1 files changed, 79 insertions, 0 deletions
diff --git a/utils/check_cfc/obj_diff.py b/utils/check_cfc/obj_diff.py
new file mode 100755
index 0000000..6f932b3
--- /dev/null
+++ b/utils/check_cfc/obj_diff.py
@@ -0,0 +1,79 @@
+#!/usr/bin/env python2.7
+
+from __future__ import print_function
+
+import argparse
+import difflib
+import os
+import subprocess
+import sys
+
+disassembler = 'objdump'
+
+def keep_line(line):
+    """Returns true for lines that should be compared in the disassembly
+    output."""
+    return "file format" not in line
+
+def disassemble(objfile):
+    """Disassemble object to a file."""
+    p = subprocess.Popen([disassembler, '-d', objfile],
+                         stdout=subprocess.PIPE,
+                         stderr=subprocess.PIPE)
+    (out, err) = p.communicate()
+    if p.returncode or err:
+        print("Disassemble failed: {}".format(objfile))
+        sys.exit(1)
+    return filter(keep_line, out.split(os.linesep))
+
+def first_diff(a, b, fromfile, tofile):
+    """Returns the first few lines of a difference, if there is one.  Python
+    diff can be very slow with large objects and the most interesting changes
+    are the first ones. Truncate data before sending to difflib.  Returns None
+    is there is no difference."""
+
+    # Find first diff
+    first_diff_idx = None
+    for idx, val in enumerate(a):
+        if val != b[idx]:
+            first_diff_idx = idx
+            break
+
+    if first_diff_idx == None:
+        # No difference
+        return None
+
+    # Diff to first line of diff plus some lines
+    context = 3
+    diff = difflib.unified_diff(a[:first_diff_idx+context],
+                                b[:first_diff_idx+context],
+                                fromfile,
+                                tofile)
+    difference = "\n".join(diff)
+    if first_diff_idx + context < len(a):
+        difference += "\n*** Diff truncated ***"
+    return difference
+
+def compare_object_files(objfilea, objfileb):
+    """Compare disassembly of two different files.
+       Allowing unavoidable differences, such as filenames.
+       Return the first difference if the disassembly differs, or None.
+    """
+    disa = disassemble(objfilea)
+    disb = disassemble(objfileb)
+    return first_diff(disa, disb, objfilea, objfileb)
+
+if __name__ == '__main__':
+    parser = argparse.ArgumentParser()
+    parser.add_argument('objfilea', nargs=1)
+    parser.add_argument('objfileb', nargs=1)
+    parser.add_argument('-v', '--verbose', action='store_true')
+    args = parser.parse_args()
+    diff = compare_object_files(args.objfilea[0], args.objfileb[0])
+    if diff:
+        print("Difference detected")
+        if args.verbose:
+            print(diff)
+        sys.exit(1)
+    else:
+        print("The same")