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
|
---|
21 | SECTION .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 | ;--------------------------------------------------------------------
|
---|
35 | BootSector_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 | ;--------------------------------------------------------------------
|
---|
88 | LoadFirstSectorFromDriveDL:
|
---|
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 |
|
---|