This is the Python runtime library for the ASN.1 SCC compiler, providing ASN.1-specific types and encoding/decoding operations.

The asn1python library provides:

• Sized Integer Types: UInt8, UInt16, UInt32, UInt64, Int8, Int16, Int32, Int64 with overflow checking
• ASN.1 Semantic Types: Asn1Real, Asn1Boolean, NullType, Asn1ObjectIdentifier
• Time Types: Asn1Date, Asn1LocalTime, Asn1UtcTime, Asn1DateLocalTime
• Encoding/Decoding: Support for UPER, ACN, XER, and BER encoding rules
• Bitstream Operations: Precise bit-level manipulation
• Cross-Language Compatibility: Identical binary output with C, Ada, and Scala implementations

pip install -e .

This library is primarily used by code generated from the ASN.1 SCC compiler. For manual usage:

from asn1python import UInt8, UInt16, BitStream, UPERCodec

# Create sized integers
value = UInt8(255)  # 8-bit unsigned integer

# Bitstream operations
stream = BitStream()
stream.write_bits(value.value, 8)

# UPER encoding
codec = UPERCodec()
encoded = codec.encode_integer(value, min_val=0, max_val=255)

This library is automatically used by Python code generated from ASN.1 specifications:

# Generated Python code uses runtime types
from asn1python import UInt8, UInt16, Asn1Real

@dataclass
class MySequence:
    field1: UInt8
    field2: UInt16
    field3: Asn1Real

Run tests:

pytest tests/

Type checking:

mypy src/asn1python/

Code formatting:

black src/ tests/

The library follows the same architectural patterns as the C, Ada, and Scala runtime libraries:

• types.py: Core ASN.1 types and operations
• bitstream.py: Bit-level operations
• codec.py*: Encoding/decoding for different ASN.1 encoding rules
• helper.py: Utility functions
• verification.py: Constraint validation

This library is part of the ASN.1 SCC project and follows the same licensing terms.