nlua_rnd.c

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/*
 * See Licensing and Copyright notice in naev.h
 */
#include <lauxlib.h>
 
#include "naev.h"
#include "nlua_rnd.h"
 
#include "log.h"
#include "map.h"
#include "ndata.h"
#include "nluadef.h"
#include "rng.h"
 
/* Random methods. */
static int rndL_int( lua_State *L );
static int rndL_sigma( lua_State *L );
static int rndL_twosigma( lua_State *L );
static int rndL_threesigma( lua_State *L );
static int rndL_uniform( lua_State *L );
static int rndL_angle( lua_State *L );
static int rndL_permutation( lua_State *L );
static const luaL_Reg rnd_methods[] = {
   { "rnd", rndL_int },
   { "sigma", rndL_sigma },
   { "twosigma", rndL_twosigma },
   { "threesigma", rndL_threesigma },
   { "uniform", rndL_uniform },
   { "angle", rndL_angle },
   { "permutation", rndL_permutation },
   {0,0}
}; 
int nlua_loadRnd( nlua_env env )
{
   nlua_register(env, "rnd", rnd_methods, 0);
   return 0;
}
 
static int rndL_int( lua_State *L )
{
   int l,h;
   int o = lua_gettop(L);
 
   if (o==0)
      lua_pushnumber(L, RNGF() ); /* random double 0 <= x <= 1 */
   else if (o==1) { /* random int 0 <= x <= parameter */
      l = luaL_checkint(L,1);
      lua_pushnumber(L, RNG(0, l));
   }
   else if (o>=2) { /* random int parameter 1 <= x <= parameter 2 */
      l = luaL_checkint(L,1);
      h = luaL_checkint(L,2);
      lua_pushnumber(L, RNG(l,h));
   }
   else
      NLUA_INVALID_PARAMETER(L,1);
 
   return 1; /* unless it's returned 0 already it'll always return a parameter */
}
static int rndL_sigma( lua_State *L )
{
   lua_pushnumber(L, RNG_1SIGMA());
   return 1;
}
static int rndL_twosigma( lua_State *L )
{
   lua_pushnumber(L, RNG_2SIGMA());
   return 1;
}
static int rndL_threesigma( lua_State *L )
{
   lua_pushnumber(L, RNG_3SIGMA());
   return 1;
}
 
static int rndL_uniform( lua_State *L )
{
   int o = lua_gettop( L );
 
   if (o==0)
      lua_pushnumber( L, RNGF() ); /* random double 0 <= x <= 1 */
   else if (o==1) { /* random int 0 <= x <= parameter */
      int l = luaL_checknumber( L, 1 );
      lua_pushnumber( L, RNGF() * l );
   }
   else if (o>=2) { /* random int parameter 1 <= x <= parameter 2 */
      int l = luaL_checknumber( L, 1 );
      int h = luaL_checknumber( L, 2 );
      lua_pushnumber( L, l + (h-l) * RNGF() );
   }
   else
      NLUA_INVALID_PARAMETER(L,1);
 
   return 1; /* unless it's returned 0 already it'll always return a parameter */
}
 
static int rndL_angle( lua_State *L )
{
   lua_pushnumber( L, RNGF() * 2. * M_PI );
   return 1;
}
 
static int rndL_permutation( lua_State *L )
{
   int *values;
   int max;
   int new_table;
 
   if (lua_isnumber(L,1)) {
      max = lua_tointeger(L,1);
      new_table = 1;
   }
   else if (lua_istable(L,1)) {
      max = (int) lua_objlen(L,1);
      new_table = 0;
   }
   else
      NLUA_INVALID_PARAMETER(L,1);
 
   /* Create the list. */
   values = malloc( sizeof(int)*max );
   for (int i=0; i<max; i++)
      values[i]=i;
 
   /* Fisher-Yates shuffling algorithm */
   for (int i = max-1; i >= 0; --i){
      /* Generate a random number in the range [0, max-1] */
      int j = randint() % (i+1);
 
      /* Swap the last element with an element at a random index. */
      int temp  = values[i];
      values[i] = values[j];
      values[j] = temp;
   }
 
   /* Now either return a new table or permute the given table. */
   lua_newtable(L);
   for (int i=0; i<max; i++) {
      lua_pushnumber( L, values[i]+1 );
      if (!new_table)
         lua_gettable(   L, 1 );
      lua_rawseti(   L, -2, i+1 );
   }
 
   free( values );
   return 1;
}