fifo.h

代码有点长,需细心阅读,仅供影音视听类产品的开发人员参考

#ifndef __FIFO_H__
#define __FIFO_H__

#include "regmap.h"
#include "getbits.h"
#include "types.h"

typedef struct
{
	unsigned char *data;
	int     size;
	int     head;
	int     tail;

	unsigned word;
	int     bit_left;
}
tFifo;

#ifdef ENABLE_INLINE
static inline int WRAPl(int r, int s)
{
	return (r < 0) ? (r + s) : r;
}
static inline int WRAPr(int r, int s)
{
	return (r >= s) ? (r - s) : r;
}
static inline void FifoTailAdv(tFifo * fifo, int n)
{
	fifo->tail = WRAPr(fifo->tail + n, fifo->size);
}
static inline void FifoHeadAdv(tFifo * fifo, int n)
{
	fifo->head = WRAPr(fifo->head + n, fifo->size);
}
#else
#define	WRAPl(r,s) (((r)<0) ? ((r)+(s)) : (r))
#define	WRAPr(r,s) (((r)>=(s)) ? ((r)-(s)) : (r))
#define	FifoTailAdv(f, n) (f->tail = WRAPr(f->tail+n,f->size))
#endif

/*
static inline unsigned FifoGetByte(tFifo *fifo)
{
  int   size = fifo->size;
  int   tail = fifo->tail;
  unsigned c = fifo->data[tail];
  fifo->tail = WRAPr(tail+1,size);
  return c;
}
*/

#ifdef ENABLE_INLINE
static inline unsigned FifoRetrieve(tFifo * fifo, int i)
{
	int     size = fifo->size;
	int     tail = fifo->tail;

	return fifo->data[WRAPr(tail + i, size)];
}
#endif


#define FifoGetLength(fifo)	(WRAPl((fifo)->head-(fifo)->tail, (fifo)->size))
#define FifoGetFree(fifo)	((fifo)->size - FifoGetLength(fifo))
#define FifoGetBitInit(fifo)	((fifo)->bit_left=0)
#define FifoGetBitRestart(fifo)	(FifoGetBitInit(fifo))

unsigned FifoGetByte(tFifo *);
unsigned FifoGetWord(tFifo *);
unsigned FifoGetBits(tFifo *, int);

#ifdef __GNUC__
static inline void FifoLoad(tFifo * f, char *p, int len)
{
	int     l1;
	int     head = f->head;
	int     size = f->size;

	if((l1 = size - head) < len)
	{
		memcpy(f->data + head, p, l1);
		len -= l1;
		p += l1;
		head = 0;
	}
	memcpy(f->data + head, p, len);
	f->head = head + len;
}
#endif

int     FifoDMARead(tFifo *, int, int);

#endif/*__FIFO_H__*/