rounding.hpp

#ifndef PASTELSYS_ROUNDING_HPP
#define PASTELSYS_ROUNDING_HPP

#include "pastel/sys/math/rounding.h"
#include "pastel/sys/math/mod.h"
#include "pastel/sys/ensure.h"
#include "pastel/sys/math/number_tests.h"
#include "pastel/sys/math/powers.h"

namespace Pastel
{

    template <Integer_Concept Integer>
    Integer roundUpTo(
        const Integer& that, const Integer& to)
    {
        PENSURE(!negative(to));

        Integer remainder = mod(that, to);
        if (positive(remainder))
        {
            return (that - remainder) + to;
        }

        return that;
    }

    template <Integer_Concept Integer>
    Integer roundUpToOdd(const Integer& that)
    {
        return odd(that) ? that : (that + 1);
    }

    template <std::floating_point Real>
    integer roundUpToOdd(const Real& that)
    {
        return Pastel::roundUpToOdd((integer)ceil(that));
    }

    template <Integer_Concept Integer>
    Integer roundUpToEven(const Integer& that)
    {
        return even(that) ? that : (that + 1);
    }

    template <std::floating_point Real>
    integer roundUpToEven(const Real& that)
    {
        return Pastel::roundUpToEven((integer)ceil(that));
    }

    template <std::unsigned_integral Integer>
    Integer roundUpToPowerOfTwo(const Integer& that)
    {
        if (zero(that))
        {
            return 1;
        }

        Integer X = that - 1;
        for (integer i = 1; i < SizeInBits<Integer>::value;i <<= 1)
        {
            X |= X >> i;
        }

        return X + 1;
    }

    template <std::signed_integral Integer>
    Integer roundUpToPowerOfTwo(const Integer& that)
    {
        return twosComplementToSigned(
            roundUpToPowerOfTwo(signedToTwosComplement(that)));
    }

    template <Integer_Concept Integer>
    Integer roundUpToPowerOfTwo(
        const Integer& that, 
        integer power)
    {
        PENSURE(!negative(power));

        Integer remainder = modPowerOfTwo(that, power);
        if (positive(remainder))
        {
            return (that - remainder) + powerOfTwo<Integer>(power);
        }

        return that;
    }

}

#endif