// -*- mode: C++; indent-tabs-mode: nil; c-basic-offset: 4 -*-

/*
 * Utilities and data structures for bit-level manipulation and data packing.
 */

/*
 * (c) 2013-2014 Jiří Weiser <xweiser1@fi.muni.cz>
 * (c) 2013 Petr Ročkai <me@mornfall.net>
 * (c) 2015 Vladimír Štill <xstill@fi.muni.cz>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include "brick-assert"

#include <type_traits>
#include <limits>

#ifdef __linux
#include <asm/byteorder.h>
#include <byteswap.h>
#elif !defined LITTLE_ENDIAN // if defined _WIN32
#define BYTE_ORDER 1234
#define LITTLE_ENDIAN 1234
#endif

#include <atomic>
#include <cstring>

#ifndef BRICK_BITLEVEL_H
#define BRICK_BITLEVEL_H

namespace brick {
namespace bitlevel {

template< typename T1, typename T2 >
constexpr inline T1 align( T1 v, T2 a ) {
    return (v % T1(a)) ? (v + T1(a) - (v % T1(a))) : v;
}

template< typename T1, typename T2 >
constexpr inline T1 downalign( T1 v, T2 a ) {
    return v - (v % T1(a));
}

namespace compiletime {

template< typename T >
constexpr unsigned MSB( T x ) {
    return x > 1 ? 1 + MSB( x >> 1 ) : 0;
}

template< typename T >
constexpr T fill( T x ) {
    return x ? x | compiletime::fill( x >> 1 ) : x;
}

template< typename T >
constexpr size_t sizeOf() {
    return std::is_empty< T >::value ? 0 : sizeof( T );
}

template< typename T >
constexpr T ones( int bits )
{
    return bits ? ( T(1) << ( bits - 1 ) ) | compiletime::ones< T >( bits - 1 ) : 0;
}

}

using compiletime::ones;

template< typename L, typename H >
struct bvpair
{
    L low; H high;
    constexpr bvpair( L l, H h = 0 ) : low( l ), high( h ) {}
    constexpr bvpair() = default;
    explicit constexpr operator bool() const { return low || high; }
#if ((__GNUC__ >= 4 && __GNUC_MINOR__ > 9) || (__clang_major__ == 3 && __clang_minor__ >= 6))
    constexpr
#endif
    bvpair operator<<( int s ) const
    {
        int rem = 8 * sizeof( low ) - s;
        int unshift = std::max( rem, 0 );
        int shift = rem < 0 ? -rem : 0;
        H carry = ( low & ~ones< L >( unshift ) ) >> unshift;
        return bvpair( low << s, ( high << s ) | ( carry << shift ) );
    }
#if ((__GNUC__ >= 4 && __GNUC_MINOR__ > 9) || (__clang_major__ == 3 && __clang_minor__ >= 6))
    constexpr
#endif
    bvpair operator>>( int s ) const
    {
        int rem = 8 * sizeof( low ) - s;
        int unshift = std::max( rem, 0 );
        int shift = rem < 0 ? -rem : 0;
        L carry = L( high & ones< H >( s ) ) << unshift;
        return bvpair( ( low >> s ) | ( carry >> shift ), high >> s );
    }
    constexpr bvpair operator&( bvpair o ) const { return bvpair( o.low & low, o.high & high ); }
    constexpr bvpair operator|( bvpair o ) const { return bvpair( o.low | low, o.high | high ); }
    bvpair &operator|=( bvpair o ) { return *this = *this | o; }
    constexpr bool operator==( bvpair o ) const { return o.low == low && o.high == high; }
    constexpr bool operator!=( bvpair o ) const { return o.low != low || o.high != high; }
    constexpr bvpair operator+() const { return *this; }
    friend std::ostream &operator<<( std::ostream &o, bvpair p ) {
        return o << p.high << "_" << p.low; }
} __attribute__((packed));

template< int i > struct _bitvec { using T = typename _bitvec< i + 1 >::T; };
template<> struct _bitvec<   8 > { using T = uint8_t; };
template<> struct _bitvec<  16 > { using T = uint16_t; };
template<> struct _bitvec<  32 > { using T = uint32_t; };
template<> struct _bitvec<  64 > { using T = uint64_t; };
template<> struct _bitvec<  80 > { using T = bvpair< uint64_t, uint16_t >; };
template<> struct _bitvec< 128 > { using T = bvpair< uint64_t, uint64_t >; };

template< int i > using bitvec = typename _bitvec< i >::T;

namespace {

uint32_t mixdown( uint64_t i ) /* due to Thomas Wang */
{
    i = (~i) + (i << 18);
    i =   i  ^ (i >> 31);
    i =   i  * 21;
    i =   i  ^ (i >> 11);
    i =   i  + (i << 6);
    i =   i  ^ (i >> 22);
    return i;
}

__attribute__((unused)) uint32_t mixdown( uint32_t a, uint32_t b )
{
    return mixdown( ( uint64_t( a ) << 32 ) | uint64_t( b ) );
}

}

/*
 *  Fills `x` by bits up to the most si significant bit.
 *  Comlexity is O(log n), n is sizeof(x)*8
 */
template< typename number >
static inline number fill( number x ) {
    static const unsigned m = sizeof( number ) * 8;
    unsigned r = 1;
    if ( !x )
        return 0;
    while ( m != r ) {
        x |= x >> r;
        r <<= 1;
    }
    return x;
}

// get index of Most Significant Bit
// templated by argument to int, long, long long (all unsigned)
template< typename T >
static inline unsigned MSB( T x ) {
    unsigned position = 0;
    while ( x ) {
        x >>= 1;
        ++position;
    }
    return position - 1;
}

template<>
inline unsigned MSB< unsigned int >( unsigned int x ) {
    static const unsigned long bits = sizeof( unsigned int ) * 8 - 1;
    return bits - __builtin_clz( x );
}

template<>
inline unsigned MSB< unsigned long >( unsigned long x ) {
    static const unsigned bits = sizeof( unsigned long ) * 8 - 1;
    return bits - __builtin_clzl( x );
}

template<>
inline unsigned MSB< unsigned long long >( unsigned long long x ) {
    static const unsigned bits = sizeof( unsigned long long ) * 8 - 1;
    return bits - __builtin_clzll( x );
}

// gets only Most Significant Bit
template< typename number >
static inline number onlyMSB( number x ) {
    return number(1) << MSB( x );
}

// gets number without Most Significant Bit
template< typename number >
static inline number withoutMSB( number x ) {
    return x & ~onlyMSB( x );
}

inline constexpr uint64_t bitshift( uint64_t t, int shift ) {
    return shift < 0 ? ( t << -shift ) : ( t >> shift );
}

inline constexpr uint64_t mask( int first, int count ) {
    return (uint64_t(-1) << first) & (uint64_t(-1) >> (64 - first - count));
}

struct BitPointer {
    using Storage = uint32_t;
    static constexpr int storageBits = sizeof( Storage ) * 8;

    BitPointer() : base( nullptr ), _bitoffset( 0 ) {}
    template< typename T > BitPointer( T *t, int offset = 0 )
        : base( static_cast< void * >( t ) ), _bitoffset( offset )
    {
        normalize();
    }

    template< typename T >
    T &ref() { ASSERT( valid() ); return *static_cast< T * >( base ); }
    uint32_t &word() { return ref< uint32_t >(); }
    uint64_t &dword() { return ref< uint64_t >(); }

    // unsafe version does not cross word boundary
    uint32_t getUnsafe( int bits ) { return _get< uint32_t >( bits ); }
    uint32_t get( int bits ) {
        return bits + _bitoffset <= 32 ? _get< uint32_t >( bits ) : _get< uint64_t >( bits );
    }

    void setUnsafe( uint32_t val, int bits ) { return _set< uint32_t >( val, bits ); }
    void set( uint32_t val, int bits ) {
        return bits + _bitoffset <= 32 ? _set< uint32_t >( val, bits ) : _set< uint64_t >( val, bits );
    }

    void normalize() {
        int shift = downalign( _bitoffset, storageBits );
        _bitoffset -= shift;
        ASSERT_EQ( shift % 8, 0 );
        base = static_cast< Storage * >( base ) + shift / storageBits;
    }
    void shift( int bits ) { _bitoffset += bits; normalize(); }
    void fromReference( BitPointer r ) { *this = r; }
    int bitoffset() { return _bitoffset; }
    bool valid() { return base; }
private:
    void *base;
    int _bitoffset;

    template< typename T >
    uint32_t _get( int bits ) {
        static_assert( std::is_unsigned< T >::value, "T has to be unsigned numeric type" );
        ASSERT( valid() );
        ASSERT_LEQ( 0, bits );
        ASSERT_LEQ( bits, 32 );
        ASSERT_LEQ( bits + _bitoffset, int( sizeof( T ) * 8 ) );
        return (ref< T >() >> _bitoffset) & mask( 0, bits );
    }

    template< typename T >
    void _set( uint32_t val, int bits ) {
        static_assert( std::is_unsigned< T >::value, "T has to be unsigned numeric type" );
        ASSERT_EQ( val & ~mask( 0, bits ), 0u );
        ASSERT_LEQ( bits, 32 );
        ASSERT_LEQ( bits + _bitoffset, int( sizeof( T ) * 8 ) );
        ref< T >() = (ref< T >() & ~mask( _bitoffset, bits )) | (T(val) << _bitoffset);
    }
};

/*
 * NB. This function will alias whatever "to" points to with an uint64_t. With
 * aggressive optimisations, this might break code that passes an address of a
 * variable of different type. When "to" points to a stack variable, take
 * precautions to avoid breaking strict aliasing rules (the violation is not
 * detected by GCC as of 4.7.3).
 */

inline void bitcopy( BitPointer from, BitPointer to, int bitcount )
{
    while ( bitcount ) {
        if ( from.bitoffset() == 0 && to.bitoffset() == 0
                && bitcount >= BitPointer::storageBits )
        {
            const int cnt = bitcount / BitPointer::storageBits;
            std::copy( &from.word(), &from.word() + cnt, &to.word() );
            const int bitcnt = cnt * BitPointer::storageBits;
            from.shift( bitcnt );
            to.shift( bitcnt );
            bitcount -= bitcnt;
        } else {
            int w = std::min( BitPointer::storageBits - from.bitoffset(), bitcount );
            to.set( from.getUnsafe( w ), w );
            from.shift( w ); to.shift( w ); bitcount -= w; // slide
        }
    }
}

template< typename T, int width = sizeof( T ) * 8 >
struct BitField
{
    static const int bitwidth = width;
    struct Virtual : BitPointer
    {
        T set( T t ) { bitcopy( BitPointer( &t ), *this, bitwidth ); return t; }
        Virtual operator=( T t ) {
            set( t );
            return *this;
        }
        Virtual operator=( Virtual v ) {
            set( v.get() );
            return *this;
        }

        operator T() const { return get(); }
        T get() const {
            union U {
                uint64_t x;
                T t;
                U() : t() { }
            } u;
            bitcopy( *this, BitPointer( &u.x ), bitwidth );
            return u.t;
        }

        Virtual &operator++() {
            T value( get() );
            set( ++value );
            return *this;
        }
        T operator++(int) {
            T value( get() );
            T result( value++ );
            set( value );
            return result;
        }

        Virtual &operator--() {
            T value( get() );
            set( --value );
            return *this;
        }
        T operator--(int) {
            T value( get() );
            T result( value-- );
            set( value );
            return result;
        }

#define OP(__op) \
        template< typename U > \
        Virtual operator __op( U value ) { \
            T t( get() ); \
            t __op value; \
            set( t ); \
            return *this; \
        }

        OP(+=)
        OP(-=)
        OP(*=)
        OP(/=)
        OP(%=)
        OP(|=)
        OP(&=)
#undef OP
    };
};

struct BitLock
{
    static const int bitwidth = 1;
    struct Virtual : BitPointer {
        using Atomic = std::atomic< uint32_t >;
        Atomic &atomic() { return *reinterpret_cast< Atomic * >( &word() ); }
        uint32_t bit() {
            ASSERT_LEQ( bitoffset(), 31 );
            return uint32_t( 1 ) << bitoffset();
        }
        void lock() {
            uint32_t l = word();
            do { l &= ~bit(); } while ( !atomic().compare_exchange_weak( l, l | bit() ) );
        }
        void unlock() { atomic().exchange( word() & ~bit() ); }
        bool locked() { return atomic().load() & bit(); }
    };
};

template< int O, typename... Args > struct BitAccess;

template< int O >
struct BitAccess< O > { static const int total = 0; };

template< int O, typename T, typename... Args >
struct BitAccess< O, T, Args... > {
    static const int offset = O;
    static const int width = T::bitwidth;
    typedef typename T::Virtual Head;
    typedef BitAccess< offset + T::bitwidth, Args... > Tail;
    static const int total = width + Tail::total;
};

template< typename BA, int I >
struct _AccessAt : _AccessAt< typename BA::Tail, I - 1 > {};

template< typename BA >
struct _AccessAt< BA, 0 > { using T = BA; };

template< typename... Args >
struct _BitTuple
{
    using Access = BitAccess< 0, Args... >;
    static const int bitwidth = Access::total;
    template< int I > using AccessAt = _AccessAt< Access, I >;
    template< int I > static int offset() { return AccessAt< I >::T::offset; }
};

template< typename... Args > struct BitTuple : _BitTuple< Args... >
{
    struct Virtual : BitPointer, _BitTuple< Args... > {};
    char storage[ align( Virtual::bitwidth, 32 ) / 8 ];
    BitTuple() { std::fill( storage, storage + sizeof( storage ), 0 ); }
    operator BitPointer() { return BitPointer( storage ); }
    bool operator<( const BitTuple &o ) const
    {
        return std::lexicographical_compare( storage, storage + sizeof( storage ),
                                             o.storage, o.storage + sizeof( storage ) );
    }
    bool operator==( const BitTuple &o ) const
    {
        return std::equal( storage, storage + sizeof( storage ),
                           o.storage, o.storage + sizeof( storage ) );
    }
};

template< int I, typename BT >
typename BT::template AccessAt< I >::T::Head get( BT &bt )
{
    typename BT::template AccessAt< I >::T::Head t;
    t.fromReference( bt );
    t.shift( BT::template offset< I >() );
    return t;
}

}

namespace t_bitlevel {

using namespace ::brick::bitlevel;

struct BitTupleTest {
    using U10 = BitField< unsigned, 10 >;
    using T10_10 = BitTuple< U10, U10 >;

    int bitcount( uint32_t word ) {
        int i = 0;
        while ( word ) {
            if ( word & 1 )
                ++i;
            word >>= 1;
        }
        return i;
    }

    TEST(mask) {
        /* only works on little endian machines ... */
        ASSERT_EQ( 0xFF00u, bitlevel::mask( 8, 8 ) );
        ASSERT_EQ( 0xF000u, bitlevel::mask( 12, 4 ) );
        ASSERT_EQ( 0x0F00u, bitlevel::mask( 8, 4 ) );
        ASSERT_EQ( 60u, bitlevel::mask( 2, 4 ) );// 0b111100
        ASSERT_EQ( 28u, bitlevel::mask( 2, 3 ) );// 0b11100
    }

    TEST(bitcopy) {
        uint32_t a = 42, b = 11;
        bitlevel::bitcopy( BitPointer( &a ), BitPointer( &b ), 32 );
        ASSERT_EQ( a, b );
        a = 0xFF00;
        bitlevel::bitcopy( BitPointer( &a ), BitPointer( &b, 8 ), 24 );
        ASSERT_EQ( b, 0xFF0000u | 42u );
        a = 0;
        bitlevel::bitcopy( BitPointer( &b, 8 ), BitPointer( &a ), 24 );
        ASSERT_EQ( a, 0xFF00u );
        bitlevel::bitcopy( BitPointer( &a, 8 ), BitPointer( &b, 8 ), 8 );

        a = 0x3FF;
        b = 0;
        bitlevel::bitcopy( BitPointer( &a, 0 ), BitPointer( &b, 0 ), 10 );
        ASSERT_EQ( b, 0x3FFu );

        unsigned char from[32], to[32];
        std::memset( from, 0, 32 );
        std::memset( to, 0, 32 );
        from[0] = 1 << 7;
        bitlevel::bitcopy( BitPointer( from, 7 ), BitPointer( to, 7 ), 1 );
        ASSERT_EQ( int( to[0] ), int( from[ 0 ] ) );
        from[0] = 1;
        to[0] = 0;
        bitlevel::bitcopy( BitPointer( from, 0 ), BitPointer( to, 7 ), 1 );
        ASSERT_EQ( int( to[0] ), 1 << 7 );

        from[0] = 13;
        from[1] = 63;
        bitlevel::bitcopy( BitPointer( from, 0 ), BitPointer( to, 32 ), 16 );
        ASSERT_EQ( int( to[4] ), int( from[0] ) );
        ASSERT_EQ( int( to[5] ), int( from[1] ) );

        from[0] = 2;
        from[1] = 2;
        std::memset( to, 0, 32 );
        bitlevel::bitcopy( BitPointer( from, 1 ), BitPointer( to, 32 ), 16 );
        ASSERT_EQ( int( to[4] ), 1 );
        ASSERT_EQ( int( to[5] ), 1 );

        from[0] = 1;
        from[1] = 1;
        std::memset( to, 0, 32 );
        bitlevel::bitcopy( BitPointer( from, 0 ), BitPointer( to, 33 ), 16 );
        ASSERT_EQ( int( to[4] ), 2 );
        ASSERT_EQ( int( to[5] ), 2 );

        from[0] = 1;
        from[1] = 1;
        std::memset( to, 0, 32 );
        for ( int i = 0; i < 16; ++i )
            bitlevel::bitcopy( BitPointer( from, i ), BitPointer( to, 33 + i ), 1 );
        ASSERT_EQ( int( to[4] ), 2 );
        ASSERT_EQ( int( to[5] ), 2 );

        for ( int i = 0; i < 16; ++i )
            from[i] = 2;
        std::memset( to, 0, 32 );
        bitlevel::bitcopy( BitPointer( from, 1 ), BitPointer( to, 3 ), 128 );
        for ( int i = 0; i < 16; ++i )
            ASSERT_EQ( int( to[i] ), 8 );
    }

    TEST(field) {
        int a = 42, b = 0;
        typedef BitField< int, 10 > F;
        F::Virtual f;
        f.fromReference( BitPointer( &b ) );
        f.set( a );
        ASSERT_EQ( a, 42 );
        ASSERT_EQ( a, f );
    }

    TEST(basic) {
        T10_10 x;
        ASSERT_EQ( T10_10::bitwidth, 20 );
        ASSERT_EQ( T10_10::offset< 0 >(), 0 );
        ASSERT_EQ( T10_10::offset< 1 >(), 10 );
        auto a = get< 0 >( x );
        auto b = get< 1 >( x );
        a.set( 5 );
        b.set( 7 );
        ASSERT_EQ( a, 5u );
        ASSERT_EQ( b, 7u );
    }

    TEST(big) {
        bitlevel::BitTuple< BitField< uint64_t, 63 >, BitField< uint64_t, 63 > > x;
        ASSERT_EQ( x.bitwidth, 126 );
        ASSERT_EQ( x.offset< 0 >(), 0 );
        ASSERT_EQ( x.offset< 1 >(), 63 );
        get< 0 >( x ).set( (1ull << 62) + 7 );
        ASSERT_EQ( get< 0 >( x ), (1ull << 62) + 7 );
        ASSERT_EQ( get< 1 >( x ), 0u );
        get< 0 >( x ).set( 0 );
        get< 1 >( x ).set( (1ull << 62) + 7 );
        ASSERT_EQ( get< 0 >( x ), 0u );
        ASSERT_EQ( get< 1 >( x ), (1ull << 62) + 7 );
        get< 0 >( x ).set( (1ull << 62) + 11 );
        ASSERT_EQ( get< 0 >( x ), (1ull << 62) + 11 );
        ASSERT_EQ( get< 1 >( x ), (1ull << 62) + 7 );
    }

    TEST(structure) {
        bitlevel::BitTuple< BitField< std::pair< uint64_t, uint64_t >, 120 >, BitField< uint64_t, 63 > > x;
        auto v = std::make_pair( (uint64_t( 1 ) << 62) + 7, uint64_t( 33 ) );
        ASSERT_EQ( x.bitwidth, 183 );
        ASSERT_EQ( x.offset< 0 >(), 0 );
        ASSERT_EQ( x.offset< 1 >(), 120 );
        get< 1 >( x ).set( 333 );
        ASSERT_EQ( get< 1 >( x ), 333u );
        get< 0 >( x ).set( v );
        ASSERT_EQ( get< 1 >( x ), 333u );
        ASSERT( get< 0 >( x ).get() == v );
    }

    TEST(nested) {
        typedef bitlevel::BitTuple< T10_10, T10_10, BitField< unsigned, 3 > > X;
        X x;
        ASSERT_EQ( X::bitwidth, 43 );
        ASSERT_EQ( X::offset< 0 >(), 0 );
        ASSERT_EQ( X::offset< 1 >(), 20 );
        ASSERT_EQ( X::offset< 2 >(), 40 );
        auto a = get< 0 >( x );
        auto b = get< 1 >( x );
        get< 0 >( a ).set( 5 );
        get< 1 >( a ).set( 7 );
        get< 0 >( b ).set( 13 );
        get< 1 >( b ).set( 533 );
        get< 2 >( x ).set( 15 ); /* we expect to lose the MSB */
        ASSERT_EQ( get< 0 >( a ), 5u );
        ASSERT_EQ( get< 1 >( a ), 7u );
        ASSERT_EQ( get< 0 >( b ), 13u );
        ASSERT_EQ( get< 1 >( b ), 533u );
        ASSERT_EQ( get< 2 >( x ), 7u );
    }

    TEST(locked) {
        bitlevel::BitTuple<
            BitField< int, 15 >,
            BitLock,
            BitField< int, 16 >
        > bt;

        get< 1 >( bt ).lock();

        ASSERT_EQ( get< 0 >( bt ), 0 );
        ASSERT_EQ( get< 2 >( bt ), 0 );
        ASSERT( get< 1 >( bt ).locked() );
        ASSERT( get< 0 >( bt ).word() );

        get< 0 >( bt ) = 1;
        get< 2 >( bt ) = 1;

        ASSERT_EQ( get< 0 >( bt ), 1 );
        ASSERT_EQ( get< 2 >( bt ), 1 );

        ASSERT_EQ( bitcount( get< 0 >( bt ).word() ), 3 );

        get< 1 >( bt ).unlock();
        ASSERT_EQ( get< 0 >( bt ), 1 );
        ASSERT_EQ( get< 2 >( bt ), 1 );
        ASSERT( !get< 1 >( bt ).locked() );

        ASSERT_EQ( bitcount( get< 0 >( bt ).word() ), 2 );

        get< 0 >( bt ) = 0;
        get< 2 >( bt ) = 0;
        ASSERT( !get< 0 >( bt ).word() );
    }

    TEST(assign) {
        bitlevel::BitTuple<
            BitField< bool, 1 >,
            BitField< int, 6 >,
            BitField< bool, 1 >
        > tuple;

        get< 0 >( tuple ) = true;
        get< 2 >( tuple ) = get< 0 >( tuple );
        ASSERT( get< 2 >( tuple ).get() );
    }

    struct OperatorTester {
        int value;
        int expected;
        OperatorTester &operator++() { UNREACHABLE( "fell through" ); return *this; }
        OperatorTester operator++( int ) { UNREACHABLE( "fell through" ); return *this; }
        OperatorTester &operator--() { UNREACHABLE( "fell through" ); return *this; }
        OperatorTester &operator--( int ) { UNREACHABLE( "fell through" ); return *this; }
        OperatorTester &operator+=( int ) { UNREACHABLE( "fell through" ); return *this; }
        OperatorTester &operator-=( int ) { UNREACHABLE( "fell through" ); return *this; }
        OperatorTester &operator*=( int ) { UNREACHABLE( "fell through" ); return *this; }
        OperatorTester &operator/=( int ) { UNREACHABLE( "fell through" ); return *this; }
        OperatorTester &operator%=( int ) { UNREACHABLE( "fell through" ); return *this; }
        void test() { ASSERT_EQ( value, expected ); }
        void set( int v, int e ) { value = v; expected = e; }
    };
    struct TPrI : OperatorTester {
        TPrI &operator++() { ++value; return *this; }
    };
    struct TPoI : OperatorTester {
        TPoI operator++( int ) { auto r = *this; value++; return r; }
    };
    struct TPrD : OperatorTester {
        TPrD &operator--() { --value; return *this; }
    };
    struct TPoD : OperatorTester {
        TPoD operator--( int ) { auto r = *this; value--; return r; }
    };
    struct TPlO : OperatorTester {
        TPlO &operator+=( int v ) { value += v; return *this; }
    };
    struct TMO : OperatorTester {
        TMO &operator-=( int v ) { value -= v; return *this; }
    };
    struct TPoO : OperatorTester {
        TPoO &operator*=( int v ) { value *= v; return *this; }
    };
    struct TSO : OperatorTester {
        TSO &operator/=( int v ) { value /= v; return *this; }
    };
    struct TPrO : OperatorTester {
        TPrO &operator%=( int v ) { value %= v; return *this; }
    };

    template< int N, typename BT, typename L >
    void checkOperator( BT &bt, int v, int e, L l ) {
        auto t = get< N >( bt ).get();
        t.set( v, e );
        get< N >( bt ) = t;
        l( get< N >( bt ) );
        get< N >( bt ).get().test();
    }

#define CHECK( N, bt, v, e, test ) checkOperator< N >( bt, v, e, []( decltype( get< N >( bt ) ) item ) { test; } )

    TEST(operators) {
        bitlevel::BitTuple<
            BitField< bool, 4 >,
            BitField< TPrI >,// ++v
            BitField< TPoI >,// v++
            BitField< TPrD >,// --v
            BitField< TPoD >,// v--
            BitField< TPlO >,// v+=
            BitField< TMO >,// v-=
            BitField< TPoO >,// v*=
            BitField< TSO >,// v/=
            BitField< TPrO >,// v%=
            BitField< bool, 4 >
        > bt;

        CHECK( 1, bt, 0, 1, ++item );
        CHECK( 2, bt, 0, 1, item++ );
        CHECK( 3, bt, 0, -1, --item );
        CHECK( 4, bt, 0, -1, item-- );
        CHECK( 5, bt, 0, 5, item += 5 );
        CHECK( 6, bt, 0, -5, item -= 5 );
        CHECK( 7, bt, 2, 14, item *= 7 );
        CHECK( 8, bt, 42, 6, item /= 7 );
        CHECK( 9, bt, 42, 9, item %= 11 );
    }
#undef CHECK

    TEST(ones)
    {
        ASSERT_EQ( bitlevel::ones< uint32_t >( 0 ), 0 );
        ASSERT_EQ( bitlevel::ones< uint32_t >( 1 ), 1 );
        ASSERT_EQ( bitlevel::ones< uint32_t >( 2 ), 3 );
        ASSERT_EQ( bitlevel::ones< uint32_t >( 31 ), std::numeric_limits< uint32_t >::max() >> 1 );
        ASSERT_EQ( bitlevel::ones< uint32_t >( 32 ), std::numeric_limits< uint32_t >::max() );
        ASSERT_EQ( bitlevel::ones< uint32_t >( 33 ), std::numeric_limits< uint32_t >::max() );
    }
};

struct BitVecTest
{
    TEST(bvpair_shiftl)
    {
        using bvp32 = bitlevel::bvpair< uint16_t, uint16_t >;
        union {
            bvp32 bvp;
            uint32_t val;
        };
        bvp = bvp32( 23, 13 );
        uint32_t check = ( 13u << 16 ) | 23u;
        ASSERT_EQ( val, check );
        bvp = bvp << 7;
        check = check << 7;
        ASSERT_EQ( val, check );
        bvp = bvp << 18;
        check = check << 18;
        ASSERT_EQ( val, check );
        bvp = bvp32( 0xFF, 0xFF );
        check = (0xFF << 16) | 0xFF;
        bvp = bvp << 20;
        check = check << 20;
        ASSERT_EQ( val, check );
    }

    TEST(bvpair_shiftr)
    {
        using bvp32 = bitlevel::bvpair< uint16_t, uint16_t >;
        union {
            bvp32 bvp;
            uint32_t val;
        };
        bvp = bvp32( 23, 13 );
        uint32_t check = ( 13u << 16 ) | 23u;
        ASSERT_EQ( val, check );
        bvp = bvp >> 7;
        check = check >> 7;
        ASSERT_EQ( val, check );
        bvp = bvp >> 18;
        check = check >> 18;
        ASSERT_EQ( val, check );
        bvp = bvp32( 0xFF, 0xFF );
        check = (0xFF << 16) | 0xFF;
        bvp = bvp >> 20;
        check = check >> 20;
        ASSERT_EQ( val, check );
    }
};

}
}

#endif
// vim: syntax=cpp tabstop=4 shiftwidth=4 expandtab