#!/usr/bin/env python

# Copyright (c) 2011
#      Daniel O'Connor <darius@dons.net.au>.  All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 1. Redistributions of source code must retain the above copyright
#    notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
#    notice, this list of conditions and the following disclaimer in the
#    documentation and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS ``AS IS'' AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED.  IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
# SUCH DAMAGE.
#

import exceptions
import numpy
import re

headerre = re.compile('^(:[A-Z:]+ ).*') 

def clean(data):
    # The instrument might return some header before the data (TEK 2024B does this)
    m = headerre.match(data)
    if m == None:
        return data
    else:
        hlen = len(m.groups()[0])
        return(data[hlen:])

def getdata(data, dtype = float):
    '''Get a single data item'''
    data = clean(data)
    return dtype(data)

def bindecode(data, dtype = numpy.float32):
    '''Decode binary data, returns numpy array'''

    data = clean(data)

    if data[0] != '#':
        raise exceptions.ValueError('data length header incorrect')
    dlenlen = int(data[1])
    dlen = int(data[2:dlenlen + 2])
    if len(data) != dlen + 2 + dlenlen:
        raise exceptions.ValueError('length mismatch, header says %d, actually got %d bytes' % (dlen + 2 + dlenlen, len(data)))
    return numpy.frombuffer(data[2 + dlenlen:], dtype = dtype)

def ascdecode(data, dtype = numpy.float32):
    '''Decode ASCII data, returns numpy array'''

    data = clean(data)
    return numpy.fromstring(data, dtype = dtype, sep = ',')