@******************************************************************************@ File：head.s@ 功能：設(shè)置SDRAM，將程序復(fù)制到SDRAM，然后跳到SDRAM繼續(xù)執(zhí)行
@******************************************************************************       
.equ		MEM_CTL_BASE,		0x48000000.equ		SDRAM_BASE,		0x30000000.text.global _start_start:	bl	disable_watch_dog	bl	memsetup	bl	copy_steppingstone_to_sdram	ldr	pc,	=set_sp				@跳到SDRAM中繼續(xù)執(zhí)行set_sp:	ldr	sp,	=0x34000000		@設(shè)置堆棧	bl	mainhalt_loop:	b	halt_loopdisable_watch_dog:	mov	r1, 	#0x53000000	mov	r2, 	#0x0	str	r2, 	[r1]	mov	pc,	lrcopy_steppingstone_to_sdram:	@copy the 4k code from steppingstone(address begins at 0x00000000) to sdram(address begins at 0x30000000)	mov	r1,	#0	ldr	r2,	=SDRAM_BASE	mov	r3,	#4*10241:	ldr	r4,	[r1],#4	str	r4,	[r2],#4	cmp	r1,	r3	bne	1b	mov	pc, 	lrmemsetup:	@ initialise the static memory 	@ set memory control registers	mov	r1, 	#MEM_CTL_BASE	adrl	r2, 	mem_cfg_val	add	r3, 	r1, #521:	ldr	r4, 	[r2], #4	str	r4, 	[r1], #4	cmp	r1, 	r3	bne	1b	mov	pc, 	lr.align 4mem_cfg_val:	.long	0x22111110		@BWSCON	.long	0x00000700		@BANKCON0	.long	0x00000700		@BANKCON1	.long	0x00000700		@BANKCON2	.long	0x00000700		@BANKCON3		.long	0x00000700		@BANKCON4	.long	0x00000700		@BANKCON5	.long	0x00018005		@BANKCON6	.long	0x00018005		@BANKCON7	.long	0x008e07a3		@REFRESH	.long	0x000000b2		@BANKSIZE	.long	0x00000030		@MRSRB6	.long	0x00000030		@MRSRB7