lib/libstand/sbrk.c

   1 /*-
   2  * Copyright (c) 1998 Michael Smith
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  *
  26  * $FreeBSD: src/lib/libstand/sbrk.c,v 1.2.2.1 2000/05/18 08:00:57 ps Exp $
  27  */
  28
  29 /*
  30  * Minimal sbrk() emulation required for malloc support.
  31  */
  32
  33 #include <string.h>
  34 #include "stand.h"
  35
  36 static size_t   maxheap, heapsize = 0;
  37 static void     *sbrkbase;
  38
  39 void
  40 setheap(void *base, void *top)
  41 {
  42     /* Align start address to 16 bytes for the malloc code. Sigh. */
  43     sbrkbase = (void *)(((uintptr_t)base + 15) & ~15);
  44     maxheap = top - sbrkbase;
  45 }
  46
  47 char *
  48 getheap(size_t *sizep)
  49 {
  50     *sizep = maxheap;
  51     return sbrkbase;
  52 }
  53
  54 char *
  55 sbrk(intptr_t incr)
  56 {
  57     char        *ret;
  58
  59     if ((heapsize + incr) <= maxheap) {
  60         ret = sbrkbase + heapsize;
  61         bzero(ret, incr);
  62         heapsize += incr;
  63         return(ret);
  64     }
  65     errno = ENOMEM;
  66     return((char *)-1);
  67 }