cremalink.core.binary module

This module provides binary utility functions for handling data conversions, checksum calculations, and bitwise operations, often required for communication with hardware devices.

cremalink.core.binary.b64_to_cmd_hex(b64_data: str) → str

Decodes a base64 string, extracts a command frame, and returns it as a hex string.

The function cleans the input base64 string, decodes it, and then uses the second byte of the decoded data as a length specifier to extract the relevant command frame.

Parameters:

b64_data – The base64 encoded data string.

Returns:

The extracted command frame as a hexadecimal string.

cremalink.core.binary.crc16_ccitt(data: bytes) → bytes

Calculates the CRC-16 CCITT checksum for the given data.

This implementation uses a specific initial value (0x1D0F) and polynomial (0x1021).

Parameters:

data – The input bytes to checksum.

Returns:

A 2-byte sequence representing the calculated CRC in big-endian format.

cremalink.core.binary.get_bit(byte_value: int, bit_index: int) → bool

Gets the value of a specific bit in a byte.

Parameters:

• byte_value – The integer representation of the byte.

• bit_index – The index of the bit to retrieve (0-7).

Returns:

True if the bit is 1, False if it is 0.

Raises:

ValueError – If bit_index is not between 0 and 7.

cremalink.core.binary.safe_byte_at(data: Iterable[int] | bytes, index: int) → int | None

Safely retrieves a byte from a sequence or iterable at a given index.

Parameters:

• data – The data to access, can be bytes or an iterable of integers.

• index – The index of the byte to retrieve.

Returns:

The byte as an integer if the index is valid, otherwise None.