pw_bytes

pw_bytes is a collection of utilities for manipulating binary data.

Compatibility

C++17

Dependencies

• pw_preprocessor

• pw_status

• pw_span

Features

pw_bytes/array.h

Functions for working with byte arrays, primarily for building fixed-size byte arrays at compile time.

pw_bytes/byte_builder.h

class ByteBuilder

ByteBuilder is a class that facilitates building or reading arrays of bytes in a fixed-size buffer. ByteBuilder handles reading and writing integers with varying endianness.

template<size_t kMaxSize>
class ByteBuffer

ByteBuilder with an internally allocated buffer.

Size report: using ByteBuffer

Label	Segment	Delta
Using ByteBuilder vs not using it	FLASH +4 quorem +4 _ctype_ +4 pw::bytes::ReadBytes() +20 pw::bytes::PutBytes() +2 main NEW +52 memmove NEW +34 pw::ByteBuilder::ResizeForAppend() NEW +32 pw::ByteBuilder::append() NEW +24 _GLOBAL__sub_I__ZN2pw5bytes2bbE NEW +4 pw::bytes::internal::ReverseBytes<>()	+180

pw_bytes/bit.h

Implementation of features provided by C++20’s <bit> header. Supported features:

• pw::endian – Implementation of the std::endian enum. If std::endian is available, pw::endian is an alias of it.

pw_bytes/endian.h

Functions for converting the endianness of integral values.

pw_bytes/units.h

Constants, functions and user-defined literals for specifying a number of bytes in powers of two, as defined by IEC 60027-2 A.2 and ISO/IEC 80000:13-2008.

The supported suffixes include:

• _B for bytes (1024⁰)

• _KiB for kibibytes (1024¹)

• _MiB for mebibytes (1024²)

• _GiB for gibibytes (1024³)

• _TiB for tebibytes (1024⁴)

• _PiB for pebibytes (1024⁵)

• _EiB for exbibytes (1024⁶)

In order to use these you must use a using namespace directive, for example:

#include "pw_bytes/units.h"

using namespace pw::bytes::unit_literals;

constexpr size_t kRandomBufferSizeBytes = 1_MiB + 42_KiB;

In some cases, the use of user-defined literals is not permitted because of the required using namespace directive. One example of this is in header files, where it is undesirable to pollute the namespace. For this situation, there are also similar functions:

#include "pw_bytes/units.h"

constexpr size_t kBufferSizeBytes = pw::bytes::MiB(1) + pw::bytes::KiB(42);

Zephyr

To enable pw_bytes for Zephyr add CONFIG_PIGWEED_BYTES=y to the project’s configuration.