** String table (keeps all strings handled by Lua)

/*
** $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
*/

#include <string.h>

#define lstring_c
#define LUA_CORE

#include "lua.h"

#include "lmem.h"
#include "lobject.h"
#include "lstate.h"
#include "lstring.h"

void luaS_resize (lua_State *L, int newsize) {
GCObject **newhash;
stringtable *tb;
int i;
if (G(L)->gcstate == GCSsweepstring)
return; /* cannot resize during GC traverse */
newhash = luaM_newvector(L, newsize, GCObject *);
tb = &G(L)->strt;
for (i=0; i<newsize; i++) newhash[i] = NULL;
/* rehash */
for (i=0; i<tb->size; i++) {
GCObject *p = tb->hash[i];
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 = newhash[h1]; /* chain it */
newhash[h1] = p;
p = next;
}
}
luaM_freearray(L, tb->hash, tb->size, TString *);
tb->size = newsize;
tb->hash = newhash;
}

static TString *newlstr (lua_State *L, const char *str, size_t l,
unsigned int h) {
TString *ts;
stringtable *tb;
if (l+1 > (MAX_SIZET - sizeof(TString))/sizeof(char))
luaM_toobig(L);
ts = cast(TString *, luaM_malloc(L, (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;
ts->tsv.reserved = 0;
memcpy(ts+1, str, l*sizeof(char));
((char *)(ts+1))[l] = '\0'; /* ending 0 */
tb = &G(L)->strt;
h = lmod(h, tb->size);
ts->tsv.next = tb->hash[h]; /* chain new entry */
tb->hash[h] = obj2gco(ts);
tb->nuse++;
if (tb->nuse > cast(lu_int32, tb->size) && tb->size <= MAX_INT/2)
luaS_resize(L, tb->size*2); /* too crowded */
return ts;
}

TString *luaS_newlstr (lua_State *L, const char *str, size_t l) {
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); /* not found */
}

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;
}