////  Radix2IntegerScanner.h//  libraries/shared/src////  Created by Tobias Schwinger on 3/23/13.//  Copyright 2013 High Fidelity, Inc.////  Distributed under the Apache License, Version 2.0.//  See the accompanying file LICENSE or http://www.apache.org/licenses/LICENSE-2.0.html// #ifndef hifi_Radix2IntegerScanner_h#define hifi_Radix2IntegerScanner_h #include <stddef.h>#include <stdint.h> namespace type_traits { // those are needed for the declaration, see below     // Note: There are better / more generally appicable implementations     // in C++11, make_signed is missing in TR1 too - so I just use C++98    // hacks that get the job done...     template< typename T > struct is_signed     { static bool const value = T(-1) < T(0); };     template< typename T, size_t S = sizeof(T) > struct make_unsigned;    template< typename T > struct make_unsigned< T, 1 > { typedef uint8_t type; };    template< typename T > struct make_unsigned< T, 2 > { typedef uint16_t type; };    template< typename T > struct make_unsigned< T, 4 > { typedef uint32_t type; };    template< typename T > struct make_unsigned< T, 8 > { typedef quint64 type; };}  /** * Bit decomposition facility for integers. */template< typename T,         bool _Signed = type_traits::is_signed<T>::value  >class Radix2IntegerScanner;   template< typename UInt >class Radix2IntegerScanner< UInt, false > {         UInt valMsb;    public:         Radix2IntegerScanner()            : valMsb(~UInt(0) &~ (~UInt(0) >> 1)) { }         explicit Radix2IntegerScanner(int bits)            : valMsb(UInt(1u) << (bits - 1)) {        }         typedef UInt state_type;         state_type initial_state()  const   { return valMsb; }        bool advance(state_type& s) const   { return (s >>= 1) != 0u; }         bool bit(UInt const& v, state_type const& s) const { return !!(v & s); }}; template< typename Int >class Radix2IntegerScanner< Int, true >{        typename type_traits::make_unsigned<Int>::type valMsb;    public:         Radix2IntegerScanner()            : valMsb(~state_type(0u) &~ (~state_type(0u) >> 1)) {        }         explicit Radix2IntegerScanner(int bits)            : valMsb(state_type(1u) << (bits - 1)) {        }          typedef typename type_traits::make_unsigned<Int>::type state_type;                state_type initial_state()  const   { return valMsb; }        bool advance(state_type& s) const   { return (s >>= 1) != 0u; }         bool bit(Int const& v, state_type const& s) const { return !!((v-valMsb) & s); }}; #endif // hifi_Radix2IntegerScanner_h