text: /*
  ** $Id: lstring.c,v 2.8.1.1 2007/12/27 13:02:25 roberto Exp $
  ** String table (keeps all strings handled by Lua)
  ** See Copyright Notice in lua.h
  */
  
  
  
  #define lstring_c
  #define LUA_CORE
  #define LUAC_CROSS_FILE
  
  #include "lua.h"
  #include C_HEADER_STRING
  
  #include "lmem.h"
  #include "lobject.h"
  #include "lstate.h"
  #include "lstring.h"
  
  #define LUAS_READONLY_STRING      1
  #define LUAS_REGULAR_STRING       0
  
  void luaS_resize (lua_State *L, int newsize) {
    stringtable *tb;
    int i;
    tb = &G(L)->strt;
    if (luaC_sweepstrgc(L) || newsize == tb->size || is_resizing_strings_gc(L))
      return;  /* cannot resize during GC traverse or doesn't need to be resized */
    set_resizing_strings_gc(L);
    if (newsize > tb->size) {
      luaM_reallocvector(L, tb->hash, tb->size, newsize, GCObject *);
      for (i=tb->size; i<newsize; i++) tb->hash[i] = NULL;
    }
    /* rehash */
    for (i=0; i<tb->size; i++) {
      GCObject *p = tb->hash[i];
      tb->hash[i] = NULL;
      while (p) {  /* for each node in the list */
        GCObject *next = p->gch.next;  /* save next */
        unsigned int h = gco2ts(p)->hash;
        int h1 = lmod(h, newsize);  /* new position */
        lua_assert(cast_int(h%newsize) == lmod(h, newsize));
        p->gch.next = tb->hash[h1];  /* chain it */
        tb->hash[h1] = p;
        p = next;
      }
    }
    if (newsize < tb->size)
      luaM_reallocvector(L, tb->hash, tb->size, newsize, GCObject *);
    tb->size = newsize;
    unset_resizing_strings_gc(L);
  }
  
  static TString *newlstr (lua_State *L, const char *str, size_t l,
                                         unsigned int h, int readonly) {
    TString *ts;
    stringtable *tb;
    if (l+1 > (MAX_SIZET - sizeof(TString))/sizeof(char))
      luaM_toobig(L);
    tb = &G(L)->strt;
    if ((tb->nuse + 1) > cast(lu_int32, tb->size) && tb->size <= MAX_INT/2)
      luaS_resize(L, tb->size*2);  /* too crowded */
    ts = cast(TString *, luaM_malloc(L, readonly ? sizeof(char**)+sizeof(TString) : (l+1)*sizeof(char)+sizeof(TString)));
    ts->tsv.len = l;
    ts->tsv.hash = h;
    ts->tsv.marked = luaC_white(G(L));
    ts->tsv.tt = LUA_TSTRING;
    if (!readonly) {
      memcpy(ts+1, str, l*sizeof(char));
      ((char *)(ts+1))[l] = '\0';  /* ending 0 */
    } else {
      *(char **)(ts+1) = (char *)str;
      luaS_readonly(ts);
    }
    h = lmod(h, tb->size);
    ts->tsv.next = tb->hash[h];  /* chain new entry */
    tb->hash[h] = obj2gco(ts);
    tb->nuse++;
    return ts;
  }
  
  
  static TString *luaS_newlstr_helper (lua_State *L, const char *str, size_t l, int readonly) {
    GCObject *o;
    unsigned int h = cast(unsigned int, l);  /* seed */
    size_t step = (l>>5)+1;  /* if string is too long, don't hash all its chars */
    size_t l1;
    for (l1=l; l1>=step; l1-=step)  /* compute hash */
      h = h ^ ((h<<5)+(h>>2)+cast(unsigned char, str[l1-1]));
    for (o = G(L)->strt.hash[lmod(h, G(L)->strt.size)];
         o != NULL;
         o = o->gch.next) {
      TString *ts = rawgco2ts(o);
      if (ts->tsv.len == l && (memcmp(str, getstr(ts), l) == 0)) {
        /* string may be dead */
        if (isdead(G(L), o)) changewhite(o);
        return ts;
      }
    }
    return newlstr(L, str, l, h, readonly);  /* not found */
  }
  
  static int lua_is_ptr_in_ro_area(const char *p) {
  #ifdef LUA_CROSS_COMPILER
    return 0;
  #else
  
  #include "compiler.h"
  
    return p >= RODATA_START_ADDRESS && p <= RODATA_END_ADDRESS;
  #endif
  }
  
  TString *luaS_newlstr (lua_State *L, const char *str, size_t l) {
    // If the pointer is in a read-only memory and the string is at least 4 chars in length,
    // create it as a read-only string instead
    if(lua_is_ptr_in_ro_area(str) && l+1 > sizeof(char**) && l == strlen(str))
      return luaS_newlstr_helper(L, str, l, LUAS_READONLY_STRING);
    else
      return luaS_newlstr_helper(L, str, l, LUAS_REGULAR_STRING);
  }
  
  
  LUAI_FUNC TString *luaS_newrolstr (lua_State *L, const char *str, size_t l) {
    if(l+1 > sizeof(char**) && l == strlen(str))
      return luaS_newlstr_helper(L, str, l, LUAS_READONLY_STRING);
    else // no point in creating a RO string, as it would actually be larger
      return luaS_newlstr_helper(L, str, l, LUAS_REGULAR_STRING);
  }
  
  
  Udata *luaS_newudata (lua_State *L, size_t s, Table *e) {
    Udata *u;
    if (s > MAX_SIZET - sizeof(Udata))
      luaM_toobig(L);
    u = cast(Udata *, luaM_malloc(L, s + sizeof(Udata)));
    u->uv.marked = luaC_white(G(L));  /* is not finalized */
    u->uv.tt = LUA_TUSERDATA;
    u->uv.len = s;
    u->uv.metatable = NULL;
    u->uv.env = e;
    /* chain it on udata list (after main thread) */
    u->uv.next = G(L)->mainthread->next;
    G(L)->mainthread->next = obj2gco(u);
    return u;
  }
  
  