[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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[553] | 31 | sti ; Enable interrupts |
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| 32 | cld ; String instructions to increment pointers |
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| 33 | call Int13hBiosInit_RestoreSystemHandler ; Needed if initialization was started on INT 13h instead on 19h |
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| 34 | LOAD_BDA_SEGMENT_TO es, ax ; Load BDA segment (zero) to ES |
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[392] | 35 | ; Fall to .PrepareBootLoaderStack |
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[243] | 36 | |
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[392] | 37 | |
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[243] | 38 | ;-------------------------------------------------------------------- |
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[392] | 39 | ; Drive detection and boot menu use lots of stack so it is |
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| 40 | ; wise to relocate stack. Otherwise something important from |
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| 41 | ; interrupt vectors are likely corrupted, likely our own DPTs if |
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| 42 | ; they are located to 30:0h. |
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| 43 | ; |
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| 44 | ; .PrepareBootLoaderStack |
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[243] | 45 | ; Parameters: |
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| 46 | ; ES: BDA and interrupt vector segment (zero) |
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| 47 | ; Returns: |
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| 48 | ; Never returns (loads operating system) |
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| 49 | ;-------------------------------------------------------------------- |
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[392] | 50 | .PrepareBootLoaderStack: |
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[243] | 51 | STORE_POST_STACK_POINTER |
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| 52 | SWITCH_TO_BOOT_MENU_STACK |
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| 53 | ; Fall to .InitializeDisplay |
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| 54 | |
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[392] | 55 | |
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[243] | 56 | ;-------------------------------------------------------------------- |
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| 57 | ; .InitializeDisplay |
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| 58 | ; Parameters: |
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[392] | 59 | ; ES: BDA and interrupt vector segment (zero) |
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[243] | 60 | ; Returns: |
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| 61 | ; Never returns (loads operating system) |
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| 62 | ;-------------------------------------------------------------------- |
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| 63 | .InitializeDisplay: |
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| 64 | ; Change display mode if necessary |
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| 65 | mov ax, [cs:ROMVARS.wDisplayMode] ; AH 00h = Set Video Mode |
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| 66 | cmp al, DEFAULT_TEXT_MODE |
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| 67 | je SHORT .InitializeDisplayLibrary |
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| 68 | int BIOS_VIDEO_INTERRUPT_10h |
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| 69 | .InitializeDisplayLibrary: |
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[392] | 70 | call DetectPrint_InitializeDisplayContext |
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| 71 | ; Fall to .InitializeBiosAndDetectDrives |
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[243] | 72 | |
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[392] | 73 | |
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[243] | 74 | ;-------------------------------------------------------------------- |
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[392] | 75 | ; .InitializeBiosAndDetectDrives |
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[243] | 76 | ; Parameters: |
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[392] | 77 | ; ES: BDA and interrupt vector segment (zero) |
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[243] | 78 | ; Returns: |
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[392] | 79 | ; DS: RAMVARS segment |
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[243] | 80 | ;-------------------------------------------------------------------- |
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[555] | 81 | .InitializeBiosAndDetectDrives: |
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[413] | 82 | %ifdef MODULE_HOTKEYS |
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| 83 | call TimerTicks_ReadFromBdaToAX |
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[524] | 84 | mov [es:BOOTVARS.hotkeyVars+HOTKEYVARS.wTimeWhenDisplayed], ax |
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[413] | 85 | %endif |
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| 86 | |
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| 87 | call Initialize_AndDetectDrives |
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| 88 | |
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| 89 | %ifdef MODULE_HOTKEYS |
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[547] | 90 | ; Last hard drive might have scrolled Hotkey Bar out of screen. |
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| 91 | ; We want to display it during wait. |
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| 92 | call HotkeyBar_UpdateDuringDriveDetection |
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| 93 | |
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[413] | 94 | .WaitUntilTimeToCloseHotkeyBar: |
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| 95 | call TimerTicks_ReadFromBdaToAX |
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[524] | 96 | sub ax, [es:BOOTVARS.hotkeyVars+HOTKEYVARS.wTimeWhenDisplayed] |
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| 97 | cmp ax, MIN_TIME_TO_DISPLAY_HOTKEY_BAR |
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[413] | 98 | jb SHORT .WaitUntilTimeToCloseHotkeyBar |
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| 99 | %endif |
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[555] | 100 | ; Fall to .ResetAllDrives |
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| 101 | |
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| 102 | |
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| 103 | ;-------------------------------------------------------------------- |
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| 104 | ; .ResetAllDrives |
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| 105 | ; Parameters: |
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| 106 | ; DS: RAMVARS segment |
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| 107 | ; ES: BDA and interrupt vector segment (zero) |
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| 108 | ; Returns: |
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| 109 | ; Nothing |
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| 110 | ;-------------------------------------------------------------------- |
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| 111 | .ResetAllDrives: |
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| 112 | ; Reset all drives in the system, not just our drives. |
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| 113 | xor ax, ax ; Disk Controller Reset |
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| 114 | mov dl, 80h ; Reset all hard drives and floppy drives |
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| 115 | int BIOS_DISK_INTERRUPT_13h |
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| 116 | ;call ResetHardDisksHandledByOurBIOS.ErrorCodeNotUsed ; Our drives only |
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[392] | 117 | ; Fall to SelectDriveToBootFrom |
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[243] | 118 | |
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[392] | 119 | |
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[243] | 120 | ;-------------------------------------------------------------------- |
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[392] | 121 | ; SelectDriveToBootFrom |
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[243] | 122 | ; Parameters: |
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| 123 | ; DS: RAMVARS segment |
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[392] | 124 | ; ES: BDA and interrupt vector segment (zero) |
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[243] | 125 | ; Returns: |
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| 126 | ; Never returns (loads operating system) |
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| 127 | ;-------------------------------------------------------------------- |
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[492] | 128 | ; The following macro could be easily inlined below. Why a macro? Depending on the combination |
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| 129 | ; of MODULE_HOTKEYS or MODULE_BOOT_MENU, this code needs to either come before or after the |
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[505] | 130 | ; call to the boot menu. |
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[492] | 131 | ; |
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| 132 | %macro TRY_TO_BOOT_DL_AND_DH_DRIVES 0 |
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| 133 | push dx ; it's OK if this is left on the stack, if we are |
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[505] | 134 | ; successful, the following call does not return |
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[528] | 135 | call BootSector_TryToLoadFromDriveDL_AndBoot |
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[492] | 136 | pop dx |
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| 137 | mov dl, dh |
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[528] | 138 | call BootSector_TryToLoadFromDriveDL_AndBoot |
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[492] | 139 | %endmacro |
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[505] | 140 | |
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[528] | 141 | |
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| 142 | SelectDriveToBootFrom: ; Function starts here |
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[395] | 143 | %ifdef MODULE_HOTKEYS |
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[528] | 144 | call HotkeyBar_UpdateDuringDriveDetection |
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| 145 | mov al, [es:BOOTVARS.hotkeyVars+HOTKEYVARS.bScancode] |
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[492] | 146 | cmp al, ROM_BOOT_HOTKEY_SCANCODE |
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[528] | 147 | je SHORT .RomBoot ; CF clear so ROM boot |
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[392] | 148 | %ifdef MODULE_BOOT_MENU |
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[492] | 149 | cmp al, BOOT_MENU_HOTKEY_SCANCODE |
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[528] | 150 | je SHORT .BootMenu |
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| 151 | %endif ; MODULE_BOOT_MENU |
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| 152 | |
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| 153 | .TryUsingHotKeysCode: |
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[492] | 154 | call HotkeyBar_GetBootDriveNumbersToDX |
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[528] | 155 | call DriveXlate_SetDriveToSwap ; Enable primary boot device translation |
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| 156 | xchg dl, dh |
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| 157 | call DriveXlate_SetDriveToSwap ; Enable secondary boot device translation |
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| 158 | xchg dl, dh |
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[529] | 159 | call DriveXlate_ToOrBack ; Translate now so boot device will appear as 00h or 80h to OS |
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[492] | 160 | TRY_TO_BOOT_DL_AND_DH_DRIVES |
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| 161 | ;; falls through to boot menu, if it is present. If not present, falls through to rom boot. |
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[505] | 162 | %endif ; MODULE_HOTKEYS |
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[392] | 163 | |
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[528] | 164 | |
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[492] | 165 | %ifdef MODULE_BOOT_MENU |
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[505] | 166 | .BootMenu: |
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[492] | 167 | call BootMenu_DisplayAndReturnDriveInDLRomBootClearCF |
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[528] | 168 | jnc SHORT .RomBoot ; CF clear so ROM boot |
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[392] | 169 | |
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[528] | 170 | call DriveXlate_Reset |
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| 171 | %ifdef MODULE_HOTKEYS |
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| 172 | jmp SHORT .TryUsingHotKeysCode ; Selected drive stored as hotkey |
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| 173 | %else ; Boot menu without hotkeys, secondary boot drive is always 00h or 80h |
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[492] | 174 | mov dh, dl ; Setup for secondary drive |
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[505] | 175 | not dh ; Floppy goes to HD, or vice versa |
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| 176 | and dh, 80h ; Go to first drive of the floppy or HD set |
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[528] | 177 | call DriveXlate_SetDriveToSwap |
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| 178 | call DriveXlate_ToOrBack |
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| 179 | TRY_TO_BOOT_DL_AND_DH_DRIVES |
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| 180 | jmp SHORT .BootMenu ; Show boot menu again |
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| 181 | %endif ; MODULE_HOTKEYS |
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[398] | 182 | |
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[505] | 183 | %endif ; MODULE_BOOT_MENU |
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[392] | 184 | |
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[528] | 185 | ; No hotkeys and no boot menu means fixed "A then C" boot order |
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[505] | 186 | %ifndef MODULE_HOTKEYS OR MODULE_BOOT_MENU |
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[529] | 187 | xor dl, dl ; Try to boot from Floppy Drive A |
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[528] | 188 | call BootSector_TryToLoadFromDriveDL_AndBoot |
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[529] | 189 | mov dl, 80h ; Try to boot from Hard Drive C |
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[528] | 190 | call BootSector_TryToLoadFromDriveDL_AndBoot |
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[386] | 191 | %endif |
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[243] | 192 | |
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[493] | 193 | .RomBoot: |
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| 194 | %ifdef MODULE_DRIVEXLATE |
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| 195 | call DriveXlate_Reset ; Clean up any drive mappings before Rom Boot |
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| 196 | %endif |
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[505] | 197 | clc |
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[521] | 198 | ;; fall through to Int19_JumpToBootSectorOrRomBoot |
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[392] | 199 | |
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[243] | 200 | ;-------------------------------------------------------------------- |
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[521] | 201 | ; Int19_JumpToBootSectorOrRomBoot |
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[243] | 202 | ; |
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| 203 | ; Switches back to the POST stack, clears the DS and ES registers, |
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| 204 | ; and either jumps to the MBR (Master Boot Record) that was just read, |
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| 205 | ; or calls the ROM's boot routine on interrupt 18. |
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| 206 | ; |
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| 207 | ; Parameters: |
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| 208 | ; DL: Drive to boot from (translated, 00h or 80h) |
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[505] | 209 | ; CF: Set for Boot Sector Boot |
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[392] | 210 | ; Clear for ROM Boot |
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[243] | 211 | ; ES:BX: (if CF set) Ptr to boot sector |
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| 212 | ; |
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| 213 | ; Returns: |
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| 214 | ; Never returns |
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| 215 | ;-------------------------------------------------------------------- |
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[521] | 216 | Int19_JumpToBootSectorOrRomBoot: |
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[243] | 217 | mov cx, es ; Preserve MBR segment (can't push because of stack change) |
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| 218 | mov ax, 0 ; NOTE: can't use XOR (LOAD_BDA_SEGMENT_TO) as it impacts CF |
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| 219 | SWITCH_BACK_TO_POST_STACK |
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| 220 | |
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| 221 | ; clear segment registers before boot sector or rom call |
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[505] | 222 | mov ds, ax |
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[243] | 223 | mov es, ax |
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| 224 | %ifdef USE_386 |
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| 225 | mov fs, ax |
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| 226 | mov gs, ax |
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| 227 | %endif |
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| 228 | jnc SHORT .romboot |
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| 229 | |
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| 230 | ; jump to boot sector |
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| 231 | push cx ; sgment address for MBR |
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| 232 | push bx ; offset address for MBR |
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| 233 | retf ; NOTE: DL is set to the drive number |
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| 234 | |
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| 235 | ; Boot by calling INT 18h (ROM Basic of ROM DOS) |
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| 236 | .romboot: |
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[505] | 237 | int BIOS_BOOT_FAILURE_INTERRUPT_18h ; Never returns |
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