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1866
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1 /*
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2 ** $Id: lmem.c,v 1.84 2012/05/23 15:41:53 roberto Exp $
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3 ** Interface to Memory Manager
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4 ** See Copyright Notice in lua.h
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5 */
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6
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7
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8 #include <stddef.h>
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9
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10 #define lmem_c
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11 #define LUA_CORE
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12
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13 #include "lua.h"
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14
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15 #include "ldebug.h"
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16 #include "ldo.h"
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17 #include "lgc.h"
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18 #include "lmem.h"
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19 #include "lobject.h"
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20 #include "lstate.h"
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21
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22
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23
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24 /*
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25 ** About the realloc function:
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26 ** void * frealloc (void *ud, void *ptr, size_t osize, size_t nsize);
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27 ** (`osize' is the old size, `nsize' is the new size)
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28 **
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29 ** * frealloc(ud, NULL, x, s) creates a new block of size `s' (no
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30 ** matter 'x').
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31 **
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32 ** * frealloc(ud, p, x, 0) frees the block `p'
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33 ** (in this specific case, frealloc must return NULL);
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34 ** particularly, frealloc(ud, NULL, 0, 0) does nothing
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35 ** (which is equivalent to free(NULL) in ANSI C)
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36 **
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37 ** frealloc returns NULL if it cannot create or reallocate the area
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38 ** (any reallocation to an equal or smaller size cannot fail!)
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39 */
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40
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41
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42
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43 #define MINSIZEARRAY 4
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44
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45
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46 void *luaM_growaux_ (lua_State *L, void *block, int *size, size_t size_elems,
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47 int limit, const char *what) {
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48 void *newblock;
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49 int newsize;
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50 if (*size >= limit/2) { /* cannot double it? */
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51 if (*size >= limit) /* cannot grow even a little? */
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52 luaG_runerror(L, "too many %s (limit is %d)", what, limit);
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53 newsize = limit; /* still have at least one free place */
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54 }
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55 else {
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56 newsize = (*size)*2;
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57 if (newsize < MINSIZEARRAY)
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58 newsize = MINSIZEARRAY; /* minimum size */
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59 }
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60 newblock = luaM_reallocv(L, block, *size, newsize, size_elems);
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61 *size = newsize; /* update only when everything else is OK */
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62 return newblock;
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63 }
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64
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65
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66 l_noret luaM_toobig (lua_State *L) {
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67 luaG_runerror(L, "memory allocation error: block too big");
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68 }
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69
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70
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71
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72 /*
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73 ** generic allocation routine.
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74 */
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75 void *luaM_realloc_ (lua_State *L, void *block, size_t osize, size_t nsize) {
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76 void *newblock;
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77 global_State *g = G(L);
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78 size_t realosize = (block) ? osize : 0;
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79 lua_assert((realosize == 0) == (block == NULL));
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80 #if defined(HARDMEMTESTS)
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81 if (nsize > realosize && g->gcrunning)
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82 luaC_fullgc(L, 1); /* force a GC whenever possible */
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83 #endif
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84 newblock = (*g->frealloc)(g->ud, block, osize, nsize);
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85 if (newblock == NULL && nsize > 0) {
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86 api_check(L, nsize > realosize,
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87 "realloc cannot fail when shrinking a block");
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88 if (g->gcrunning) {
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89 luaC_fullgc(L, 1); /* try to free some memory... */
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90 newblock = (*g->frealloc)(g->ud, block, osize, nsize); /* try again */
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91 }
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92 if (newblock == NULL)
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93 luaD_throw(L, LUA_ERRMEM);
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94 }
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95 lua_assert((nsize == 0) == (newblock == NULL));
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96 g->GCdebt = (g->GCdebt + nsize) - realosize;
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97 return newblock;
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98 }
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99
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