python-osc/pythonosc/parsing/osc_types.py at main · ZipFile/python-osc · GitHub

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"""Functions to get OSC types from datagrams and vice versa"""

import struct

from pythonosc.parsing import ntp

from datetime import datetime, timedelta

from typing import Union, Tuple, cast

MidiPacket = Tuple[int, int, int, int]

class ParseError(Exception):

"""Base exception for when a datagram parsing error occurs."""

class BuildError(Exception):

"""Base exception for when a datagram building error occurs."""

# Constant for special ntp datagram sequences that represent an immediate time.

IMMEDIATELY = 0

# Datagram length in bytes for types that have a fixed size.

_INT_DGRAM_LEN = 4

_INT64_DGRAM_LEN = 8

_UINT64_DGRAM_LEN = 8

_FLOAT_DGRAM_LEN = 4

_DOUBLE_DGRAM_LEN = 8

_TIMETAG_DGRAM_LEN = 8

# Strings and blob dgram length is always a multiple of 4 bytes.

_STRING_DGRAM_PAD = 4

_BLOB_DGRAM_PAD = 4

_EMPTY_STR_DGRAM = b"\x00\x00\x00\x00"

def write_string(val: str) -> bytes:

"""Returns the OSC string equivalent of the given python string.

Raises:

- BuildError if the string could not be encoded.

"""

try:

dgram = val.encode("utf-8") # Default, but better be explicit.

except (UnicodeEncodeError, AttributeError) as e:

raise BuildError(f"Incorrect string, could not encode {e}")

diff = _STRING_DGRAM_PAD - (len(dgram) % _STRING_DGRAM_PAD)

dgram += b"\x00" * diff

return dgram

def get_string(dgram: bytes, start_index: int) -> Tuple[str, int]:

"""Get a python string from the datagram, starting at pos start_index.

According to the specifications, a string is:

"A sequence of non-null ASCII characters followed by a null,

followed by 0-3 additional null characters to make the total number

of bits a multiple of 32".

Args:

dgram: A datagram packet.

start_index: An index where the string starts in the datagram.

Returns:

A tuple containing the string and the new end index.

Raises:

ParseError if the datagram could not be parsed.

"""

if start_index < 0:

raise ParseError("start_index < 0")

offset = 0

try:

while dgram[start_index + offset] != 0:

offset += 1

# OSC spec: "followed by a null, followed by 0-3 additional null characters

# to make the total number of bits a multiple of 32"

# This means the total length (including the first null) must be a multiple of 4.

total_len = offset + 1

if total_len % 4 != 0:

total_len += 4 - (total_len % 4)

if start_index + total_len > len(dgram):

raise ParseError("Datagram is too short")

data_str = dgram[start_index : start_index + offset]

return data_str.decode("utf-8"), start_index + total_len

except IndexError as ie:

raise ParseError(f"Could not parse datagram {ie}")

except TypeError as te:

raise ParseError(f"Could not parse datagram {te}")

def write_int(val: int) -> bytes:

"""Returns the datagram for the given integer parameter value

Raises:

- BuildError if the int could not be converted.

"""

try:

return struct.pack(">i", val)

except struct.error as e:

raise BuildError(f"Wrong argument value passed: {e}")

def get_int(dgram: bytes, start_index: int) -> Tuple[int, int]:

"""Get a 32-bit big-endian two's complement integer from the datagram.

Args:

dgram: A datagram packet.

start_index: An index where the integer starts in the datagram.

Returns:

A tuple containing the integer and the new end index.

Raises:

ParseError if the datagram could not be parsed.

"""

try:

if len(dgram[start_index:]) < _INT_DGRAM_LEN:

raise ParseError("Datagram is too short")

return (

struct.unpack(">i", dgram[start_index : start_index + _INT_DGRAM_LEN])[0],

start_index + _INT_DGRAM_LEN,

)

except (struct.error, TypeError) as e:

raise ParseError(f"Could not parse datagram {e}")

def write_int64(val: int) -> bytes:

"""Returns the datagram for the given 64-bit big-endian signed parameter value

Raises:

- BuildError if the int64 could not be converted.

"""

try:

return struct.pack(">q", val)

except struct.error as e:

raise BuildError(f"Wrong argument value passed: {e}")

def get_int64(dgram: bytes, start_index: int) -> Tuple[int, int]:

"""Get a 64-bit big-endian signed integer from the datagram.

Args:

dgram: A datagram packet.

start_index: An index where the 64-bit integer starts in the datagram.

Returns:

A tuple containing the 64-bit integer and the new end index.

Raises:

ParseError if the datagram could not be parsed.

"""

try:

if len(dgram[start_index:]) < _INT64_DGRAM_LEN:

raise ParseError("Datagram is too short")

return (

struct.unpack(">q", dgram[start_index : start_index + _INT64_DGRAM_LEN])[0],

start_index + _INT64_DGRAM_LEN,

)

except (struct.error, TypeError) as e:

raise ParseError(f"Could not parse datagram {e}")

def get_uint64(dgram: bytes, start_index: int) -> Tuple[int, int]:

"""Get a 64-bit big-endian unsigned integer from the datagram.

Args:

dgram: A datagram packet.

start_index: An index where the integer starts in the datagram.

Returns:

A tuple containing the integer and the new end index.

Raises:

ParseError if the datagram could not be parsed.

"""

try:

if len(dgram[start_index:]) < _UINT64_DGRAM_LEN:

raise ParseError("Datagram is too short")

return (

struct.unpack(">Q", dgram[start_index : start_index + _UINT64_DGRAM_LEN])[

start_index + _UINT64_DGRAM_LEN,

)

except (struct.error, TypeError) as e:

raise ParseError(f"Could not parse datagram {e}")

def get_timetag(dgram: bytes, start_index: int) -> Tuple[Tuple[datetime, int], int]:

"""Get a 64-bit OSC time tag from the datagram.

Args:

dgram: A datagram packet.

start_index: An index where the osc time tag starts in the datagram.

Returns:

A tuple containing the tuple of time of sending in utc as datetime and the

fraction of the current second and the new end index.

Raises:

ParseError if the datagram could not be parsed.

"""

try:

if len(dgram[start_index:]) < _TIMETAG_DGRAM_LEN:

raise ParseError("Datagram is too short")

timetag, _ = get_uint64(dgram, start_index)

seconds, fraction = ntp.parse_timestamp(timetag)

utc = datetime.combine(ntp._NTP_EPOCH, datetime.min.time()) + timedelta(

seconds=seconds

)

return (utc, fraction), start_index + _TIMETAG_DGRAM_LEN

except (struct.error, TypeError) as e:

raise ParseError(f"Could not parse datagram {e}")

def write_float(val: float) -> bytes:

"""Returns the datagram for the given float parameter value

Raises:

- BuildError if the float could not be converted.

"""

try:

return struct.pack(">f", val)

except struct.error as e:

raise BuildError(f"Wrong argument value passed: {e}")

def get_float(dgram: bytes, start_index: int) -> Tuple[float, int]:

"""Get a 32-bit big-endian IEEE 754 floating point number from the datagram.

Args:

dgram: A datagram packet.

start_index: An index where the float starts in the datagram.

Returns:

A tuple containing the float and the new end index.

Raises:

ParseError if the datagram could not be parsed.

"""

try:

if len(dgram[start_index:]) < _FLOAT_DGRAM_LEN:

# Noticed that Reaktor doesn't send the last bunch of \x00 needed to make

# the float representation complete in some cases, thus we pad here to

# account for that.

dgram = dgram + b"\x00" * (_FLOAT_DGRAM_LEN - len(dgram[start_index:]))

return (

struct.unpack(">f", dgram[start_index : start_index + _FLOAT_DGRAM_LEN])[0],

start_index + _FLOAT_DGRAM_LEN,

)

except (struct.error, TypeError) as e:

raise ParseError(f"Could not parse datagram {e}")

def write_double(val: float) -> bytes:

"""Returns the datagram for the given double parameter value

Raises:

- BuildError if the double could not be converted.

"""

try:

return struct.pack(">d", val)

except struct.error as e:

raise BuildError(f"Wrong argument value passed: {e}")

def get_double(dgram: bytes, start_index: int) -> Tuple[float, int]:

"""Get a 64-bit big-endian IEEE 754 floating point number from the datagram.

Args:

dgram: A datagram packet.

start_index: An index where the double starts in the datagram.

Returns:

A tuple containing the double and the new end index.

Raises:

ParseError if the datagram could not be parsed.

"""

try:

if len(dgram[start_index:]) < _DOUBLE_DGRAM_LEN:

raise ParseError("Datagram is too short")

return (

struct.unpack(">d", dgram[start_index : start_index + _DOUBLE_DGRAM_LEN])[

start_index + _DOUBLE_DGRAM_LEN,

)

except (struct.error, TypeError) as e:

raise ParseError(f"Could not parse datagram {e}")

def get_blob(dgram: bytes, start_index: int) -> Tuple[bytes, int]:

"""Get a blob from the datagram.

According to the specifications, a blob is made of

"an int32 size count, followed by that many 8-bit bytes of arbitrary

binary data, followed by 0-3 additional zero bytes to make the total

number of bits a multiple of 32".

Args:

dgram: A datagram packet.

start_index: An index where the float starts in the datagram.

Returns:

A tuple containing the blob and the new end index.

Raises:

ParseError if the datagram could not be parsed.

"""

size, int_offset = get_int(dgram, start_index)

# Make the size a multiple of 32 bits.

total_size = size + (-size % _BLOB_DGRAM_PAD)

end_index = int_offset + size

if end_index - start_index > len(dgram[start_index:]):

raise ParseError("Datagram is too short.")

return dgram[int_offset : int_offset + size], int_offset + total_size

def write_blob(val: bytes) -> bytes:

"""Returns the datagram for the given blob parameter value.

Raises:

- BuildError if the value was empty or if its size didn't fit an OSC int.

"""

if not val:

raise BuildError("Blob value cannot be empty")

dgram = write_int(len(val))

dgram += val

while len(dgram) % _BLOB_DGRAM_PAD != 0:

dgram += b"\x00"

return dgram

def get_date(dgram: bytes, start_index: int) -> Tuple[float, int]:

"""Get a 64-bit big-endian fixed-point time tag as a date from the datagram.

According to the specifications, a date is represented as is:

"the first 32 bits specify the number of seconds since midnight on

January 1, 1900, and the last 32 bits specify fractional parts of a second

to a precision of about 200 picoseconds".

Args:

dgram: A datagram packet.

start_index: An index where the date starts in the datagram.

Returns:

A tuple containing the system date and the new end index.

returns osc_immediately (0) if the corresponding OSC sequence was found.

Raises:

ParseError if the datagram could not be parsed.

"""

# Check for the special case first.

if dgram[start_index : start_index + _TIMETAG_DGRAM_LEN] == ntp.IMMEDIATELY:

return IMMEDIATELY, start_index + _TIMETAG_DGRAM_LEN

if len(dgram[start_index:]) < _TIMETAG_DGRAM_LEN:

raise ParseError("Datagram is too short")

timetag, start_index = get_uint64(dgram, start_index)

seconds = timetag * ntp._NTP_TIMESTAMP_TO_SECONDS

return ntp.ntp_time_to_system_epoch(seconds), start_index

def write_date(system_time: Union[int, float]) -> bytes:

if system_time == IMMEDIATELY:

return ntp.IMMEDIATELY

try:

return ntp.system_time_to_ntp(system_time)

except ntp.NtpError as ntpe:

raise BuildError(ntpe)

def write_rgba(val: bytes) -> bytes:

"""Returns the datagram for the given rgba32 parameter value

Raises:

- BuildError if the int could not be converted.

"""

try:

return struct.pack(">I", val)

except struct.error as e:

raise BuildError(f"Wrong argument value passed: {e}")

def get_rgba(dgram: bytes, start_index: int) -> Tuple[bytes, int]:

"""Get an rgba32 integer from the datagram.

Args:

dgram: A datagram packet.

start_index: An index where the integer starts in the datagram.

Returns:

A tuple containing the integer and the new end index.

Raises:

ParseError if the datagram could not be parsed.

"""

try:

if len(dgram[start_index:]) < _INT_DGRAM_LEN:

raise ParseError("Datagram is too short")

return (

struct.unpack(">I", dgram[start_index : start_index + _INT_DGRAM_LEN])[0],

start_index + _INT_DGRAM_LEN,

)

except (struct.error, TypeError) as e:

raise ParseError(f"Could not parse datagram {e}")

def write_midi(val: MidiPacket) -> bytes:

"""Returns the datagram for the given MIDI message parameter value

A valid MIDI message: (port id, status byte, data1, data2).

Raises:

- BuildError if the MIDI message could not be converted.

"""

if len(val) != 4:

raise BuildError("MIDI message length is invalid")

try:

value = sum((value & 0xFF) << 8 * (3 - pos) for pos, value in enumerate(val))

return struct.pack(">I", value)

except struct.error as e:

raise BuildError(f"Wrong argument value passed: {e}")

def get_midi(dgram: bytes, start_index: int) -> Tuple[MidiPacket, int]:

"""Get a MIDI message (port id, status byte, data1, data2) from the datagram.

Args:

dgram: A datagram packet.

start_index: An index where the MIDI message starts in the datagram.

Returns:

A tuple containing the MIDI message and the new end index.

Raises:

ParseError if the datagram could not be parsed.

"""

try:

if len(dgram[start_index:]) < _INT_DGRAM_LEN:

raise ParseError("Datagram is too short")

val = struct.unpack(">I", dgram[start_index : start_index + _INT_DGRAM_LEN])[0]

midi_msg = cast(

MidiPacket, tuple((val & 0xFF << 8 * i) >> 8 * i for i in range(3, -1, -1))

)

return (midi_msg, start_index + _INT_DGRAM_LEN)

except (struct.error, TypeError) as e:

raise ParseError(f"Could not parse datagram {e}")

python-osc/pythonosc/parsing/osc_types.py at main · ZipFile/python-osc · GitHub

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