src/lmem.c

   1 /*
   2 ** $Id: lmem.c,v 1.17 1999/05/24 17:51:05 roberto Exp $
   3 ** Interface to Memory Manager
   4 ** See Copyright Notice in lua.h
   5 */
   6
   7
   8 #include <stdlib.h>
   9
  10 #include "lmem.h"
  11 #include "lstate.h"
  12 #include "lua.h"
  13
  14
  15 /*
  16 ** real ANSI systems do not need these tests;
  17 ** but some systems (Sun OS) are not that ANSI...
  18 */
  19 #ifdef OLD_ANSI
  20 #define realloc(b,s)    ((b) == NULL ? malloc(s) : (realloc)(b, s))
  21 #define free(b)         if (b) (free)(b)
  22 #endif
  23
  24
  25 #define MINSIZE 8       /* minimum size for "growing" vectors */
  26
  27
  28
  29
  30 static unsigned long power2 (unsigned long n) {
  31   unsigned long p = MINSIZE;
  32   while (p<=n) p<<=1;
  33   return p;
  34 }
  35
  36
  37 void *luaM_growaux (void *block, unsigned long nelems, int inc, int size,
  38                        char *errormsg, unsigned long limit) {
  39   unsigned long newn = nelems+inc;
  40   if (newn >= limit) lua_error(errormsg);
  41   if ((newn ^ nelems) <= nelems ||  /* still the same power of 2 limit? */
  42        (nelems > 0 && newn < MINSIZE))  /* or block already is MINSIZE? */
  43       return block;  /* do not need to reallocate */
  44   else  /* it crossed a power of 2 boundary; grow to next power */
  45     return luaM_realloc(block, power2(newn)*size);
  46 }
  47
  48
  49 #ifndef DEBUG
  50
  51 /*
  52 ** generic allocation routine.
  53 */
  54 void *luaM_realloc (void *block, unsigned long size) {
  55   size_t s = (size_t)size;
  56   if (s != size)
  57     lua_error("memory allocation error: block too big");
  58   if (size == 0) {
  59     free(block);  /* block may be NULL, that is OK for free */
  60     return NULL;
  61   }
  62   block = realloc(block, s);
  63   if (block == NULL)
  64     lua_error(memEM);
  65   return block;
  66 }
  67
  68
  69
  70 #else
  71 /* DEBUG */
  72
  73 #include <string.h>
  74
  75
  76 #define HEADER  (sizeof(double))
  77 #define MARKSIZE        16
  78
  79 #define MARK    55
  80
  81
  82 #define blocksize(b)    ((unsigned long *)((char *)(b) - HEADER))
  83
  84 unsigned long numblocks = 0;
  85 unsigned long totalmem = 0;
  86
  87
  88 static void *checkblock (void *block) {
  89   if (block == NULL)
  90     return NULL;
  91   else {
  92     unsigned long *b = blocksize(block);
  93     unsigned long size = *b;
  94     int i;
  95     for (i=0;i<MARKSIZE;i++)
  96       LUA_ASSERT(*(((char *)b)+HEADER+size+i) == MARK+i, "corrupted block");
  97     numblocks--;
  98     totalmem -= size;
  99     return b;
 100   }
 101 }
 102
 103
 104 static void freeblock (void *block) {
 105   if (block)
 106     memset(block, -1, *blocksize(block));  /* erase block */
 107   free(checkblock(block));
 108 }
 109
 110
 111 void *luaM_realloc (void *block, unsigned long size) {
 112   unsigned long realsize = HEADER+size+MARKSIZE;
 113   if (realsize != (size_t)realsize)
 114     lua_error("memory allocation error: block too big");
 115   if (size == 0) {
 116     freeblock(block);
 117     return NULL;
 118   }
 119   else {
 120     char *newblock = malloc(realsize);
 121     int i;
 122     if (block) {
 123       unsigned long oldsize = *blocksize(block);
 124       if (oldsize > size) oldsize = size;
 125       memcpy(newblock+HEADER, block, oldsize);
 126       freeblock(block);  /* erase (and check) old copy */
 127     }
 128     if (newblock == NULL)
 129       lua_error(memEM);
 130     totalmem += size;
 131     numblocks++;
 132     *(unsigned long *)newblock = size;
 133     for (i=0;i<MARKSIZE;i++)
 134       *(newblock+HEADER+size+i) = MARK+i;
 135     return newblock+HEADER;
 136   }
 137 }
 138
 139
 140 #endif