// ==========================================================================
//                 SeqAn - The Library for Sequence Analysis
// ==========================================================================
// Copyright (c) 2006-2024, Knut Reinert, FU Berlin
// Copyright (c) 2013 NVIDIA Corporation
// All rights reserved.
//
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// modification, are permitted provided that the following conditions are met:
//
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//       notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above copyright
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//     * Neither the name of Knut Reinert or the FU Berlin nor the names of
//       its contributors may be used to endorse or promote products derived
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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// OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
// DAMAGE.
//
// ==========================================================================
// Author: Manuel Holtgrewe <manuel.holtgrewe@fu-berlin.de>
// ==========================================================================
// Mathematical Metafunctions.
// ==========================================================================

#ifndef SEQAN_INCLUDE_SEQAN_BASIC_METAPROGRAMMING_MATH_H_
#define SEQAN_INCLUDE_SEQAN_BASIC_METAPROGRAMMING_MATH_H_

#include <seqan/platform.h>

namespace seqan2 {

// ============================================================================
// Forwards
// ============================================================================

// ============================================================================
// Tags, Classes, Enums
// ============================================================================

template <int VALUE>
struct ConstInt {};

template <unsigned int VALUE>
struct ConstUInt {};

// ============================================================================
// Metafunctions
// ============================================================================

/*!
 * @defgroup MetaprogrammingMath Metaprogramming Math
 * @brief Metafunctions for mathematical computations.
 */

// ----------------------------------------------------------------------------
// Metafunction Log2
// ----------------------------------------------------------------------------

/*!
 * @mfn MetaprogrammingMath#Log2
 * @brief Compute ceiled logarithm to base 2 using metaprogramming.
 *
 * @signature uint64_t Log2<NUMERUS>::VALUE;
 *
 * @tparam NUMERUS <tt>int64_t</tt> value to use for the numerus.
 *
 * @return uint64_t <tt>ceil(log2(NUMERUS))</tt>
 *
 * @section Example
 *
 * @snippet demos/dox/basic/metaprogramming_math.cpp log2 call
 */

template <uint64_t numerus, uint64_t base>
struct LogN
{
    static const uint64_t VALUE = LogN<(numerus + 1) / base, base>::VALUE + 1; // ceil(log(numerus) / log(base))
};

template <uint64_t numerus>
struct Log2: LogN<numerus, 2> {};

// Base cases.
template <uint64_t base> struct LogN<1, base> { static const uint64_t VALUE = 0; };
template <uint64_t base> struct LogN<0, base> { static const uint64_t VALUE = 0; };

// ----------------------------------------------------------------------------
// Metafunction Log2Floor
// ----------------------------------------------------------------------------

/*!
 * @mfn MetaprogrammingMath#Log2Floor
 * @brief Compute floored logarithm to base 2 using metaprogramming.
 *
 * @signature uint64_t Log2Floor<NUMERUS>::VALUE;
 *
 * @tparam NUMERUS <tt>int64_t</tt> value to use for the numerus.
 *
 * @return uint64_t <tt>floor(log2(NUMERUS))</tt>
 *
 * @section Example
 *
 * @snippet demos/dox/basic/metaprogramming_math.cpp log2floor call
 */

template <uint64_t numerus, uint64_t base>
struct LogNFloor
{
    static const uint64_t VALUE = LogNFloor<numerus / base, base>::VALUE + 1; // floor(log(numerus) / log(base))
};

template <uint64_t numerus>
struct Log2Floor: LogNFloor<numerus, 2> {};

// Base cases.
template <uint64_t base> struct LogNFloor<1, base> { static const uint64_t VALUE = 0; };
template <uint64_t base> struct LogNFloor<0, base> { static const uint64_t VALUE = 0; };

// ----------------------------------------------------------------------------
// Metafunction Power
// ----------------------------------------------------------------------------

/*!
 * @mfn MetaprogrammingMath#Power
 * @brief Compute power of a number.
 *
 * @signature uint64_t Power<BASE, EXPONENT>::VALUE;
 *
 * @tparam BASE     The base of the term (<tt>int64_t</tt>).
 * @tparam EXPONENT The exponent of the term (<tt>int64_t</tt>).
 *
 * @return uint64_t BASE<sup>EXPONENT</sup>
 *
 * @snippet demos/dox/basic/metaprogramming_math.cpp power call
 */

template <int64_t base, int64_t exponent>
struct Power {
    static const uint64_t VALUE =
            Power<base, exponent / 2>::VALUE *
            Power<base, exponent - (exponent / 2)>::VALUE;
};

// Base cases.
template <int64_t base> struct Power<base, 1> { static const uint64_t VALUE = base; };
template <int64_t base> struct Power<base, 0> { static const uint64_t VALUE = 1; };

// ----------------------------------------------------------------------------
// Metafunction Min
// ----------------------------------------------------------------------------

template <unsigned A, unsigned B>
struct Min
{
    static const unsigned VALUE = (A <= B) ? A : B;
};

// ----------------------------------------------------------------------------
// Metafunction Max
// ----------------------------------------------------------------------------

template <unsigned A, unsigned B>
struct Max
{
    static const unsigned VALUE = (A >= B) ? A : B;
};

// ============================================================================
// Functions
// ============================================================================

}  // namespace seqan2

#endif  // #ifndef SEQAN_INCLUDE_SEQAN_BASIC_METAPROGRAMMING_MATH_H_
