NTR_Launcher/ndsbootloader/source/load_crt0.s
ApacheThunder a4e5a00409 Big changes....
* Stage2 launcher UI added. This is a heavily modified HBMenu with
ability to launch carts! This menu can be used to boot a bootloader NDS
file for flascharts that the direct cart launcher fails to boot.
* New audio files added for new menu.
* HBMenu UI loaded by default if booted with no cart inserted.
* INI file folder now located in NTR_Launcher folder instead. A default
ini file from NitroFS (if mount of nitrofs succeeds) will be copied to
SD if one is not present.
* Stage2 launchers are expected to be in NTR Launcehr folder though you
can navigate to any folder you want in the UI so stage2 launchers aren't
the only thing this can be used for. You can also use this as a means of
booting homebrew off SD in NTR mode.
2024-04-10 22:59:52 -05:00

148 lines
4.4 KiB
ArmAsm

/*-----------------------------------------------------------------
Copyright (C) 2005 Michael "Chishm" Chisholm
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
If you use this code, please give due credit and email me about your
project at chishm@hotmail.com
------------------------------------------------------------------*/
@---------------------------------------------------------------------------------
.section ".init"
.global _start
.global storedFileCluster
.global initDisc
.global wantToPatchDLDI
.global argStart
.global argSize
.global dsiSD
.global dsiMode
@---------------------------------------------------------------------------------
.align 4
.arm
@---------------------------------------------------------------------------------
_start:
@---------------------------------------------------------------------------------
b startUp
storedFileCluster:
.word 0x0FFFFFFF @ default BOOT.NDS
initDisc:
.word 0x00000001 @ init the disc by default
wantToPatchDLDI:
.word 0x00000001 @ by default patch the DLDI section of the loaded NDS
@ Used for passing arguments to the loaded app
argStart:
.word _end - _start
argSize:
.word 0x00000000
dldiOffset:
.word _dldi_start - _start
dsiSD:
.word 0
dsiMode:
.word 0
startUp:
mov r0, #0x04000000
mov r1, #0
str r1, [r0,#0x208] @ REG_IME
str r1, [r0,#0x210] @ REG_IE
str r1, [r0,#0x218] @ REG_AUXIE
mov r0, #0x12 @ Switch to IRQ Mode
msr cpsr, r0
ldr sp, =__sp_irq @ Set IRQ stack
mov r0, #0x13 @ Switch to SVC Mode
msr cpsr, r0
ldr sp, =__sp_svc @ Set SVC stack
mov r0, #0x1F @ Switch to System Mode
msr cpsr, r0
ldr sp, =__sp_usr @ Set user stack
ldr r0, =__bss_start @ Clear BSS section to 0x00
ldr r1, =__bss_end
sub r1, r1, r0
bl ClearMem
mov r0, #0 @ int argc
mov r1, #0 @ char *argv[]
ldr r3, =main
bl _blx_r3_stub @ jump to user code
@ If the user ever returns, restart
b _start
@---------------------------------------------------------------------------------
_blx_r3_stub:
@---------------------------------------------------------------------------------
bx r3
@---------------------------------------------------------------------------------
@ Clear memory to 0x00 if length != 0
@ r0 = Start Address
@ r1 = Length
@---------------------------------------------------------------------------------
ClearMem:
@---------------------------------------------------------------------------------
mov r2, #3 @ Round down to nearest word boundary
add r1, r1, r2 @ Shouldn't be needed
bics r1, r1, r2 @ Clear 2 LSB (and set Z)
bxeq lr @ Quit if copy size is 0
mov r2, #0
ClrLoop:
stmia r0!, {r2}
subs r1, r1, #4
bne ClrLoop
bx lr
@---------------------------------------------------------------------------------
@ Copy memory if length != 0
@ r1 = Source Address
@ r2 = Dest Address
@ r4 = Dest Address + Length
@---------------------------------------------------------------------------------
CopyMemCheck:
@---------------------------------------------------------------------------------
sub r3, r4, r2 @ Is there any data to copy?
@---------------------------------------------------------------------------------
@ Copy memory
@ r1 = Source Address
@ r2 = Dest Address
@ r3 = Length
@---------------------------------------------------------------------------------
CopyMem:
@---------------------------------------------------------------------------------
mov r0, #3 @ These commands are used in cases where
add r3, r3, r0 @ the length is not a multiple of 4,
bics r3, r3, r0 @ even though it should be.
bxeq lr @ Length is zero, so exit
CIDLoop:
ldmia r1!, {r0}
stmia r2!, {r0}
subs r3, r3, #4
bne CIDLoop
bx lr
@---------------------------------------------------------------------------------
.align
.pool
.end
@---------------------------------------------------------------------------------