| 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 BootSector_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 | test dl, dl
|
|---|
| 45 | js SHORT .PrintFailedToLoadErrorCode ; Hard Drive
|
|---|
| 46 | cmp ah, RET_HD_TIMEOUT
|
|---|
| 47 | je SHORT .ReturnWithCFclearSinceFailedToLoadBootSector
|
|---|
| 48 | cmp ah, RET_HD_NOMEDIA
|
|---|
| 49 | je SHORT .ReturnWithCFclearSinceFailedToLoadBootSector
|
|---|
| 50 | .PrintFailedToLoadErrorCode:
|
|---|
| 51 | call DetectPrint_FailedToLoadFirstSector
|
|---|
| 52 | jmp SHORT .ReturnWithCFclearSinceFailedToLoadBootSector
|
|---|
| 53 |
|
|---|
| 54 |
|
|---|
| 55 | .FirstSectorLoadedToESBX:
|
|---|
| 56 | test dl, dl
|
|---|
| 57 | jns SHORT .AlwaysBootFromFloppyDriveForBooterGames
|
|---|
| 58 | cmp WORD [es:bx+510], 0AA55h ; Valid boot sector?
|
|---|
| 59 | jne SHORT .FirstHardDiskSectorNotBootable
|
|---|
| 60 | .AlwaysBootFromFloppyDriveForBooterGames:
|
|---|
| 61 | clc ; Boot Sector loaded successfully
|
|---|
| 62 | jmp SHORT Int19h_JumpToBootSectorInESBXOrRomBoot
|
|---|
| 63 |
|
|---|
| 64 | .FirstHardDiskSectorNotBootable:
|
|---|
| 65 | mov si, g_szBootSectorNotFound
|
|---|
| 66 | call DetectPrint_NullTerminatedStringFromCSSI
|
|---|
| 67 | .ReturnWithCFclearSinceFailedToLoadBootSector:
|
|---|
| 68 | clc
|
|---|
| 69 | ret
|
|---|
| 70 |
|
|---|
| 71 |
|
|---|
| 72 | ;--------------------------------------------------------------------
|
|---|
| 73 | ; BootSector_LoadFirstSectorFromDriveDL
|
|---|
| 74 | ; Parameters:
|
|---|
| 75 | ; DL: Drive to boot from (translated, 00h or 80h)
|
|---|
| 76 | ; Returns:
|
|---|
| 77 | ; AH: INT 13h error code
|
|---|
| 78 | ; ES:BX: Ptr to boot sector (if successful)
|
|---|
| 79 | ; CF: Cleared if read successful
|
|---|
| 80 | ; Set if any error
|
|---|
| 81 | ; Corrupts registers:
|
|---|
| 82 | ; AL, CX, DH, DI
|
|---|
| 83 | ;--------------------------------------------------------------------
|
|---|
| 84 | BootSector_LoadFirstSectorFromDriveDL:
|
|---|
| 85 | LOAD_BDA_SEGMENT_TO es, bx ; ES:BX now points to...
|
|---|
| 86 | mov bx, BOOTVARS.rgbBootSect ; ...boot sector location
|
|---|
| 87 | mov di, BOOT_READ_RETRY_TIMES ; Initialize retry counter
|
|---|
| 88 |
|
|---|
| 89 | .ReadRetryLoop:
|
|---|
| 90 | mov ax, 0201h ; Read 1 sector
|
|---|
| 91 | mov cx, 1 ; Cylinder 0, Sector 1
|
|---|
| 92 | xor dh, dh ; Head 0
|
|---|
| 93 | int BIOS_DISK_INTERRUPT_13h
|
|---|
| 94 | jc SHORT .FailedToLoadFirstSector
|
|---|
| 95 | .Return:
|
|---|
| 96 | ret
|
|---|
| 97 |
|
|---|
| 98 | .FailedToLoadFirstSector:
|
|---|
| 99 | dec di ; Decrement retry counter (preserve CF)
|
|---|
| 100 | jz SHORT .Return ; Loop while retries left
|
|---|
| 101 |
|
|---|
| 102 | ; Reset drive and retry
|
|---|
| 103 | xor ax, ax ; AH=00h, Disk Controller Reset
|
|---|
| 104 | test dl, dl ; Floppy drive?
|
|---|
| 105 | eCMOVS ah, RESET_HARD_DISK ; AH=0Dh, Reset Hard Disk (Alternate reset)
|
|---|
| 106 | int BIOS_DISK_INTERRUPT_13h
|
|---|
| 107 | jmp SHORT .ReadRetryLoop
|
|---|
| 108 |
|
|---|
