#!/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 select
import socket

# See this for more info
# http://www.staff.uni-bayreuth.de/~btp918/cmt2007/geraete/agilent_34410A_dmm/manual/SCPI_Sockets.pdf
#
# ToDo: Implement the SRQ & DCL channel (I don't have any supported hardware)

SCPI_PORT = 5025

class SCPISockDevice(object):
    def __init__(self, host, port = SCPI_PORT):
        self.sock = socket.create_connection((host, port))

    def flush(self):
        while True:
            r, w, x = select.select([self.sock], [], [], 0)
            if len(r) == 0:
                break
            self.sock.recv(1024)

    def write(self, data):
        trail = ''
        if data[-1] != b'\n':
            trail = b'\n'

        self.sock.send(data + trail)

    def read(self, timeout = None):
        res = b''
        if timeout == None:
            timeout = 0.1

        while True:
            r, w, x = select.select([self.sock], [], [], timeout)
            if len(r) == 0:
                break
            res = res + self.sock.recv(1024)
            if res[-1] == b'\n':
                break

        return res.rstrip(b'\n')