Merge pull request #3 from chris-torrence/master

Add po2dsk.py to go other direction

README.md

@@ -6,7 +6,7 @@ into those of a .po (ProDOS-order) file.  Most Apple II emulators can handle bot
 but certain utilities (with which I wanted to use existing .dsk images) assume
 ProDOS-ordered files.
 
-Usage is just (assuming you've done chmod 755 dsk2po.py, else precede with python command):
+Usage is just (assuming you've done `chmod 755 dsk2po.py`, else precede with python command):
 
     ./dsk2po.py image.dsk
 
@@ -18,3 +18,7 @@ This can be used as an action for find, like so:
     find imagefolders/\*/\*.dsk -exec ./dsk2po.py {} \;
 
 ...which was mostly the point.
+
+You can also go the opposite direction:
+
+    ./po2dsk.py image.po

po2dsk.py

@@ -0,0 +1,35 @@
+#!/usr/bin/env python3
+# scramble po back into dsk
+# Chris Torrence, Oct 2020
+import sys, getopt, re
+from dsk2po import dsk2po
+def main(argv=None):
+  print("po2dsk - convert po files to dsk files")
+
+  try:
+    opts, args = getopt.getopt(sys.argv[1:], '')
+  except getopt.GetoptError as err:
+    print(str(err))
+    usage()
+    return 1
+  try:
+    filenameIn = args[0]
+  except:
+    print('You need to provide the name of a PO file to begin.')
+    return 1
+
+  tracks = []
+  # Note that the same algorithm can be used to convert in either direction
+  with open(filenameIn, mode="rb") as fileIn:
+    for track in range(35):
+      trackbuffer = fileIn.read(4096)
+      tracks.append(dsk2po(trackbuffer))
+  dskfilename = re.sub('\.po$', '', filenameIn, flags=re.IGNORECASE) + ".dsk"
+  print('Writing dsk image to {}'.format(dskfilename))
+  with open(dskfilename, mode="wb") as file:
+    for track in tracks:
+      file.write(track)
+  return 1
+
+if __name__ == "__main__":
+  sys.exit(main())