Reference

StructDef (struct representation)

class pycstruct.StructDef(default_byteorder='native')

This class represents a struct definition

Parameters:default_byteorder (str, optional) – Byte order of each element unless explicilty set for the element. Valid values are ‘native’, ‘little’ and ‘big’.
add(type, name, length=1, byteorder='')

Add a new element in the struct definition. The element will be added directly after the previous element. Padding is never added.

  • Supported data types:

    Name Size in bytes Comment
    int8 1 Integer
    uint8 1 Unsigned integer
    bool8 1 True (<>0) or False (0)
    int16 2 Integer
    uint16 2 Unsigned integer
    bool16 2 True (<>0) or False (0)
    float16 2 Floating point number
    int32 4 Integer
    uint32 4 Unsigned integer
    bool32 4 True (<>0) or False (0)
    float32 4 Floating point number
    int64 8 Integer
    uint64 8 Unsigned integer
    bool64 8 True (<>0) or False (0)
    float64 8 Floating point number
    utf-8 1 UTF-8/ASCII string. Use length parameter to set the length of the string including null termination
    struct struct size Embedded struct. The actual StructDef object shall be set as type and not ‘struct’ string.
    bitfield bitfield size
    Bitfield. The actual
    BitfieldDef() object shall be

    set as type and not ‘bitfield’ string.
    enum enum size Enum. The actual EnumDef() object shall be set as type and not ‘enum’ string.
Parameters:
  • type (str) – Element data type. See above.
  • name (str) – Name of element. Needs to be unique.
  • length (int, optional) – Number of elements. If > 1 this is an array/list of elements with equal size. Default is 1.
  • byteorder (str, optional) – Byteorder of this element. Valid values are ‘native’, ‘little’ and ‘big’. If not specified the default byteorder is used.
deserialize(buffer)

Deserialize buffer into dictionary

Parameters:buffer (bytearray) – Buffer that contains the data to deserialize
Returns:A dictionary keyed with the element names
Return type:dict
serialize(data)

Serialize dictionary into buffer

Parameters:data (dict) – A dictionary keyed with element names. Elements can be omitted from the dictionary (defaults to value 0).
Returns:A buffer that contains data
Return type:bytearray
size()

Get size of structure

Returns:Number of bytes this structure represents
Return type:int

BitfieldDef (bitfield representation)

class pycstruct.BitfieldDef(byteorder='native')

This class represents a bit field definition

The size of the bit field is 1, 2, 3, .., 8 bytes depending on the number of elements added to the bit field. If a larger size is required than what is required by the elements you have to add additional, “dummy”, elements.

Parameters:byteorder (str, optional) – Byte order of the bitfield. Valid values are ‘native’, ‘little’ and ‘big’.
add(name, nbr_of_bits=1, signed=False)

Add a new element in the bitfield definition. The element will be added directly after the previous element.

The size of the bitfield will expand when required, but adding more than in total 64 bits (8 bytes) will generate an exception.

Parameters:
  • name (str) – Name of element. Needs to be unique.
  • nbr_of_bits (int, optional) – Number of bits this element represents. Default is 1.
  • signed (bool, optional) – Should the bit field be signed or not. Default is False.
assigned_bits()

Get size of bitfield in bits excluding padding bits

Returns:Number of bits this bitfield represents excluding padding bits
Return type:int
deserialize(buffer)

Deserialize buffer into dictionary

Parameters:buffer (bytearray) – Buffer that contains the data to deserialize (1 - 8 bytes)
Returns:A dictionary keyed with the element names
Return type:dict
serialize(data)

Serialize dictionary into buffer

Parameters:data (dict) – A dictionary keyed with element names. Elements can be omitted from the dictionary (defaults to value 0).
Returns:A buffer that contains data
Return type:bytearray
size()

Get size of bitfield in bytes

Returns:Number of bytes this bitfield represents
Return type:int

EnumDef (enum representation)

class pycstruct.EnumDef(byteorder='native')

This class represents an enum definition

The size of the enum is 1, 2, 3, .., 8 bytes depending on the value of the largest enum constant. If a larger size is required than what is required by the constants you have to add a dummy constant with a value which will force a the enum to have a particular size.

This implementation assumes that an enum is always signed.

Parameters:byteorder (str, optional) – Byte order of the enum. Valid values are ‘native’, ‘little’ and ‘big’.
add(name, value=None)

Add a new constant in the enum definition. Multiple constant might be assigned to the same value.

The size of the enum will expand when required, but adding a value requiering a size larger than 64 bits will generate an exception.

Parameters:
  • name (str) – Name of constant. Needs to be unique.
  • value (int, optional) – Value of the constant. Automatically assigned to next available value (0, 1, 2, …) if not provided.
deserialize(buffer)

Deserialize buffer into a string (constant name)

Parameters:buffer (bytearray) – Buffer that contains the data to deserialize (1 - 8 bytes)
Returns:The constant name (string)
Return type:str
get_name(value)

Get the name representation of the value

Returns:The constant name
Return type:str
get_value(name)

Get the value representation of the name

Returns:The value
Return type:int
serialize(data)

Serialize string (constant name) into buffer

Parameters:data (str) – A string representing the constant name.
Returns:A buffer that contains data
Return type:bytearray
size()

Get size of enum in bytes

Returns:Number of bytes this enum represents
Return type:int