A C++ template library for embedded applications
MIT licensed
Designed and
maintained by
John Wellbelove
Support the development
of the ETL

Memory Cast

20.11.0

Helper classes that simplify the interpretation of memory blocks.
The member functions contain both compile and run time error checks for correct sized buffers.

etl::mem_cast
etl::mem_cast_ptr
etl::mem_cast_types
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Error types

class mem_cast_exception : public etl::exception
The base exception type for mem_cast types.

class mem_cast_size_exception : public etl::mem_cast_exception
The exception type when the type size is too large.

class mem_cast_nullptr_exception : public etl::mem_cast_exception
The exception type when the buffer pointer is null.
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mem_cast
This class owns an internal memory block, as defined by the template parameters.

template <size_t Size, size_t Alignment>
class mem_cast
The class is parameterised by the required memory block size and alignment.
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Member constants

static ETL_CONSTANT size_t Size;
static ETL_CONSTANT size_t Alignment;
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Member functions
mem_cast()
Default constructor.
The internal memory block contents are undefined.
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template <size_t Other_Size, size_t Other_Alignment>
mem_cast(const mem_cast<Other_Size, Other_Alignment>& other)
Copy constructor.
Copies the contents of the source buffer.
Static asserts if the other buffer is not large enough.
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template <size_t Other_Size, size_t Other_Alignment>
mem_cast& operator =(const mem_cast<Other_Size, Other_Alignment>& rhs)
Assignment operator.
Static asserts if the rhs buffer is not large enough.
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template <typename T>
void assign(const T& value)
Assign from value.
Static asserts if the buffer is not large enough.
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template <typename T>
void assign_at_offset(size_t offset, const T& value)
Assign from value at an offset from the start of the memory block.
Raises an etl::mem_cast_size_exception ETL_ASSERT if the buffer is not large enough.
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template <typename T, size_t Offset>
void assign_at_offset(const T& value)
Assign from value at an offset from the start of the memory block.
Static asserts if the buffer is not large enough.
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template <typename T, typename... TArgs>
void emplace(TArgs... args)
Emplace from parameters.
Static asserts if the buffer is not large enough.
C++11 or above.
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template <typename T, typename... TArgs>
void emplace_at_offset(size_t offset, TArgs... args)
Emplace from parameters at an offset from the start of the memory block.
Raises an etl::mem_cast_size_exception ETL_ASSERT if the buffer is not large enough.
C++11 or above.
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template <typename T, size_t Offset, typename... TArgs>
void emplace_at_offset(TArgs... args)
Emplace from parameters at an offset from the start of the memory block.
Static asserts if the buffer is not large enough.
C++11 or above.
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template <typename T>
ETL_NODISCARD T& ref()
Get a reference to T.
Static asserts if the buffer is not large enough.
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template <typename T>
ETL_NODISCARD const T& ref() const
Get a const reference to T.
Static asserts if the buffer is not large enough.
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template <typename T>
ETL_NODISCARD T& ref_at_offset(size_t offset)
Get a reference to T at an offset from the start of the memory block (dynamic).
Raises an etl::mem_cast_size_exception ETL_ASSERT if the buffer is not large enough.
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template <typename T>
ETL_NODISCARD const T& ref_at_offset(size_t offset) const
Get a const reference to T at an offset from the start of the memory block (dynamic).
Raises an etl::mem_cast_size_exception ETL_ASSERT if the buffer is not large enough.
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template <typename T, size_t Offset>
ETL_NODISCARD T& ref_at_offset()
Get a reference to T at an offset from the start of the memory block (static).
Static asserts if the buffer is not large enough.
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template <typename T, size_t Offset>
ETL_NODISCARD const T& ref_at_offset() const
Get a const reference to T at an offset from the start of the memory block (static).
Static asserts if the buffer is not large enough.
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ETL_NODISCARD static ETL_CONSTEXPR size_t size()
Get the size of the buffer.
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ETL_NODISCARD static ETL_CONSTEXPR size_t alignment()
Get the alignment of the buffer.
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ETL_NODISCARD char* data()
Get a pointer to the internal buffer.
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ETL_NODISCARD const char* data() const
Get a const pointer to the internal buffer
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mem_cast_ptr
This class contains a pointer to an external memory block.
class mem_cast_ptr
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Member constants

static ETL_CONSTANT size_t Undefined_Size;
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Member functions
mem_cast_ptr()
Default constructor.
The internal pointer to the memory block is initialised as nullptr.
The size is defined as Undefined_Size.
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mem_cast_ptr(const mem_cast_ptr& other)
Copy constructor.
Copies the memory block pointer, not the contents of the memory block.
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mem_cast_ptr& operator =(const mem_cast_ptr& rhs)
Assignment operator.
Copies the memory block pointer, not the contents of the memory block.
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template <typename T>
void assign(const T& value)
Assign from value.
Raises an etl::mem_cast_nullptr_exception ETL_ASSERT if the memory block pointer is null.
Raises an etl::mem_cast_size_exception ETL_ASSERT if the buffer is not large enough.
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template <typename T>
void assign_at_offset(size_t offset, const T& value)
Assign from value at an offset from the start of the memory block.
Raises an etl::mem_cast_nullptr_exception ETL_ASSERT if the memory block pointer is null.
Raises an etl::mem_cast_size_exception ETL_ASSERT if the buffer is not large enough.
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template <typename T, size_t Offset>
void assign_at_offset(const T& value)
Assign from value at an offset from the start of the memory block.
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template <typename T, typename... TArgs>
void emplace(TArgs... args)
Emplace from parameters.
C++11 or above.
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template <typename T, typename... TArgs>
void emplace_at_offset(size_t offset, TArgs... args)
Emplace from parameters at offset.
Raises an etl::mem_cast_nullptr_exception ETL_ASSERT if the memory block pointer is null.
Raises an etl::mem_cast_size_exception ETL_ASSERT if the buffer is not large enough.
C++11 or above.
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template <typename T, size_t Offset, typename... TArgs>
void emplace_at_offset(TArgs... args)
Emplace from parameters at offset.
Raises an etl::mem_cast_nullptr_exception ETL_ASSERT if the memory block pointer is null.
Raises an etl::mem_cast_size_exception ETL_ASSERT if the buffer is not large enough.
C++11 or above.
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template <typename T>
ETL_NODISCARD T& ref()
Get a reference to T.
Raises an etl::mem_cast_nullptr_exception ETL_ASSERT if the memory block pointer is null.
Raises an etl::mem_cast_size_exception ETL_ASSERT if the buffer is not large enough.
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template <typename T>
ETL_NODISCARD const T& ref() const
Get a const reference to T.
Raises an etl::mem_cast_nullptr_exception ETL_ASSERT if the memory block pointer is null.
Raises an ETL_ASSERT if the buffer is not large enough.
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template <typename T>
ETL_NODISCARD T& ref_at_offset(size_t offset)
Get a reference to T at an offset from the start of the memory block (dynamic).
Raises an etl::mem_cast_nullptr_exception ETL_ASSERT if the memory block pointer is null.
Raises an etl::mem_cast_size_exception ETL_ASSERT if the buffer is not large enough.
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template <typename T>
ETL_NODISCARD const T& ref_at_offset(size_t offset) const
Get a const reference to T at offset (dynamic).
Raises an etl::mem_cast_nullptr_exception ETL_ASSERT if the memory block pointer is null.
Raises an etl::mem_cast_size_exception ETL_ASSERT if the buffer is not large enough.
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template <typename T, size_t Offset>
ETL_NODISCARD T& ref_at_offset()
Get a reference to T at an offset from the start of the memory block (static).
Raises an etl::mem_cast_nullptr_exception ETL_ASSERT if the memory block pointer is null.
Raises an etl::mem_cast_size_exception ETL_ASSERT if the buffer is not large enough.
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template <typename T, size_t Offset>
ETL_NODISCARD const T& ref_at_offset() const
Get a const reference to T at an offset from the start of the memory block (static).
Raises an etl::mem_cast_nullptr_exception ETL_ASSERT if the memory block pointer is null.
Raises an etl::mem_cast_size_exception ETL_ASSERT if the buffer is not large enough.
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ETL_NODISCARD size_t size() const
Get the size of the buffer.
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ETL_NODISCARD size_t alignment() const
Get the alignment of the buffer.
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void data(char* pbuffer, size_t buffer_size = Undefined_Size)
Set the pointer to the external buffer.
The default size is Undefined_Size.
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ETL_NODISCARD char* data()
Get a pointer to the internal buffer.
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ETL_NODISCARD const char* data() const
Get a const pointer to the internal buffer
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mem_cast_types
A variant of etl::mem_cast that deduces the size and alignment from the supplied list of types.
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C++03
template <typename T1,         typename T2  = char, typename T3  = char, typename T4  = char,
          typename T5  = char, typename T6  = char, typename T7  = char, typename T8  = char,
          typename T9  = char, typename T10 = char, typename T11 = char, typename T12 = char,
          typename T13 = char, typename T14 = char, typename T15 = char, typename T16 = char>
struct mem_cast_types :
  public etl::mem_cast<etl::largest<T1, T2, T3, T4, T5, T6, T7, T8,
                                    T9, T10, T11, T12, T13, T14, T15, T16>::size,
                       etl::largest<T1, T2, T3, T4, T5, T6, T7, T8,
                                    T9, T10, T11, T12, T13, T14, T15, T16>::alignment>
{
};
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C++11 and above
template <typename... TTypes>
using mem_cast_types = etl::mem_cast<etl::largest<TTypes...>::size, etl::largest<TTypes...>::alignment>;

mem_cast.h