mirror of
https://github.com/ApacheThunder/XuluMenu.git
synced 2025-06-19 03:55:32 -04:00
2550af0c99
* Can now boot stage2 (in safe block mode) if holding L-Shoulder + R-Shoulder + A + B + DPAD Up on boot. This allows using built in stage2 usb update mode for "bootleg" style N-Cards that have Xulumenu installed. * This button combo will not do anything for regular N-Card users as they already have a proper stage2 section on nand and it will always end up booting to USB update mode with this button combo before xulumenu can boot.
109 lines
3.1 KiB
ArmAsm
109 lines
3.1 KiB
ArmAsm
@---------------------------------------------------------------------------------
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.section ".init"
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.global _start
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@---------------------------------------------------------------------------------
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.align 4
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.arm
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@---------------------------------------------------------------------------------
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_start:
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@---------------------------------------------------------------------------------
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mov r0, #0x04000000 @ IME = 0;
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add r0, r0, #0x208
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strh r0, [r0]
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mov r0, #0x12 @ Switch to IRQ Mode
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msr cpsr, r0
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ldr sp, =__sp_irq @ Set IRQ stack
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mov r0, #0x13 @ Switch to SVC Mode
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msr cpsr, r0
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ldr sp, =__sp_svc @ Set SVC stack
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mov r0, #0x1F @ Switch to System Mode
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msr cpsr, r0
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ldr sp, =__sp_usr @ Set user stack
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ldr r0, =__bss_start @ Clear BSS section to 0x00
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ldr r1, =__bss_end
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sub r1, r1, r0
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bl ClearMem
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@ Load ARM9 region into main RAM
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ldr r1, =__arm9_source_start
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ldr r2, =__arm9_start
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ldr r3, =__arm9_source_end
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sub r3, r3, r1
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bl CopyMem
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@ Start ARM9 binary
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ldr r0, =0x02FFFE24
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ldr r1, =_arm9_start
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str r1, [r0]
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mov r0, #0 @ int argc
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mov r1, #0 @ char *argv[]
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ldr r3, =arm7_main
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bl _blx_r3_stub @ jump to user code
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@ If the user ever returns, restart
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b _start
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@---------------------------------------------------------------------------------
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_blx_r3_stub:
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@---------------------------------------------------------------------------------
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bx r3
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@---------------------------------------------------------------------------------
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@ Clear memory to 0x00 if length != 0
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@ r0 = Start Address
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@ r1 = Length
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@---------------------------------------------------------------------------------
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ClearMem:
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@---------------------------------------------------------------------------------
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mov r2, #3 @ Round down to nearest word boundary
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add r1, r1, r2 @ Shouldn't be needed
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bics r1, r1, r2 @ Clear 2 LSB (and set Z)
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bxeq lr @ Quit if copy size is 0
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mov r2, #0
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ClrLoop:
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stmia r0!, {r2}
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subs r1, r1, #4
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bne ClrLoop
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bx lr
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@---------------------------------------------------------------------------------
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@ Copy memory if length != 0
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@ r1 = Source Address
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@ r2 = Dest Address
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@ r4 = Dest Address + Length
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@---------------------------------------------------------------------------------
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CopyMemCheck:
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@---------------------------------------------------------------------------------
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sub r3, r4, r2 @ Is there any data to copy?
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@---------------------------------------------------------------------------------
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@ Copy memory
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@ r1 = Source Address
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@ r2 = Dest Address
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@ r3 = Length
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@---------------------------------------------------------------------------------
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CopyMem:
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@---------------------------------------------------------------------------------
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mov r0, #3 @ These commands are used in cases where
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add r3, r3, r0 @ the length is not a multiple of 4,
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bics r3, r3, r0 @ even though it should be.
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bxeq lr @ Length is zero, so exit
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CIDLoop:
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ldmia r1!, {r0}
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stmia r2!, {r0}
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subs r3, r3, #4
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bne CIDLoop
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bx lr
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@---------------------------------------------------------------------------------
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.align
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.pool
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.end
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@---------------------------------------------------------------------------------
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