crow

Utility library

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Bitwise Operations

Crow Library by Ross Smith

#include "crow/binary.hpp"
namespace Crow;

Contents

• Bitwise Operations
  • Contents
  • Bit manipulation
  • Byte order
  • Overflow detection

Bit manipulation

template <BitwiseType T>
    constexpr bool has_bit(T flags, T required) noexcept;
template <BitwiseType T>
    constexpr bool has_bits(T flags, T required) noexcept;

Test for the presence of specific bits. The has_bit() function returns true if flags and required have any bits in common; has_bits() returns true if flags contains all of the bits in required. Both functions will return false if required=0.

Byte order

template <PrimitiveScalarType T> constexpr T swap_ends(T t) noexcept;

Returns the value with reversed byte order.

template <PrimitiveScalarType T> constexpr T big_endian(T t) noexcept;
template <PrimitiveScalarType T> constexpr T little_endian(T t) noexcept;

These convert between big or little endian and the native byte order.

template <PrimitiveScalarType T> constexpr T read_be(const void* ptr) noexcept;
template <PrimitiveScalarType T> constexpr T read_le(const void* ptr) noexcept;
template <PrimitiveScalarType T> constexpr void write_be(T t, void* ptr) noexcept;
template <PrimitiveScalarType T> constexpr void write_le(T t, void* ptr) noexcept;

Read or write a value from a sequence of bytes, assuming it is stored in big or little endian order. Behaviour is undefined if the pointer is null or there is not enough space in the array being read or written.

Overflow detection

template <std::integral T>
    constexpr std::optional<T> checked_add(T x, T y) noexcept;
template <std::integral T>
    constexpr std::optional<T> checked_subtract(T x, T y) noexcept;

These perform integer addition and subtraction with overflow detection. They return the sum or difference if the operation is valid, or an empty value if overflow or underflow occurs.