[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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[505] | 5 | ; XTIDE Universal BIOS and Associated Tools |
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[526] | 6 | ; Copyright (C) 2009-2010 by Tomi Tilli, 2011-2013 by XTIDE Universal BIOS Team. |
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[376] | 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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[505] | 12 | ; |
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[376] | 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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[505] | 16 | ; GNU General Public License for more details. |
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[376] | 17 | ; Visit http://www.gnu.org/licenses/old-licenses/gpl-2.0.html |
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[505] | 18 | ; |
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[376] | 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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[524] | 82 | mov [es:BOOTVARS.hotkeyVars+HOTKEYVARS.wTimeWhenDisplayed], ax |
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[413] | 83 | %endif |
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| 84 | |
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| 85 | call Initialize_AndDetectDrives |
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| 86 | |
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| 87 | %ifdef MODULE_HOTKEYS |
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[547] | 88 | ; Last hard drive might have scrolled Hotkey Bar out of screen. |
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| 89 | ; We want to display it during wait. |
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| 90 | call HotkeyBar_UpdateDuringDriveDetection |
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| 91 | |
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[413] | 92 | .WaitUntilTimeToCloseHotkeyBar: |
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| 93 | call TimerTicks_ReadFromBdaToAX |
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[524] | 94 | sub ax, [es:BOOTVARS.hotkeyVars+HOTKEYVARS.wTimeWhenDisplayed] |
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| 95 | cmp ax, MIN_TIME_TO_DISPLAY_HOTKEY_BAR |
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[413] | 96 | jb SHORT .WaitUntilTimeToCloseHotkeyBar |
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| 97 | %endif |
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[392] | 98 | ; Fall to SelectDriveToBootFrom |
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[243] | 99 | |
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[392] | 100 | |
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[243] | 101 | ;-------------------------------------------------------------------- |
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[392] | 102 | ; SelectDriveToBootFrom |
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[243] | 103 | ; Parameters: |
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| 104 | ; DS: RAMVARS segment |
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[392] | 105 | ; ES: BDA and interrupt vector segment (zero) |
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[243] | 106 | ; Returns: |
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| 107 | ; Never returns (loads operating system) |
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| 108 | ;-------------------------------------------------------------------- |
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[492] | 109 | ; The following macro could be easily inlined below. Why a macro? Depending on the combination |
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| 110 | ; of MODULE_HOTKEYS or MODULE_BOOT_MENU, this code needs to either come before or after the |
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[505] | 111 | ; call to the boot menu. |
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[492] | 112 | ; |
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| 113 | %macro TRY_TO_BOOT_DL_AND_DH_DRIVES 0 |
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| 114 | push dx ; it's OK if this is left on the stack, if we are |
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[505] | 115 | ; successful, the following call does not return |
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[528] | 116 | call BootSector_TryToLoadFromDriveDL_AndBoot |
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[492] | 117 | pop dx |
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| 118 | mov dl, dh |
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[528] | 119 | call BootSector_TryToLoadFromDriveDL_AndBoot |
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[492] | 120 | %endmacro |
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[505] | 121 | |
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[528] | 122 | |
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| 123 | SelectDriveToBootFrom: ; Function starts here |
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[395] | 124 | %ifdef MODULE_HOTKEYS |
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[528] | 125 | call HotkeyBar_UpdateDuringDriveDetection |
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| 126 | mov al, [es:BOOTVARS.hotkeyVars+HOTKEYVARS.bScancode] |
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[492] | 127 | cmp al, ROM_BOOT_HOTKEY_SCANCODE |
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[528] | 128 | je SHORT .RomBoot ; CF clear so ROM boot |
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[392] | 129 | %ifdef MODULE_BOOT_MENU |
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[492] | 130 | cmp al, BOOT_MENU_HOTKEY_SCANCODE |
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[528] | 131 | je SHORT .BootMenu |
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| 132 | %endif ; MODULE_BOOT_MENU |
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| 133 | |
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| 134 | .TryUsingHotKeysCode: |
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[492] | 135 | call HotkeyBar_GetBootDriveNumbersToDX |
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[528] | 136 | call DriveXlate_SetDriveToSwap ; Enable primary boot device translation |
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| 137 | xchg dl, dh |
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| 138 | call DriveXlate_SetDriveToSwap ; Enable secondary boot device translation |
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| 139 | xchg dl, dh |
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[529] | 140 | call DriveXlate_ToOrBack ; Translate now so boot device will appear as 00h or 80h to OS |
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[492] | 141 | TRY_TO_BOOT_DL_AND_DH_DRIVES |
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| 142 | ;; falls through to boot menu, if it is present. If not present, falls through to rom boot. |
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[505] | 143 | %endif ; MODULE_HOTKEYS |
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[392] | 144 | |
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[528] | 145 | |
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[492] | 146 | %ifdef MODULE_BOOT_MENU |
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[505] | 147 | .BootMenu: |
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[492] | 148 | call BootMenu_DisplayAndReturnDriveInDLRomBootClearCF |
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[528] | 149 | jnc SHORT .RomBoot ; CF clear so ROM boot |
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[392] | 150 | |
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[528] | 151 | call DriveXlate_Reset |
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| 152 | %ifdef MODULE_HOTKEYS |
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| 153 | jmp SHORT .TryUsingHotKeysCode ; Selected drive stored as hotkey |
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| 154 | %else ; Boot menu without hotkeys, secondary boot drive is always 00h or 80h |
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[492] | 155 | mov dh, dl ; Setup for secondary drive |
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[505] | 156 | not dh ; Floppy goes to HD, or vice versa |
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| 157 | and dh, 80h ; Go to first drive of the floppy or HD set |
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[528] | 158 | call DriveXlate_SetDriveToSwap |
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| 159 | call DriveXlate_ToOrBack |
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| 160 | TRY_TO_BOOT_DL_AND_DH_DRIVES |
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| 161 | jmp SHORT .BootMenu ; Show boot menu again |
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| 162 | %endif ; MODULE_HOTKEYS |
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[398] | 163 | |
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[505] | 164 | %endif ; MODULE_BOOT_MENU |
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[392] | 165 | |
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[528] | 166 | ; No hotkeys and no boot menu means fixed "A then C" boot order |
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[505] | 167 | %ifndef MODULE_HOTKEYS OR MODULE_BOOT_MENU |
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[529] | 168 | xor dl, dl ; Try to boot from Floppy Drive A |
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[528] | 169 | call BootSector_TryToLoadFromDriveDL_AndBoot |
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[529] | 170 | mov dl, 80h ; Try to boot from Hard Drive C |
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[528] | 171 | call BootSector_TryToLoadFromDriveDL_AndBoot |
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[386] | 172 | %endif |
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[243] | 173 | |
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[493] | 174 | .RomBoot: |
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| 175 | %ifdef MODULE_DRIVEXLATE |
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| 176 | call DriveXlate_Reset ; Clean up any drive mappings before Rom Boot |
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| 177 | %endif |
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[505] | 178 | clc |
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[521] | 179 | ;; fall through to Int19_JumpToBootSectorOrRomBoot |
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[392] | 180 | |
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[243] | 181 | ;-------------------------------------------------------------------- |
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[521] | 182 | ; Int19_JumpToBootSectorOrRomBoot |
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[243] | 183 | ; |
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| 184 | ; Switches back to the POST stack, clears the DS and ES registers, |
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| 185 | ; and either jumps to the MBR (Master Boot Record) that was just read, |
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| 186 | ; or calls the ROM's boot routine on interrupt 18. |
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| 187 | ; |
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| 188 | ; Parameters: |
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| 189 | ; DL: Drive to boot from (translated, 00h or 80h) |
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[505] | 190 | ; CF: Set for Boot Sector Boot |
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[392] | 191 | ; Clear for ROM Boot |
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[243] | 192 | ; ES:BX: (if CF set) Ptr to boot sector |
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| 193 | ; |
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| 194 | ; Returns: |
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| 195 | ; Never returns |
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| 196 | ;-------------------------------------------------------------------- |
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[521] | 197 | Int19_JumpToBootSectorOrRomBoot: |
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[243] | 198 | mov cx, es ; Preserve MBR segment (can't push because of stack change) |
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| 199 | mov ax, 0 ; NOTE: can't use XOR (LOAD_BDA_SEGMENT_TO) as it impacts CF |
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| 200 | SWITCH_BACK_TO_POST_STACK |
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| 201 | |
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| 202 | ; clear segment registers before boot sector or rom call |
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[505] | 203 | mov ds, ax |
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[243] | 204 | mov es, ax |
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| 205 | %ifdef USE_386 |
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| 206 | mov fs, ax |
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| 207 | mov gs, ax |
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| 208 | %endif |
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| 209 | jnc SHORT .romboot |
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| 210 | |
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| 211 | ; jump to boot sector |
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| 212 | push cx ; sgment address for MBR |
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| 213 | push bx ; offset address for MBR |
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| 214 | retf ; NOTE: DL is set to the drive number |
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| 215 | |
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| 216 | ; Boot by calling INT 18h (ROM Basic of ROM DOS) |
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| 217 | .romboot: |
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[505] | 218 | int BIOS_BOOT_FAILURE_INTERRUPT_18h ; Never returns |
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