mirror of
https://github.com/lua/lua
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81 lines
2.2 KiB
C
81 lines
2.2 KiB
C
/*
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** $Id: lmem.c,v 1.61 2002/12/04 17:38:31 roberto Exp roberto $
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** Interface to Memory Manager
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** See Copyright Notice in lua.h
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*/
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#include <stddef.h>
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#define lmem_c
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#include "lua.h"
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#include "ldebug.h"
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#include "ldo.h"
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#include "lmem.h"
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#include "lobject.h"
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#include "lstate.h"
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/*
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** About the realloc function:
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** void * realloc (void *ud, void *ptr, size_t osize, size_t nsize);
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** (`osize' is the old size, `nsize' is the new size)
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**
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** Lua ensures that (ptr == NULL) iff (osize == 0).
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**
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** * realloc(ud, NULL, 0, x) creates a new block of size `x'
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**
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** * realloc(ud, p, x, 0) frees the block `p'
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** (in this specific case, realloc must return NULL).
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** particularly, realloc(ud, NULL, 0, 0) does nothing
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** (which is equivalent to free(NULL) in ANSI C)
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**
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** realloc returns NULL if it cannot create or reallocate the area
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** (any reallocation to an equal or smaller size cannot fail!)
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*/
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#define MINSIZEARRAY 4
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void *luaM_growaux (lua_State *L, void *block, int *size, int size_elems,
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int limit, const char *errormsg) {
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void *newblock;
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int newsize = (*size)*2;
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if (newsize < MINSIZEARRAY)
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newsize = MINSIZEARRAY; /* minimum size */
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else if (*size >= limit/2) { /* cannot double it? */
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if (*size < limit - MINSIZEARRAY) /* try something smaller... */
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newsize = limit; /* still have at least MINSIZEARRAY free places */
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else luaG_runerror(L, errormsg);
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}
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newblock = luaM_realloc(L, block,
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cast(lu_mem, *size)*cast(lu_mem, size_elems),
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cast(lu_mem, newsize)*cast(lu_mem, size_elems));
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*size = newsize; /* update only when everything else is OK */
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return newblock;
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}
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/*
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** generic allocation routine.
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*/
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void *luaM_realloc (lua_State *L, void *block, lu_mem osize, lu_mem nsize) {
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global_State *g = G(L);
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lua_assert((osize == 0) == (block == NULL));
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if (nsize >= MAX_SIZET)
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luaG_runerror(L, "memory allocation error: block too big");
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block = (*g->realloc)(g->ud, block, osize, nsize);
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if (block == NULL && nsize > 0)
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luaD_throw(L, LUA_ERRMEM);
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lua_assert((nsize == 0) == (block == NULL));
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g->nblocks -= osize;
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g->nblocks += nsize;
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return block;
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}
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