pmd-red/asm/crt0.s
2017-12-10 22:41:46 -08:00

104 lines
1.9 KiB
ArmAsm

.include "constants/gba_constants.inc"
.syntax unified
.global Start
.text
.arm
Start: @ 8000000
b Init
.include "asm/rom_header.inc"
.arm
.align 2, 0
.global Init
Init: @ 80000C0
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_sys
ldr r1, =INTR_VECTOR
adr r0, IntrMain
str r0, [r1]
ldr r1, =AgbMain
mov lr, pc
bx r1
b Init
.align 2, 0
sp_sys: .word IWRAM_END - 0x100
sp_irq: .word IWRAM_END - 0x60
.pool
.arm
.align 2, 0
.global IntrMain
IntrMain: @ 8000104
mov r3, REG_BASE
add r3, r3, 0x200
ldr r2, [r3, OFFSET_REG_IE - 0x200]
ldrh r1, [r3, OFFSET_REG_IME - 0x200]
mrs r0, spsr
stmdb sp!, {r0-r3,lr}
mov r0, 1
strh r0, [r3, OFFSET_REG_IME - 0x200]
and r1, r2, r2, lsr 16
mov r12, 0
ands r0, r1, INTR_FLAG_SERIAL | INTR_FLAG_TIMER3
bne IntrMain_FoundIntr
add r12, r12, 0x4
ands r0, r1, INTR_FLAG_VBLANK
bne IntrMain_FoundIntr
add r12, r12, 0x4
ands r0, r1, INTR_FLAG_VCOUNT
bne IntrMain_FoundIntr
add r12, r12, 0x4
ands r0, r1, INTR_FLAG_TIMER2
bne IntrMain_FoundIntr
add r12, r12, 0x4
ands r0, r1, INTR_FLAG_TIMER3
bne IntrMain_FoundIntr
add r12, r12, 0x4
ands r0, r1, INTR_FLAG_GAMEPAK
strbne r0, [r3, OFFSET_REG_SOUNDCNT_X - 0x200]
IntrMain_Loop:
bne IntrMain_Loop
IntrMain_FoundIntr:
strh r0, [r3, OFFSET_REG_IF - 0x200]
mov r1, INTR_FLAG_GAMEPAK | INTR_FLAG_SERIAL
bic r2, r2, r0
and r1, r1, r2
strh r1, [r3, OFFSET_REG_IE - 0x200]
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, IntrMain_RetAddr
bx r0
IntrMain_RetAddr:
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, OFFSET_REG_IE - 0x200]
strh r1, [r3, OFFSET_REG_IME - 0x200]
msr spsr_cf, r0
bx lr
.pool
.align 2, 0 @ Don't pad with nop.