pokefirered/src/crt0.s

127 lines
2.5 KiB
ArmAsm

.include "constants/gba_constants.inc"
.include "constants/misc_constants.inc"
.include "constants/version.inc"
.syntax unified
.arm
.align 2, 0
.global start_vector
start_vector:
mov r0, #PSR_IRQ_MODE
msr cpsr_cf, r0
ldr sp, sp_irq
mov r0, #PSR_SYS_MODE
msr cpsr_cf, r0
ldr sp, sp_usr
ldr r1, =INTR_VECTOR
adr r0, intr_main
str r0, [r1]
ldr r1, =AgbMain
mov lr, pc
bx r1
b start_vector
.align 2, 0
sp_usr: .word IWRAM_END - 0x1C0
sp_irq: .word IWRAM_END - 0x60
.pool
.arm
.align 2, 0
.global intr_main
intr_main:
mov r3, #REG_BASE
add r3, r3, #OFFSET_REG_IE
ldr r2, [r3]
ldrh r1, [r3, #REG_IME - REG_IE]
mrs r0, spsr
stmdb sp!, {r0-r3,lr}
mov r0, #0
strh r0, [r3, #REG_IME - REG_IE]
and r1, r2, r2, lsr #16
mov r12, #0
ands r0, r1, #INTR_FLAG_VCOUNT
bne jump_intr
add r12, r12, 0x4
mov r0, 0x1
strh r0, [r3, #REG_IME - REG_IE]
ands r0, r1, #INTR_FLAG_SERIAL
bne jump_intr
add r12, r12, 0x4
ands r0, r1, #INTR_FLAG_TIMER3
bne jump_intr
add r12, r12, 0x4
ands r0, r1, #INTR_FLAG_HBLANK
bne jump_intr
add r12, r12, 0x4
ands r0, r1, #INTR_FLAG_VBLANK
bne jump_intr
add r12, r12, 0x4
ands r0, r1, #INTR_FLAG_TIMER0
bne jump_intr
add r12, r12, 0x4
ands r0, r1, #INTR_FLAG_TIMER1
bne jump_intr
add r12, r12, 0x4
ands r0, r1, #INTR_FLAG_TIMER2
bne jump_intr
add r12, r12, 0x4
ands r0, r1, #INTR_FLAG_DMA0
bne jump_intr
add r12, r12, 0x4
ands r0, r1, #INTR_FLAG_DMA1
bne jump_intr
add r12, r12, 0x4
ands r0, r1, #INTR_FLAG_DMA2
bne jump_intr
add r12, r12, 0x4
ands r0, r1, #INTR_FLAG_DMA3
bne jump_intr
add r12, r12, 0x4
ands r0, r1, #INTR_FLAG_KEYPAD
bne jump_intr
add r12, r12, 0x4
ands r0, r1, #INTR_FLAG_GAMEPAK
strbne r0, [r3, #REG_SOUNDCNT_X - REG_IE]
loop:
bne loop @ spin
jump_intr:
strh r0, [r3, #REG_IF - REG_IE]
bic r2, r2, r0
ldr r0, =gSTWIStatus
ldr r0, [r0]
ldrb r0, [r0, 0xA]
mov r1, #INTR_FLAG_TIMER0
lsl r0, r1, r0
orr r0, r0, #INTR_FLAG_GAMEPAK
orr r1, r0, #INTR_FLAG_SERIAL | INTR_FLAG_TIMER3 | INTR_FLAG_VCOUNT | INTR_FLAG_HBLANK
and r1, r1, r2
strh r1, [r3, #0]
mrs r3, cpsr
bic r3, r3, #PSR_I_BIT | PSR_F_BIT | PSR_MODE_MASK
orr r3, r3, #PSR_SYS_MODE
msr cpsr_cf, r3
ldr r1, =gIntrTable
add r1, r1, r12
ldr r0, [r1]
stmdb sp!, {lr}
adr lr, intr_return
bx r0
intr_return:
ldmia sp!, {lr}
mrs r3, cpsr
bic r3, r3, #PSR_I_BIT | PSR_F_BIT | PSR_MODE_MASK
orr r3, r3, #PSR_I_BIT | PSR_IRQ_MODE
msr cpsr_cf, r3
ldmia sp!, {r0-r3,lr}
strh r2, [r3, #0]
strh r1, [r3, #REG_IME - REG_IE]
msr spsr_cf, r0
bx lr
.pool
.align 2, 0 @ Don't pad with nop.