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/* luaload.c
*
* Kamil Kaminski
* kkaminsk.com
*
* Loading a Lua table in C
*
*
*/
#include <lua.h>
#include <lauxlib.h>
#include <lualib.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
struct platform
{
unsigned int xres_w;
unsigned int yres_w;
unsigned int bpp_w;
float fovy_w;
float znear_w;
float zfar_w;
};
const char *LuaGetFieldString(lua_State *L, const char *);
double luaGetFieldNumber(lua_State *, const char *);
int luaLoadConfig(lua_State *, const char *);
int luaFillPlatform(lua_State *, struct platform *);
void printPlatform(struct platform *);
const char *LuaGetFieldString(lua_State *L, const char *key)
{
if (!L || !key)
return NULL;
const char *ret = NULL;
/* push the key string onto stack */
lua_pushstring(L, key);
lua_gettable(L, -2);
if (!lua_isstring(L, -1))
{
fprintf(stderr, "Lua: \"%s\" field within the table is not a string\n", key);
lua_pop(L, 1);
return ret;
}
ret = lua_tostring(L, -1);
lua_pop(L, 1);
return ret;
}
double luaGetFieldNumber(lua_State *L, const char *key)
{
if (!L || !key)
return -1.0;
double ret = -1.0;
/* push the key string onto stack */
lua_pushstring(L, key);
/* remember, -1 points to top of the stack, our table should a second
* item from the top, this call effectively accesses t[key] and
* pushes that value on the stack */
lua_gettable(L, -2);
if (!lua_isnumber(L, -1))
{
fprintf(stderr, "Lua: \"%s\" field within the table is NaN\n", key);
lua_pop(L, 1);
return ret;
}
/* finally retrieve our value */
ret = lua_tonumber(L, -1);
/* value is no longer needed, pop it */
lua_pop(L, 1);
return ret;
}
int luaLoadConfig(lua_State *L, const char *fname)
{
if (!L || !fname)
return -1;
int status;
/* load the file containing the config */
/* call a function, what function? dry run the script? */
status = (luaL_loadfile(L, fname) || lua_pcall(L, 0, 0, 0));
if (status)
{
fprintf(stderr, "Lua: %s\n", lua_tostring(L, -1));
return -1;
}
return 0;
}
int luaFillPlatform(lua_State *L, struct platform *p)
{
if (!L || !p)
return -1;
double ret;
/* pushes the table on the stack */
lua_getglobal(L, "platform");
if (!lua_istable(L, -1))
{
fprintf(stderr, "Lua: failed to parse \"platform\" table\n");
lua_pop(L, 1);
return -1;
}
if ((ret = luaGetFieldNumber(L, "xres_w")) != -1.0)
p->xres_w = (unsigned int) ret;
if ((ret = luaGetFieldNumber(L, "yres_w")) != -1.0)
p->yres_w = (unsigned int) ret;
if ((ret = luaGetFieldNumber(L, "bpp_w")) != -1.0)
p->bpp_w = (unsigned int) ret;
if ((ret = luaGetFieldNumber(L, "fovy_w")) != -1.0)
p->fovy_w = (float) ret;
if ((ret = luaGetFieldNumber(L, "znear_w")) != -1.0)
p->znear_w = (float) ret;
if ((ret = luaGetFieldNumber(L, "zfar_w")) != -1.0)
p->zfar_w = (float) ret;
/* pop the table */
lua_pop(L, 1);
return 0;
}
void printPlatform(struct platform *p)
{
if (!p)
return;
printf("xres_w : %u\n"
"yres_w : %u\n"
"bpp_w : %u\n"
"fovy_w : %f\n"
"znear_w: %f\n"
"zfar_w : %f",
p->xres_w, p->yres_w, p->bpp_w, p->fovy_w,
p->znear_w, p->zfar_w);
puts("");
}
int main(int argc, char **argv)
{
lua_State *L;
/* create new lua state */
L = luaL_newstate();
/* load lua libraries */
luaL_openlibs(L);
struct platform p;
memset(&p, 0, sizeof(p));
luaLoadConfig(L, "config.lua");
luaFillPlatform(L, &p);
printPlatform(&p);
lua_close(L);
return 0;
}
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