Fix reading of Oxford Instruments binary .ebsp files of version 4

CHANGELOG.rst

@@ -148,6 +148,8 @@ Removed
 
 Fixed
 -----
+- Oxford Instruments .ebsp files of version 4 can now be read.
+  (`#602 <https://github.com/pyxem/kikuchipy/pull/602>`_)
 - When loading EBSD patterns from H5OINA files, the detector tilt and binning are
   available in the returned signal's ``detector`` attribute.
   (`#600 <https://github.com/pyxem/kikuchipy/pull/600>`_)

kikuchipy/conftest.py

@@ -344,7 +344,7 @@ def oxford_binary_file(tmpdir, request):
     fname = tmpdir.join("dummy_oxford_file.ebsp")
     f = open(fname, mode="w")
 
-    if ver != 0:
+    if ver > 0:
         np.array(-ver, dtype=np.int64).tofile(f)
 
     pattern_header_size = 16
@@ -366,8 +366,11 @@ def oxford_binary_file(tmpdir, request):
     pattern_starts = np.arange(n_patterns, dtype=np.int64)
     pattern_starts *= pattern_header_size + n_bytes + pattern_footer_size
     pattern_starts += n_patterns * 8
-    if ver != 0:
+    if ver in [1, 2, 3]:
         pattern_starts += 8
+    elif ver > 3:
+        np.array(0, dtype=np.uint8).tofile(f)
+        pattern_starts += 9
 
     pattern_starts = np.roll(pattern_starts, shift=1)
     if not all_present:

kikuchipy/io/plugins/oxford_binary.py

@@ -18,9 +18,11 @@
 """Reader of uncompressed EBSD patterns from a Oxford Instruments binary
 .ebsp file.
 
-Information about the file format was provided by Oxford Instruments.
+Information about the file format was generously provided by Oxford
+Instruments.
 """
 
+import logging
 import os
 from pathlib import Path
 import struct
@@ -35,6 +37,8 @@
 __all__ = ["file_reader"]
 
 
+_logger = logging.getLogger(__name__)
+
 # Plugin characteristics
 # ----------------------
 format_name = "Oxford binary"
@@ -114,6 +118,14 @@ def __init__(self, file: BinaryIO):
         self.file = file  # Already open file
 
         self.version = self.get_version()
+        _logger.debug(f"Reading Oxford binary file of version {self.version}")
+
+        # If version > 3, read in the extra byte after file version and
+        # add it to the debug log
+        if self.version > 3:  # pragma: no cover
+            self.file.seek(self.pattern_starts_byte_position - 1)
+            unknown_byte = np.fromfile(self.file, dtype=np.uint8, count=1)[0]
+            _logger.debug(f"Unknown byte (uint8) in file of version 4: {unknown_byte}")
 
         # Number of patterns in the file is not known, so this is
         # guessed from the file header where the file byte positions of
@@ -204,13 +216,16 @@ def pattern_order(self) -> np.ndarray:
     @property
     def pattern_starts_byte_position(self) -> int:
         """File byte position of file byte positions of patterns. For
-        .ebsp file version 0, this is at the first byte, while for later
-        versions, this is at the ninth byte, after the file version.
+        .ebsp file version 0, this is at the first byte, for versions
+        1-3 this is at the ninth byte, while for version 4 this is at
+        the tenth byte.
         """
-        if self.version != 0:
-            return 8
-        else:
+        if self.version == 0:
             return 0
+        elif self.version > 3:
+            return 9
+        else:
+            return 8
 
     def get_memmap(self) -> np.memmap:
         """Return a memory map of the pattern header, actual patterns,

kikuchipy/io/plugins/tests/test_oxford_binary.py

@@ -92,6 +92,7 @@ def test_not_all_patterns_present(self, oxford_binary_file):
             (((2, 3), (60, 60), np.uint8, 2, False, True), 2, (2, 3)),
             (((2, 3), (60, 60), np.uint16, 1, False, True), 1, (2, 3)),
             (((2, 3), (60, 60), np.uint8, 0, False, True), 0, (6,)),
+            (((2, 3), (60, 60), np.uint8, 4, False, True), 4, (2, 3)),
         ],
         indirect=["oxford_binary_file"],
     )