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62 lines (57 loc) · 1.37 KB
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/// A sample C extension.
// Demonstrates using ldoc's C/C++ support. Can either use /// or /*** */ etc.
// @module mylib
#include <string.h>
#include <math.h>
// includes for Lua
#include <lua.h>
#include <lauxlib.h>
#include <lualib.h>
/***
Create a table with given array and hash slots.
@function createtable
@param narr initial array slots, default 0
@param nrec initial hash slots, default 0
*/
static int l_createtable (lua_State *L) {
int narr = luaL_optint(L,1,0);
int nrec = luaL_optint(L,2,0);
lua_createtable(L,narr,nrec);
return 1;
}
/***
Solve a quadratic equation.
@function solve
@param a coefficient of x^2
@param b coefficient of x
@param c constant
@return first root
@return second root
*/
static int l_solve (lua_State *L) {
double a = lua_tonumber(L,1); // coeff of x*x
double b = lua_tonumber(L,2); // coef of x
double c = lua_tonumber(L,3); // constant
double abc = b*b - 4*a*c;
if (abc < 0.0) {
lua_pushnil(L);
lua_pushstring(L,"imaginary roots!");
return 2;
} else {
abc = sqrt(abc);
a = 2*a;
lua_pushnumber(L,(-b + abc)/a);
lua_pushnumber(L,(+b - abc)/a);
return 2;
}
}
static const luaL_reg mylib[] = {
{"createtable",l_createtable},
{"solve",l_solve},
{NULL,NULL}
};
int luaopen_mylib(lua_State *L)
{
luaL_register (L, "mylib", mylib);
return 1;
}