Buffer.h

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/* BUFFER.H */

/*
 * definitions for buffer modules.
 */
#ifndef _BUFFER_H_
#define _BUFFER_H_

#include "standard.h"

typedef struct {
  int head, tail;
  int full;
  int n;
  size_t len;
  void *data;
} Buffer;

Buffer *mkbuffer(int n, size_t len);
/*
 * mkbuffer creates a buffer for up to n records of length len;
 */ 

int bsize(Buffer *b);
/*
 * returns the total size of the buffer (n)
 */

int bhead(Buffer *b);
/*
 * returns the position of the buffer's head 
 */

int btail(Buffer *b);
/*
 * returns the position of the buffer's tail
 */

void bwrite(Buffer *b, void *data);
/* 
 * writes a record from *data to the buffer
 */

int bread(Buffer *b, void *data);
/* 
 * reads a record from the buffer to *data
 */

int blevel(Buffer *b);
/*
 * returns the number of records in the buffer
 */

void *bpeek(Buffer *b, int n);
/*
 * bpeek returns a pointer to the nth record in the buffer.
 */

void closebuffer(Buffer *b);
/*
 * frees up memory used by buffer b
 */


#endif

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