fifo.c

基于linux下C语言实现的CMPP通信协议

/* 
	file:fifo.c
	first in first out(fifo) by jiniang 2005.02.04
*/
#include <stdlib.h>
#include <string.h>
#include <pthread.h>
#include "fifo.h"

pthread_mutex_t fifo_mutex=PTHREAD_MUTEX_INITIALIZER;	//fifo lock

int fifo_init(struct fifo *p,unsigned int buf_size)
{
	p->first=0;
	p->last=0;
	p->current=0;
	p->max=buf_size;
	return 0;
}

int fifo_destroy(struct fifo* p)
{
	return p->current;
}

int fifo_put(struct fifo* p, void* data, unsigned int size)
{
	int ret;
	pthread_mutex_lock(&fifo_mutex);
	if(p->max && p->current>=p->max)
	{
		ret=1;		//buf is full;
	}
	else
	{
		struct node *n=(struct node*)malloc(sizeof(struct node));
		if(!n)
		{
			ret=1;	//can't get space
		}
		else
		{
			n->size=size;
			n->data=malloc(size);
			if(!n->data)
			{
				free(n);
				ret=1;	//can't get space
			}
			else
			{
				memcpy(n->data,data,size);
				n->next=0;
			
				if(!p->first || !p->last)			//put first time
				{
					p->first=n;
					p->last=n;
				}
				else
				{
					p->last->next=n;
					p->last=n;
				}
				p->current++;
				ret=0;
			}
		}
	}
	pthread_mutex_unlock(&fifo_mutex);
	return ret;
}

int fifo_get(struct fifo* p, void* data, unsigned int* size)
{
	int ret;
	pthread_mutex_lock(&fifo_mutex);
	if(!p->first || !p->last)
	{
		ret=1;
	}
	else
	{
		struct node *n=p->first;
		*size=n->size;
		memcpy(data,n->data,*size);
		p->first=n->next;
		free(n->data);
		free(n);
		p->current--;
		ret=0;
	}
	pthread_mutex_unlock(&fifo_mutex);
	return ret;
}

int fifo_isempty(struct fifo* p)
{
		return (!p->current);
}

int fifo_isfull(struct fifo* p)
{
	if(!p->max) return 0;						//if fifo=0 then return 0 It's means not full
	return (p->current >= p->max);
}

int fifo_setmax(struct fifo* p,unsigned int size)
{
	int ret;
	pthread_mutex_unlock(&fifo_mutex);
	if(size < p->current)
	{
		ret=1;
	}
	else
	{
		p->max=size;
		ret=0;
	}
	pthread_mutex_unlock(&fifo_mutex);
	return ret;
}

int fifo_getcurrent(struct fifo* p)
{
	return p->current;
}