sbrk.c

MIPS处理器的bootloader,龙芯就是用的修改过的PMON2

/* $Id: sbrk.c,v 1.2 2002/08/09 20:56:57 pefo Exp $ */

/*
 * Copyright (c) 2000-2002 Opsycon AB  (www.opsycon.se)
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by Opsycon AB.
 * 4. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 */
#include <sys/types.h>
#include <unistd.h>

#define NULL 0
#define ALLOCSIZE 32*1024


char allocbuf[ALLOCSIZE];
char *allocp1 = allocbuf;

/*
 *  sbrk() is alloc() on page 101 of K & R  Edition 2
 *      This sbrk is used by PMON, the sbrk in crt1.s is used
 *      by clients.
 */
char *
sbrk(int n)
{
	if (allocp1 + n <= allocbuf + ALLOCSIZE) {
		allocp1 += n;
		return (allocp1 - n);
	} else
		return (NULL);
}