src/malloc/lite_malloc.c

   1 #include <stdlib.h>
   2 #include <stdint.h>
   3 #include <limits.h>
   4 #include <errno.h>
   5 #include "libc.h"
   6
   7 #define ALIGN 16
   8
   9 void *__expand_heap(size_t *);
  10
  11 static void *__simple_malloc(size_t n)
  12 {
  13         static char *cur, *end;
  14         static volatile int lock[1];
  15         size_t align=1, pad;
  16         void *p;
  17
  18         if (!n) n++;
  19         while (align<n && align<ALIGN)
  20                 align += align;
  21
  22         LOCK(lock);
  23
  24         pad = -(uintptr_t)cur & align-1;
  25
  26         if (n <= SIZE_MAX/2 + ALIGN) n += pad;
  27
  28         if (n > end-cur) {
  29                 size_t m = n;
  30                 char *new = __expand_heap(&m);
  31                 if (!new) {
  32                         UNLOCK(lock);
  33                         return 0;
  34                 }
  35                 if (new != end) {
  36                         cur = new;
  37                         n -= pad;
  38                         pad = 0;
  39                 }
  40                 end = new + m;
  41         }
  42
  43         p = cur + pad;
  44         cur += n;
  45         UNLOCK(lock);
  46         return p;
  47 }
  48
  49 weak_alias(__simple_malloc, malloc);
  50 weak_alias(__simple_malloc, __malloc0);