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Towards external strings

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Long strings have a pointer to string contents.
This commit is contained in:
Roberto Ierusalimschy
2023-11-08 13:24:38 -03:00
parent b8a9d14032
commit 7f4906f565
4 changed files with 36 additions and 22 deletions
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19
lstring.c
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@@ -140,24 +140,25 @@ void luaS_init (lua_State *L) {
/*
** creates a new string object
*/
static TString *createstrobj (lua_State *L, size_t l, int tag, unsigned int h) {
static TString *createstrobj (lua_State *L, size_t totalsize, int tag,
unsigned int h) {
TString *ts;
GCObject *o;
size_t totalsize; /* total size of TString object */
totalsize = sizelstring(l);
o = luaC_newobj(L, tag, totalsize);
ts = gco2ts(o);
ts->hash = h;
ts->extra = 0;
getstr(ts)[l] = '\0'; /* ending 0 */
return ts;
}
TString *luaS_createlngstrobj (lua_State *L, size_t l) {
TString *ts = createstrobj(L, l, LUA_VLNGSTR, G(L)->seed);
size_t totalsize = sizestrlng(l);
TString *ts = createstrobj(L, totalsize, LUA_VLNGSTR, G(L)->seed);
ts->u.lnglen = l;
ts->shrlen = 0xFF; /* signals that it is a long string */
ts->shrlen = -1; /* signals that it is a long string */
ts->contents = cast_charp(ts) + sizeof(TString);
ts->contents[l] = '\0'; /* ending 0 */
return ts;
}
@@ -194,7 +195,8 @@ static TString *internshrstr (lua_State *L, const char *str, size_t l) {
TString **list = &tb->hash[lmod(h, tb->size)];
lua_assert(str != NULL); /* otherwise 'memcmp'/'memcpy' are undefined */
for (ts = *list; ts != NULL; ts = ts->u.hnext) {
if (l == ts->shrlen && (memcmp(str, getshrstr(ts), l * sizeof(char)) == 0)) {
if (l == cast_uint(ts->shrlen) &&
(memcmp(str, getshrstr(ts), l * sizeof(char)) == 0)) {
/* found! */
if (isdead(g, ts)) /* dead (but not collected yet)? */
changewhite(ts); /* resurrect it */
@@ -206,8 +208,9 @@ static TString *internshrstr (lua_State *L, const char *str, size_t l) {
growstrtab(L, tb);
list = &tb->hash[lmod(h, tb->size)]; /* rehash with new size */
}
ts = createstrobj(L, l, LUA_VSHRSTR, h);
ts = createstrobj(L, sizestrshr(l), LUA_VSHRSTR, h);
ts->shrlen = cast_byte(l);
getshrstr(ts)[l] = '\0'; /* ending 0 */
memcpy(getshrstr(ts), str, l * sizeof(char));
ts->u.hnext = *list;
*list = ts;