# py-packed-struct
An implementation of C-like packed structures in Python based on the [`bitstruct`](https://bitstruct.readthedocs.io/en/latest/index.html) package
**py-packed-struct** allows to define C-like structures in an elegant way and to convert them into `bytes` objects without having to specify the format as required by `struct`:
```python
# with struct
>>> from struct import *
>>> one, two, three = 1, 2, 3
>>> pack(">bhl", one, two, three)
b'\x01\x00\x02\x00\x00\x00\x03'
# with py-packed-struct
>>> from packed_struct import *
>>> s = Struct({"one": c_signed_int(8), "two": c_signed_int(16), "three": c_signed_int(32) })
>>> s.set_data(one = 1, two = 2, three = 3)
>>> serialized = s.pack(byte_endianness="big")
>>> print(serialized)
b'\x01\x00\x02\x00\x00\x00\x03'
>>>
>>> s.unpack(serialized)
>>> {'one': 1, 'two': 2, 'three': 3}
```
Who needs to remember struct format strings? :)
In addition, **py-packed-struct** allows to work with bit-fields and nested structures (see [examples](https://github.com/lu-maca/py-packed-struct/tree/main/examples)).
Installation
----
```bash
pip install py-packed-struct
```
Supported features
----
- C-like struct
- bit-fields handling
- byte endianess
- (TODO) bit endianness
Example
----
This example can be found in [`example/mqtt`](https://github.com/lu-maca/py-packed-struct/tree/main/examples/mqtt). `publisher.py` publishes a message on a MQTT topic and `subscriber.c` is subscribed to that topic. The publisher publishes the following structure:
```python
person = Struct(
{
"name": c_char(10*8),
"age": c_unsigned_int(8),
"weight": c_float(32),
"dresses": Struct(
{
"tshirt": c_char(10*8),
"shorts": c_char(10*8),
"shoes": Struct(
{
"number": c_unsigned_int(8),
"brand": c_char(10*8)
}
)
}
)
}
)
# set data values
person.set_data(name="Luca", age=29, weight=76.9)
person.dresses.set_data(tshirt="foo", shorts="boo")
person.dresses.shoes.set_data(number=42, brand="bar")
```
The subscriber copies the incoming buffer in the following `struct`:
```c
typedef struct __attribute__((packed)) {
uint8_t number;
char brand[10];
} shoes_t;
typedef struct __attribute__((packed)) {
char tshirt[10];
char shorts[10];
shoes_t shoes;
} clothes_t;
typedef struct __attribute__((packed)) {
char name[10];
uint8_t age;
float weight;
clothes_t clothes;
} person;
```
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"description": "# py-packed-struct\nAn implementation of C-like packed structures in Python based on the [`bitstruct`](https://bitstruct.readthedocs.io/en/latest/index.html) package\n\n**py-packed-struct** allows to define C-like structures in an elegant way and to convert them into `bytes` objects without having to specify the format as required by `struct`:\n```python\n# with struct\n>>> from struct import *\n>>> one, two, three = 1, 2, 3\n>>> pack(\">bhl\", one, two, three)\nb'\\x01\\x00\\x02\\x00\\x00\\x00\\x03'\n\n# with py-packed-struct\n>>> from packed_struct import *\n>>> s = Struct({\"one\": c_signed_int(8), \"two\": c_signed_int(16), \"three\": c_signed_int(32) })\n>>> s.set_data(one = 1, two = 2, three = 3)\n>>> serialized = s.pack(byte_endianness=\"big\")\n>>> print(serialized)\nb'\\x01\\x00\\x02\\x00\\x00\\x00\\x03'\n>>>\n>>> s.unpack(serialized)\n>>> {'one': 1, 'two': 2, 'three': 3}\n```\nWho needs to remember struct format strings? :)\n\nIn addition, **py-packed-struct** allows to work with bit-fields and nested structures (see [examples](https://github.com/lu-maca/py-packed-struct/tree/main/examples)).\n\nInstallation\n----\n```bash\npip install py-packed-struct\n```\n\nSupported features\n----\n- C-like struct\n- bit-fields handling\n- byte endianess\n- (TODO) bit endianness\n\n\nExample\n----\nThis example can be found in [`example/mqtt`](https://github.com/lu-maca/py-packed-struct/tree/main/examples/mqtt). `publisher.py` publishes a message on a MQTT topic and `subscriber.c` is subscribed to that topic. The publisher publishes the following structure:\n```python\nperson = Struct(\n {\n \"name\": c_char(10*8),\n \"age\": c_unsigned_int(8),\n \"weight\": c_float(32),\n \"dresses\": Struct(\n {\n \"tshirt\": c_char(10*8),\n \"shorts\": c_char(10*8),\n \"shoes\": Struct(\n {\n \"number\": c_unsigned_int(8),\n \"brand\": c_char(10*8)\n }\n )\n }\n )\n }\n)\n# set data values\nperson.set_data(name=\"Luca\", age=29, weight=76.9)\nperson.dresses.set_data(tshirt=\"foo\", shorts=\"boo\")\nperson.dresses.shoes.set_data(number=42, brand=\"bar\")\n```\nThe subscriber copies the incoming buffer in the following `struct`:\n```c\ntypedef struct __attribute__((packed)) {\n\tuint8_t number;\n\tchar brand[10];\n} shoes_t;\n\ntypedef struct __attribute__((packed)) {\n\tchar tshirt[10];\n\tchar shorts[10];\n\tshoes_t shoes;\n} clothes_t;\n\ntypedef struct __attribute__((packed)) {\n\tchar name[10];\n\tuint8_t age;\n\tfloat weight;\n\tclothes_t clothes;\n} person;\n```\n\nThe result is the following:\n\n\n\n\n",
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