scale_integer.hpp

#ifndef PASTELSYS_SCALE_INTEGER_HPP
#define PASTELSYS_SCALE_INTEGER_HPP

#include "pastel/sys/integer/scale_integer.h"

namespace Pastel
{

    template <
        int FromBits, 
        int ToBits, 
        typename Integer,
        RequiresC<(ToBits < FromBits)>>
    Integer scaleInteger(const Integer& number)
    {
        PASTEL_STATIC_ASSERT(FromBits > 0);
        PASTEL_STATIC_ASSERT(ToBits > 0);

        static constexpr int DeltaBits = FromBits - ToBits;
        PASTEL_STATIC_ASSERT(DeltaBits >= 0);

        return (number >> DeltaBits);
    }

    template <
        int FromBits, 
        int ToBits, 
        typename Integer,
        RequiresC<(ToBits == FromBits)>>
    Integer scaleInteger(const Integer& number)
    {
        return number;
    }

    template <
        int FromBits, 
        int ToBits, 
        typename Integer,
        RequiresC<(ToBits > FromBits && ToBits <= 2 * FromBits)>>
    Integer scaleInteger(const Integer& number)
    {
        PASTEL_STATIC_ASSERT(FromBits > 0);
        PASTEL_STATIC_ASSERT(ToBits > 0);

        static constexpr int DeltaBits = ToBits - FromBits;
        PASTEL_STATIC_ASSERT(DeltaBits >= 0);

        return (number << DeltaBits) +
            (number >> (FromBits - DeltaBits));
    }

    template <
        int FromBits, 
        int ToBits, 
        typename Integer,
        RequiresC<(ToBits > 2 * FromBits && ToBits <= 3 * FromBits)>>
    Integer scaleInteger(const Integer& number)
    {
        PASTEL_STATIC_ASSERT(FromBits > 0);
        PASTEL_STATIC_ASSERT(ToBits > 0);

        static constexpr int DeltaBits = ToBits - FromBits;
        PASTEL_STATIC_ASSERT(DeltaBits >= 0);

        return (number << DeltaBits) +
            (number << (DeltaBits - FromBits)) +
            (number >> (2 * FromBits - DeltaBits));
    }

    template <
        int FromBits, 
        int ToBits, 
        typename Integer,
        RequiresC<(ToBits > 3 * FromBits && ToBits <= 4 * FromBits)>>
    Integer scaleInteger(const Integer& number)
    {
        PASTEL_STATIC_ASSERT(FromBits > 0);
        PASTEL_STATIC_ASSERT(ToBits > 0);

        static constexpr int DeltaBits = ToBits - FromBits;
        PASTEL_STATIC_ASSERT(DeltaBits >= 0);

        return (number << DeltaBits) +
            (number << (DeltaBits - FromBits)) +
            (number << (DeltaBits - 2 * FromBits)) +
            (number >> (3 * FromBits - DeltaBits));
    }

}

#endif