[392] | 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, 2011-2012 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 |
---|
| 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 | ;-------------------------------------------------------------------- |
---|
[492] | 35 | BootSector_TryToLoadFromDriveDL_AndBoot: |
---|
[392] | 36 | call DetectPrint_TryToBootFromDL |
---|
| 37 | call LoadFirstSectorFromDriveDL |
---|
| 38 | jc SHORT .FailedToLoadFirstSector |
---|
| 39 | |
---|
| 40 | test dl, dl |
---|
| 41 | jns SHORT .AlwaysBootFromFloppyDriveForBooterGames |
---|
| 42 | cmp WORD [es:bx+510], 0AA55h ; Valid boot sector? |
---|
| 43 | jne SHORT .FirstHardDiskSectorNotBootable |
---|
| 44 | .AlwaysBootFromFloppyDriveForBooterGames: |
---|
| 45 | stc |
---|
[492] | 46 | jmp SHORT JumpToBootSector_or_RomBoot |
---|
[392] | 47 | .FailedToLoadFirstSector: |
---|
| 48 | call DetectPrint_FailedToLoadFirstSector |
---|
| 49 | ret |
---|
| 50 | .FirstHardDiskSectorNotBootable: |
---|
| 51 | mov si, g_szBootSectorNotFound |
---|
| 52 | call DetectPrint_NullTerminatedStringFromCSSIandSetCF |
---|
| 53 | ret |
---|
| 54 | |
---|
[492] | 55 | %ifndef CHECK_FOR_UNUSED_ENTRYPOINTS |
---|
| 56 | %ifdef MODULE_DRIVEXLATE |
---|
| 57 | %if TryToBoot_FallThroughTo_BootSector_TryToLoadFromDriveDL_AndBoot <> BootSector_TryToLoadFromDriveDL_AndBoot |
---|
| 58 | %error "TryToBoot_FallThroughTo_BootSector_TryToLoadFromDriveDL_AndBoot <> BootSector_TryToLoadFromDriveDL_AndBoot, BootSector must come immediately after int19h.asm" |
---|
| 59 | %endif |
---|
| 60 | %endif |
---|
| 61 | %endif |
---|
| 62 | |
---|
[392] | 63 | ;-------------------------------------------------------------------- |
---|
| 64 | ; LoadFirstSectorFromDriveDL |
---|
| 65 | ; Parameters: |
---|
| 66 | ; DL: Drive to boot from (translated, 00h or 80h) |
---|
| 67 | ; Returns: |
---|
| 68 | ; AH: INT 13h error code |
---|
| 69 | ; ES:BX: Ptr to boot sector (if successful) |
---|
| 70 | ; CF: Cleared if read successful |
---|
| 71 | ; Set if any error |
---|
| 72 | ; Corrupts registers: |
---|
| 73 | ; AL, CX, DH, DI |
---|
| 74 | ;-------------------------------------------------------------------- |
---|
| 75 | LoadFirstSectorFromDriveDL: |
---|
| 76 | LOAD_BDA_SEGMENT_TO es, bx ; ES:BX now points to... |
---|
| 77 | mov bx, BOOTVARS.rgbBootSect ; ...boot sector location |
---|
| 78 | mov di, BOOT_READ_RETRY_TIMES ; Initialize retry counter |
---|
| 79 | |
---|
| 80 | .ReadRetryLoop: |
---|
| 81 | call .LoadFirstSectorFromDLtoESBX |
---|
| 82 | jnc SHORT .Return |
---|
[428] | 83 | dec di ; Decrement retry counter (preserve CF) |
---|
| 84 | jz SHORT .Return ; Loop while retries left |
---|
[392] | 85 | |
---|
[428] | 86 | ; Reset drive and retry |
---|
[392] | 87 | xor ax, ax ; AH=0h, Disk Controller Reset |
---|
| 88 | test dl, dl ; Floppy drive? |
---|
[428] | 89 | eCMOVS ah, RESET_HARD_DISK ; AH=Dh, Reset Hard Disk (Alternate reset) |
---|
[392] | 90 | int BIOS_DISK_INTERRUPT_13h |
---|
[428] | 91 | jmp SHORT .ReadRetryLoop |
---|
[392] | 92 | |
---|
[428] | 93 | |
---|
[392] | 94 | ;-------------------------------------------------------------------- |
---|
| 95 | ; .LoadFirstSectorFromDLtoESBX |
---|
| 96 | ; Parameters: |
---|
| 97 | ; DL: Drive to boot from (translated, 00h or 80h) |
---|
| 98 | ; ES:BX: Destination buffer for boot sector |
---|
| 99 | ; Returns: |
---|
| 100 | ; AH: INT 13h error code |
---|
| 101 | ; ES:BX: Ptr to boot sector |
---|
| 102 | ; CF: Cleared if read successful |
---|
| 103 | ; Set if any error |
---|
| 104 | ; Corrupts registers: |
---|
| 105 | ; AL, CX, DH |
---|
| 106 | ;-------------------------------------------------------------------- |
---|
| 107 | .LoadFirstSectorFromDLtoESBX: |
---|
| 108 | mov ax, 0201h ; Read 1 sector |
---|
| 109 | mov cx, 1 ; Cylinder 0, Sector 1 |
---|
| 110 | xor dh, dh ; Head 0 |
---|
| 111 | int BIOS_DISK_INTERRUPT_13h |
---|
[428] | 112 | .Return: |
---|
[392] | 113 | ret |
---|