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rewrite MersenneTwister.Random to support negative numbers and generally be more robust

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This commit is contained in:
Mark Cannon
2011-08-22 20:49:50 -07:00
parent e8d3af2485
commit ed86859798
1 changed files with 34 additions and 22 deletions
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src/RageUtil.cpp
+34 -22
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@@ -106,30 +106,42 @@ namespace
static int Random( lua_State *L ) static int Random( lua_State *L )
{ {
int min = 0, max = 0; switch( lua_gettop(L) )
{
/* [0..1) */
case 0:
{
/* we get values in [0..(2^32-1)]; divide by 2^32. */
/* XXX: get rid of long long to double conversion */
double r = double(g_LuaPRNG()) / double(0x100000000llu);
lua_pushnumber( L, r );
return 1;
}
/* [m..n] */ /* [1..u] */
if( lua_isnumber(L, 2) ) case 1:
{ {
min = IArg(1); int upper = IArg(1);
max = IArg(2); luaL_argcheck( L, 1 <= upper, 1, "interval is empty" );
lua_pushnumber( L, (g_LuaPRNG() % (max-min+1)) + min ); lua_pushnumber( L, g_LuaPRNG(upper) + 1 );
} return 1;
/* [1..m] */ }
else if( lua_isnumber(L, 1) ) /* [l..u] */
{ case 2:
max = IArg(1); {
lua_pushnumber( L, (g_LuaPRNG() % max) + 1 ); int lower = IArg(1);
} int upper = IArg(2);
else luaL_argcheck( L, lower < upper, 2, "interval is empty" );
/* [0..1) */ lua_pushnumber( L, (int(g_LuaPRNG()) % (upper-lower+1)) + lower );
{ return 1;
/* we get values in [0..(2^32-1)]; divide by 2^32. */ }
double rand = double(g_LuaPRNG()) / double(0x100000000llu);
lua_pushnumber( L, rand );
}
return 1; /* wrong amount of arguments */
default:
{
return luaL_error( L, "wrong number of arguments" );
}
}
} }
const luaL_Reg MersenneTwisterTable[] = const luaL_Reg MersenneTwisterTable[] =