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Optimised advance template call

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This commit is contained in:
John Wellbelove 2026-09-14 16:22:17 +01:00
parent 8e3ad413cf
commit 295439c2cd
1 changed files with 50 additions and 16 deletions
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66
include/etl/cyclic_value.h
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@ -39,6 +39,7 @@ SOFTWARE.
#include "algorithm.h"
#include "exception.h"
#include "integral_limits.h"
#include "negative.h"
#include "static_assert.h"
#include "type_traits.h"
@ -46,6 +47,12 @@ namespace etl
{
namespace private_cyclic_value
{
template <typename T>
struct traits
{
typedef typename etl::make_unsigned<T>::type unsigned_type;
};
//*************************************************************************
/// Advances a value and wraps it at the supplied limits.
///\param value The current value.
@ -54,13 +61,14 @@ namespace etl
///\param n The number of steps.
///\return The advanced value.
//*************************************************************************
template <typename T, typename TStep>
template <typename T>
ETL_NODISCARD
static ETL_CONSTEXPR14 T advance(T value, T min_value, T max_value, TStep n) ETL_NOEXCEPT
static ETL_CONSTEXPR14 T advance(T value, T min_value, T max_value, typename traits<T>::unsigned_type unsigned_abs_value,
typename traits<T>::unsigned_type unsigned_value, bool is_negative) ETL_NOEXCEPT
{
typedef typename etl::make_unsigned<T>::type unsigned_type;
typedef typename traits<T>::unsigned_type unsigned_type;
if (n == 0)
if (unsigned_abs_value == 0)
{
return value;
}
@ -71,7 +79,7 @@ namespace etl
if (is_full_range)
{
// This is safe as the type's own overflow behaviour is modulo wrap-around.
return static_cast<T>(etl::to_unsigned(value) + static_cast<unsigned_type>(n));
return static_cast<T>(etl::to_unsigned(value) + unsigned_value);
}
else
{
@ -82,10 +90,10 @@ namespace etl
const unsigned_type current = etl::to_unsigned(value) - etl::to_unsigned(min_value);
// Reduce the step to something within a single lap of the range.
const unsigned_type step = etl::absolute_unsigned(n) % range;
const unsigned_type step = unsigned_abs_value % range;
// Direction-corrected offset to add, always in [0, range).
const unsigned_type offset = (n > 0) ? step : (range - step) % range;
const unsigned_type offset = is_negative ? (range - step) % range : step;
return static_cast<T>(etl::to_unsigned(min_value) + (current + offset) % range);
}
@ -109,6 +117,10 @@ namespace etl
template <typename T, T First, T Last>
class cyclic_value<T, First, Last, false>
{
private:
typedef typename private_cyclic_value::traits<T>::unsigned_type unsigned_type;
public:
//*************************************************************************
@ -170,7 +182,11 @@ namespace etl
template <typename TStep>
ETL_CONSTEXPR14 cyclic_value& operator-=(TStep n) ETL_LVALUE_REF_QUALIFIER ETL_NOEXCEPT
{
value = private_cyclic_value::advance(value, First, Last, -n);
const unsigned_type unsigned_abs_value = etl::absolute_unsigned(n);
const unsigned_type unsigned_value = static_cast<unsigned_type>(n);
const bool is_negative = etl::is_negative(-n);
value = private_cyclic_value::advance(value, First, Last, unsigned_abs_value, unsigned_value, is_negative);
return *this;
}
@ -207,7 +223,11 @@ namespace etl
template <typename TStep>
ETL_CONSTEXPR14 void advance(TStep n) ETL_NOEXCEPT
{
value = private_cyclic_value::advance(value, First, Last, n);
const unsigned_type unsigned_abs_value = etl::absolute_unsigned(n);
const unsigned_type unsigned_value = static_cast<unsigned_type>(n);
const bool is_negative = etl::is_negative(n);
value = private_cyclic_value::advance(value, First, Last, unsigned_abs_value, unsigned_value, is_negative);
}
//*************************************************************************
@ -224,7 +244,7 @@ namespace etl
//*************************************************************************
ETL_CONSTEXPR14 cyclic_value& operator++() ETL_NOEXCEPT
{
value = private_cyclic_value::advance(value, First, Last, 1);
value = private_cyclic_value::advance(value, First, Last, static_cast<unsigned_type>(1), static_cast<unsigned_type>(1), false);
return *this;
}
@ -246,7 +266,7 @@ namespace etl
//*************************************************************************
ETL_CONSTEXPR14 cyclic_value& operator--() ETL_NOEXCEPT
{
value = private_cyclic_value::advance(value, First, Last, int(-1));
value = private_cyclic_value::advance(value, First, Last, static_cast<unsigned_type>(1), static_cast<unsigned_type>(1), true);
return *this;
}
@ -356,6 +376,10 @@ namespace etl
template <typename T, T First, T Last>
class cyclic_value<T, First, Last, true>
{
private:
typedef typename private_cyclic_value::traits<T>::unsigned_type unsigned_type;
public:
//*************************************************************************
@ -449,9 +473,14 @@ namespace etl
/// Advances to value by a number of steps.
///\param n The number of steps to advance.
//*************************************************************************
ETL_CONSTEXPR14 void advance(int n) ETL_NOEXCEPT
template <typename TStep>
ETL_CONSTEXPR14 void advance(TStep n) ETL_NOEXCEPT
{
value = private_cyclic_value::advance(value, first_value, last_value, n);
const unsigned_type unsigned_abs_value = etl::absolute_unsigned(n);
const unsigned_type unsigned_value = static_cast<unsigned_type>(n);
const bool is_negative = etl::is_negative(n);
value = private_cyclic_value::advance(value, first_value, last_value, unsigned_abs_value, unsigned_value, is_negative);
}
//*************************************************************************
@ -468,7 +497,7 @@ namespace etl
//*************************************************************************
ETL_CONSTEXPR14 cyclic_value& operator++() ETL_LVALUE_REF_QUALIFIER ETL_NOEXCEPT
{
value = private_cyclic_value::advance(value, first_value, last_value, 1);
value = private_cyclic_value::advance(value, first_value, last_value, static_cast<unsigned_type>(1), static_cast<unsigned_type>(1), false);
return *this;
}
@ -490,7 +519,7 @@ namespace etl
//*************************************************************************
ETL_CONSTEXPR14 cyclic_value& operator--() ETL_LVALUE_REF_QUALIFIER ETL_NOEXCEPT
{
value = private_cyclic_value::advance(value, first_value, last_value, int(-1));
value = private_cyclic_value::advance(value, first_value, last_value, static_cast<unsigned_type>(1), static_cast<unsigned_type>(1), true);
return *this;
}
@ -549,7 +578,12 @@ namespace etl
template <typename TStep>
ETL_CONSTEXPR14 cyclic_value& operator-=(TStep n) ETL_LVALUE_REF_QUALIFIER ETL_NOEXCEPT
{
value = private_cyclic_value::advance(value, first_value, last_value, -n);
const unsigned_type unsigned_abs_value = etl::absolute_unsigned(n);
const unsigned_type unsigned_value = static_cast<unsigned_type>(n);
const bool is_negative = etl::is_negative(-n);
value = private_cyclic_value::advance(value, first_value, last_value, unsigned_abs_value, unsigned_value, is_negative);
return *this;
}