[243] | 1 | ; Project name : XTIDE Universal BIOS |
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| 2 | ; Description : Int 19h Handler (Boot Loader). |
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| 3 | |
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[376] | 4 | ; |
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| 5 | ; XTIDE Universal BIOS and Associated Tools |
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| 6 | ; Copyright (C) 2009-2010 by Tomi Tilli, 2011-2012 by XTIDE Universal BIOS Team. |
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| 7 | ; |
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| 8 | ; This program is free software; you can redistribute it and/or modify |
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| 9 | ; it under the terms of the GNU General Public License as published by |
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| 10 | ; the Free Software Foundation; either version 2 of the License, or |
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| 11 | ; (at your option) any later version. |
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| 12 | ; |
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| 13 | ; This program is distributed in the hope that it will be useful, |
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| 14 | ; but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 15 | ; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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| 16 | ; GNU General Public License for more details. |
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| 17 | ; Visit http://www.gnu.org/licenses/old-licenses/gpl-2.0.html |
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| 18 | ; |
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| 19 | |
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[243] | 20 | ; Section containing code |
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| 21 | SECTION .text |
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| 22 | |
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| 23 | ;-------------------------------------------------------------------- |
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| 24 | ; Int19h_BootLoaderHandler |
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| 25 | ; Parameters: |
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| 26 | ; Nothing |
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| 27 | ; Returns: |
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| 28 | ; Never returns (loads operating system) |
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| 29 | ;-------------------------------------------------------------------- |
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| 30 | Int19h_BootLoaderHandler: |
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[414] | 31 | sti ; Enable interrupts |
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| 32 | cld ; String instructions to increment pointers |
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| 33 | LOAD_BDA_SEGMENT_TO es, ax ; Load BDA segment (zero) to ES |
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[392] | 34 | ; Fall to .PrepareBootLoaderStack |
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[243] | 35 | |
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[392] | 36 | |
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[243] | 37 | ;-------------------------------------------------------------------- |
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[392] | 38 | ; Drive detection and boot menu use lots of stack so it is |
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| 39 | ; wise to relocate stack. Otherwise something important from |
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| 40 | ; interrupt vectors are likely corrupted, likely our own DPTs if |
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| 41 | ; they are located to 30:0h. |
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| 42 | ; |
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| 43 | ; .PrepareBootLoaderStack |
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[243] | 44 | ; Parameters: |
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| 45 | ; ES: BDA and interrupt vector segment (zero) |
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| 46 | ; Returns: |
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| 47 | ; Never returns (loads operating system) |
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| 48 | ;-------------------------------------------------------------------- |
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[392] | 49 | .PrepareBootLoaderStack: |
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[243] | 50 | STORE_POST_STACK_POINTER |
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| 51 | SWITCH_TO_BOOT_MENU_STACK |
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| 52 | ; Fall to .InitializeDisplay |
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| 53 | |
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[392] | 54 | |
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[243] | 55 | ;-------------------------------------------------------------------- |
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| 56 | ; .InitializeDisplay |
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| 57 | ; Parameters: |
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[392] | 58 | ; ES: BDA and interrupt vector segment (zero) |
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[243] | 59 | ; Returns: |
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| 60 | ; Never returns (loads operating system) |
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| 61 | ;-------------------------------------------------------------------- |
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| 62 | .InitializeDisplay: |
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| 63 | ; Change display mode if necessary |
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| 64 | mov ax, [cs:ROMVARS.wDisplayMode] ; AH 00h = Set Video Mode |
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| 65 | cmp al, DEFAULT_TEXT_MODE |
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| 66 | je SHORT .InitializeDisplayLibrary |
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| 67 | int BIOS_VIDEO_INTERRUPT_10h |
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| 68 | .InitializeDisplayLibrary: |
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[392] | 69 | call DetectPrint_InitializeDisplayContext |
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| 70 | ; Fall to .InitializeBiosAndDetectDrives |
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[243] | 71 | |
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[392] | 72 | |
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[243] | 73 | ;-------------------------------------------------------------------- |
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[392] | 74 | ; .InitializeBiosAndDetectDrives |
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[243] | 75 | ; Parameters: |
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[392] | 76 | ; ES: BDA and interrupt vector segment (zero) |
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[243] | 77 | ; Returns: |
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[392] | 78 | ; DS: RAMVARS segment |
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[243] | 79 | ;-------------------------------------------------------------------- |
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[413] | 80 | %ifdef MODULE_HOTKEYS |
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| 81 | call TimerTicks_ReadFromBdaToAX |
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| 82 | add ax, MIN_TIME_TO_DISPLAY_HOTKEY_BAR |
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| 83 | mov [es:BOOTVARS.hotkeyVars+HOTKEYVARS.wTimeToClose], ax |
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| 84 | %endif |
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| 85 | |
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| 86 | call Initialize_AndDetectDrives |
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| 87 | |
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| 88 | %ifdef MODULE_HOTKEYS |
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| 89 | .WaitUntilTimeToCloseHotkeyBar: |
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| 90 | call TimerTicks_ReadFromBdaToAX |
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| 91 | cmp ax, [es:BOOTVARS.hotkeyVars+HOTKEYVARS.wTimeToClose] |
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| 92 | jb SHORT .WaitUntilTimeToCloseHotkeyBar |
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| 93 | %endif |
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[392] | 94 | ; Fall to SelectDriveToBootFrom |
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[243] | 95 | |
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[392] | 96 | |
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[243] | 97 | ;-------------------------------------------------------------------- |
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[392] | 98 | ; SelectDriveToBootFrom |
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[243] | 99 | ; Parameters: |
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| 100 | ; DS: RAMVARS segment |
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[392] | 101 | ; ES: BDA and interrupt vector segment (zero) |
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[243] | 102 | ; Returns: |
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| 103 | ; Never returns (loads operating system) |
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| 104 | ;-------------------------------------------------------------------- |
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[392] | 105 | SelectDriveToBootFrom: |
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[395] | 106 | %ifdef MODULE_HOTKEYS |
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[392] | 107 | call HotkeyBar_UpdateDuringDriveDetection |
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[243] | 108 | |
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[392] | 109 | %ifdef MODULE_BOOT_MENU |
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| 110 | mov di, BOOTVARS.hotkeyVars+HOTKEYVARS.bScancode |
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| 111 | cmp BYTE [es:di], BOOT_MENU_HOTKEY_SCANCODE |
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| 112 | jne SHORT .DoNotDisplayBootMenu |
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[243] | 113 | |
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[392] | 114 | ; Stop blinking the Boot Menu hotkey and display menu |
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| 115 | mov BYTE [es:di], 0 |
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| 116 | call HotkeyBar_DrawToTopOfScreen |
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| 117 | call BootMenu_DisplayAndStoreSelectionAsHotkey |
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| 118 | .DoNotDisplayBootMenu: |
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| 119 | %endif |
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| 120 | |
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| 121 | ; Check if ROM boot (INT 18h) wanted |
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| 122 | cmp BYTE [es:BOOTVARS.hotkeyVars+HOTKEYVARS.bScancode], ROM_BOOT_HOTKEY_SCANCODE |
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| 123 | je SHORT JumpToBootSector_or_RomBoot ; CF clear so ROM boot |
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| 124 | |
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[398] | 125 | ; Get Primary boot drive number to DL |
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[392] | 126 | call HotkeyBar_GetPrimaryBootDriveNumberToDL |
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[395] | 127 | %else |
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[417] | 128 | xor dl, dl ; Try to boot from Floppy Drive A |
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[398] | 129 | %endif ; MODULE_HOTKEYS |
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| 130 | |
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| 131 | ; Try to boot from Primary boot drive (00h by default) |
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[392] | 132 | call TryToBootFromPrimaryOrSecondaryBootDevice |
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| 133 | jc SHORT JumpToBootSector_or_RomBoot |
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| 134 | |
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| 135 | ; Try to boot from Secondary boot device (80h by default) |
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[395] | 136 | %ifdef MODULE_HOTKEYS |
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[392] | 137 | call HotkeyBar_GetSecondaryBootDriveNumberToDL |
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[395] | 138 | %else |
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[417] | 139 | mov dl, 80h ; Try to boot from Hard Drive C |
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[395] | 140 | %endif |
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[392] | 141 | call TryToBootFromPrimaryOrSecondaryBootDevice |
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| 142 | |
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[386] | 143 | %ifdef MODULE_BOOT_MENU |
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[392] | 144 | ; Force Boot Menu hotkey to display boot menu |
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| 145 | mov BYTE [es:BOOTVARS.hotkeyVars+HOTKEYVARS.bScancode], BOOT_MENU_HOTKEY_SCANCODE |
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| 146 | jnc SHORT SelectDriveToBootFrom |
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[386] | 147 | %endif |
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[392] | 148 | ; Fall to JumpToBootSector_or_RomBoot |
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[243] | 149 | |
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[392] | 150 | |
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[243] | 151 | ;-------------------------------------------------------------------- |
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[392] | 152 | ; JumpToBootSector_or_RomBoot |
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[243] | 153 | ; |
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| 154 | ; Switches back to the POST stack, clears the DS and ES registers, |
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| 155 | ; and either jumps to the MBR (Master Boot Record) that was just read, |
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| 156 | ; or calls the ROM's boot routine on interrupt 18. |
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| 157 | ; |
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| 158 | ; Parameters: |
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| 159 | ; DL: Drive to boot from (translated, 00h or 80h) |
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| 160 | ; CF: Set for Boot Sector Boot |
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[392] | 161 | ; Clear for ROM Boot |
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[243] | 162 | ; ES:BX: (if CF set) Ptr to boot sector |
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| 163 | ; |
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| 164 | ; Returns: |
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| 165 | ; Never returns |
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| 166 | ;-------------------------------------------------------------------- |
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[392] | 167 | JumpToBootSector_or_RomBoot: |
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[243] | 168 | mov cx, es ; Preserve MBR segment (can't push because of stack change) |
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| 169 | mov ax, 0 ; NOTE: can't use XOR (LOAD_BDA_SEGMENT_TO) as it impacts CF |
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| 170 | SWITCH_BACK_TO_POST_STACK |
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| 171 | |
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| 172 | ; clear segment registers before boot sector or rom call |
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| 173 | mov ds, ax |
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| 174 | mov es, ax |
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| 175 | %ifdef USE_386 |
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| 176 | mov fs, ax |
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| 177 | mov gs, ax |
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| 178 | %endif |
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| 179 | jnc SHORT .romboot |
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| 180 | |
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| 181 | ; jump to boot sector |
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| 182 | push cx ; sgment address for MBR |
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| 183 | push bx ; offset address for MBR |
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| 184 | retf ; NOTE: DL is set to the drive number |
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| 185 | |
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| 186 | ; Boot by calling INT 18h (ROM Basic of ROM DOS) |
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| 187 | .romboot: |
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[392] | 188 | int BIOS_BOOT_FAILURE_INTERRUPT_18h ; Never returns |
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| 189 | |
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| 190 | |
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| 191 | ;-------------------------------------------------------------------- |
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| 192 | ; TryToBootFromPrimaryOrSecondaryBootDevice |
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| 193 | ; Parameters |
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| 194 | ; DL: Drive selected as boot device |
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| 195 | ; DS: RAMVARS segment |
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| 196 | ; ES: BDA and interrupt vector segment (zero) |
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| 197 | ; Returns: |
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| 198 | ; DL: Drive to boot from (translated, 00h or 80h) |
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| 199 | ; CF: Set for Boot Sector Boot |
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| 200 | ; Clear for ROM Boot |
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| 201 | ; ES:BX: (if CF set) Ptr to boot sector |
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| 202 | ; Corrupts registers: |
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| 203 | ; AX, CX, DH, SI, DI, (DL if failed to read boot sector) |
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| 204 | ;-------------------------------------------------------------------- |
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[395] | 205 | %ifndef MODULE_HOTKEYS |
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| 206 | TryToBootFromPrimaryOrSecondaryBootDevice EQU BootSector_TryToLoadFromDriveDL |
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| 207 | |
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| 208 | %else |
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[392] | 209 | TryToBootFromPrimaryOrSecondaryBootDevice: |
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| 210 | call DriveXlate_SetDriveToSwap |
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| 211 | call DriveXlate_ToOrBack |
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| 212 | jmp BootSector_TryToLoadFromDriveDL |
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[395] | 213 | %endif |
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