dsp_stream.c

来自「基于DM642平台的H.264编码器优化代码」· C语言 代码 · 共 70 行

/********************************************
   码流函数列表
*********************************************/
#include <string.h>

#include "dsp_type.h"
#include "dsp_global.h"
#include "dsp_stream.h"
/*
void initBuffer()
{
	pbfr = buffer;
	ByteBfr = 0;
	leftcnt = 8;
	bytecnt = 0;


}
*/
//最终码流形成函数
void BitstreamPutBits(UInt val, UChar nbits)
{
   

	char i;
	UInt mask;
	if (nbits==0)
		return;

	mask = 1 << (nbits-1);	  // selects first (leftmost) bit 

	for (i=0; i<nbits; i++)
	{
		ByteBfr <<= 1;

		if (val & mask)
			ByteBfr|= 1;

		mask >>= 1;				  // select next bit 
		leftcnt--;

		if (leftcnt==0)			   //8 bit buffer full 
		{
			*(pbfr++) = ByteBfr;
			leftcnt = 8;
			bytecnt++;
			if( (bytecnt%256) == 0 )
			{
				memcpy (pstream, buffer, 256); //dma
			    pstream +=256;
				pbfr = buffer;
			
			}

		}
	}
free(pstream);//码流释放
}
void stuffingBitstrm()
{
	char i,n;
	n = leftcnt;
	BitstreamPutBits(0,1);
	n--;//before leftcnt--,leftcnt can not be 0,this is ensured by BitstreamPutBits(UInt val, UChar nbits)
	for(i=0; i<n; i++)
	{
		BitstreamPutBits(1,1);
	}

}