source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/Handlers/Int19h.asm@ 520

Last change on this file since 520 was 520, checked in by aitotat@…, 11 years ago

Changes to XTIDE Universal BIOS:

  • Slave drives are again initialized properly
  • Delay for Hotkeybar now works properly
File size: 7.6 KB
Line 
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, 2011-2012 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
21SECTION .text
22
23;--------------------------------------------------------------------
24; Int19h_BootLoaderHandler
25; Parameters:
26; Nothing
27; Returns:
28; Never returns (loads operating system)
29;--------------------------------------------------------------------
30Int19h_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 add ax, BYTE MIN_TIME_TO_DISPLAY_HOTKEY_BAR
83 mov [es:BOOTVARS.hotkeyVars+HOTKEYVARS.wTimeToClose], ax
84%endif
85
86 call Initialize_AndDetectDrives
87
88%ifdef MODULE_HOTKEYS
89.WaitUntilTimeToCloseHotkeyBar:
90 call TimerTicks_ReadFromBdaToAX
91 cmp ax, [es:BOOTVARS.hotkeyVars+HOTKEYVARS.wTimeToClose]
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;--------------------------------------------------------------------
105SelectDriveToBootFrom:
106
107; The following macro could be easily inlined below. Why a macro? Depending on the combination
108; of MODULE_HOTKEYS or MODULE_BOOT_MENU, this code needs to either come before or after the
109; call to the boot menu.
110;
111%macro TRY_TO_BOOT_DL_AND_DH_DRIVES 0
112 push dx ; it's OK if this is left on the stack, if we are
113 ; successful, the following call does not return
114 call TryToBootFromPrimaryOrSecondaryBootDevice_AndBoot
115 pop dx
116 mov dl, dh
117 call TryToBootFromPrimaryOrSecondaryBootDevice_AndBoot
118%endmacro
119
120%ifdef MODULE_HOTKEYS
121 call HotkeyBar_ScanHotkeysFromKeyBufferAndStoreToBootvars
122 cmp al, ROM_BOOT_HOTKEY_SCANCODE
123 je .RomBoot ; CF clear so ROM boot
124%ifdef MODULE_BOOT_MENU
125 cmp al, BOOT_MENU_HOTKEY_SCANCODE
126 je .BootMenu
127%endif
128 call HotkeyBar_GetBootDriveNumbersToDX
129.TryUsingHotKeysCode:
130 TRY_TO_BOOT_DL_AND_DH_DRIVES
131 ;; falls through to boot menu, if it is present. If not present, falls through to rom boot.
132%endif ; MODULE_HOTKEYS
133
134%ifdef MODULE_BOOT_MENU
135.BootMenu:
136 call BootMenu_DisplayAndReturnDriveInDLRomBootClearCF
137 jnc .RomBoot ; CF clear so ROM boot
138
139 mov dh, dl ; Setup for secondary drive
140 not dh ; Floppy goes to HD, or vice versa
141 and dh, 80h ; Go to first drive of the floppy or HD set
142
143%ifdef MODULE_HOTKEYS
144 jmp .TryUsingHotKeysCode
145%else
146 TRY_TO_BOOT_DL_AND_DH_DRIVES
147 jmp .BootMenu
148%endif
149%endif ; MODULE_BOOT_MENU
150
151%ifndef MODULE_HOTKEYS OR MODULE_BOOT_MENU
152 xor dl, dl ; Try to boot from Floppy Drive A
153 call TryToBootFromPrimaryOrSecondaryBootDevice_AndBoot
154 mov dl, 80h ; Try to boot from Hard Drive C
155 call TryToBootFromPrimaryOrSecondaryBootDevice_AndBoot
156%endif
157
158.RomBoot:
159%ifdef MODULE_DRIVEXLATE
160 call DriveXlate_Reset ; Clean up any drive mappings before Rom Boot
161%endif
162 clc
163 ;; fall through to JumpToBootSector_or_RomBoot
164
165;--------------------------------------------------------------------
166; JumpToBootSector_or_RomBoot
167;
168; Switches back to the POST stack, clears the DS and ES registers,
169; and either jumps to the MBR (Master Boot Record) that was just read,
170; or calls the ROM's boot routine on interrupt 18.
171;
172; Parameters:
173; DL: Drive to boot from (translated, 00h or 80h)
174; CF: Set for Boot Sector Boot
175; Clear for ROM Boot
176; ES:BX: (if CF set) Ptr to boot sector
177;
178; Returns:
179; Never returns
180;--------------------------------------------------------------------
181JumpToBootSector_or_RomBoot:
182 mov cx, es ; Preserve MBR segment (can't push because of stack change)
183 mov ax, 0 ; NOTE: can't use XOR (LOAD_BDA_SEGMENT_TO) as it impacts CF
184 SWITCH_BACK_TO_POST_STACK
185
186; clear segment registers before boot sector or rom call
187 mov ds, ax
188 mov es, ax
189%ifdef USE_386
190 mov fs, ax
191 mov gs, ax
192%endif
193 jnc SHORT .romboot
194
195; jump to boot sector
196 push cx ; sgment address for MBR
197 push bx ; offset address for MBR
198 retf ; NOTE: DL is set to the drive number
199
200; Boot by calling INT 18h (ROM Basic of ROM DOS)
201.romboot:
202 int BIOS_BOOT_FAILURE_INTERRUPT_18h ; Never returns
203
204
205;--------------------------------------------------------------------
206; TryToBootFromPrimaryOrSecondaryBootDevice_AndBoot
207; Parameters
208; DL: Drive selected as boot device
209; DS: RAMVARS segment
210; ES: BDA and interrupt vector segment (zero)
211; Returns:
212; DL: Drive to boot from (translated, 00h or 80h)
213; CF: Set for Boot Sector Boot
214; Clear for ROM Boot
215; ES:BX: (if CF set) Ptr to boot sector
216; Corrupts registers:
217; AX, CX, DH, SI, DI, (DL if failed to read boot sector)
218;--------------------------------------------------------------------
219%ifndef MODULE_DRIVEXLATE
220TryToBootFromPrimaryOrSecondaryBootDevice_AndBoot EQU BootSector_TryToLoadFromDriveDL_AndBoot
221
222%else
223TryToBootFromPrimaryOrSecondaryBootDevice_AndBoot:
224 call DriveXlate_SetDriveToSwap
225 call DriveXlate_ToOrBack
226 ; fall through to TryToBoot_FallThroughTo_BootSector_TryToLoadFromDriveDL_AndBoot
227
228TryToBoot_FallThroughTo_BootSector_TryToLoadFromDriveDL_AndBoot:
229; fall through to BootSector_TryToLoadFromDriveDL_AndBoot
230%endif
231
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