Moved the SIZ, COD, TLM, and PLT segment parsing back to being object methods. #94
This commit is contained in:
John Evans
parent
d174411359
commit
e53a9a9157
1 changed files with 164 additions and 159 deletions
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@ -150,30 +150,19 @@ class Codestream(object):
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segment = Segment(marker_id=the_id, offset=offset, length=0)
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segment = Segment(marker_id=the_id, offset=offset, length=0)
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elif marker_id == 0xff51:
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elif marker_id == 0xff51:
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# Need to keep track of the number of components from SIZ for
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segment = self._parse_siz_segment(fptr)
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# other markers
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segment = _parse_siz_segment(fptr)
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self._csiz = len(segment.ssiz)
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elif marker_id == 0xff52:
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elif marker_id == 0xff52:
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segment = _parse_cod_segment(fptr)
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segment = self._parse_cod_segment(fptr)
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sop = (segment.scod & 2) > 0
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eph = (segment.scod & 4) > 0
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if sop or eph:
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self._parse_tpart_flag = True
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else:
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self._parse_tpart_flag = False
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elif marker_id == 0xff53:
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elif marker_id == 0xff53:
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segment = self._parse_coc_segment(fptr)
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segment = self._parse_coc_segment(fptr)
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elif marker_id == 0xff55:
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elif marker_id == 0xff55:
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segment = _parse_tlm_segment(fptr)
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segment = self._parse_tlm_segment(fptr)
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elif marker_id == 0xff58:
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elif marker_id == 0xff58:
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segment = _parse_plt_segment(fptr)
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segment = self._parse_plt_segment(fptr)
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elif marker_id == 0xff5c:
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elif marker_id == 0xff5c:
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segment = _parse_qcd_segment(fptr)
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segment = _parse_qcd_segment(fptr)
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@ -326,6 +315,81 @@ class Codestream(object):
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return COCsegment(ccoc, scoc, spcoc, length, offset)
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return COCsegment(ccoc, scoc, spcoc, length, offset)
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def _parse_cod_segment(self, fptr):
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"""Parse the COD segment.
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Parameters
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----------
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fptr : file
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Open file object.
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Returns
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-------
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COD segment instance.
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"""
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offset = fptr.tell() - 2
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offset = fptr.tell() - 2
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read_buffer = fptr.read(3)
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length, scod = struct.unpack('>HB', read_buffer)
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numbytes = offset + 2 + length - fptr.tell()
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spcod = fptr.read(numbytes)
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spcod = np.frombuffer(spcod, dtype=np.uint8)
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sop = (scod & 2) > 0
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eph = (scod & 4) > 0
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if sop or eph:
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self._parse_tpart_flag = True
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else:
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self._parse_tpart_flag = False
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return CODsegment(scod, spcod, length, offset)
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def _parse_plt_segment(self, fptr):
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"""Parse the PLT segment.
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The packet headers are not parsed, i.e. they remain "uninterpreted"
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raw data beffers.
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Parameters
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----------
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fptr : file
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Open file object.
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Returns
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-------
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PLT segment instance.
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"""
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offset = fptr.tell() - 2
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read_buffer = fptr.read(3)
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length, zplt = struct.unpack('>HB', read_buffer)
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numbytes = length - 3
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read_buffer = fptr.read(numbytes)
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iplt = np.frombuffer(read_buffer, dtype=np.uint8)
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packet_len = []
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plen = 0
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for byte in iplt:
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plen |= (byte & 0x7f)
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if byte & 0x80:
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# Continue by or-ing in the next byte.
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plen <<= 7
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else:
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packet_len.append(plen)
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plen = 0
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iplt = packet_len
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return PLTsegment(zplt, iplt, length, offset)
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def _parse_pod_segment(self, fptr):
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def _parse_pod_segment(self, fptr):
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"""Parse the POD segment.
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"""Parse the POD segment.
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@ -423,6 +487,91 @@ class Codestream(object):
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return RGNsegment(length, offset, crgn, srgn, sprgn)
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return RGNsegment(length, offset, crgn, srgn, sprgn)
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def _parse_siz_segment(self, fptr):
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"""Parse the SIZ segment.
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Parameters
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----------
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fptr : file
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Open file object.
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Returns
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-------
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SIZsegment instance.
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"""
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offset = fptr.tell() - 2
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read_buffer = fptr.read(2)
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length, = struct.unpack('>H', read_buffer)
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xy_buffer = fptr.read(36)
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num_components, = struct.unpack('>H', xy_buffer[-2:])
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component_buffer = fptr.read(num_components * 3)
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segment = SIZsegment(xy_buffer, component_buffer, length, offset)
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# Need to keep track of the number of components from SIZ for
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# other markers
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self._csiz = len(segment.ssiz)
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return segment
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def _parse_tlm_segment(self, fptr):
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"""Parse the TLM segment.
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Parameters
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----------
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fptr : file
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Open file object.
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Returns
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-------
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TLM segment instance.
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"""
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offset = fptr.tell() - 2
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read_buffer = fptr.read(2)
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length, = struct.unpack('>H', read_buffer)
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read_buffer = fptr.read(2)
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ztlm, stlm = struct.unpack('>BB', read_buffer)
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ttlm_st = (stlm >> 4) & 0x3
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ptlm_sp = (stlm >> 6) & 0x1
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nbytes = length - 4
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if ttlm_st == 0:
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ntiles = nbytes / ((ptlm_sp + 1) * 2)
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else:
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ntiles = nbytes / (ttlm_st + (ptlm_sp + 1) * 2)
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read_buffer = fptr.read(nbytes)
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if ttlm_st == 0:
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ttlm = None
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fmt = ''
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elif ttlm_st == 1:
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fmt = 'B'
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elif ttlm_st == 2:
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fmt = 'H'
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if ptlm_sp == 0:
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fmt += 'H'
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else:
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fmt += 'I'
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data = struct.unpack('>' + fmt * int(ntiles), read_buffer)
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if ttlm_st == 0:
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ttlm = None
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ptlm = data
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else:
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ttlm = data[0::2]
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ptlm = data[1::2]
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return TLMsegment(length, offset, ztlm, ttlm, ptlm)
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class Segment(object):
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class Segment(object):
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"""Segment information.
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"""Segment information.
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@ -1435,59 +1584,6 @@ def _print_quantization_style(sqcc):
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return msg
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return msg
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def _parse_tlm_segment(fptr):
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"""Parse the TLM segment.
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Parameters
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----------
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fptr : file
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Open file object.
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Returns
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-------
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TLM segment instance.
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"""
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offset = fptr.tell() - 2
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read_buffer = fptr.read(2)
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length, = struct.unpack('>H', read_buffer)
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read_buffer = fptr.read(2)
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ztlm, stlm = struct.unpack('>BB', read_buffer)
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ttlm_st = (stlm >> 4) & 0x3
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ptlm_sp = (stlm >> 6) & 0x1
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nbytes = length - 4
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if ttlm_st == 0:
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ntiles = nbytes / ((ptlm_sp + 1) * 2)
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else:
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ntiles = nbytes / (ttlm_st + (ptlm_sp + 1) * 2)
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read_buffer = fptr.read(nbytes)
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if ttlm_st == 0:
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ttlm = None
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fmt = ''
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elif ttlm_st == 1:
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fmt = 'B'
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elif ttlm_st == 2:
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fmt = 'H'
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if ptlm_sp == 0:
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fmt += 'H'
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else:
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fmt += 'I'
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data = struct.unpack('>' + fmt * int(ntiles), read_buffer)
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if ttlm_st == 0:
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ttlm = None
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ptlm = data
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else:
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ttlm = data[0::2]
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ptlm = data[1::2]
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return TLMsegment(length, offset, ztlm, ttlm, ptlm)
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def _parse_sot_segment(fptr):
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def _parse_sot_segment(fptr):
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"""Parse the SOT segment.
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"""Parse the SOT segment.
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@ -1581,46 +1677,6 @@ def _parse_ppt_segment(fptr):
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return PPTsegment(zppt, ippt, length, offset)
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return PPTsegment(zppt, ippt, length, offset)
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def _parse_plt_segment(fptr):
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"""Parse the PLT segment.
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The packet headers are not parsed, i.e. they remain "uninterpreted"
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raw data beffers.
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Parameters
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----------
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fptr : file
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Open file object.
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Returns
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-------
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PLT segment instance.
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"""
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offset = fptr.tell() - 2
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read_buffer = fptr.read(3)
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length, zplt = struct.unpack('>HB', read_buffer)
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numbytes = length - 3
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read_buffer = fptr.read(numbytes)
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iplt = np.frombuffer(read_buffer, dtype=np.uint8)
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packet_len = []
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plen = 0
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for byte in iplt:
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plen |= (byte & 0x7f)
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if byte & 0x80:
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# Continue by or-ing in the next byte.
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plen <<= 7
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else:
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packet_len.append(plen)
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plen = 0
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iplt = packet_len
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return PLTsegment(zplt, iplt, length, offset)
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def _parse_ppm_segment(fptr):
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def _parse_ppm_segment(fptr):
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"""Parse the PPM segment.
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"""Parse the PPM segment.
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@ -1710,57 +1766,6 @@ def _parse_cme_segment(fptr):
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return CMEsegment(rcme, ccme, length, offset)
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return CMEsegment(rcme, ccme, length, offset)
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def _parse_siz_segment(fptr):
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"""Parse the SIZ segment.
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Parameters
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----------
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fptr : file
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Open file object.
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Returns
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-------
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SIZsegment instance.
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"""
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offset = fptr.tell() - 2
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read_buffer = fptr.read(2)
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length, = struct.unpack('>H', read_buffer)
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xy_buffer = fptr.read(36)
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num_components, = struct.unpack('>H', xy_buffer[-2:])
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component_buffer = fptr.read(num_components * 3)
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return SIZsegment(xy_buffer, component_buffer, length, offset)
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def _parse_cod_segment(fptr):
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"""Parse the COD segment.
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Parameters
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----------
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fptr : file
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Open file object.
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Returns
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-------
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COD segment instance.
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"""
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offset = fptr.tell() - 2
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offset = fptr.tell() - 2
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read_buffer = fptr.read(3)
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length, scod = struct.unpack('>HB', read_buffer)
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numbytes = offset + 2 + length - fptr.tell()
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spcod = fptr.read(numbytes)
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spcod = np.frombuffer(spcod, dtype=np.uint8)
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return CODsegment(scod, spcod, length, offset)
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def _parse_generic_segment(fptr, marker_id):
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def _parse_generic_segment(fptr, marker_id):
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"""Parse a generic marker segment.
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"""Parse a generic marker segment.
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