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+# LeCrunch
+# Copyright (C) 2010 Anthony LaTorre 
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import sys
+import re
+import array
+import StringIO
+import struct
+import numpy as np
+import scope
+
+# data types in lecroy binary blocks, where:
+# length  -- byte length of type
+# string  -- string representation of type
+# packfmt -- format string for struct.unpack()
+class String:
+    length = 16
+    string = 'string'
+class Byte:
+    length = 1
+    string = 'byte'
+    packfmt = 'b'
+class Word:
+    length = 2
+    string = 'word'
+    packfmt = 'h'
+class Long:
+    length = 4
+    string = 'long'
+    packfmt = 'l'
+class Enum:
+    length = 2
+    string = 'enum'
+    packfmt = 'h'
+class Float:
+    length = 4
+    string = 'float'
+    packfmt = 'f'
+class Double:
+    length = 8
+    string = 'double'
+    packfmt = 'd'
+class TimeStamp:
+    length = 16
+    string = 'time_stamp'
+    packfmt = 'dbbbbhh'
+class UnitDefinition:
+    length = 48
+    string = 'unit_definition'
+
+# byte length of wavedesc block
+wavedesclength = 346
+
+# template of wavedesc block, where each entry in tuple is:
+# (variable name, byte position from beginning of block, datatype)
+wavedesc_template = ( ('descriptor_name'    , 0   , String),
+                      ('template_name'      , 16  , String),
+                      ('comm_type'          , 32  , Enum),
+                      ('comm_order'         , 34  , Enum),
+                      ('wave_descriptor'    , 36  , Long),
+                      ('user_text'          , 40  , Long),
+                      ('res_desc1'          , 44  , Long),
+                      ('trigtime_array'     , 48  , Long),
+                      ('ris_time_array'     , 52  , Long),
+                      ('res_array1'         , 56  , Long),
+                      ('wave_array_1'       , 60  , Long),
+                      ('wave_array_2'       , 64  , Long),
+                      ('res_array_2'        , 68  , Long),
+                      ('res_array_3'        , 72  , Long),
+                      ('instrument_name'    , 76  , String),
+                      ('instrument_number'  , 92  , Long),
+                      ('trace_label'        , 96  , String),
+                      ('reserved1'          , 112 , Word),
+                      ('reserved2'          , 114 , Word),
+                      ('wave_array_count'   , 116 , Long),
+                      ('pnts_per_screen'    , 120 , Long),
+                      ('first_valid_pnt'    , 124 , Long),
+                      ('last_valid_pnt'     , 128 , Long),
+                      ('first_point'        , 132 , Long),
+                      ('sparsing_factor'    , 136 , Long),
+                      ('segment_index'      , 140 , Long),
+                      ('subarray_count'     , 144 , Long),
+                      ('sweeps_per_acq'     , 148 , Long),
+                      ('points_per_pair'    , 152 , Word),
+                      ('pair_offset'        , 154 , Word),
+                      ('vertical_gain'      , 156 , Float),
+                      ('vertical_offset'    , 160 , Float),
+                      ('max_value'          , 164 , Float),
+                      ('min_value'          , 168 , Float),
+                      ('nominal_bits'       , 172 , Word),
+                      ('nom_subarray_count' , 174 , Word),
+                      ('horiz_interval'     , 176 , Float),
+                      ('horiz_offset'       , 180 , Double),
+                      ('pixel_offset'       , 188 , Double),
+                      ('vertunit'           , 196 , UnitDefinition),
+                      ('horunit'            , 244 , UnitDefinition),
+                      ('horiz_uncertainty'  , 292 , Float),
+                      ('trigger_time'       , 296 , TimeStamp),
+                      ('acq_duration'       , 312 , Float),
+                      ('record_type'        , 316 , Enum),
+                      ('processing_done'    , 318 , Enum),
+                      ('reserved5'          , 320 , Word),
+                      ('ris_sweeps'         , 322 , Word),
+                      ('timebase'           , 324 , Enum),
+                      ('vert_coupling'      , 326 , Enum),
+                      ('probe_att'          , 328 , Float),
+                      ('fixed_vert_gain'    , 332 , Enum),
+                      ('bandwidth_limit'    , 334 , Enum),
+                      ('vertical_vernier'   , 336 , Float),
+                      ('acq_vert_offset'    , 340 , Float),
+                      ('wave_source'        , 344 , Enum) )
+
+class LeCroyScope(scope.Scope):
+    """
+    A class for triggering and fetching waveforms from the oscilloscope.
+
+    .. note::
+
+       You must call connect() on the object before fetching waveforms.
+    """
+    def __init__(self, host, port=1861, timeout=2.0):
+        super(LeCroyScope, self).__init__(host, port, timeout)
+
+    def connect(self):
+        """Connect to the oscilloscope."""
+        super(LeCroyScope, self).connect()
+        # initialize some parameters
+        self.send('comm_header short')
+        self.check_last_command()
+        self.send('comm_format DEF9,BYTE,BIN')
+        self.check_last_command()
+
+    def getchannels(self):
+        """Returns a list of the active channels on the scope."""
+        channels = []
+        for i in range(1, 5):
+            self.send('c%i:trace?' %i)
+            if 'ON' in self.recv():
+                channels.append(i)
+        return channels
+
+    def trigger(self):
+        """Trigger the oscilloscope and wait for an acquisition."""
+        self.send('arm;wait')
+
+    def getwavedesc(self, channel):
+        if channel not in range(1, 5):
+            raise Exception('channel must be in %s.' % str(range(1, 5)))
+
+        self.send('c%s:wf? all' % str(channel))
+
+        msg = self.recv()
+        if not int(msg[1]) == channel:
+            raise RuntimeError('waveforms out of sync or comm_header is off.')
+
+        data = StringIO.StringIO(msg)
+
+        startpos = re.search('WAVEDESC', data.read()).start()
+
+        wavedesc = {}
+
+        # check endian
+        data.seek(startpos + 34)
+        if struct.unpack('<'+Enum.packfmt, data.read(Enum.length)) == 0:
+            endian = '>'
+            wavedesc['little_endian'] = True
+            np.little_endian = True
+        else:
+            endian = '<'
+            wavedesc['little_endian'] = False
+            np.little_endian = False
+
+        data.seek(startpos)
+
+        # build dictionary of wave description
+        for name, pos, datatype in wavedesc_template:
+            raw = data.read(datatype.length)
+            if datatype in (String, UnitDefinition):
+                wavedesc[name] = raw.rstrip('\x00')
+            elif datatype in (TimeStamp,):
+                wavedesc[name] = struct.unpack(endian+datatype.packfmt, raw)
+            else:
+                wavedesc[name] = struct.unpack(endian+datatype.packfmt, raw)[0]
+
+        # determine data type
+        if wavedesc['comm_type'] == 0:
+            wavedesc['dtype'] = np.int8
+        elif wavedesc['comm_type'] == 1:
+            wavedesc['dtype'] = np.int16
+        else:
+            raise Exception('unknown comm_type.')
+            
+        return wavedesc
+
+    def getwaveform(self, channel, wavedesc):
+        """
+        Request, process, and return the x and y arrays for channel number
+        *channel* from the oscilloscope.
+        """ 
+
+        if channel not in range(1, 5):
+            raise Exception('channel must be in %s.' % str(range(1, 5)))
+
+        self.send('c%s:wf? dat1' % str(channel))
+
+        msg = self.recv()
+        if not int(msg[1]) == channel:
+            raise RuntimeError('waveforms out of sync or comm_header is off.')
+
+        return np.fromstring(msg[22:], wavedesc['dtype'], wavedesc['wave_array_count'])