1 | ; Project name : XTIDE Universal BIOS |
---|
2 | ; Description : Int 19h Handler (Boot Loader). |
---|
3 | |
---|
4 | ; |
---|
5 | ; XTIDE Universal BIOS and Associated Tools |
---|
6 | ; Copyright (C) 2009-2010 by Tomi Tilli, 2011-2013 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 | |
---|
20 | ; Section containing code |
---|
21 | SECTION .text |
---|
22 | |
---|
23 | ;-------------------------------------------------------------------- |
---|
24 | ; Int19h_BootLoaderHandler |
---|
25 | ; Parameters: |
---|
26 | ; Nothing |
---|
27 | ; Returns: |
---|
28 | ; Never returns (loads operating system) |
---|
29 | ;-------------------------------------------------------------------- |
---|
30 | Int19h_BootLoaderHandler: |
---|
31 | sti ; Enable interrupts |
---|
32 | cld ; String instructions to increment pointers |
---|
33 | LOAD_BDA_SEGMENT_TO es, ax ; Load BDA segment (zero) to ES |
---|
34 | ; Fall to .PrepareBootLoaderStack |
---|
35 | |
---|
36 | |
---|
37 | ;-------------------------------------------------------------------- |
---|
38 | ; Drive detection and boot menu use lots of stack so it is |
---|
39 | ; wise to relocate stack. Otherwise something important from |
---|
40 | ; interrupt vectors are likely corrupted, likely our own DPTs if |
---|
41 | ; they are located to 30:0h. |
---|
42 | ; |
---|
43 | ; .PrepareBootLoaderStack |
---|
44 | ; Parameters: |
---|
45 | ; ES: BDA and interrupt vector segment (zero) |
---|
46 | ; Returns: |
---|
47 | ; Never returns (loads operating system) |
---|
48 | ;-------------------------------------------------------------------- |
---|
49 | .PrepareBootLoaderStack: |
---|
50 | STORE_POST_STACK_POINTER |
---|
51 | SWITCH_TO_BOOT_MENU_STACK |
---|
52 | ; Fall to .InitializeDisplay |
---|
53 | |
---|
54 | |
---|
55 | ;-------------------------------------------------------------------- |
---|
56 | ; .InitializeDisplay |
---|
57 | ; Parameters: |
---|
58 | ; ES: BDA and interrupt vector segment (zero) |
---|
59 | ; Returns: |
---|
60 | ; Never returns (loads operating system) |
---|
61 | ;-------------------------------------------------------------------- |
---|
62 | .InitializeDisplay: |
---|
63 | ; Change display mode if necessary |
---|
64 | mov ax, [cs:ROMVARS.wDisplayMode] ; AH 00h = Set Video Mode |
---|
65 | cmp al, DEFAULT_TEXT_MODE |
---|
66 | je SHORT .InitializeDisplayLibrary |
---|
67 | int BIOS_VIDEO_INTERRUPT_10h |
---|
68 | .InitializeDisplayLibrary: |
---|
69 | call DetectPrint_InitializeDisplayContext |
---|
70 | ; Fall to .InitializeBiosAndDetectDrives |
---|
71 | |
---|
72 | |
---|
73 | ;-------------------------------------------------------------------- |
---|
74 | ; .InitializeBiosAndDetectDrives |
---|
75 | ; Parameters: |
---|
76 | ; ES: BDA and interrupt vector segment (zero) |
---|
77 | ; Returns: |
---|
78 | ; DS: RAMVARS segment |
---|
79 | ;-------------------------------------------------------------------- |
---|
80 | %ifdef MODULE_HOTKEYS |
---|
81 | call TimerTicks_ReadFromBdaToAX |
---|
82 | mov [es:BOOTVARS.hotkeyVars+HOTKEYVARS.wTimeWhenDisplayed], ax |
---|
83 | %endif |
---|
84 | |
---|
85 | call Initialize_AndDetectDrives |
---|
86 | |
---|
87 | %ifdef MODULE_HOTKEYS |
---|
88 | .WaitUntilTimeToCloseHotkeyBar: |
---|
89 | call TimerTicks_ReadFromBdaToAX |
---|
90 | sub ax, [es:BOOTVARS.hotkeyVars+HOTKEYVARS.wTimeWhenDisplayed] |
---|
91 | cmp ax, MIN_TIME_TO_DISPLAY_HOTKEY_BAR |
---|
92 | jb SHORT .WaitUntilTimeToCloseHotkeyBar |
---|
93 | %endif |
---|
94 | ; Fall to SelectDriveToBootFrom |
---|
95 | |
---|
96 | |
---|
97 | ;-------------------------------------------------------------------- |
---|
98 | ; SelectDriveToBootFrom |
---|
99 | ; Parameters: |
---|
100 | ; DS: RAMVARS segment |
---|
101 | ; ES: BDA and interrupt vector segment (zero) |
---|
102 | ; Returns: |
---|
103 | ; Never returns (loads operating system) |
---|
104 | ;-------------------------------------------------------------------- |
---|
105 | ; The following macro could be easily inlined below. Why a macro? Depending on the combination |
---|
106 | ; of MODULE_HOTKEYS or MODULE_BOOT_MENU, this code needs to either come before or after the |
---|
107 | ; call to the boot menu. |
---|
108 | ; |
---|
109 | %macro TRY_TO_BOOT_DL_AND_DH_DRIVES 0 |
---|
110 | push dx ; it's OK if this is left on the stack, if we are |
---|
111 | ; successful, the following call does not return |
---|
112 | call BootSector_TryToLoadFromDriveDL_AndBoot |
---|
113 | pop dx |
---|
114 | mov dl, dh |
---|
115 | call BootSector_TryToLoadFromDriveDL_AndBoot |
---|
116 | %endmacro |
---|
117 | |
---|
118 | |
---|
119 | SelectDriveToBootFrom: ; Function starts here |
---|
120 | %ifdef MODULE_HOTKEYS |
---|
121 | call HotkeyBar_UpdateDuringDriveDetection |
---|
122 | mov al, [es:BOOTVARS.hotkeyVars+HOTKEYVARS.bScancode] |
---|
123 | cmp al, ROM_BOOT_HOTKEY_SCANCODE |
---|
124 | je SHORT .RomBoot ; CF clear so ROM boot |
---|
125 | %ifdef MODULE_BOOT_MENU |
---|
126 | cmp al, BOOT_MENU_HOTKEY_SCANCODE |
---|
127 | je SHORT .BootMenu |
---|
128 | %endif ; MODULE_BOOT_MENU |
---|
129 | |
---|
130 | .TryUsingHotKeysCode: |
---|
131 | call HotkeyBar_GetBootDriveNumbersToDX |
---|
132 | call DriveXlate_SetDriveToSwap ; Enable primary boot device translation |
---|
133 | xchg dl, dh |
---|
134 | call DriveXlate_SetDriveToSwap ; Enable secondary boot device translation |
---|
135 | xchg dl, dh |
---|
136 | call DriveXlate_ToOrBack ; Translate now so boot device will appear as 00h or 80h to OS |
---|
137 | TRY_TO_BOOT_DL_AND_DH_DRIVES |
---|
138 | ;; falls through to boot menu, if it is present. If not present, falls through to rom boot. |
---|
139 | %endif ; MODULE_HOTKEYS |
---|
140 | |
---|
141 | |
---|
142 | %ifdef MODULE_BOOT_MENU |
---|
143 | .BootMenu: |
---|
144 | call BootMenu_DisplayAndReturnDriveInDLRomBootClearCF |
---|
145 | jnc SHORT .RomBoot ; CF clear so ROM boot |
---|
146 | |
---|
147 | call DriveXlate_Reset |
---|
148 | %ifdef MODULE_HOTKEYS |
---|
149 | jmp SHORT .TryUsingHotKeysCode ; Selected drive stored as hotkey |
---|
150 | %else ; Boot menu without hotkeys, secondary boot drive is always 00h or 80h |
---|
151 | mov dh, dl ; Setup for secondary drive |
---|
152 | not dh ; Floppy goes to HD, or vice versa |
---|
153 | and dh, 80h ; Go to first drive of the floppy or HD set |
---|
154 | call DriveXlate_SetDriveToSwap |
---|
155 | call DriveXlate_ToOrBack |
---|
156 | TRY_TO_BOOT_DL_AND_DH_DRIVES |
---|
157 | jmp SHORT .BootMenu ; Show boot menu again |
---|
158 | %endif ; MODULE_HOTKEYS |
---|
159 | |
---|
160 | %endif ; MODULE_BOOT_MENU |
---|
161 | |
---|
162 | ; No hotkeys and no boot menu means fixed "A then C" boot order |
---|
163 | %ifndef MODULE_HOTKEYS OR MODULE_BOOT_MENU |
---|
164 | xor dl, dl ; Try to boot from Floppy Drive A |
---|
165 | call BootSector_TryToLoadFromDriveDL_AndBoot |
---|
166 | mov dl, 80h ; Try to boot from Hard Drive C |
---|
167 | call BootSector_TryToLoadFromDriveDL_AndBoot |
---|
168 | %endif |
---|
169 | |
---|
170 | .RomBoot: |
---|
171 | %ifdef MODULE_DRIVEXLATE |
---|
172 | call DriveXlate_Reset ; Clean up any drive mappings before Rom Boot |
---|
173 | %endif |
---|
174 | clc |
---|
175 | ;; fall through to Int19_JumpToBootSectorOrRomBoot |
---|
176 | |
---|
177 | ;-------------------------------------------------------------------- |
---|
178 | ; Int19_JumpToBootSectorOrRomBoot |
---|
179 | ; |
---|
180 | ; Switches back to the POST stack, clears the DS and ES registers, |
---|
181 | ; and either jumps to the MBR (Master Boot Record) that was just read, |
---|
182 | ; or calls the ROM's boot routine on interrupt 18. |
---|
183 | ; |
---|
184 | ; Parameters: |
---|
185 | ; DL: Drive to boot from (translated, 00h or 80h) |
---|
186 | ; CF: Set for Boot Sector Boot |
---|
187 | ; Clear for ROM Boot |
---|
188 | ; ES:BX: (if CF set) Ptr to boot sector |
---|
189 | ; |
---|
190 | ; Returns: |
---|
191 | ; Never returns |
---|
192 | ;-------------------------------------------------------------------- |
---|
193 | Int19_JumpToBootSectorOrRomBoot: |
---|
194 | mov cx, es ; Preserve MBR segment (can't push because of stack change) |
---|
195 | mov ax, 0 ; NOTE: can't use XOR (LOAD_BDA_SEGMENT_TO) as it impacts CF |
---|
196 | SWITCH_BACK_TO_POST_STACK |
---|
197 | |
---|
198 | ; clear segment registers before boot sector or rom call |
---|
199 | mov ds, ax |
---|
200 | mov es, ax |
---|
201 | %ifdef USE_386 |
---|
202 | mov fs, ax |
---|
203 | mov gs, ax |
---|
204 | %endif |
---|
205 | jnc SHORT .romboot |
---|
206 | |
---|
207 | ; jump to boot sector |
---|
208 | push cx ; sgment address for MBR |
---|
209 | push bx ; offset address for MBR |
---|
210 | retf ; NOTE: DL is set to the drive number |
---|
211 | |
---|
212 | ; Boot by calling INT 18h (ROM Basic of ROM DOS) |
---|
213 | .romboot: |
---|
214 | int BIOS_BOOT_FAILURE_INTERRUPT_18h ; Never returns |
---|