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authorRoberto Ierusalimschy <roberto@inf.puc-rio.br>2015-01-16 14:54:37 -0200
committerRoberto Ierusalimschy <roberto@inf.puc-rio.br>2015-01-16 14:54:37 -0200
commit7e2015a46df7976bddee313b994742e49e420714 (patch)
tree0b2db30f1214a478ccb3664d165c8a431f0d5850 /lstring.c
parent5b01cb39b5ec36c544152351c35c43149d9bbfec (diff)
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size of short strings stored in a single byte, to reduce the size
of struct 'TString'
Diffstat (limited to 'lstring.c')
-rw-r--r--lstring.c27
1 files changed, 15 insertions, 12 deletions
diff --git a/lstring.c b/lstring.c
index 27b06dd3..29e4630c 100644
--- a/lstring.c
+++ b/lstring.c
@@ -1,5 +1,5 @@
1/* 1/*
2** $Id: lstring.c,v 2.44 2014/07/21 16:02:10 roberto Exp roberto $ 2** $Id: lstring.c,v 2.45 2014/11/02 19:19:04 roberto Exp roberto $
3** String table (keeps all strings handled by Lua) 3** String table (keeps all strings handled by Lua)
4** See Copyright Notice in lua.h 4** See Copyright Notice in lua.h
5*/ 5*/
@@ -36,10 +36,10 @@
36** equality for long strings 36** equality for long strings
37*/ 37*/
38int luaS_eqlngstr (TString *a, TString *b) { 38int luaS_eqlngstr (TString *a, TString *b) {
39 size_t len = a->len; 39 size_t len = a->u.lnglen;
40 lua_assert(a->tt == LUA_TLNGSTR && b->tt == LUA_TLNGSTR); 40 lua_assert(a->tt == LUA_TLNGSTR && b->tt == LUA_TLNGSTR);
41 return (a == b) || /* same instance or... */ 41 return (a == b) || /* same instance or... */
42 ((len == b->len) && /* equal length and ... */ 42 ((len == b->u.lnglen) && /* equal length and ... */
43 (memcmp(getstr(a), getstr(b), len) == 0)); /* equal contents */ 43 (memcmp(getstr(a), getstr(b), len) == 0)); /* equal contents */
44} 44}
45 45
@@ -69,9 +69,9 @@ void luaS_resize (lua_State *L, int newsize) {
69 TString *p = tb->hash[i]; 69 TString *p = tb->hash[i];
70 tb->hash[i] = NULL; 70 tb->hash[i] = NULL;
71 while (p) { /* for each node in the list */ 71 while (p) { /* for each node in the list */
72 TString *hnext = p->hnext; /* save next */ 72 TString *hnext = p->u.hnext; /* save next */
73 unsigned int h = lmod(p->hash, newsize); /* new position */ 73 unsigned int h = lmod(p->hash, newsize); /* new position */
74 p->hnext = tb->hash[h]; /* chain it */ 74 p->u.hnext = tb->hash[h]; /* chain it */
75 tb->hash[h] = p; 75 tb->hash[h] = p;
76 p = hnext; 76 p = hnext;
77 } 77 }
@@ -97,7 +97,6 @@ static TString *createstrobj (lua_State *L, const char *str, size_t l,
97 totalsize = sizelstring(l); 97 totalsize = sizelstring(l);
98 o = luaC_newobj(L, tag, totalsize); 98 o = luaC_newobj(L, tag, totalsize);
99 ts = gco2ts(o); 99 ts = gco2ts(o);
100 ts->len = l;
101 ts->hash = h; 100 ts->hash = h;
102 ts->extra = 0; 101 ts->extra = 0;
103 memcpy(getaddrstr(ts), str, l * sizeof(char)); 102 memcpy(getaddrstr(ts), str, l * sizeof(char));
@@ -110,8 +109,8 @@ void luaS_remove (lua_State *L, TString *ts) {
110 stringtable *tb = &G(L)->strt; 109 stringtable *tb = &G(L)->strt;
111 TString **p = &tb->hash[lmod(ts->hash, tb->size)]; 110 TString **p = &tb->hash[lmod(ts->hash, tb->size)];
112 while (*p != ts) /* find previous element */ 111 while (*p != ts) /* find previous element */
113 p = &(*p)->hnext; 112 p = &(*p)->u.hnext;
114 *p = (*p)->hnext; /* remove element from its list */ 113 *p = (*p)->u.hnext; /* remove element from its list */
115 tb->nuse--; 114 tb->nuse--;
116} 115}
117 116
@@ -124,8 +123,8 @@ static TString *internshrstr (lua_State *L, const char *str, size_t l) {
124 global_State *g = G(L); 123 global_State *g = G(L);
125 unsigned int h = luaS_hash(str, l, g->seed); 124 unsigned int h = luaS_hash(str, l, g->seed);
126 TString **list = &g->strt.hash[lmod(h, g->strt.size)]; 125 TString **list = &g->strt.hash[lmod(h, g->strt.size)];
127 for (ts = *list; ts != NULL; ts = ts->hnext) { 126 for (ts = *list; ts != NULL; ts = ts->u.hnext) {
128 if (l == ts->len && 127 if (l == ts->shrlen &&
129 (memcmp(str, getstr(ts), l * sizeof(char)) == 0)) { 128 (memcmp(str, getstr(ts), l * sizeof(char)) == 0)) {
130 /* found! */ 129 /* found! */
131 if (isdead(g, ts)) /* dead (but not collected yet)? */ 130 if (isdead(g, ts)) /* dead (but not collected yet)? */
@@ -138,7 +137,8 @@ static TString *internshrstr (lua_State *L, const char *str, size_t l) {
138 list = &g->strt.hash[lmod(h, g->strt.size)]; /* recompute with new size */ 137 list = &g->strt.hash[lmod(h, g->strt.size)]; /* recompute with new size */
139 } 138 }
140 ts = createstrobj(L, str, l, LUA_TSHRSTR, h); 139 ts = createstrobj(L, str, l, LUA_TSHRSTR, h);
141 ts->hnext = *list; 140 ts->shrlen = cast_byte(l);
141 ts->u.hnext = *list;
142 *list = ts; 142 *list = ts;
143 g->strt.nuse++; 143 g->strt.nuse++;
144 return ts; 144 return ts;
@@ -152,9 +152,12 @@ TString *luaS_newlstr (lua_State *L, const char *str, size_t l) {
152 if (l <= LUAI_MAXSHORTLEN) /* short string? */ 152 if (l <= LUAI_MAXSHORTLEN) /* short string? */
153 return internshrstr(L, str, l); 153 return internshrstr(L, str, l);
154 else { 154 else {
155 TString *ts;
155 if (l + 1 > (MAX_SIZE - sizeof(TString))/sizeof(char)) 156 if (l + 1 > (MAX_SIZE - sizeof(TString))/sizeof(char))
156 luaM_toobig(L); 157 luaM_toobig(L);
157 return createstrobj(L, str, l, LUA_TLNGSTR, G(L)->seed); 158 ts = createstrobj(L, str, l, LUA_TLNGSTR, G(L)->seed);
159 ts->u.lnglen = l;
160 return ts;
158 } 161 }
159} 162}
160 163