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  1. /*
  2. ** $Id: lstring.c,v 2.8.1.1 2007/12/27 13:02:25 roberto Exp $
  3. ** String table (keeps all strings handled by Lua)
  4. ** See Copyright Notice in lua.h
  5. */
  6.  
  7.  
  8. #include <string.h>
  9.  
  10. #define lstring_c
  11. #define LUA_CORE
  12.  
  13. #include "lua.h"
  14.  
  15. #include "lmem.h"
  16. #include "lobject.h"
  17. #include "lstate.h"
  18. #include "lstring.h"
  19.  
  20.  
  21.  
  22. void luaS_resize (lua_State *L, int newsize) {
  23.   GCObject **newhash;
  24.   stringtable *tb;
  25.   int i;
  26.   if (G(L)->gcstate == GCSsweepstring)
  27.     return;  /* cannot resize during GC traverse */
  28.   newhash = luaM_newvector(L, newsize, GCObject *);
  29.   tb = &G(L)->strt;
  30.   for (i=0; i<newsize; i++) newhash[i] = NULL;
  31.   /* rehash */
  32.   for (i=0; i<tb->size; i++) {
  33.     GCObject *p = tb->hash[i];
  34.     while (p) {  /* for each node in the list */
  35.       GCObject *next = p->gch.next;  /* save next */
  36.       unsigned int h = gco2ts(p)->hash;
  37.       int h1 = lmod(h, newsize);  /* new position */
  38.       lua_assert(cast_int(h%newsize) == lmod(h, newsize));
  39.       p->gch.next = newhash[h1];  /* chain it */
  40.       newhash[h1] = p;
  41.       p = next;
  42.     }
  43.   }
  44.   luaM_freearray(L, tb->hash, tb->size, TString *);
  45.   tb->size = newsize;
  46.   tb->hash = newhash;
  47. }
  48.  
  49.  
  50. static TString *newlstr (lua_State *L, const char *str, size_t l,
  51.                                        unsigned int h) {
  52.   TString *ts;
  53.   stringtable *tb;
  54.   if (l+1 > (MAX_SIZET - sizeof(TString))/sizeof(char))
  55.     luaM_toobig(L);
  56.   ts = cast(TString *, luaM_malloc(L, (l+1)*sizeof(char)+sizeof(TString)));
  57.   ts->tsv.len = l;
  58.   ts->tsv.hash = h;
  59.   ts->tsv.marked = luaC_white(G(L));
  60.   ts->tsv.tt = LUA_TSTRING;
  61.   ts->tsv.reserved = 0;
  62.   memcpy(ts+1, str, l*sizeof(char));
  63.   ((char *)(ts+1))[l] = '\0';  /* ending 0 */
  64.   tb = &G(L)->strt;
  65.   h = lmod(h, tb->size);
  66.   ts->tsv.next = tb->hash[h];  /* chain new entry */
  67.   tb->hash[h] = obj2gco(ts);
  68.   tb->nuse++;
  69.   if (tb->nuse > cast(lu_int32, tb->size) && tb->size <= MAX_INT/2)
  70.     luaS_resize(L, tb->size*2);  /* too crowded */
  71.   return ts;
  72. }
  73.  
  74.  
  75. TString *luaS_newlstr (lua_State *L, const char *str, size_t l) {
  76.   GCObject *o;
  77.   unsigned int h = cast(unsigned int, l);  /* seed */
  78.   size_t step = (l>>5)+1;  /* if string is too long, don't hash all its chars */
  79.   size_t l1;
  80.   for (l1=l; l1>=step; l1-=step)  /* compute hash */
  81.     h = h ^ ((h<<5)+(h>>2)+cast(unsigned char, str[l1-1]));
  82.   for (o = G(L)->strt.hash[lmod(h, G(L)->strt.size)];
  83.        o != NULL;
  84.        o = o->gch.next) {
  85.     TString *ts = rawgco2ts(o);
  86.     if (ts->tsv.len == l && (memcmp(str, getstr(ts), l) == 0)) {
  87.       /* string may be dead */
  88.       if (isdead(G(L), o)) changewhite(o);
  89.       return ts;
  90.     }
  91.   }
  92.   return newlstr(L, str, l, h);  /* not found */
  93. }
  94.  
  95.  
  96. Udata *luaS_newudata (lua_State *L, size_t s, Table *e) {
  97.   Udata *u;
  98.   if (s > MAX_SIZET - sizeof(Udata))
  99.     luaM_toobig(L);
  100.   u = cast(Udata *, luaM_malloc(L, s + sizeof(Udata)));
  101.   u->uv.marked = luaC_white(G(L));  /* is not finalized */
  102.   u->uv.tt = LUA_TUSERDATA;
  103.   u->uv.len = s;
  104.   u->uv.metatable = NULL;
  105.   u->uv.env = e;
  106.   /* chain it on udata list (after main thread) */
  107.   u->uv.next = G(L)->mainthread->next;
  108.   G(L)->mainthread->next = obj2gco(u);
  109.   return u;
  110. }
  111.  
  112.