[243] | 1 | ; Project name : XTIDE Universal BIOS |
---|
| 2 | ; Description : Int 19h Handler (Boot Loader). |
---|
| 3 | |
---|
[376] | 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 | |
---|
[243] | 20 | ; Section containing code |
---|
| 21 | SECTION .text |
---|
| 22 | |
---|
| 23 | ;-------------------------------------------------------------------- |
---|
[249] | 24 | ; INT 19h handler that properly reboots the computer when |
---|
| 25 | ; INT 19h is called. |
---|
| 26 | ; |
---|
| 27 | ; Int19h_ResetHandler |
---|
| 28 | ; Parameters: |
---|
| 29 | ; Nothing |
---|
| 30 | ; Returns: |
---|
| 31 | ; Never returns (reboots computer) |
---|
| 32 | ;-------------------------------------------------------------------- |
---|
| 33 | Int19h_ResetHandler: |
---|
| 34 | mov ax, BOOT_FLAG_WARM ; Skip memory tests |
---|
| 35 | jmp Reboot_ComputerWithBootFlagInAX |
---|
| 36 | |
---|
| 37 | |
---|
| 38 | ;-------------------------------------------------------------------- |
---|
[243] | 39 | ; Int19h_BootLoaderHandler |
---|
| 40 | ; Parameters: |
---|
| 41 | ; Nothing |
---|
| 42 | ; Returns: |
---|
| 43 | ; Never returns (loads operating system) |
---|
| 44 | ;-------------------------------------------------------------------- |
---|
| 45 | ALIGN JUMP_ALIGN |
---|
| 46 | Int19h_BootLoaderHandler: |
---|
[282] | 47 | sti |
---|
[250] | 48 | ; Install INT 19h handler for proper reboot |
---|
[243] | 49 | LOAD_BDA_SEGMENT_TO es, ax |
---|
[258] | 50 | mov al, BIOS_BOOT_LOADER_INTERRUPT_19h ; INT 19h interrupt vector offset |
---|
[250] | 51 | mov si, Int19h_ResetHandler ; INT 19h handler to reboot the system |
---|
[258] | 52 | call Interrupts_InstallHandlerToVectorInALFromCSSI |
---|
[250] | 53 | call Initialize_AndDetectDrives ; Installs new boot menu loader |
---|
[243] | 54 | ; Fall to .PrepareStackAndSelectDriveFromBootMenu |
---|
| 55 | |
---|
| 56 | ;-------------------------------------------------------------------- |
---|
| 57 | ; .PrepareStackAndSelectDriveFromBootMenu |
---|
| 58 | ; Parameters: |
---|
| 59 | ; ES: BDA and interrupt vector segment (zero) |
---|
| 60 | ; Returns: |
---|
| 61 | ; Never returns (loads operating system) |
---|
| 62 | ;-------------------------------------------------------------------- |
---|
| 63 | .PrepareStackAndSelectDriveFromBootMenu: |
---|
| 64 | STORE_POST_STACK_POINTER |
---|
| 65 | SWITCH_TO_BOOT_MENU_STACK |
---|
| 66 | ; Fall to .InitializeDisplay |
---|
| 67 | |
---|
| 68 | ;-------------------------------------------------------------------- |
---|
| 69 | ; .InitializeDisplay |
---|
| 70 | ; Parameters: |
---|
| 71 | ; Nothing |
---|
| 72 | ; Returns: |
---|
| 73 | ; Never returns (loads operating system) |
---|
| 74 | ;-------------------------------------------------------------------- |
---|
| 75 | .InitializeDisplay: |
---|
| 76 | ; Change display mode if necessary |
---|
| 77 | mov ax, [cs:ROMVARS.wDisplayMode] ; AH 00h = Set Video Mode |
---|
| 78 | cmp al, DEFAULT_TEXT_MODE |
---|
| 79 | je SHORT .InitializeDisplayLibrary |
---|
| 80 | int BIOS_VIDEO_INTERRUPT_10h |
---|
| 81 | .InitializeDisplayLibrary: |
---|
| 82 | call BootMenuPrint_InitializeDisplayContext |
---|
| 83 | ; Fall to .SelectDriveToBootFrom |
---|
| 84 | |
---|
| 85 | ;-------------------------------------------------------------------- |
---|
| 86 | ; .SelectDriveToBootFrom |
---|
| 87 | ; Parameters: |
---|
| 88 | ; Nothing |
---|
| 89 | ; Returns: |
---|
| 90 | ; Never returns (loads operating system) |
---|
| 91 | ;-------------------------------------------------------------------- |
---|
| 92 | .SelectDriveToBootFrom: |
---|
| 93 | call RamVars_GetSegmentToDS |
---|
| 94 | cmp WORD [cs:ROMVARS.wfDisplayBootMenu], BYTE 0 |
---|
| 95 | jne SHORT ProcessBootMenuSelectionsUntilBootableDriveSelected ; Display boot menu |
---|
| 96 | ; Fall to BootFromDriveAthenTryDriveC |
---|
| 97 | |
---|
| 98 | ;-------------------------------------------------------------------- |
---|
| 99 | ; BootFromDriveAthenTryDriveC |
---|
| 100 | ; Parameters: |
---|
| 101 | ; DS: RAMVARS segment |
---|
| 102 | ; Returns: |
---|
| 103 | ; Never returns (loads operating system) |
---|
| 104 | ;-------------------------------------------------------------------- |
---|
| 105 | BootFromDriveAthenTryDriveC: |
---|
| 106 | xor dx, dx ; DL = 00h = Floppy Drive A |
---|
| 107 | call BootSector_TryToLoadFromDriveDL |
---|
| 108 | jc SHORT Int19hMenu_JumpToBootSector_or_RomBoot |
---|
| 109 | mov dl, 80h ; DL = 80h = First Hard Drive (usually C) |
---|
| 110 | call BootSector_TryToLoadFromDriveDL |
---|
| 111 | jmp SHORT Int19hMenu_JumpToBootSector_or_RomBoot ; ROM Boot if error |
---|
| 112 | |
---|
| 113 | |
---|
| 114 | ;-------------------------------------------------------------------- |
---|
| 115 | ; ProcessBootMenuSelectionsUntilBootableDriveSelected |
---|
| 116 | ; Parameters: |
---|
| 117 | ; DS: RAMVARS segment |
---|
| 118 | ; Returns: |
---|
| 119 | ; Never returns |
---|
| 120 | ;-------------------------------------------------------------------- |
---|
| 121 | ProcessBootMenuSelectionsUntilBootableDriveSelected: |
---|
| 122 | call BootMenu_DisplayAndReturnSelectionInDX |
---|
| 123 | call DriveXlate_ToOrBack ; Translate drive number |
---|
| 124 | call BootSector_TryToLoadFromDriveDL |
---|
| 125 | jnc SHORT ProcessBootMenuSelectionsUntilBootableDriveSelected ; Boot failure, show menu again |
---|
| 126 | ; Fall to Int19hMenu_JumpToBootSector_or_RomBoot |
---|
| 127 | ; (CF is set or we wouldn't be here, see "jnc" immediately above) |
---|
| 128 | |
---|
| 129 | ;-------------------------------------------------------------------- |
---|
| 130 | ; Int19hMenu_JumpToBootSector_or_RomBoot |
---|
| 131 | ; |
---|
| 132 | ; Switches back to the POST stack, clears the DS and ES registers, |
---|
| 133 | ; and either jumps to the MBR (Master Boot Record) that was just read, |
---|
| 134 | ; or calls the ROM's boot routine on interrupt 18. |
---|
| 135 | ; |
---|
| 136 | ; Parameters: |
---|
| 137 | ; DL: Drive to boot from (translated, 00h or 80h) |
---|
| 138 | ; CF: Set for Boot Sector Boot |
---|
| 139 | ; Clear for Rom Boot |
---|
| 140 | ; ES:BX: (if CF set) Ptr to boot sector |
---|
| 141 | ; |
---|
| 142 | ; Returns: |
---|
| 143 | ; Never returns |
---|
| 144 | ;-------------------------------------------------------------------- |
---|
| 145 | ALIGN JUMP_ALIGN |
---|
| 146 | Int19hMenu_JumpToBootSector_or_RomBoot: |
---|
| 147 | mov cx, es ; Preserve MBR segment (can't push because of stack change) |
---|
| 148 | mov ax, 0 ; NOTE: can't use XOR (LOAD_BDA_SEGMENT_TO) as it impacts CF |
---|
| 149 | SWITCH_BACK_TO_POST_STACK |
---|
| 150 | |
---|
| 151 | ; clear segment registers before boot sector or rom call |
---|
| 152 | mov ds, ax |
---|
| 153 | mov es, ax |
---|
| 154 | %ifdef USE_386 |
---|
| 155 | mov fs, ax |
---|
| 156 | mov gs, ax |
---|
| 157 | %endif |
---|
| 158 | jnc SHORT .romboot |
---|
| 159 | |
---|
| 160 | ; jump to boot sector |
---|
| 161 | push cx ; sgment address for MBR |
---|
| 162 | push bx ; offset address for MBR |
---|
| 163 | retf ; NOTE: DL is set to the drive number |
---|
| 164 | |
---|
| 165 | ; Boot by calling INT 18h (ROM Basic of ROM DOS) |
---|
| 166 | .romboot: |
---|
| 167 | int BIOS_BOOT_FAILURE_INTERRUPT_18h ; Never returns |
---|