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authorWilliam Wilgus <me.theuser@yahoo.com>2018-11-17 02:44:30 -0500
committerWilliam Wilgus <me.theuser@yahoo.com>2019-07-11 00:09:54 -0500
commita332924f68e1237ec69af84ef10362fd9b4623c3 (patch)
tree5ae8ad47430b1befb87d259c636b3789f558350b
parentc6fcb1cf45b249b059c2d53a062f9a6c7f449047 (diff)
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lua late bound cfunction tables
We have quite a bit of ram tied up in lua with our c libraries I was searching for a way to free up some of this when I came across read only tables in e-lua but that involved a lot of patching through the source Instead I came up with this.. it frees about 15k ram without much slowdown in code execution since after a function gets called it is automatically added to the table If you have a performance issue you can call the bind method to bind a specific function or the whole table in one shot for instance rb table rb("lcd_clear") -- binds/returns function rb.lcd_clear() rb(nil) -- binds every function in rb table + removes latebind metatable .. -- added pairs and ipairs code from lua 5.2 -- cleaned up code + made more seamless existing fields are now saved rather than overwritten when table is bound Change-Id: I1c20e76b736c032dedc727d2e58928641e40191d
-rw-r--r--apps/plugins/lua/lauxlib.c132
1 files changed, 132 insertions, 0 deletions
diff --git a/apps/plugins/lua/lauxlib.c b/apps/plugins/lua/lauxlib.c
index 5e7c15931d..2e4b3b1e3c 100644
--- a/apps/plugins/lua/lauxlib.c
+++ b/apps/plugins/lua/lauxlib.c
@@ -254,10 +254,142 @@ static int libsize_storenames (lua_State *L, const char* libname, const luaL_Reg
}
+#if 0
LUALIB_API void (luaL_register) (lua_State *L, const char *libname,
const luaL_Reg *l) {
luaI_openlib(L, libname, l, 0);
}
+#else /* late bind cfunction tables to save ram */
+static int latebind_func_index(lua_State *L)
+{
+ const luaL_Reg *llib;
+ /* name @ top of stack 1(basetable;name)-1*/
+ const char *name = lua_tostring(L, -1);
+
+ lua_pushstring (L, "__latebind");/* basetable;name;__latebind;*/
+ lua_rawget (L, -3);/* basetable;name;__latebind(t);*/
+
+ luaL_argcheck(L, lua_istable(L, -3) && lua_istable(L, -1), 1,
+ "__latebind table expected");
+ /* (btable;name;__latebind(t)) */
+
+ /* lookup late bound func(s), lua_objlen allows check of multiple luaL_Reg */
+ for(int i = lua_objlen(L, -1); i > 0; i--) {
+ lua_rawgeti (L, -1, i);/* btable;name;__lb(t);llib*/
+ llib = (const luaL_Reg *) lua_touserdata (L, -1);
+ lua_pop(L, 1); /* (btable;name;__lb(t);llib) -> (btable;name;__lb(t)) */
+
+ if(!llib)
+ continue;
+
+ for (; llib->name; llib++) {
+ if(!name || strcmp(name, llib->name) == 0) {
+ /* don't overwrite existing keys within basetable */
+ lua_pushstring(L, llib->name); /* (btable;name;__lb(t);llib->name) */
+ lua_rawget(L, -4); /* (btable;name;__lb(t);btable[func]?) */
+
+ if(lua_isnil(L, -1)) {
+ /* if function is used it is added to the base table */
+ lua_pop(L, 1);
+ lua_pushcclosure(L, llib->func, 0); /* (btable;name;__lb(t);llib->func) */
+ }
+
+ if(!name) /* nil name binds all functions in table immediately */
+ lua_setfield(L, -4, llib->name); /* (btable;name;mtable) */
+ else {
+ lua_pushvalue(L, -1); /* dupe closure or existing func */
+ /* (btable;name;__lb(t);llib->func;llib->func) */
+ lua_setfield(L, -5, llib->name); /* (btable;name;__lb(t);llib->func) */
+ /* returns the closure */
+ return 1;
+ }
+ }
+ }
+ }
+
+ lua_pop(L, 2); /* (btable;name;__lb(t)) -> (btable) */
+ if(!name) {
+ lua_pushnil(L); /* remove metatable (btable;name;__lb(t);nil)*/
+ lua_setmetatable(L, -2);
+ lua_pushnil(L); /* remove __latebind table*/
+ lua_setfield (L, -2, "__latebind");
+ }
+
+ return 0;
+}
+
+
+static int latebind_func_pairs(lua_State *L)
+{
+ /* basetable @ top of stack 1(basetable)-1 */
+ luaL_argcheck(L, lua_istable(L, 1), 1, "table expected");
+ lua_getglobal(L, "pairs"); /* function to be called / returned (btable;pairs) */
+
+ lua_createtable(L, 0, 15); /* btable;pairs;newtable; */
+ /* clone base table */
+ lua_pushnil(L); /* first key */
+ while(lua_next(L, 1) != 0) {
+ /* (btable;pairs;ntable;k;v) */
+ lua_pushvalue(L, -2); /* dupe key Stk = (..;k;v -> ..k;v;k)*/
+ lua_insert(L, -2); /* Stk = (..k;k;v) */
+ lua_rawset(L, 3); /* btable;pairs;ntable;k */
+ }
+
+ lua_pushnil(L); /*nil name retrieves all unbound late bound functions */
+ latebind_func_index(L);/* (btable;pairs;ntable;nil) -> (btable;pairs;ntable) */
+
+ /* (btable;pairs;ntable) */
+ lua_call(L, 1, 3); /* pairs(ntable) -> (btable;iter;state;value) */
+
+ return 3;
+}
+
+
+LUALIB_API void (luaL_register) (lua_State *L, const char *libname,
+ const luaL_Reg *l) {
+ if(!libname)
+ {
+ /* if there is no libname register normally */
+ luaI_openlib(L, libname, l, 0);
+ return;
+ }
+
+ /* store empty table instead of passed luaL_Reg table */
+ static const struct luaL_reg late_lib [] =
+ {
+ {NULL, NULL}
+ };
+
+ static const struct luaL_reg late_meta [] =
+ {
+ {"__index", latebind_func_index},
+ {"__pairs", latebind_func_pairs},
+ {"__call", latebind_func_index}, /* allows t("func") -- nil binds all */
+ {NULL, NULL}
+ };
+
+ libsize_storenames(L, libname, l); /* store func names */
+ luaI_openlib(L, libname, late_lib, 0); /* basetable; */
+
+ luaL_findtable(L, -1,"__latebind", 0); /* create table if doesn't exist */
+ /* basetable;__latebind(t); */
+ /* save pointer to real luaL_reg */
+ lua_pushlightuserdata (L, (void *) l); /*basetable;__lb(t);userdata;*/
+ lua_rawseti(L, -2, lua_objlen(L, -2) + 1); /*lb(t)[n] = userdata */
+
+ lua_pop(L, 1);/* (basetable;__latebind(t)) -> (basetable) */
+
+ if(luaL_newmetatable(L, "META_LATEBIND"))
+ {
+ luaI_openlib(L, NULL, late_meta, 0); /*basetable;metatable*/
+ lua_pushvalue(L, -1); /* dupe the metatable (basetable;mt;mt) */
+ lua_setfield (L, -2, "__metatable"); /* metatable[__metatable] = metatable */
+ }
+
+ lua_setmetatable(L, -2); /* (basetable;mt) -> (basetable+mtable) */
+ /* base table is top of stack (basetable) */
+}
+#endif
#if 0
static int libsize (const luaL_Reg *l) {