Atmosphere/fusee/fusee-secondary/src/start.s
2018-05-08 14:56:17 +02:00

56 lines
1.3 KiB
ArmAsm

.macro CLEAR_GPR_REG_ITER
mov r\@, #0
.endm
.section .text.start, "ax", %progbits
.arm
.align 5
.global _start
.type _start, %function
_start:
/* Switch to system mode, mask all interrupts, clear all flags */
msr cpsr_cxsf, #0xDF
/* Relocate ourselves if necessary */
ldr r2, =__start__
adr r3, _start
cmp r2, r3
bne _relocation_loop_end
ldr r4, =__bss_start__
sub r4, r4, r2 /* size >= 32, obviously, and we've declared 32-byte-alignment */
_relocation_loop:
ldmia r3!, {r5-r12}
stmia r2!, {r5-r12}
subs r4, #0x20
bne _relocation_loop
ldr r12, =_relocation_loop_end
bx r12
_relocation_loop_end:
/* Set the stack pointer */
ldr sp, =__stack_top__
mov fp, #0
bl __program_init
/* Set r0 to r12 to 0 (for debugging) & call main */
.rept 13
CLEAR_GPR_REG_ITER
.endr
ldr r0, =__program_argc
ldr r1, =__program_argv
ldr lr, =__program_exit
ldr r0, [r0]
ldr r1, [r1]
b main
/* No need to include this in normal programs: */
.section .chainloader.text.start, "ax", %progbits
.arm
.align 5
.global relocate_and_chainload
.type relocate_and_chainload, %function
relocate_and_chainload:
ldr sp, =__stack_top__
b relocate_and_chainload_main