source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/Handlers/Int19h/BootSector.asm@ 561

Last change on this file since 561 was 528, checked in by aitotat@…, 12 years ago

Changes to XTIDE Universal BIOS:

  • Swapping Floppy and Hard Drives at the same time work again (broke in r492).
  • Hotkeys again work in boot menu (broke in r492).
File size: 3.9 KB
Line 
1; Project name : XTIDE Universal BIOS
2; Description : Reading and jumping to boot sector.
3
4;
5; XTIDE Universal BIOS and Associated Tools
6; Copyright (C) 2009-2010 by Tomi Tilli, 2011-2013 by XTIDE Universal BIOS Team.
7;
8; This program is free software; you can redistribute it and/or modify
9; it under the terms of the GNU General Public License as published by
10; the Free Software Foundation; either version 2 of the License, or
11; (at your option) any later version.
12;
13; This program is distributed in the hope that it will be useful,
14; but WITHOUT ANY WARRANTY; without even the implied warranty of
15; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16; GNU General Public License for more details.
17; Visit http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
18;
19
20; Section containing code
21SECTION .text
22
23;--------------------------------------------------------------------
24; BootSector_TryToLoadFromDriveDL_AndBoot
25; Parameters:
26; DL: Drive to boot from (translated, 00h or 80h)
27; DS: RAMVARS segment
28; Returns:
29; ES:BX: Ptr to boot sector (if successful)
30; CF: Set if boot sector loaded successfully
31; Cleared if failed to load boot sector
32; Corrupts registers:
33; AX, CX, DH, SI, DI, (DL if failed to read boot sector)
34;--------------------------------------------------------------------
35BootSector_TryToLoadFromDriveDL_AndBoot:
36 call DetectPrint_TryToBootFromDL
37 call LoadFirstSectorFromDriveDL
38 jnc SHORT .FirstSectorLoadedToESBX
39
40 ; Do not display timeout error (80h) for floppy drives since
41 ; it most likely mean no diskette in drive. This way we do not
42 ; display error code every time user intends to boot from hard disk
43 ; when A then C boot order is used.
44 js SHORT .PrintFailedToLoadErrorCode ; Hard Drive
45 cmp ah, RET_HD_TIMEOUT
46 je SHORT .ReturnWithCFclearSinceFailedToLoadBootSector
47 cmp ah, RET_HD_NOMEDIA
48 je SHORT .ReturnWithCFclearSinceFailedToLoadBootSector
49.PrintFailedToLoadErrorCode:
50%ifdef USE_186
51 push .ReturnWithCFclearSinceFailedToLoadBootSector
52 jmp DetectPrint_FailedToLoadFirstSector
53%else
54 call DetectPrint_FailedToLoadFirstSector
55 jmp .ReturnWithCFclearSinceFailedToLoadBootSector
56%endif
57
58
59.FirstSectorLoadedToESBX:
60 test dl, dl
61 jns SHORT .AlwaysBootFromFloppyDriveForBooterGames
62 cmp WORD [es:bx+510], 0AA55h ; Valid boot sector?
63 jne SHORT .FirstHardDiskSectorNotBootable
64.AlwaysBootFromFloppyDriveForBooterGames:
65 stc ; Boot Sector loaded succesfully
66 jmp SHORT Int19_JumpToBootSectorOrRomBoot
67
68.FirstHardDiskSectorNotBootable:
69 mov si, g_szBootSectorNotFound
70 call DetectPrint_NullTerminatedStringFromCSSI
71.ReturnWithCFclearSinceFailedToLoadBootSector:
72 clc
73 ret
74
75
76;--------------------------------------------------------------------
77; LoadFirstSectorFromDriveDL
78; Parameters:
79; DL: Drive to boot from (translated, 00h or 80h)
80; Returns:
81; AH: INT 13h error code
82; ES:BX: Ptr to boot sector (if successful)
83; CF: Cleared if read successful
84; Set if any error
85; Corrupts registers:
86; AL, CX, DH, DI
87;--------------------------------------------------------------------
88LoadFirstSectorFromDriveDL:
89 LOAD_BDA_SEGMENT_TO es, bx ; ES:BX now points to...
90 mov bx, BOOTVARS.rgbBootSect ; ...boot sector location
91 mov di, BOOT_READ_RETRY_TIMES ; Initialize retry counter
92
93.ReadRetryLoop:
94 mov ax, 0201h ; Read 1 sector
95 mov cx, 1 ; Cylinder 0, Sector 1
96 xor dh, dh ; Head 0
97 int BIOS_DISK_INTERRUPT_13h
98 jc SHORT .FailedToLoadFirstSector
99.Return:
100 ret
101
102.FailedToLoadFirstSector:
103 dec di ; Decrement retry counter (preserve CF)
104 jz SHORT .Return ; Loop while retries left
105
106 ; Reset drive and retry
107 xor ax, ax ; AH=00h, Disk Controller Reset
108 test dl, dl ; Floppy drive?
109 eCMOVS ah, RESET_HARD_DISK ; AH=0Dh, Reset Hard Disk (Alternate reset)
110 int BIOS_DISK_INTERRUPT_13h
111 jmp SHORT .ReadRetryLoop
112
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