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kernel.s
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kernel.s
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@ This file is part of the Team 28 Project
@ Licensing information can be found in the LICENSE file
@ (C) 2014 The Team 28 Authors. All rights reserved.
.global start
.include "ports.s"
.section .text
@ ------------------------------------------------------------------------------
@ Entry point of the application
@ ------------------------------------------------------------------------------
kernel:
bl setup_stack
bl setup_ivt
bl setup_vfp
bl setup_gfx
bl setup_cache
bl setup_input
bl setup_sound
b setup_game
@ ------------------------------------------------------------------------------
@ Sets up stacks for all operating modes
@ ------------------------------------------------------------------------------
setup_stack:
mov r0, #0xD1 @ FIQ
msr cpsr, r0
ldr sp, =stack_fiq
mov r0, #0xD2 @ IRQ
msr cpsr, r0
ldr sp, =stack_irq
mov r0, #0xD7 @ ABT
msr cpsr, r0
ldr sp, =stack_abt
mov r0, #0xDB @ UND
msr cpsr, r0
ldr sp, =stack_und
mov r0, #0xDF @ SYS
msr cpsr, r0
ldr sp, =stack_sys
mov r0, #0xD3 @ SVC
msr cpsr, r0
ldr sp, =stack_svc
mov pc, lr
@ ------------------------------------------------------------------------------
@ Relocates the interrupt vector table
@ ------------------------------------------------------------------------------
setup_ivt:
ldr r10, =ivt_start
ldr r11, =0x00000000
ldm r10!, {r0 - r7}
stm r11!, {r0 - r7}
ldm r10, {r0 - r7}
stm r11, {r0 - r7}
mov pc, lr
@ ------------------------------------------------------------------------------
@ Enables the L1 cache
@ ------------------------------------------------------------------------------
setup_cache:
mov r0, #0
mcr p15, 0, r0, c7, c7, 0 @ Invalidate caches
mcr p15, 0, r0, c8, c7, 0 @ Invalidate TLB
mrc p15, 0, r0, c1, c0, 0
ldr r1, =0x1004
orr r0, r0, r1 @ Set L1 enable bit
mcr p15, 0, r0, c1, c0, 0
mov pc, lr
@ ------------------------------------------------------------------------------
@ Enables the vectored floating point unit
@ ------------------------------------------------------------------------------
setup_vfp:
mrc p15, #0, r0, c1, c0, #2
orr r0, r0, #0xF00000 @ Single + double precision
mcr p15, #0, r0, c1, c0, #2
mov r0, #0x40000000 @ Set VFP enable bit
fmxr fpexc, r0
mov pc, lr
@ ------------------------------------------------------------------------------
@ Interrupt vector table
@
@ On startup, this table has to be relocated to the start of memory.
@ It contains jump to interrupt handlers.
@ ------------------------------------------------------------------------------
ivt_start:
.rept 8
ldr pc, [pc, #0x18]
.endr
.word handler_hang
.word handler_undef
.word handler_hang
.word handler_hang
.word handler_hang
.word .
.word handler_hang
.word handler_hang
@ ------------------------------------------------------------------------------
@ Hang when something bad happens
@ ------------------------------------------------------------------------------
handler_hang:
b .
@ ------------------------------------------------------------------------------
@ Undefined instructions - clears FP exception bit
@ Like pro windows devs, we put a shitton of effort
@ into making an awesome, blue panic screeen
@ ------------------------------------------------------------------------------
handler_undef:
@ Reset VFP
mov r0, #0x40000000
fmxr fpexc, r0
@ Arguments for printf
vstm.f32 sp!, {s0 - s31}
stmfd sp!, {r0 - r12}
stmfd sp!, {lr}
@ Nice blue background
ldr r0, =0xFFFF0000
bl gfx_clear
@ Print address
ldr r0, =1f
mov r1, #100
mov r2, #100
ldr r3, =0xFFFFFFFF
bl printf
add sp, sp, #4
@ Present error message
bl gfx_swap
@ Hang
b .
1:
.ascii "VFP crashed:\n"
.ascii " PC: %8x\n"
.ascii " r0: %8x r1: %8x r2: %8x r3: %8x\n"
.ascii " r4: %8x r5: %8x r6: %8x r7: %8x\n"
.ascii " r8: %8x r9: %8x r10: %8x r11: %8x\n"
.ascii " s0: %8x s1: %8x s2: %8x s3: %8x\n"
.ascii " s4: %8x s5: %8x s6: %8x s7: %8x\n"
.ascii " s8: %8x s9: %8x s10: %8x s11: %8x\n"
.ascii "s12: %8x s13: %8x s14: %8x s15: %8x\n"
.ascii "s16: %8x s17: %8x s18: %8x s19: %8x\n"
.ascii "s20: %8x s21: %8x s22: %8x s23: %8x\n"
.ascii "s24: %8x s25: %8x s26: %8x s27: %8x\n"
.ascii "s28: %8x s29: %8x s30: %8x s31: %8x\n"
.ascii "\0"
.align 2