www.pudn.com > CRGAB.zip > CIRQUE.C

/*------------------------------------------------- 
03/02/91 
You are free to use the code in this file for ANY 
purpose whatsoever. 
If you can sell it.....go for it. 
--------------------- 
Conrad Thornton 
RR1 Box 87C 
Downsville,La. 71234 
--------------------------------------------------*/ 
#include  
#include  
#include  
 
#define ITEMSIZE (sizeof(char) + sizeof(char *)) 
#define ITSOK	  0 
#define ERROR	 -1 
#define QUEFULL  -2 
#define QUEEMPTY -3 
 
static char *cir_que,*writehead,*readtail,*queend; 
 
int setupque(int); 
int quewrite(char *,int); 
int queread(char **,int *); 
int quekill(void); 
 
static int QUESTART; 
static int ITEMSINQUE; 
/*-------------------------------------------------*/ 
int setupque(qsize) 
int qsize; 
{ 
	int quesize; 
 
	quesize = qsize * ITEMSIZE; 
	cir_que = (char *)malloc(quesize+1); 
	if(cir_que == (char *)NULL) 
	   return(ERROR); 
	memset(cir_que,'\0',quesize); 
	readtail  = cir_que; 
	writehead = readtail; 
	queend	  = readtail+quesize; 
	QUESTART  = 1; 
	ITEMSINQUE= 0; 
	return(ITSOK); 
} 
/*-------------------------------------------------*/ 
int quewrite(data,type) 
char *data; 
int  type; 
{ 
	if(writehead == readtail && ! QUESTART) 
	   return(QUEFULL); 
	if(writehead == queend) { 
	   if(readtail == cir_que) 
	      return(QUEFULL); 
	   writehead =	cir_que; 
	} 
	*writehead++ = (char) type;/* ins type and data */ 
	memcpy(writehead,&data,sizeof(char *)); 
	writehead += sizeof(char *); 
	QUESTART   = 0; 
	ITEMSINQUE++; 
	return(ITSOK); 
} 
/*------------------------------------------------------*/ 
int queovwrite(data,type) 
char *data; 
int  type; 
{ 
	char *p; 
	int  ecode,j; 
 
	if(writehead == queend) 
	   writehead = cir_que; 
	if(readtail  == queend) 
	   readtail  = cir_que; 
	if(writehead == readtail && ! QUESTART) { 
	   ecode = queread(&p,&j); /* free previous malloc */ 
	   if(ecode < 0) 
	      return(ERROR); 
	   free(p); 
	   readtail += ITEMSIZE; 
	}	      /* now we can write in the old space */ 
	*writehead++ = (char) type; 
	memcpy(writehead,&data,sizeof(char *)); 
	writehead += sizeof(char *); 
	QUESTART   = 0; 
	ITEMSINQUE++; 
	return(ITSOK); 
} 
/*--------------------------------------------------------*/ 
int queread(p,type) 
char **p; 
int  *type; 
{ 
	if(readtail == writehead) 
	   return(QUEEMPTY); 
	if(readtail == queend) { 
	   if(writehead == cir_que) 
	      return(QUEEMPTY); 
	   readtail = cir_que; 
	} 
	*type = (int) *readtail++; 
	memcpy(p,readtail,sizeof(char *)); 
	readtail += sizeof(char *); 
	ITEMSINQUE--; 
	if(ITEMSINQUE == 0) { 
	   readtail  = cir_que; 
	   writehead = cir_que; 
	   QUESTART  = 1; 
	} 
	return(ITSOK); 
} 
/*------------------------------------------------------*/ 
int quekill() 
{ 
	if(ITEMSINQUE) 
	   return(ERROR); 
	free(cir_que); 
	return(ITSOK); 
} 
/*-----------------------------------------------------*/