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/*
** $Id: lstring.c,v 2.19 2011/05/03 16:01:57 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) {
int i;
stringtable *tb = &G(L)->strt;
/* cannot resize while GC is traversing strings */
luaC_runtilstate(L, ~bitmask(GCSsweepstring));
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 = gch(p)->next; /* save next */
unsigned int h = lmod(gco2ts(p)->hash, newsize); /* new position */
gch(p)->next = tb->hash[h]; /* chain it */
tb->hash[h] = p;
resetoldbit(p); /* see MOVE OLD rule */
p = next;
}
}
if (newsize < tb->size) {
/* shrinking slice must be empty */
lua_assert(tb->hash[newsize] == NULL && tb->hash[tb->size - 1] == NULL);
luaM_reallocvector(L, tb->hash, tb->size, newsize, GCObject *);
}
tb->size = newsize;
}
static TString *newlstr (lua_State *L, const char *str, size_t l,
unsigned int h) {
size_t totalsize; /* total size of TString object */
GCObject **list; /* (pointer to) list where it will be inserted */
TString *ts;
stringtable *tb = &G(L)->strt;
if (l+1 > (MAX_SIZET - sizeof(TString))/sizeof(char))
luaM_toobig(L);
if (tb->nuse >= cast(lu_int32, tb->size) && tb->size <= MAX_INT/2)
luaS_resize(L, tb->size*2); /* too crowded */
totalsize = sizeof(TString) + ((l + 1) * sizeof(char));
list = &tb->hash[lmod(h, tb->size)];
ts = &luaC_newobj(L, LUA_TSTRING, totalsize, list, 0)->ts;
ts->tsv.len = l;
ts->tsv.hash = h;
ts->tsv.reserved = 0;
memcpy(ts+1, str, l*sizeof(char));
((char *)(ts+1))[l] = '\0'; /* ending 0 */
tb->nuse++;
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 = gch(o)->next) {
TString *ts = rawgco2ts(o);
if (h == ts->tsv.hash &&
ts->tsv.len == l &&
(memcmp(str, getstr(ts), l * sizeof(char)) == 0)) {
if (isdead(G(L), o)) /* string is dead (but was not collected yet)? */
changewhite(o); /* resurrect it */
return ts;
}
}
return newlstr(L, str, l, h); /* not found; create a new string */
}
TString *luaS_new (lua_State *L, const char *str) {
return luaS_newlstr(L, str, strlen(str));
}
Udata *luaS_newudata (lua_State *L, size_t s, Table *e) {
Udata *u;
if (s > MAX_SIZET - sizeof(Udata))
luaM_toobig(L);
u = &luaC_newobj(L, LUA_TUSERDATA, sizeof(Udata) + s, NULL, 0)->u;
u->uv.len = s;
u->uv.metatable = NULL;
u->uv.env = e;
return u;
}
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