fread.c

Algorithms for Image Processing and Computer Vision Source Code

/* This is file FREAD.C */
/* This file may have been modified by DJ Delorie (Jan 1991).  If so,
** these modifications are Coyright (C) 1993 DJ Delorie, 24 Kirsten Ave,
** Rochester NH, 03867-2954, USA.
*/

/*
 * Copyright (c) 1980 Regents of the University of California.
 * All rights reserved.  The Berkeley software License Agreement
 * specifies the terms and conditions for redistribution.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)fread.c	5.2 (Berkeley) 3/9/86";
#endif LIBC_SCCS and not lint

#include <stdio.h>
#include <stdlib.h>

size_t
fread(ptr, size, count, iop)
	register void *ptr;
	size_t size, count;
	register FILE *iop;
{
	register int s;
	int c;

	s = size * count;
	while (s > 0) {
		if (iop->_cnt < s) {
			if (iop->_cnt > 0) {
				bcopy(iop->_ptr, ptr, iop->_cnt);
				ptr += iop->_cnt;
				s -= iop->_cnt;
			}
			/*
			 * filbuf clobbers _cnt & _ptr,
			 * so don't waste time setting them.
			 */
			if ((c = _filbuf(iop)) == EOF)
				break;
			*(char *)ptr++ = c;
			s--;
		}
		if (iop->_cnt >= s) {
			bcopy(iop->_ptr, ptr, s);
			iop->_ptr += s;
			iop->_cnt -= s;
			return (count);
		}
	}
	return (size != 0 ? count - ((s + size - 1) / size) : 0);
}