Split data for sending through HID API into appropriate chunks

Each chunk must not be larger than 64 bytes,
report ID must be prepended to each chunk.

led-badge-11x44.py

@@ -419,6 +419,7 @@ def header(lengths, speeds, modes, blink, ants, brightness=100):
 
 parser = argparse.ArgumentParser(formatter_class=argparse.RawDescriptionHelpFormatter, description='Upload messages or graphics to a 11x44 led badge via USB HID.\nVersion %s from https://github.com/jnweiger/led-badge-ls32\n -- see there for more examples and for updates.' % __version, epilog='Example combining image and text:\n sudo %s "I:HEART2:you"' % sys.argv[0])
 parser.add_argument('-t', '--type', default='11x44', help="Type of display: supported values are 12x48 or (default) 11x44. Rename the program to led-badge-12x48, to switch the default.")
+parser.add_argument('-H', '--hid', default='0', help="Set to 1 to ensure connect via HID API, program will then not fallback to usb.core library")
 parser.add_argument('-s', '--speed', default='4', help="Scroll speed (Range 1..8). Up to 8 comma-separated values")
 parser.add_argument('-B', '--brightness', default='100', help="Brightness for the display in percent: 25, 50, 75, or 100")
 parser.add_argument('-m', '--mode',  default='0', help="Up to 8 mode values: Scroll-left(0) -right(1) -up(2) -down(3); still-centered(4); animation(5); drop-down(6); curtain(7); laser(8); See '--mode-help' for more details.")
@@ -453,6 +454,8 @@ if have_pyhidapi:
   devinfo = pyhidapi.hid_enumerate(0x0416, 0x5020)
   #dev = pyhidapi.hid_open(0x0416, 0x5020)
 else:
+  if args.hid != "0":
+    sys.exit("HID API access is needed but not initialized. Fix your setup")
   dev = usb.core.find(idVendor=0x0416, idProduct=0x5020)
 
 if have_pyhidapi:
@@ -516,7 +519,12 @@ if len(buf) > 8192:
   sys.exit(1)
 
 if have_pyhidapi:
-  pyhidapi.hid_write(dev, buf)
+  for i in range(int(len(buf)/64)):
+    # sendbuf must contain "report ID" as first byte. "0" does the job here.
+    sendbuf=array('B',[0])
+    # Then, put the 64 payload bytes into the buffer
+    sendbuf.extend(buf[i*64:i*64+64])
+    pyhidapi.hid_write(dev,sendbuf)
 else:
   for i in range(int(len(buf)/64)):
     time.sleep(0.1)