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smallest.h
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/******************************************************************************
The MIT License(MIT)
Embedded Template Library.
https://github.com/ETLCPP/etl
https://www.etlcpp.com
Copyright(c) 2014 John Wellbelove
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files(the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions :
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
******************************************************************************/
#ifndef ETL_SMALLEST_INCLUDED
#define ETL_SMALLEST_INCLUDED
#include "platform.h"
#include "integral_limits.h"
#include <stdint.h>
namespace etl
{
#if ETL_USING_CPP11 && !defined(ETL_SMALLEST_TYPE_FORCE_CPP03_IMPLEMENTATION)
//***************************************************************************
//***************************************************************************
template <typename T1, typename... TRest>
class smallest_type
{
private:
// Define 'smallest_other' as 'smallest_type' with all but the first
// parameter.
using smallest_other = typename smallest_type<TRest...>::type;
public:
// Set 'type' to be the smallest of the first parameter and any of the
// others. This is recursive.
using type = typename etl::conditional<(etl::size_of<T1>::value < etl::size_of< smallest_other>::value), // Boolean
T1, // TrueType
smallest_other> // FalseType
::type; // The smallest type of the two.
// The size of the smallest type.
enum
{
size = etl::size_of<type>::value
};
};
//***************************************************************************
// Specialisation for one template parameter.
//***************************************************************************
template <typename T1>
class smallest_type<T1>
{
public:
using type = T1;
enum
{
size = etl::size_of<type>::value
};
};
#if ETL_USING_CPP11
template <typename... T>
using smallest_type_t = typename smallest_type<T...>::type;
#endif
#if ETL_USING_CPP17
template <typename... T>
constexpr size_t smallest_type_v = smallest_type<T...>::size;
#endif
#else
#include "private/smallest_cpp03.h"
#endif
namespace private_smallest
{
//*************************************************************************
// Determine the type to hold the number of bits based on the index.
//*************************************************************************
template <int index>
struct best_fit_uint_type;
//*************************************************************************
// Less than or equal to 8 bits.
//*************************************************************************
template <>
struct best_fit_uint_type<0>
{
typedef uint_least8_t type;
};
//*************************************************************************
// 9 to 16 bits.
//*************************************************************************
template <>
struct best_fit_uint_type<1>
{
typedef uint_least16_t type;
};
//*************************************************************************
// 17 to 31 bits.
//*************************************************************************
template <>
struct best_fit_uint_type<2>
{
typedef uint_least32_t type;
};
#if ETL_USING_64BIT_TYPES
//*************************************************************************
// Greater than 32 bits.
//*************************************************************************
template <>
struct best_fit_uint_type<3>
{
typedef uint_least64_t type;
};
#endif
//*************************************************************************
// Determine the type to hold the number of bits based on the index.
//*************************************************************************
template <int index>
struct best_fit_int_type;
//*************************************************************************
// Less than or equal to 8 bits.
//*************************************************************************
template <>
struct best_fit_int_type<0>
{
typedef int_least8_t type;
};
//*************************************************************************
// 9 to 16 bits.
//*************************************************************************
template <>
struct best_fit_int_type<1>
{
typedef int_least16_t type;
};
//*************************************************************************
// 17 to 31 bits.
//*************************************************************************
template <>
struct best_fit_int_type<2>
{
typedef int_least32_t type;
};
#if ETL_USING_64BIT_TYPES
//*************************************************************************
// Greater than 32 bits.
//*************************************************************************
template <>
struct best_fit_int_type<3>
{
typedef int_least64_t type;
};
#endif
} // namespace private_smallest
//***************************************************************************
//***************************************************************************
template <size_t NBITS>
struct smallest_uint_for_bits
{
private:
// Determines the index of the best unsigned type for the required number of
// bits.
static ETL_CONSTANT int TYPE_INDEX = ((NBITS > 8) ? 1 : 0) + ((NBITS > 16) ? 1 : 0) + ((NBITS > 32) ? 1 : 0);
public:
typedef typename private_smallest::best_fit_uint_type<TYPE_INDEX>::type type;
};
template <size_t NBITS>
ETL_CONSTANT int smallest_uint_for_bits<NBITS>::TYPE_INDEX;
#if ETL_USING_CPP11
template <size_t NBITS>
using smallest_uint_for_bits_t = typename smallest_uint_for_bits<NBITS>::type;
#endif
//***************************************************************************
//***************************************************************************
template <size_t NBITS>
struct smallest_int_for_bits
{
private:
// Determines the index of the best unsigned type for the required number of
// bits.
static ETL_CONSTANT int TYPE_INDEX = ((NBITS > 8) ? 1 : 0) + ((NBITS > 16) ? 1 : 0) + ((NBITS > 32) ? 1 : 0);
public:
typedef typename private_smallest::best_fit_int_type<TYPE_INDEX>::type type;
};
template <size_t NBITS>
ETL_CONSTANT int smallest_int_for_bits<NBITS>::TYPE_INDEX;
#if ETL_USING_CPP11
template <size_t NBITS>
using smallest_int_for_bits_t = typename smallest_int_for_bits<NBITS>::type;
#endif
//***************************************************************************
//***************************************************************************
template <uintmax_t VALUE>
struct smallest_uint_for_value
{
private:
// Determines the index of the best unsigned type for the required value.
static ETL_CONSTANT int TYPE_INDEX = ((VALUE > UINT_LEAST8_MAX) ? 1 : 0) + ((VALUE > UINT16_MAX) ? 1 : 0) + ((VALUE > UINT32_MAX) ? 1 : 0);
public:
typedef typename private_smallest::best_fit_uint_type<TYPE_INDEX>::type type;
};
template <uintmax_t VALUE>
ETL_CONSTANT int smallest_uint_for_value<VALUE>::TYPE_INDEX;
#if ETL_USING_CPP11
template <uintmax_t VALUE>
using smallest_uint_for_value_t = typename smallest_uint_for_value<VALUE>::type;
#endif
//***************************************************************************
//***************************************************************************
template <intmax_t VALUE>
struct smallest_int_for_value
{
private:
// Determines the index of the best signed type for the required value.
static ETL_CONSTANT int TYPE_INDEX = (((VALUE > intmax_t(INT_LEAST8_MAX)) || (VALUE < intmax_t(INT_LEAST8_MIN))) ? 1 : 0)
+ (((VALUE > intmax_t(INT16_MAX)) || (VALUE < intmax_t(INT16_MIN))) ? 1 : 0)
+ (((VALUE > intmax_t(INT32_MAX)) || (VALUE < intmax_t(INT32_MIN))) ? 1 : 0);
public:
typedef typename private_smallest::best_fit_int_type<TYPE_INDEX>::type type;
};
template <intmax_t VALUE>
ETL_CONSTANT int smallest_int_for_value<VALUE>::TYPE_INDEX;
#if ETL_USING_CPP11
template <intmax_t VALUE>
using smallest_int_for_value_t = typename smallest_int_for_value<VALUE>::type;
#endif
} // namespace etl
#endif
etl::smallest_int_for_bits
Definition smallest.h:233
etl::smallest_int_for_value
Definition smallest.h:288
etl::smallest_type
Definition smallest.h:46
etl::smallest_uint_for_bits
Definition smallest.h:205
etl::smallest_uint_for_value
Definition smallest.h:261
integral_limits.h
etl
Definition absolute.h:40
etl::size
ETL_CONSTEXPR TContainer::size_type size(const TContainer &container)
Definition iterator.h:1434
platform.h
etl::type
etl::private_smallest::best_fit_int_type
Definition smallest.h:156
etl::private_smallest::best_fit_uint_type
Definition smallest.h:112