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table sizes don't need to be primes; power of 2 gives the same performance.

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This commit is contained in:
Roberto Ierusalimschy 1999-11-29 14:38:48 -02:00
parent d015f1fc02
commit c5fa0895e9
1 changed files with 6 additions and 15 deletions
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21
lmem.c
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@ -1,5 +1,5 @@
/*
** $Id: lmem.c,v 1.19 1999/10/19 13:33:22 roberto Exp roberto $
** $Id: lmem.c,v 1.20 1999/11/22 13:12:07 roberto Exp roberto $
** Interface to Memory Manager
** See Copyright Notice in lua.h
*/
@ -10,6 +10,7 @@
#define LUA_REENTRANT
#include "lmem.h"
#include "lobject.h"
#include "lstate.h"
#include "lua.h"
@ -24,27 +25,17 @@
#endif
#define MINSIZE 8 /* minimum size for "growing" vectors */
static unsigned long power2 (unsigned long n) {
unsigned long p = MINSIZE;
while (p<=n) p<<=1;
return p;
}
void *luaM_growaux (lua_State *L, void *block, unsigned long nelems, int inc, int size,
const char *errormsg, unsigned long limit) {
void *luaM_growaux (lua_State *L, void *block, unsigned long nelems,
int inc, int size, const char *errormsg, unsigned long limit) {
unsigned long newn = nelems+inc;
if (newn >= limit) lua_error(L, errormsg);
if ((newn ^ nelems) <= nelems || /* still the same power of 2 limit? */
(nelems > 0 && newn < MINSIZE)) /* or block already is MINSIZE? */
(nelems > 0 && newn < MINPOWER2)) /* or block already is MINPOWER2? */
return block; /* do not need to reallocate */
else /* it crossed a power of 2 boundary; grow to next power */
return luaM_realloc(L, block, power2(newn)*size);
return luaM_realloc(L, block, luaO_power2(newn)*size);
}