Add info.py demo.

diff --git a/doc/demo/info.py b/doc/demo/info.py
new file mode 100755 (executable)
index 0000000..552bd8a
--- /dev/null
+++ b/doc/demo/info.py
@@ -0,0 +1,112 @@
+#!/usr/bin/env python
+#
+# Copyright
+
+"""Gather and display information about a comedi device.
+"""
+
+from pycomedi import PyComediError as _PyComediError
+import pycomedi.constant as _constant
+from pycomedi.device import Device as _Device
+from pycomedi.subdevice import StreamingSubdevice as _StreamingSubdevice
+
+
+def display_maxdata(subdevice):
+    if subdevice.maxdata_is_chan_specific():
+        print('  max data value: (channel specific)')
+        for channel in subdevice.channels():
+            print('    chan{}: {}'.format(
+                    channel.index, channel.get_maxdata()))
+    else:
+        print('  max data value: {}'.format(
+                subdevice.channel(0).get_maxdata()))
+
+def display_ranges(subdevice):
+    if subdevice.range_is_chan_specific():
+        print('  ranges: (channel specific)')
+        for channel in subdevice.channels():
+            print('    chan{}: {}'.format(
+                    channel.index,
+                    ', '.join(str(r) for r in channel.ranges())))
+    else:
+        print('  ranges: {}'.format(
+                ', '.join(str(r) for r in subdevice.channel(0).ranges())))
+
+def display_max_generic_timed(subdevice):
+    """Fastest supported single-channel command"""
+    try:
+        command = subdevice.get_cmd_generic_timed(chanlist_len=1)
+    except _PyComediError, e:
+        if e.function_name != 'comedi_get_cmd_generic_timed':
+            raise
+        print('  command fast 1chan: (not supported)')
+    else:
+        print('  command fast 1chan:')
+        print('    start: {} {}'.format(command.start_src, command.start_arg))
+        print('    scan_begin: {} {}'.format(
+                command.scan_begin_src, command.scan_begin_arg))
+        print('    convert: {} {}'.format(
+                command.convert_src, command.convert_arg))
+        print('    scan_end: {} {}'.format(
+                command.scan_end_src, command.scan_end_arg))
+        print('    stop: {} {}'.format(command.stop_src, command.stop_arg))
+
+def display_command(subdevice):
+    try:
+        command = subdevice.get_cmd_src_mask()
+    except _PyComediError, e:
+        if e.function_name != 'comedi_get_cmd_src_mask':
+            raise
+        print('  command: (not supported)')
+    else:
+        print('  command:')
+        print('    start: {}'.format(command.start_src))
+        print('    scan_begin: {}'.format(command.scan_begin_src))
+        print('    convert: {}'.format(command.convert_src))
+        print('    scan_end: {}'.format(command.scan_end_src))
+        print('    stop: {}'.format(command.stop_src))
+        display_max_generic_timed(subdevice=subdevice)
+
+def display_subdevice(subdevice):
+    print('subdevice {}:'.format(subdevice.index))
+    subtype = subdevice.get_type()
+    print('  type: {}'.format(subtype))
+    if subtype == _constant.SUBDEVICE_TYPE.unused:
+        return
+    print('  flags: {}'.format(subdevice.get_flags()))
+    print('  number of channels: {}'.format(subdevice.get_n_channels()))
+    display_maxdata(subdevice=subdevice)
+    display_ranges(subdevice=subdevice)
+    # For testing commands, assume every device supports streaming and
+    # catch errors later.
+    streaming_subdevice = subdevice.device.subdevice(
+        index=subdevice.index, factory=_StreamingSubdevice)
+    display_command(subdevice=streaming_subdevice)
+
+def display(device):
+    print('overall info')
+    print('  comedi version: {}'.format(
+            '.'.join(str(x) for x in device.get_version())))
+    print('  driver name: {}'.format(device.get_driver_name()))
+    print('  board name: {}'.format(device.get_board_name()))
+    print('  number of subdevices: {}'.format(device.get_n_subdevices()))
+    for subdevice in device.subdevices():
+        display_subdevice(subdevice=subdevice)
+
+
+if __name__ == '__main__':
+    import argparse
+
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument(
+        '-f', '--filename', default='/dev/comedi0',
+        help='path to comedi device file')
+
+    args = parser.parse_args()
+
+    device = _Device(filename=args.filename)
+    device.open()
+    try:
+        display(device)
+    finally:
+        device.close()