cq.c

来自「C语言源代码及相关资料」· C语言 代码 · 共 82 行

#include "cq.h"

int		CQ_len ( CQ * pQ )
{
int	len = 0;

	if ( pQ->rd <= pQ->wt )
		len = pQ->wt - pQ->rd;
	else
		len = pQ->wt - pQ->rd + pQ->size;
	return len;
}

int		CQ_space ( CQ * pQ )
{
int	len = 0;

	if ( pQ->wt < pQ->rd )
		len = pQ->rd - 1 - pQ->wt;
	else
		len = pQ->rd - 1 - pQ->wt + pQ->size;
	return len;
}

int		CQ_write_in ( CQ * pQ, unsigned char * pbuf, int nSize )
{
int		wt = pQ->wt;
int		rd = pQ->rd;
int		n  = pQ->size;
unsigned
char *	q  = pQ->data;
unsigned
char *	p  = pbuf;

	if ( p == 0 ) return 0;
	if ( q == 0 ) return 0;
	while ( rd <= wt )
	{
		if ( wt + 1 >= n  && rd == 0 ) break;

		q[ wt++ ] = *p++;
		if ( wt >= n ) wt = 0;

		if ( --nSize <= 0 ) break;
	}

	while ( wt < rd - 1 )
	{
		q[ wt++ ] = *p++;
	//	if ( wt >= n ) wt = 0;

		if ( --nSize <= 0 ) break;
	}
	pQ->wt = wt;

	return (int)(p - pbuf);
}

int		CQ_read_out ( CQ * pQ, unsigned char * pbuf, int nSize )
{
int		wt = pQ->wt;
int		rd = pQ->rd;
int		n  = pQ->size;
unsigned
char *	q  = pQ->data;
unsigned
char *	p  = pbuf;
	if ( p == 0 ) return 0;
	if ( q == 0 ) return 0;

	while ( rd != wt )
	{
		*p++ = q[ rd++ ];
		if ( rd >= n ) rd = 0;

		if ( --nSize <= 0 ) break;
	}
	pQ->rd = rd;

	return (int)(p - pbuf);
}