72 lines
2.3 KiB
ArmAsm
72 lines
2.3 KiB
ArmAsm
.section .text.start
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.align 4
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.global _start
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_start:
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b start
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.word 0, 0
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start:
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@ Change the stack pointer
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mov sp, #0x27000000
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@ Disable caches / mpu
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mrc p15, 0, r0, c1, c0, 0 @ read control register
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bic r0, #(1<<12) @ - instruction cache disable
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bic r0, #(1<<2) @ - data cache disable
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bic r0, #(1<<0) @ - mpu disable
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mcr p15, 0, r0, c1, c0, 0 @ write control register
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@ Give read/write access to all the memory regions
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ldr r0, =0x33333333
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mcr p15, 0, r0, c5, c0, 2 @ write data access
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mcr p15, 0, r0, c5, c0, 3 @ write instruction access
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@ Sets MPU permissions and cache settings
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ldr r0, =0xFFFF001D @ ffff0000 32k | bootrom (unprotected part)
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ldr r1, =0x3000801B @ fff00000 16k | dtcm
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ldr r2, =0x01FF801D @ 01ff8000 32k | itcm
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ldr r3, =0x08000029 @ 08000000 2M | arm9 mem (O3DS / N3DS)
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ldr r4, =0x10000029 @ 10000000 2M | io mem (ARM9 / first 2MB)
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ldr r5, =0x20000037 @ 20000000 256M | fcram (O3DS / N3DS)
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ldr r6, =0x1FF00027 @ 1FF00000 1M | dsp / axi wram
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ldr r7, =0x1800002D @ 18000000 8M | vram (+ 2MB)
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mov r8, #0x25
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mcr p15, 0, r0, c6, c0, 0
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mcr p15, 0, r1, c6, c1, 0
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mcr p15, 0, r2, c6, c2, 0
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mcr p15, 0, r3, c6, c3, 0
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mcr p15, 0, r4, c6, c4, 0
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mcr p15, 0, r5, c6, c5, 0
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mcr p15, 0, r6, c6, c6, 0
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mcr p15, 0, r7, c6, c7, 0
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mcr p15, 0, r8, c3, c0, 0 @ Write bufferable 0, 2, 5
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mcr p15, 0, r8, c2, c0, 0 @ Data cacheable 0, 2, 5
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mcr p15, 0, r8, c2, c0, 1 @ Inst cacheable 0, 2, 5
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@ Enable dctm
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ldr r0, =0x3000800A @ set dtcm
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mcr p15, 0, r0, c9, c1, 0 @ set the dtcm Region Register
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@ Enable caches
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mrc p15, 0, r0, c1, c0, 0 @ read control register
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orr r0, r0, #(1<<18) @ - itcm enable
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orr r0, r0, #(1<<16) @ - dtcm enable
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orr r0, r0, #(1<<12) @ - instruction cache enable
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orr r0, r0, #(1<<2) @ - data cache enable
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orr r0, r0, #(1<<0) @ - mpu enable
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mcr p15, 0, r0, c1, c0, 0 @ write control register
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@ Flush caches
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mov r0, #0
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mcr p15, 0, r0, c7, c5, 0 @ flush I-cache
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mcr p15, 0, r0, c7, c6, 0 @ flush D-cache
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mcr p15, 0, r0, c7, c10, 4 @ drain write buffer
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@ Fixes mounting of SDMC
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ldr r0, =0x10000020
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mov r1, #0x340
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str r1, [r0]
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b main
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