wbuf.c

来自「基于4个mips核的noc设计」· C语言 代码 · 共 65 行

/*
 * Copyright (c) 1990 The Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by the University of California, Berkeley.  The name of the
 * University may not be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#include <stdio.h>
#include "local.h"

/*
 * Write the given character into the (probably full) buffer for
 * the given file.  Flush the buffer out if it is or becomes full,
 * or if c=='\n' and the file is line buffered.
 */

int __swbuf( int c, FILE *fp)
{
	register int n;

	/*
	 * In case we cannot write, or longjmp takes us out early,
	 * make sure _w is 0 (if fully- or un-buffered) or -_bf._size
	 * (if line buffered) so that we will get called again.
	 * If we did not do this, a sufficient number of putc()
	 * calls might wrap _w from negative to positive.
	 */
	fp->_w = fp->_lbfsize;
	if (cantwrite(fp))
		return (EOF);
	c = (unsigned char)c;

	/*
	 * If it is completely full, flush it out.  Then, in any case,
	 * stuff c into the buffer.  If this causes the buffer to fill
	 * completely, or if c is '\n' and the file is line buffered,
	 * flush it (perhaps a second time).  The second flush will always
	 * happen on unbuffered streams, where _bf._size==1; fflush()
	 * guarantees that putc() will always call wbuf() by setting _w
	 * to 0, so we need not do anything else.
	 */
	n = fp->_p - fp->_bf._base;
	if (n >= fp->_bf._size) {
		if (_fflush(fp))
			return (EOF);
		n = 0;
	}
	fp->_w--;
	*fp->_p++ = c;
	if (++n == fp->_bf._size || (fp->_flags & __SLBF && c == '\n'))
		if (_fflush(fp))
			return (EOF);
	return (c);
}