| 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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| 4 | ; |
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| 5 | ; XTIDE Universal BIOS and Associated Tools |
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| 6 | ; Copyright (C) 2009-2010 by Tomi Tilli, 2011-2013 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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| 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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| 31 | sti ; Enable interrupts |
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| 32 | %ifdef CLD_NEEDED |
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| 33 | cld ; String instructions to increment pointers |
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| 34 | %endif |
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| 35 | %ifdef MODULE_VERY_LATE_INIT |
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| 36 | LOAD_BDA_SEGMENT_TO ds, ax ; Load BDA segment (zero) to DS |
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| 37 | les ax, [TEMPORARY_VECTOR_FOR_SYSTEM_INT13h*4] |
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| 38 | mov [BIOS_DISK_INTERRUPT_13h*4], ax |
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| 39 | mov [BIOS_DISK_INTERRUPT_13h*4+2], es |
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| 40 | push ds ; BDA segment (zero)... |
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| 41 | pop es ; ...to ES |
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| 42 | %else |
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| 43 | LOAD_BDA_SEGMENT_TO es, ax ; Load BDA segment (zero) to ES |
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| 44 | %endif |
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| 45 | ; Fall to .PrepareBootLoaderStack |
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| 46 | |
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| 47 | |
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| 48 | ;-------------------------------------------------------------------- |
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| 49 | ; Drive detection and boot menu use lots of stack so it is |
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| 50 | ; wise to relocate stack. Otherwise something important from |
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| 51 | ; interrupt vectors are likely corrupted, likely our own DPTs if |
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| 52 | ; they are located to 30:0h. |
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| 53 | ; |
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| 54 | ; .PrepareBootLoaderStack |
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| 55 | ; Parameters: |
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| 56 | ; ES: BDA and interrupt vector segment (zero) |
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| 57 | ; Returns: |
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| 58 | ; Never returns (loads operating system) |
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| 59 | ;-------------------------------------------------------------------- |
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| 60 | .PrepareBootLoaderStack: |
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| 61 | STORE_POST_STACK_POINTER |
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| 62 | SWITCH_TO_BOOT_MENU_STACK |
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| 63 | ; Fall to .InitializeDisplay |
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| 64 | |
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| 65 | |
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| 66 | ;-------------------------------------------------------------------- |
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| 67 | ; .InitializeDisplay |
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| 68 | ; Parameters: |
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| 69 | ; ES: BDA and interrupt vector segment (zero) |
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| 70 | ; Returns: |
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| 71 | ; Never returns (loads operating system) |
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| 72 | ;-------------------------------------------------------------------- |
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| 73 | .InitializeDisplay: |
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| 74 | ; Change display mode if necessary |
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| 75 | mov ax, [cs:ROMVARS.wDisplayMode] ; AH 00h = Set Video Mode |
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| 76 | cmp al, DEFAULT_TEXT_MODE |
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| 77 | je SHORT .InitializeDisplayLibrary |
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| 78 | int BIOS_VIDEO_INTERRUPT_10h |
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| 79 | .InitializeDisplayLibrary: |
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| 80 | call DetectPrint_InitializeDisplayContext |
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| 81 | ; Fall to .InitializeBiosAndDetectDrives |
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| 82 | |
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| 83 | |
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| 84 | ;-------------------------------------------------------------------- |
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| 85 | ; .InitializeBiosAndDetectDrives |
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| 86 | ; Parameters: |
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| 87 | ; ES: BDA and interrupt vector segment (zero) |
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| 88 | ; Returns: |
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| 89 | ; DS: RAMVARS segment |
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| 90 | ;-------------------------------------------------------------------- |
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| 91 | .InitializeBiosAndDetectDrives: |
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| 92 | call Initialize_AndDetectDrives |
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| 93 | |
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| 94 | %ifdef MODULE_HOTKEYS |
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| 95 | ; Last hard drive might have scrolled Hotkey Bar out of screen. |
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| 96 | ; We want to display it during wait. |
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| 97 | ;call HotkeyBar_UpdateDuringDriveDetection |
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| 98 | |
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| 99 | .WaitUntilTimeToCloseHotkeyBar: |
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| 100 | call TimerTicks_ReadFromBdaToAX |
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| 101 | sub ax, [es:BOOTVARS.hotkeyVars+HOTKEYVARS.wTimeWhenDisplayed] |
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| 102 | cmp ax, MIN_TIME_TO_DISPLAY_HOTKEY_BAR |
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| 103 | jb SHORT .WaitUntilTimeToCloseHotkeyBar |
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| 104 | |
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| 105 | ; Restore system timer tick handler since hotkeys are no longer needed |
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| 106 | cli |
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| 107 | mov ax, [es:BOOTVARS.hotkeyVars+HOTKEYVARS.fpPrevTimerHandler] |
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| 108 | mov [es:SYSTEM_TIMER_TICK*4], ax |
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| 109 | mov ax, [es:BOOTVARS.hotkeyVars+HOTKEYVARS.fpPrevTimerHandler+2] |
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| 110 | mov [es:SYSTEM_TIMER_TICK*4+2], ax |
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| 111 | sti |
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| 112 | %endif |
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| 113 | ; Fall to .ResetAllDrives |
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| 114 | |
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| 115 | |
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| 116 | ;-------------------------------------------------------------------- |
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| 117 | ; .ResetAllDrives |
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| 118 | ; Parameters: |
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| 119 | ; DS: RAMVARS segment |
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| 120 | ; ES: BDA and interrupt vector segment (zero) |
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| 121 | ; Returns: |
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| 122 | ; Nothing |
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| 123 | ;-------------------------------------------------------------------- |
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| 124 | .ResetAllDrives: |
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| 125 | ; Reset all drives in the system, not just our drives. |
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| 126 | xor ax, ax ; Disk Controller Reset |
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| 127 | mov dl, 80h ; Reset all hard drives and floppy drives |
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| 128 | int BIOS_DISK_INTERRUPT_13h |
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| 129 | ; Fall to SelectDriveToBootFrom |
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| 130 | |
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| 131 | |
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| 132 | ;-------------------------------------------------------------------- |
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| 133 | ; SelectDriveToBootFrom |
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| 134 | ; Parameters: |
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| 135 | ; DS: RAMVARS segment |
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| 136 | ; ES: BDA and interrupt vector segment (zero) |
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| 137 | ; Returns: |
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| 138 | ; Never returns (loads operating system) |
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| 139 | ;-------------------------------------------------------------------- |
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| 140 | ; The following macro could be easily inlined below. Why a macro? Depending on the combination |
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| 141 | ; of MODULE_HOTKEYS or MODULE_BOOT_MENU, this code needs to either come before or after the |
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| 142 | ; call to the boot menu. |
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| 143 | ; |
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| 144 | %macro TRY_TO_BOOT_DL_AND_DH_DRIVES 0 |
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| 145 | push dx ; it's OK if this is left on the stack, if we are |
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| 146 | ; successful, the following call does not return |
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| 147 | call BootSector_TryToLoadFromDriveDL_AndBoot |
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| 148 | pop dx |
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| 149 | mov dl, dh |
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| 150 | call BootSector_TryToLoadFromDriveDL_AndBoot |
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| 151 | %endmacro |
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| 152 | |
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| 153 | |
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| 154 | SelectDriveToBootFrom: ; Function starts here |
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| 155 | %ifdef MODULE_HOTKEYS |
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| 156 | mov al, [es:BOOTVARS.hotkeyVars+HOTKEYVARS.bScancode] |
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| 157 | cmp al, ROM_BOOT_HOTKEY_SCANCODE |
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| 158 | je SHORT .RomBoot ; CF clear so ROM boot |
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| 159 | %ifdef MODULE_BOOT_MENU |
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| 160 | cmp al, BOOT_MENU_HOTKEY_SCANCODE |
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| 161 | je SHORT .BootMenu |
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| 162 | %endif ; MODULE_BOOT_MENU |
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| 163 | |
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| 164 | .TryUsingHotKeysCode: |
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| 165 | call HotkeyBar_GetBootDriveNumbersToDX |
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| 166 | call DriveXlate_SetDriveToSwap ; Enable primary boot device translation |
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| 167 | xchg dl, dh |
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| 168 | call DriveXlate_SetDriveToSwap ; Enable secondary boot device translation |
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| 169 | xchg dl, dh |
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| 170 | call DriveXlate_ToOrBack ; Translate now so boot device will appear as 00h or 80h to OS |
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| 171 | TRY_TO_BOOT_DL_AND_DH_DRIVES |
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| 172 | ;; falls through to boot menu, if it is present. If not present, falls through to rom boot. |
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| 173 | %endif ; MODULE_HOTKEYS |
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| 174 | |
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| 175 | |
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| 176 | %ifdef MODULE_BOOT_MENU |
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| 177 | .BootMenu: |
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| 178 | call BootMenu_DisplayAndReturnDriveInDLRomBootClearCF |
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| 179 | jnc SHORT .RomBoot ; CF clear so ROM boot |
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| 180 | |
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| 181 | call DriveXlate_Reset |
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| 182 | %ifdef MODULE_HOTKEYS |
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| 183 | jmp SHORT .TryUsingHotKeysCode ; Selected drive stored as hotkey |
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| 184 | %else ; Boot menu without hotkeys, secondary boot drive is always 00h or 80h |
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| 185 | mov dh, dl ; Setup for secondary drive |
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| 186 | not dh ; Floppy goes to HD, or vice versa |
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| 187 | and dh, 80h ; Go to first drive of the floppy or HD set |
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| 188 | call DriveXlate_SetDriveToSwap |
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| 189 | call DriveXlate_ToOrBack |
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| 190 | TRY_TO_BOOT_DL_AND_DH_DRIVES |
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| 191 | jmp SHORT .BootMenu ; Show boot menu again |
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| 192 | %endif ; MODULE_HOTKEYS |
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| 193 | |
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| 194 | %endif ; MODULE_BOOT_MENU |
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| 195 | |
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| 196 | ; No hotkeys and no boot menu means fixed "A then C" boot order |
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| 197 | %ifndef MODULE_HOTKEYS OR MODULE_BOOT_MENU |
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| 198 | xor dl, dl ; Try to boot from Floppy Drive A |
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| 199 | call BootSector_TryToLoadFromDriveDL_AndBoot |
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| 200 | mov dl, 80h ; Try to boot from Hard Drive C |
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| 201 | call BootSector_TryToLoadFromDriveDL_AndBoot |
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| 202 | %endif |
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| 203 | |
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| 204 | .RomBoot: |
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| 205 | %ifdef MODULE_DRIVEXLATE |
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| 206 | call DriveXlate_Reset ; Clean up any drive mappings before Rom Boot |
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| 207 | %endif |
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| 208 | stc |
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| 209 | ;; fall through to Int19h_JumpToBootSectorInESBXOrRomBoot |
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| 210 | |
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| 211 | ;-------------------------------------------------------------------- |
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| 212 | ; Int19h_JumpToBootSectorInESBXOrRomBoot |
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| 213 | ; |
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| 214 | ; Switches back to the POST stack, clears the DS and ES registers, |
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| 215 | ; and either jumps to the MBR (Master Boot Record) that was just read, |
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| 216 | ; or calls the ROM's boot routine on interrupt 18. |
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| 217 | ; |
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| 218 | ; Parameters: |
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| 219 | ; DL: Drive to boot from (translated, 00h or 80h) |
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| 220 | ; CF: Clear for Boot Sector Boot |
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| 221 | ; Set for ROM Boot |
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| 222 | ; ES:BX: (if CF clear) Ptr to boot sector (ES = zero) |
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| 223 | ; |
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| 224 | ; Returns: |
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| 225 | ; Never returns |
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| 226 | ;-------------------------------------------------------------------- |
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| 227 | Int19h_JumpToBootSectorInESBXOrRomBoot: |
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| 228 | mov ax, es ; Clear AX. NOTE: can't use XOR (LOAD_BDA_SEGMENT_TO) as it impacts CF |
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| 229 | SWITCH_BACK_TO_POST_STACK |
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| 230 | |
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| 231 | ; clear segment registers before boot sector or rom call |
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| 232 | Int19h_JumpToBootSectorInESBXOrRomBootWithoutStackChange: |
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| 233 | mov ax, es ; Clear AX and preserve CF |
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| 234 | mov ds, ax |
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| 235 | %ifdef USE_386 |
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| 236 | mov fs, ax |
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| 237 | mov gs, ax |
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| 238 | %endif |
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| 239 | jc SHORT .RomBoot |
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| 240 | |
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| 241 | ; jump to boot sector |
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| 242 | push es ; sgment address for MBR |
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| 243 | push bx ; offset address for MBR |
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| 244 | retf ; NOTE: DL is set to the drive number |
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| 245 | |
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| 246 | ; Boot by calling INT 18h (ROM Basic of ROM DOS) |
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| 247 | .RomBoot: |
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| 248 | int BIOS_BOOT_FAILURE_INTERRUPT_18h ; Never returns |
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