alloc.c

   1 #include <stdlib.h>
   2 #include "alloc.h"
   3 #include "error.h"
   4
   5 #define ALIGNMENT 16 /* XXX: assuming that this alignment is enough */
   6 #define SPACE 2048 /* must be multiple of ALIGNMENT */
   7
   8 typedef union { char irrelevant[ALIGNMENT]; double d; } aligned;
   9 static aligned realspace[SPACE / ALIGNMENT];
  10 #define space ((char *) realspace)
  11 static unsigned int avail = SPACE; /* multiple of ALIGNMENT; 0<=avail<=SPACE */
  12
  13 /*@null@*//*@out@*/char *alloc(n)
  14 unsigned int n;
  15 {
  16   char *x;
  17   n = ALIGNMENT + n - (n & (ALIGNMENT - 1)); /* XXX: could overflow */
  18   if (n <= avail) { avail -= n; return space + avail; }
  19   x = malloc(n);
  20   if (!x) errno = error_nomem;
  21   return x;
  22 }
  23
  24 void alloc_free(x)
  25 char *x;
  26 {
  27   if (x >= space)
  28     if (x < space + SPACE)
  29       return; /* XXX: assuming that pointers are flat */
  30   free(x);
  31 }