openblt

a hobby OS from the late 90s
git clone http://frotz.net/git/openblt.git
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memory.c (3167B)

      1 /* $Id: //depot/blt/lib/memory.c#4 $
      2 **
      3 ** Copyright 1998 Brian J. Swetland
      4 ** All rights reserved.
      5 **
      6 ** Redistribution and use in source and binary forms, with or without
      7 ** modification, are permitted provided that the following conditions
      8 ** are met:
      9 ** 1. Redistributions of source code must retain the above copyright
     10 **    notice, this list of conditions, and the following disclaimer.
     11 ** 2. Redistributions in binary form must reproduce the above copyright
     12 **    notice, this list of conditions, and the following disclaimer in the
     13 **    documentation and/or other materials provided with the distribution.
     14 ** 3. The name of the author may not be used to endorse or promote products
     15 **    derived from this software without specific prior written permission.
     16 **
     17 ** THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     18 ** IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     19 ** OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     20 ** IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     21 ** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     22 ** NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     23 ** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     24 ** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     25 ** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     26 ** THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     27 */
     28 
     29 #include <stdlib.h>
     30 #include <unistd.h>
     31 #include <blt/types.h>
     32 #include <blt/syscall.h>
     33 #include <blt/libsyms.h>
     34 #include "malloc.h"
     35 
     36 weak_alias (_sbrk, sbrk)
     37 weak_alias (_malloc, malloc)
     38 weak_alias (_free, free)
     39 weak_alias (_realloc, realloc)
     40 
     41 static unsigned int __sbrk_max;
     42 static unsigned int __sbrk_cur;
     43 static int sem_malloc;
     44 
     45 void *_sbrk(int size)
     46 {
     47     if(size < 0 ){
     48         __sbrk_cur -= size;
     49         return (void *) __sbrk_cur;
     50     } else {
     51         unsigned int tmp = __sbrk_cur;
     52         __sbrk_cur += size;
     53         if(__sbrk_cur > __sbrk_max){
     54             __sbrk_max = __sbrk_cur;
     55             os_brk(__sbrk_max);
     56         }
     57         return (void *) tmp;
     58     }
     59 
     60     return (void *) __sbrk_cur;
     61 }
     62 
     63 void *_malloc(size_t size)
     64 {
     65     void *r;
     66     sem_acquire(sem_malloc);
     67     r = __malloc(size);
     68     sem_release(sem_malloc);
     69     return r;
     70 }
     71 
     72 void _free(void *ptr)
     73 {
     74     sem_acquire(sem_malloc);
     75     __free(ptr);
     76     sem_release(sem_malloc);
     77 }
     78 
     79 void *_realloc(void *ptr, size_t size)
     80 {
     81     void *r;
     82     sem_acquire(sem_malloc);
     83     r = __realloc(ptr,size);
     84     sem_release(sem_malloc);
     85     return r;
     86 }
     87 
     88 
     89 void * _default_morecore(long size)
     90 {
     91     void *result;
     92 
     93     result = sbrk(size);
     94     if (result == (void *) -1)
     95         return NULL;
     96     return result;
     97 }
     98 
     99 void __libc_init_memory(unsigned int top_of_binary,
    100                         unsigned int start_bss, unsigned int bss_length)
    101 {
    102 	int i;
    103     unsigned char *x = (unsigned char *) start_bss;
    104     unsigned int tob = (top_of_binary/4096+2)*4096;
    105     os_brk(tob);
    106 
    107 	for (i = 0; i < bss_length; i++)
    108 		x[i] = 0;
    109 
    110     __sbrk_max = __sbrk_cur  = tob;
    111 	
    112     sem_malloc = sem_create(1,"libc_malloc_sem");
    113 }