"""Stuff to parse AIFF-C and AIFF files.

Unless explicitly stated otherwise, the description below is true
both for AIFF-C files and AIFF files.

An AIFF-C file has the following structure.

 +-----------------+
 | FORM |
 +-----------------+
 | <size> |
 +----+------------+
 | | AIFC |
 | +------------+
 | | <chunks> |
 | | . |
 | | . |
 | | . |
 +----+------------+

An AIFF file has the string "AIFF" instead of "AIFC".

A chunk consists of an identifier (4 bytes) followed by a size (4 bytes,
big endian order), followed by the data. The size field does not include
the size of the 8 byte header.

The following chunk types are recognized.

 FVER
 <version number of AIFF-C defining document> (AIFF-C only).
 MARK
 <# of markers> (2 bytes)
 list of markers:
 <marker ID> (2 bytes, must be > 0)
 <position> (4 bytes)
 <marker name> ("pstring")
 COMM
 <# of channels> (2 bytes)
 <# of sound frames> (4 bytes)
 <size of the samples> (2 bytes)
 <sampling frequency> (10 bytes, IEEE 80-bit extended
 floating point)
 in AIFF-C files only:
 <compression type> (4 bytes)
 <human-readable version of compression type> ("pstring")
 SSND
 <offset> (4 bytes, not used by this program)
 <blocksize> (4 bytes, not used by this program)
 <sound data>

A pstring consists of 1 byte length, a string of characters, and 0 or 1
byte pad to make the total length even.

Usage.

Reading AIFF files:
 f = aifc.open(file, 'r')
where file is either the name of a file or an open file pointer.
The open file pointer must have methods read(), seek(), and close().
In some types of audio files, if the setpos() method is not used,
the seek() method is not necessary.

This returns an instance of a class with the following public methods:
 getnchannels() -- returns number of audio channels (1 for
 mono, 2 for stereo)
 getsampwidth() -- returns sample width in bytes
 getframerate() -- returns sampling frequency
 getnframes() -- returns number of audio frames
 getcomptype() -- returns compression type ('NONE' for AIFF files)
 getcompname() -- returns human-readable version of
 compression type ('not compressed' for AIFF files)
 getparams() -- returns a namedtuple consisting of all of the
 above in the above order
 getmarkers() -- get the list of marks in the audio file or None
 if there are no marks
 getmark(id) -- get mark with the specified id (raises an error
 if the mark does not exist)
 readframes(n) -- returns at most n frames of audio
 rewind() -- rewind to the beginning of the audio stream
 setpos(pos) -- seek to the specified position
 tell() -- return the current position
 close() -- close the instance (make it unusable)
The position returned by tell(), the position given to setpos() and
the position of marks are all compatible and have nothing to do with
the actual position in the file.
The close() method is called automatically when the class instance
is destroyed.

Writing AIFF files:
 f = aifc.open(file, 'w')
where file is either the name of a file or an open file pointer.
The open file pointer must have methods write(), tell(), seek(), and
close().

This returns an instance of a class with the following public methods:
 aiff() -- create an AIFF file (AIFF-C default)
 aifc() -- create an AIFF-C file
 setnchannels(n) -- set the number of channels
 setsampwidth(n) -- set the sample width
 setframerate(n) -- set the frame rate
 setnframes(n) -- set the number of frames
 setcomptype(type, name)
 -- set the compression type and the
 human-readable compression type
 setparams(tuple)
 -- set all parameters at once
 setmark(id, pos, name)
 -- add specified mark to the list of marks
 tell() -- return current position in output file (useful
 in combination with setmark())
 writeframesraw(data)
 -- write audio frames without pathing up the
 file header
 writeframes(data)
 -- write audio frames and patch up the file header
 close() -- patch up the file header and close the
 output file
You should set the parameters before the first writeframesraw or
writeframes. The total number of frames does not need to be set,
but when it is set to the correct value, the header does not have to
be patched up.
It is best to first set all parameters, perhaps possibly the
compression type, and then write audio frames using writeframesraw.
When all frames have been written, either call writeframes(b'') or
close() to patch up the sizes in the header.
Marks can be added anytime. If there are any marks, you must call
close() after all frames have been written.
The close() method is called automatically when the class instance
is destroyed.

When a file is opened with the extension '.aiff', an AIFF file is
written, otherwise an AIFF-C file is written. This default can be
changed by calling aiff() or aifc() before the first writeframes or
writeframesraw.
"""

import struct
import builtins
import warnings

__all__ = ["Error", "open", "openfp"]

class Error(Exception):
 pass

_AIFC_version = 0xA2805140 # Version 1 of AIFF-C

def _read_long(file):
 try:
 return struct.unpack('>l', file.read(4))[0]
 except struct.error:
 raise EOFError from None

def _read_ulong(file):
 try:
 return struct.unpack('>L', file.read(4))[0]
 except struct.error:
 raise EOFError from None

def _read_short(file):
 try:
 return struct.unpack('>h', file.read(2))[0]
 except struct.error:
 raise EOFError from None

def _read_ushort(file):
 try:
 return struct.unpack('>H', file.read(2))[0]
 except struct.error:
 raise EOFError from None

def _read_string(file):
 length = ord(file.read(1))
 if length == 0:
 data = b''
 else:
 data = file.read(length)
 if length & 1 == 0:
 dummy = file.read(1)
 return data

_HUGE_VAL = 1.79769313486231e+308 # See <limits.h>

def _read_float(f): # 10 bytes
 expon = _read_short(f) # 2 bytes
 sign = 1
 if expon < 0:
 sign = -1
 expon = expon + 0x8000
 himant = _read_ulong(f) # 4 bytes
 lomant = _read_ulong(f) # 4 bytes
 if expon == himant == lomant == 0:
 f = 0.0
 elif expon == 0x7FFF:
 f = _HUGE_VAL
 else:
 expon = expon - 16383
 f = (himant * 0x100000000 + lomant) * pow(2.0, expon - 63)
 return sign * f

def _write_short(f, x):
 f.write(struct.pack('>h', x))

def _write_ushort(f, x):
 f.write(struct.pack('>H', x))

def _write_long(f, x):
 f.write(struct.pack('>l', x))

def _write_ulong(f, x):
 f.write(struct.pack('>L', x))

def _write_string(f, s):
 if len(s) > 255:
 raise ValueError("string exceeds maximum pstring length")
 f.write(struct.pack('B', len(s)))
 f.write(s)
 if len(s) & 1 == 0:
 f.write(b'\x00')

def _write_float(f, x):
 import math
 if x < 0:
 sign = 0x8000
 x = x * -1
 else:
 sign = 0
 if x == 0:
 expon = 0
 himant = 0
 lomant = 0
 else:
 fmant, expon = math.frexp(x)
 if expon > 16384 or fmant >= 1 or fmant != fmant: # Infinity or NaN
 expon = sign|0x7FFF
 himant = 0
 lomant = 0
 else: # Finite
 expon = expon + 16382
 if expon < 0: # denormalized
 fmant = math.ldexp(fmant, expon)
 expon = 0
 expon = expon | sign
 fmant = math.ldexp(fmant, 32)
 fsmant = math.floor(fmant)
 himant = int(fsmant)
 fmant = math.ldexp(fmant - fsmant, 32)
 fsmant = math.floor(fmant)
 lomant = int(fsmant)
 _write_ushort(f, expon)
 _write_ulong(f, himant)
 _write_ulong(f, lomant)

from chunk import Chunk
from collections import namedtuple

_aifc_params = namedtuple('_aifc_params',
 'nchannels sampwidth framerate nframes comptype compname')

_aifc_params.nchannels.__doc__ = 'Number of audio channels (1 for mono, 2 for stereo)'
_aifc_params.sampwidth.__doc__ = 'Sample width in bytes'
_aifc_params.framerate.__doc__ = 'Sampling frequency'
_aifc_params.nframes.__doc__ = 'Number of audio frames'
_aifc_params.comptype.__doc__ = 'Compression type ("NONE" for AIFF files)'
_aifc_params.compname.__doc__ = ("""\
A human-readable version of the compression type
('not compressed' for AIFF files)""")


class Aifc_read:
 # Variables used in this class:
 #
 # These variables are available to the user though appropriate
 # methods of this class:
 # _file -- the open file with methods read(), close(), and seek()
 # set through the __init__() method
 # _nchannels -- the number of audio channels
 # available through the getnchannels() method
 # _nframes -- the number of audio frames
 # available through the getnframes() method
 # _sampwidth -- the number of bytes per audio sample
 # available through the getsampwidth() method
 # _framerate -- the sampling frequency
 # available through the getframerate() method
 # _comptype -- the AIFF-C compression type ('NONE' if AIFF)
 # available through the getcomptype() method
 # _compname -- the human-readable AIFF-C compression type
 # available through the getcomptype() method
 # _markers -- the marks in the audio file
 # available through the getmarkers() and getmark()
 # methods
 # _soundpos -- the position in the audio stream
 # available through the tell() method, set through the
 # setpos() method
 #
 # These variables are used internally only:
 # _version -- the AIFF-C version number
 # _decomp -- the decompressor from builtin module cl
 # _comm_chunk_read -- 1 iff the COMM chunk has been read
 # _aifc -- 1 iff reading an AIFF-C file
 # _ssnd_seek_needed -- 1 iff positioned correctly in audio
 # file for readframes()
 # _ssnd_chunk -- instantiation of a chunk class for the SSND chunk
 # _framesize -- size of one frame in the file

 _file = None # Set here since __del__ checks it

 def initfp(self, file):
 self._version = 0
 self._convert = None
 self._markers = []
 self._soundpos = 0
 self._file = file
 chunk = Chunk(file)
 if chunk.getname() != b'FORM':
 raise Error('file does not start with FORM id')
 formdata = chunk.read(4)
 if formdata == b'AIFF':
 self._aifc = 0
 elif formdata == b'AIFC':
 self._aifc = 1
 else:
 raise Error('not an AIFF or AIFF-C file')
 self._comm_chunk_read = 0
 self._ssnd_chunk = None
 while 1:
 self._ssnd_seek_needed = 1
 try:
 chunk = Chunk(self._file)
 except EOFError:
 break
 chunkname = chunk.getname()
 if chunkname == b'COMM':
 self._read_comm_chunk(chunk)
 self._comm_chunk_read = 1
 elif chunkname == b'SSND':
 self._ssnd_chunk = chunk
 dummy = chunk.read(8)
 self._ssnd_seek_needed = 0
 elif chunkname == b'FVER':
 self._version = _read_ulong(chunk)
 elif chunkname == b'MARK':
 self._readmark(chunk)
 chunk.skip()
 if not self._comm_chunk_read or not self._ssnd_chunk:
 raise Error('COMM chunk and/or SSND chunk missing')

 def __init__(self, f):
 if isinstance(f, str):
 file_object = builtins.open(f, 'rb')
 try:
 self.initfp(file_object)
 except:
 file_object.close()
 raise
 else:
 # assume it is an open file object already
 self.initfp(f)

 def __enter__(self):
 return self

 def __exit__(self, *args):
 self.close()

 #
 # User visible methods.
 #
 def getfp(self):
 return self._file

 def rewind(self):
 self._ssnd_seek_needed = 1
 self._soundpos = 0

 def close(self):
 file = self._file
 if file is not None:
 self._file = None
 file.close()

 def tell(self):
 return self._soundpos

 def getnchannels(self):
 return self._nchannels

 def getnframes(self):
 return self._nframes

 def getsampwidth(self):
 return self._sampwidth

 def getframerate(self):
 return self._framerate

 def getcomptype(self):
 return self._comptype

 def getcompname(self):
 return self._compname

## def getversion(self):
## return self._version

 def getparams(self):
 return _aifc_params(self.getnchannels(), self.getsampwidth(),
 self.getframerate(), self.getnframes(),
 self.getcomptype(), self.getcompname())

 def getmarkers(self):
 if len(self._markers) == 0:
 return None
 return self._markers

 def getmark(self, id):
 for marker in self._markers:
 if id == marker[0]:
 return marker
 raise Error('marker {0!r} does not exist'.format(id))

 def setpos(self, pos):
 if pos < 0 or pos > self._nframes:
 raise Error('position not in range')
 self._soundpos = pos
 self._ssnd_seek_needed = 1

 def readframes(self, nframes):
 if self._ssnd_seek_needed:
 self._ssnd_chunk.seek(0)
 dummy = self._ssnd_chunk.read(8)
 pos = self._soundpos * self._framesize
 if pos:
 self._ssnd_chunk.seek(pos + 8)
 self._ssnd_seek_needed = 0
 if nframes == 0:
 return b''
 data = self._ssnd_chunk.read(nframes * self._framesize)
 if self._convert and data:
 data = self._convert(data)
 self._soundpos = self._soundpos + len(data) // (self._nchannels
 * self._sampwidth)
 return data

 #
 # Internal methods.
 #

 def _alaw2lin(self, data):
 import audioop
 return audioop.alaw2lin(data, 2)

 def _ulaw2lin(self, data):
 import audioop
 return audioop.ulaw2lin(data, 2)

 def _adpcm2lin(self, data):
 import audioop
 if not hasattr(self, '_adpcmstate'):
 # first time
 self._adpcmstate = None
 data, self._adpcmstate = audioop.adpcm2lin(data, 2, self._adpcmstate)
 return data

 def _read_comm_chunk(self, chunk):
 self._nchannels = _read_short(chunk)
 self._nframes = _read_long(chunk)
 self._sampwidth = (_read_short(chunk) + 7) // 8
 self._framerate = int(_read_float(chunk))
 if self._sampwidth <= 0:
 raise Error('bad sample width')
 if self._nchannels <= 0:
 raise Error('bad # of channels')
 self._framesize = self._nchannels * self._sampwidth
 if self._aifc:
 #DEBUG: SGI's soundeditor produces a bad size :-(
 kludge = 0
 if chunk.chunksize == 18:
 kludge = 1
 warnings.warn('Warning: bad COMM chunk size')
 chunk.chunksize = 23
 #DEBUG end
 self._comptype = chunk.read(4)
 #DEBUG start
 if kludge:
 length = ord(chunk.file.read(1))
 if length & 1 == 0:
 length = length + 1
 chunk.chunksize = chunk.chunksize + length
 chunk.file.seek(-1, 1)
 #DEBUG end
 self._compname = _read_string(chunk)
 if self._comptype != b'NONE':
 if self._comptype == b'G722':
 self._convert = self._adpcm2lin
 elif self._comptype in (b'ulaw', b'ULAW'):
 self._convert = self._ulaw2lin
 elif self._comptype in (b'alaw', b'ALAW'):
 self._convert = self._alaw2lin
 else:
 raise Error('unsupported compression type')
 self._sampwidth = 2
 else:
 self._comptype = b'NONE'
 self._compname = b'not compressed'

 def _readmark(self, chunk):
 nmarkers = _read_short(chunk)
 # Some files appear to contain invalid counts.
 # Cope with this by testing for EOF.
 try:
 for i in range(nmarkers):
 id = _read_short(chunk)
 pos = _read_long(chunk)
 name = _read_string(chunk)
 if pos or name:
 # some files appear to have
 # dummy markers consisting of
 # a position 0 and name ''
 self._markers.append((id, pos, name))
 except EOFError:
 w = ('Warning: MARK chunk contains only %s marker%s instead of %s' %
 (len(self._markers), '' if len(self._markers) == 1 else 's',
 nmarkers))
 warnings.warn(w)

class Aifc_write:
 # Variables used in this class:
 #
 # These variables are user settable through appropriate methods
 # of this class:
 # _file -- the open file with methods write(), close(), tell(), seek()
 # set through the __init__() method
 # _comptype -- the AIFF-C compression type ('NONE' in AIFF)
 # set through the setcomptype() or setparams() method
 # _compname -- the human-readable AIFF-C compression type
 # set through the setcomptype() or setparams() method
 # _nchannels -- the number of audio channels
 # set through the setnchannels() or setparams() method
 # _sampwidth -- the number of bytes per audio sample
 # set through the setsampwidth() or setparams() method
 # _framerate -- the sampling frequency
 # set through the setframerate() or setparams() method
 # _nframes -- the number of audio frames written to the header
 # set through the setnframes() or setparams() method
 # _aifc -- whether we're writing an AIFF-C file or an AIFF file
 # set through the aifc() method, reset through the
 # aiff() method
 #
 # These variables are used internally only:
 # _version -- the AIFF-C version number
 # _comp -- the compressor from builtin module cl
 # _nframeswritten -- the number of audio frames actually written
 # _datalength -- the size of the audio samples written to the header
 # _datawritten -- the size of the audio samples actually written

 _file = None # Set here since __del__ checks it

 def __init__(self, f):
 if isinstance(f, str):
 file_object = builtins.open(f, 'wb')
 try:
 self.initfp(file_object)
 except:
 file_object.close()
 raise

 # treat .aiff file extensions as non-compressed audio
 if f.endswith('.aiff'):
 self._aifc = 0
 else:
 # assume it is an open file object already
 self.initfp(f)

 def initfp(self, file):
 self._file = file
 self._version = _AIFC_version
 self._comptype = b'NONE'
 self._compname = b'not compressed'
 self._convert = None
 self._nchannels = 0
 self._sampwidth = 0
 self._framerate = 0
 self._nframes = 0
 self._nframeswritten = 0
 self._datawritten = 0
 self._datalength = 0
 self._markers = []
 self._marklength = 0
 self._aifc = 1 # AIFF-C is default

 def __del__(self):
 self.close()

 def __enter__(self):
 return self

 def __exit__(self, *args):
 self.close()

 #
 # User visible methods.
 #
 def aiff(self):
 if self._nframeswritten:
 raise Error('cannot change parameters after starting to write')
 self._aifc = 0

 def aifc(self):
 if self._nframeswritten:
 raise Error('cannot change parameters after starting to write')
 self._aifc = 1

 def setnchannels(self, nchannels):
 if self._nframeswritten:
 raise Error('cannot change parameters after starting to write')
 if nchannels < 1:
 raise Error('bad # of channels')
 self._nchannels = nchannels

 def getnchannels(self):
 if not self._nchannels:
 raise Error('number of channels not set')
 return self._nchannels

 def setsampwidth(self, sampwidth):
 if self._nframeswritten:
 raise Error('cannot change parameters after starting to write')
 if sampwidth < 1 or sampwidth > 4:
 raise Error('bad sample width')
 self._sampwidth = sampwidth

 def getsampwidth(self):
 if not self._sampwidth:
 raise Error('sample width not set')
 return self._sampwidth

 def setframerate(self, framerate):
 if self._nframeswritten:
 raise Error('cannot change parameters after starting to write')
 if framerate <= 0:
 raise Error('bad frame rate')
 self._framerate = framerate

 def getframerate(self):
 if not self._framerate:
 raise Error('frame rate not set')
 return self._framerate

 def setnframes(self, nframes):
 if self._nframeswritten:
 raise Error('cannot change parameters after starting to write')
 self._nframes = nframes

 def getnframes(self):
 return self._nframeswritten

 def setcomptype(self, comptype, compname):
 if self._nframeswritten:
 raise Error('cannot change parameters after starting to write')
 if comptype not in (b'NONE', b'ulaw', b'ULAW',
 b'alaw', b'ALAW', b'G722'):
 raise Error('unsupported compression type')
 self._comptype = comptype
 self._compname = compname

 def getcomptype(self):
 return self._comptype

 def getcompname(self):
 return self._compname

## def setversion(self, version):
## if self._nframeswritten:
## raise Error, 'cannot change parameters after starting to write'
## self._version = version

 def setparams(self, params):
 nchannels, sampwidth, framerate, nframes, comptype, compname = params
 if self._nframeswritten:
 raise Error('cannot change parameters after starting to write')
 if comptype not in (b'NONE', b'ulaw', b'ULAW',
 b'alaw', b'ALAW', b'G722'):
 raise Error('unsupported compression type')
 self.setnchannels(nchannels)
 self.setsampwidth(sampwidth)
 self.setframerate(framerate)
 self.setnframes(nframes)
 self.setcomptype(comptype, compname)

 def getparams(self):
 if not self._nchannels or not self._sampwidth or not self._framerate:
 raise Error('not all parameters set')
 return _aifc_params(self._nchannels, self._sampwidth, self._framerate,
 self._nframes, self._comptype, self._compname)

 def setmark(self, id, pos, name):
 if id <= 0:
 raise Error('marker ID must be > 0')
 if pos < 0:
 raise Error('marker position must be >= 0')
 if not isinstance(name, bytes):
 raise Error('marker name must be bytes')
 for i in range(len(self._markers)):
 if id == self._markers[i][0]:
 self._markers[i] = id, pos, name
 return
 self._markers.append((id, pos, name))

 def getmark(self, id):
 for marker in self._markers:
 if id == marker[0]:
 return marker
 raise Error('marker {0!r} does not exist'.format(id))

 def getmarkers(self):
 if len(self._markers) == 0:
 return None
 return self._markers

 def tell(self):
 return self._nframeswritten

 def writeframesraw(self, data):
 if not isinstance(data, (bytes, bytearray)):
 data = memoryview(data).cast('B')
 self._ensure_header_written(len(data))
 nframes = len(data) // (self._sampwidth * self._nchannels)
 if self._convert:
 data = self._convert(data)
 self._file.write(data)
 self._nframeswritten = self._nframeswritten + nframes
 self._datawritten = self._datawritten + len(data)

 def writeframes(self, data):
 self.writeframesraw(data)
 if self._nframeswritten != self._nframes or \
 self._datalength != self._datawritten:
 self._patchheader()

 def close(self):
 if self._file is None:
 return
 try:
 self._ensure_header_written(0)
 if self._datawritten & 1:
 # quick pad to even size
 self._file.write(b'\x00')
 self._datawritten = self._datawritten + 1
 self._writemarkers()
 if self._nframeswritten != self._nframes or \
 self._datalength != self._datawritten or \
 self._marklength:
 self._patchheader()
 finally:
 # Prevent ref cycles
 self._convert = None
 f = self._file
 self._file = None
 f.close()

 #
 # Internal methods.
 #

 def _lin2alaw(self, data):
 import audioop
 return audioop.lin2alaw(data, 2)

 def _lin2ulaw(self, data):
 import audioop
 return audioop.lin2ulaw(data, 2)

 def _lin2adpcm(self, data):
 import audioop
 if not hasattr(self, '_adpcmstate'):
 self._adpcmstate = None
 data, self._adpcmstate = audioop.lin2adpcm(data, 2, self._adpcmstate)
 return data

 def _ensure_header_written(self, datasize):
 if not self._nframeswritten:
 if self._comptype in (b'ULAW', b'ulaw', b'ALAW', b'alaw', b'G722'):
 if not self._sampwidth:
 self._sampwidth = 2
 if self._sampwidth != 2:
 raise Error('sample width must be 2 when compressing '
 'with ulaw/ULAW, alaw/ALAW or G7.22 (ADPCM)')
 if not self._nchannels:
 raise Error('# channels not specified')
 if not self._sampwidth:
 raise Error('sample width not specified')
 if not self._framerate:
 raise Error('sampling rate not specified')
 self._write_header(datasize)

 def _init_compression(self):
 if self._comptype == b'G722':
 self._convert = self._lin2adpcm
 elif self._comptype in (b'ulaw', b'ULAW'):
 self._convert = self._lin2ulaw
 elif self._comptype in (b'alaw', b'ALAW'):
 self._convert = self._lin2alaw

 def _write_header(self, initlength):
 if self._aifc and self._comptype != b'NONE':
 self._init_compression()
 self._file.write(b'FORM')
 if not self._nframes:
 self._nframes = initlength // (self._nchannels * self._sampwidth)
 self._datalength = self._nframes * self._nchannels * self._sampwidth
 if self._datalength & 1:
 self._datalength = self._datalength + 1
 if self._aifc:
 if self._comptype in (b'ulaw', b'ULAW', b'alaw', b'ALAW'):
 self._datalength = self._datalength // 2
 if self._datalength & 1:
 self._datalength = self._datalength + 1
 elif self._comptype == b'G722':
 self._datalength = (self._datalength + 3) // 4
 if self._datalength & 1:
 self._datalength = self._datalength + 1
 try:
 self._form_length_pos = self._file.tell()
 except (AttributeError, OSError):
 self._form_length_pos = None
 commlength = self._write_form_length(self._datalength)
 if self._aifc:
 self._file.write(b'AIFC')
 self._file.write(b'FVER')
 _write_ulong(self._file, 4)
 _write_ulong(self._file, self._version)
 else:
 self._file.write(b'AIFF')
 self._file.write(b'COMM')
 _write_ulong(self._file, commlength)
 _write_short(self._file, self._nchannels)
 if self._form_length_pos is not None:
 self._nframes_pos = self._file.tell()
 _write_ulong(self._file, self._nframes)
 if self._comptype in (b'ULAW', b'ulaw', b'ALAW', b'alaw', b'G722'):
 _write_short(self._file, 8)
 else:
 _write_short(self._file, self._sampwidth * 8)
 _write_float(self._file, self._framerate)
 if self._aifc:
 self._file.write(self._comptype)
 _write_string(self._file, self._compname)
 self._file.write(b'SSND')
 if self._form_length_pos is not None:
 self._ssnd_length_pos = self._file.tell()
 _write_ulong(self._file, self._datalength + 8)
 _write_ulong(self._file, 0)
 _write_ulong(self._file, 0)

 def _write_form_length(self, datalength):
 if self._aifc:
 commlength = 18 + 5 + len(self._compname)
 if commlength & 1:
 commlength = commlength + 1
 verslength = 12
 else:
 commlength = 18
 verslength = 0
 _write_ulong(self._file, 4 + verslength + self._marklength + \
 8 + commlength + 16 + datalength)
 return commlength

 def _patchheader(self):
 curpos = self._file.tell()
 if self._datawritten & 1:
 datalength = self._datawritten + 1
 self._file.write(b'\x00')
 else:
 datalength = self._datawritten
 if datalength == self._datalength and \
 self._nframes == self._nframeswritten and \
 self._marklength == 0:
 self._file.seek(curpos, 0)
 return
 self._file.seek(self._form_length_pos, 0)
 dummy = self._write_form_length(datalength)
 self._file.seek(self._nframes_pos, 0)
 _write_ulong(self._file, self._nframeswritten)
 self._file.seek(self._ssnd_length_pos, 0)
 _write_ulong(self._file, datalength + 8)
 self._file.seek(curpos, 0)
 self._nframes = self._nframeswritten
 self._datalength = datalength

 def _writemarkers(self):
 if len(self._markers) == 0:
 return
 self._file.write(b'MARK')
 length = 2
 for marker in self._markers:
 id, pos, name = marker
 length = length + len(name) + 1 + 6
 if len(name) & 1 == 0:
 length = length + 1
 _write_ulong(self._file, length)
 self._marklength = length + 8
 _write_short(self._file, len(self._markers))
 for marker in self._markers:
 id, pos, name = marker
 _write_short(self._file, id)
 _write_ulong(self._file, pos)
 _write_string(self._file, name)

def open(f, mode=None):
 if mode is None:
 if hasattr(f, 'mode'):
 mode = f.mode
 else:
 mode = 'rb'
 if mode in ('r', 'rb'):
 return Aifc_read(f)
 elif mode in ('w', 'wb'):
 return Aifc_write(f)
 else:
 raise Error("mode must be 'r', 'rb', 'w', or 'wb'")

def openfp(f, mode=None):
 warnings.warn("aifc.openfp is deprecated since Python 3.7. "
 "Use aifc.open instead.", DeprecationWarning, stacklevel=2)
 return open(f, mode=mode)

if __name__ == '__main__':
 import sys
 if not sys.argv[1:]:
 sys.argv.append('/usr/demos/data/audio/bach.aiff')
 fn = sys.argv[1]
 with open(fn, 'r') as f:
 print("Reading", fn)
 print("nchannels =", f.getnchannels())
 print("nframes =", f.getnframes())
 print("sampwidth =", f.getsampwidth())
 print("framerate =", f.getframerate())
 print("comptype =", f.getcomptype())
 print("compname =", f.getcompname())
 if sys.argv[2:]:
 gn = sys.argv[2]
 print("Writing", gn)
 with open(gn, 'w') as g:
 g.setparams(f.getparams())
 while 1:
 data = f.readframes(1024)
 if not data:
 break
 g.writeframes(data)
 print("Done.")