r5sdk/r5dev/mathlib/halton.cpp

//========= Copyright <20> 1996-2005, Valve Corporation, All rights reserved. ============//
//
// Purpose: 
//
//=====================================================================================//

#include "core/stdafx.h"
#include "mathlib/halton.h"

// NOTE: This has to be the last file included!
//#include "tier0/memdbgon.h"


HaltonSequenceGenerator_t::HaltonSequenceGenerator_t(int b)
{
	base = b;
	fbase = (float)b;
	seed = 1;

}

float HaltonSequenceGenerator_t::GetElement(int /*elem*/)
{
	int tmpseed = seed;
	float ret = 0.0f;
	float base_inv = 1.0f / fbase;
	while (tmpseed)
	{
		int dig = tmpseed % base;
		ret += ((float)dig) * base_inv;
		base_inv /= fbase;
		tmpseed /= base;
	}
	return ret;
}


int InsideOut(int nTotal, int nCounter)
{
	int b = 0;
	for (int m = nTotal, k = 1; k < nTotal; k <<= 1)
	{
		if (nCounter << 1 >= m)
		{
			b += k;
			nCounter -= (m + 1) >> 1;
			m >>= 1;
		}
		else
		{
			m = (m + 1) >> 1;
		}
	}
	Assert((b >= 0) && (b < nTotal));
	return b;
}