS_DISK_INTERRUPT_13h*4+2], es
66.SystemHandlerAlreadyInPlace:
67 ret
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