!/* crt0.s - Dreamcast Startup Code
! * @author : Groepaz/Hitmen
! */

	.section .text

	.global	start
	.global ___main

!	.global _exit
!	.global _atexit

start:   ! entry point

!/*
! * Cache activation
! */
	mov.l	setup_cache_addr,r0	! make sure to run in the P2 area
	mov.l	p2_mask,r1
	or	r1,r0
	jmp	@r0
	nop

setup_cache:
	mov.l	ccr_addr,r0		! enable the cache
	mov.w	ccr_data,r1
	mov.l	r1,@r0

!/*
! * After changing the CCR, eight instruction have to be executed before
! * the cached area may the entered
! */

	mov.l	go_addr,r0		! 1
	nop				! 2
	nop				! 3
	nop				! 4
	nop				! 5
	nop				! 6
	nop				! 7
	nop				! 8
	jmp	@r0			! go
	or 	r0,r0			! fill branch-delay slot

!/*
! * The following code now runs in cached mode
! */

go:
	mov.l	stack_k,r15		! init stackpointer

!/*
! * Clear the BSS Section
! */

	mov.l	edata_k,r0		! addr. of end of data section
	mov.l	end_k,r1		! addr. of end of bss section
	mov	#0,r2
start_l:
	mov.l 	r2,@r0
	add	#4,r0
	cmp/ge	r0,r1
	bt	start_l

	mov.l	set_fpscr_k, r1		! init floating point stuff
	jsr	@r1
	mov	#0,r4

	lds	r3,fpscr

!/*
! * Call the mainline
! */

	mov.l	start_k,r0		! get address of function main
	jsr	@r0
	or	r0,r0			! fill branch-delay slot

!/*
! * Call EXIT
! */

!	mov	r0,r4
!
!	mov.l	exit_k,r0		! get address of function exit
!	jsr	@r0
!	or	r0,r0			! fill branch-delay slot
	rts
	nop

!/*
! * reset the Dreamcast
! */

!reset:
!  mov.l reset_k,r0			! get reset address
!  jsr @r0
!  or  r0,r0				! fill branch-delay slot

!/*
! * "main" will be called at the beginning of main(void)
! */

___main:
  rts
  nop

!/*
! * void exit(int) - called at the end of int main(void)
! */

!_exit:
!  rts
!  nop
!_atexit:
!  rts
!  nop


	.align	2

!/*
! * Symbols to be resolved by the linker
! */
start_k:
	.long	_main			! adress of int main(void)
!exit_k:
!	.long	_exit			! adress of void exit(int)
set_fpscr_k:
	.long	___set_fpscr		! adress of floating point init
edata_k:              
	.long	_edata			! end of initialized data
end_k:               
	.long	_end			! end of bss area / start of heap memory
stack_k:
	.long	_stack			! stack top
reset_k:
	.long	0xa0000108		! reset adress
setup_cache_addr:
	.long	setup_cache
go_addr:
	.long	go
p2_mask:
	.long	0xa0000000
ccr_addr:
	.long	0xff00001c
ccr_data:
	.word	0x090d


!/*
! * Define a stack section in memory
! */

#ifdef __ELF__
	.section .stack,"aw"
#else
	.section .stack
#endif