memdma_init.asm

ADI公司BF533读取SDRAM数据

#include "defBF533.h"

.section L1_data_a;
.align 4;

/**************************************************************************************
	Memory DMA descriptor
**************************************************************************************/
.global MemDMAQueue;
MemDMAQueue:
.byte4 _MemDMAQueue[16];
MemDMAQueue.end:

.section L1_code;
.align 4;

/***************************************************************************************
	The sub_code initializes memory DMA descriptors
	Descriptors locates in the memory which label is MemDMAQueue
	Use p0 to store the address of the descriptor
	Use p1 to stroe the modify address
	The loop write the next descriptor address for each descriptor
	and the next descriptor address of the last descriptor points to 
	the first one 
***************************************************************************************/
.global memdma_init;
memdma_init:

	p0.h = hi(EBIU_AMBCTL0);
	p0.l = lo(EBIU_AMBCTL0);
	r0.l = 0x7bb0;
	r0.h = 0x7bb0;
	[p0] = r0;

	p0.h = hi(EBIU_AMBCTL1);
	p0.l = lo(EBIU_AMBCTL1);
	r0.l = 0x7bb0;
	r0.h = 0x7bb0;
	[p0] = r0;

	//Async Memory Global Control Register
	p0.h = hi(EBIU_AMGCTL);
	p0.l = lo(EBIU_AMGCTL);
	r0.l = w[p0];
	r1 = 0xf;
	r0 = r0 | r1;
	w[p0] = r1;		
	ssync;
	
	p0.l = 0x0000;
	p0.h = 0x2020;
	r0.l = 0x00ff;
	w[p0] = r0.l;
	
	p0.l = 0x0000;
	p0.h = 0x2022;
	w[p0] = r0.l;
	
	p0.l = 0x0000;
	p0.h = 0x2023;
	w[p0] = r0.l;
	
	p0.l = MemDMAQueue;
	p0.h = MemDMAQueue;
	p1 = 16(z);//modify address

	r0 = p0;
	r1 = p0;
	r0 += 16;
	
	p2 = 2;
	lsetup(start,end)lc0 = p2;
	start:
	r0 += 16;
	end:
	w[p0 ++ p1] = r0.l;//(++):   p0 + p1 post_modify
	
	w[p0 ++ p1] = r1.l;
	r1 += 16;
	[p0] = r1;
	
	rts;
memdma_init.end: