Enable specifying byte order in packed

igor2/packed.py

@@ -43,15 +43,38 @@
 # a later record in the packed file.
 
 
-def load(filename, strict=True, ignore_unknown=True):
+def load(filename, strict=True, ignore_unknown=True, initial_byte_order=None):
+    """Load a packed experiment file.
+
+    Parameters
+    ----------
+    filename : str or file-like object
+        The path to the file or a file-like object representing the packed
+        experiment file.
+    strict : bool, optional
+        This parameter is ignored. Defaults to True.
+    ignore_unknown : bool, optional
+        If True, ignore unknown record types. Defaults to True.
+    initial_byte_order : str or None, optional
+        The initial byte order to use for unpacking. Must be one of '>', '=',
+        '<'. If None, '=' is used. Defaults to None.
+
+    Returns
+    -------
+    records : list of Record
+        The records in the packed experiment file.
+    filesystem : dict
+        The filesystem structure of the packed experiment file.
+    """
     logger.debug('loading a packed experiment file from {}'.format(filename))
     records = []
     if hasattr(filename, 'read'):
         f = filename  # filename is actually a stream object
     else:
         f = open(filename, 'rb')
     byte_order = None
-    initial_byte_order = '='
+    if initial_byte_order is None:
+        initial_byte_order = '='
     try:
         while True:
             PackedFileRecordHeader.byte_order = initial_byte_order
@@ -80,7 +103,8 @@ def load(filename, strict=True, ignore_unknown=True):
             data = bytes(f.read(header['numDataBytes']))
             if len(data) < header['numDataBytes']:
                 raise ValueError(
-                    ('not enough data for the next record ({} < {})'
+                    ('not enough data for the next record ({} < {}), '
+                     'try loading with a different initial byte order'
                      ).format(len(b), header['numDataBytes']))
             record_type = _RECORD_TYPE.get(
                 header['recordType'] & PACKEDRECTYPE_MASK, _UnknownRecord)

tests/test_pxp.py

@@ -129,3 +129,26 @@ def test_pxp():
         28.72983551, 28.05199242, 29.29024887, 31.3501091,
         32.7331543, 32.87995529, 32.28799438, 31.99738503],
         dtype=np.float32))
+
+
+def test_pxt():
+    data = loadpxp(data_dir / 'packed-byteorder.pxt', initial_byte_order='>')
+    records = data[0]
+    assert len(records) == 2
+    assert records[0].variables == {'version': 2,
+                                    'variables': {
+                                        'var_header': {'numSysVars': 0,
+                                                       'numUserVars': 0,
+                                                       'numUserStrs': 0,
+                                                       'numDependentVars': 0,
+                                                       'numDependentStrs': 0},
+                                        'sysVars': {},
+                                        'userVars': {},
+                                        'userStrs': {},
+                                        'dependentVars': [],
+                                        'dependentStrs': []}}
+    assert np.allclose(records[1].wave['wave']["wData"][:30, 0], np.array(
+        [14603., 13701., 14907., 13795., 14339., 14942., 14984., 14261.,
+         12647., 14242., 14470., 13913., 14158., 14754., 14462., 14346.,
+         14219., 13467., 13595., 14331., 13960., 12934., 12897., 13557.,
+         13105., 12797., 13234., 13053., 13455., 12825.], dtype='>f8'))