byte_stream_writer
byte_stream_writer.hFrom:
20.17.0A binary streaming utility that allows boolean, integral and floating point values to be written to an array of char or unsigned char. Values may be stored in the byte stream in big or little endian format. This is specified in the constructor.
If a callback delegate is set, then this will be called after each write. The stream buffer indexes will be reset after every write, allowing a small buffer to be used.
From: 20.29.0
class byte_stream_writerNote for floating point
Be aware that floating point representations can change between platforms.
For example,long doubleis 8 bytes for MS compilers and 12 for GCC.
Types
iterator char*
const_iterator const char*
callback_parameter_type etl::span<char>
callback_type etl::delegate<void(callback_parameter_type)>Constructors
byte_stream_writer(etl::span<char> span,
etl::endian stream_endianness,
callback_type callback = callback_type())Description
Construct from span.
Callback parameter is available from 20.29.0
byte_stream_writer(etl::span<unsigned char> span,
etl::endian stream_endianness,
callback_type callback = callback_type())Description
Construct from span.
byte_stream_writer(char* begin,
char* end,
etl::endian stream_endianness,
callback_type callback = callback_type())Description
Construct from range.
byte_stream_writer(char* begin,
size_t length,
etl::endian stream_endianness,
callback_type callback = callback_type())Description
Construct from begin and length.
template <typename T, size_t Size>
byte_stream_writer(T(&begin)[Size],
etl::endian stream_endianness,
callback_type callback = callback_type())Description
Construct from array.
Write
Checked
The following function will only write to the buffer if there is enough room to do so.
bool write(bool value)Description
Write a boolean value to the stream.
Returns true if successful, otherwise false.
template <typename T>
bool write(T value)Description
Write an integral or floating point value to the stream.
Returns true if successful, otherwise false.
template <typename T>
bool write(const etl::span<T>& range)Description
Write a range of integral or floating point values to the stream.
Returns true if successful, otherwise false.
template <typename T>
bool write(const T* start, size_t length)Description
Write a range of integral or floating point values to the stream.
Returns true if successful, otherwise false.
Unchecked
From: 20.18.0
The following functions will always write to the buffer. They do not check for free space.
bool write_unchecked(bool value)Description
Write a boolean value to the stream.
Returns true if successful, otherwise false.
template <typename T>
void write_unchecked(T value)Description
Write an integral or floating point value to the stream.
template <typename T>
void write_unchecked(const etl::span<T>& range)Description
Write a range of integral or floating point values to the stream.
template <typename T>
void write_unchecked(const T* start, size_t length)Description
Write a range of integral or floating point values to the stream.
Access
void restart(size_t n = 0U)Description
Sets the index back to position n in the stream. Default = 0.
template <typename T>
bool skip(size_t n)Description
Skip n items of T, if the total space is available.
Returns true if the skip was possible.
Asserts etl::byte_stream_overflow and returns false if the skip size was not possible.
From: 20.29.0
const_iterator begin() constDescription
Returns start of the stream.
const_iterator end() constDescription
Returns end of the stream.
const_iterator cbegin() constDescription
Returns start of the stream.
const_iterator cend() constDescription
Returns end of the stream.
etl::span<char> used_data() constDescription
Returns a span of the used portion of the stream.
etl::span<char> free_data() constDescription
Returns a span of the free portion of the stream.
etl::span<char> data() constDescription
Returns a span of whole the stream.
Status
bool full() constDescription
Returns true if the byte stream writer has reached the end.
bool empty() constDescription
Returns true if the byte stream is empty.
size_t size_bytes() constDescription
Returns the number of bytes used in the stream.
size_t capacity() constDescription
Returns the maximum number of bytes in the stream.
template <typename T>
size_t available() constDescription
The number of T left in the stream.
size_t available_bytes() constDescription
The number of bytes left in the stream.
etl::endian get_endianness() constDescription
Gets the endianness of the stream.
Callback
void set_callback(callback_type callback_)Description
Sets the delegate that is called after every write.
From: 20.29.0
callback_type get_callback() constDescription
Gets the delegate that is called after every write.
Non-member functions
Default implementation of the write functions. For integral and floating point types only. Specialise these to support custom types.
template <typename T> 20.18.0
T write_unchecked(etl::byte_stream_writer& stream)template <typename T>
etl::optional<T> write(etl::byte_stream_writer& stream)Examples
Using a large buffer and processing the bytes at the end
void WriteBytesToConsole(etl::span<char> sp)
{
for (auto itr = sp.begin(); itr != sp.end(); ++itr)
{
putc(*itr);
}
}
std::array<int32_t, 4> data = { int32_t(0x00000001), int32_t(0xA55AA55A),
int32_t(0x5AA55AA5), int32_t(0xFFFFFFFF) };
std::array<char, 4 * sizeof(int32_t)> storage;
etl::byte_stream_writer writer(storage.data(), storage.size(), etl::endian::big);
for (auto i : data)
{
writer.write(i);
}
etl::span<char> sp = writer.used_data();
WriteBytesToConsole(sp);
```cpp
**Using a small buffer and processing the bytes after every write**
void WriteBytesToConsole(etl::span<char> sp)
{
for (auto itr = sp.begin(); itr != sp.end(); ++itr)
{
putc(*itr);
}
}
std::array<int32_t, 4> data = { int32_t(0x00000001), int32_t(0xA55AA55A),
int32_t(0x5AA55AA5), int32_t(0xFFFFFFFF) };
std::array<char, sizeof(int32_t)> storage;
etl::byte_stream_writer writer(storage.data(), storage.size(), etl::endian::big);
for (auto i : data)
{
writer.write(i);
etl::span<char> sp = writer.used_data();
WriteBytesToConsole(sp);
writer.restart();
}
**Using a small buffer and processing the bytes after every write with a callback**
```cpp
void WriteBytesToConsole(etl::byte_stream_writer::callback_parameter_type sp)
{
for (auto itr = sp.begin(); itr != sp.end(); ++itr)
{
putc(*itr);
}
}
std::array<int32_t, 4> data = { int32_t(0x00000001), int32_t(0xA55AA55A),
int32_t(0x5AA55AA5), int32_t(0xFFFFFFFF) };
std::array<char, sizeof(int32_t)> storage;
auto callback =
etl::delegate<void<etl::byte_stream_writer::callback_parameter_type>>::create<WriteBytesToConsole>();
etl::byte_stream_writer writer(storage.data(), storage.size(), etl::endian::big, callback);
for (auto i : data)
{
writer.write(i); // Sends the bytes to WriteBytesToConsole
}
```cpp