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# -*- coding: ISO-8859-1 -*-

##########################################################################

# USPP Library (Universal Serial Port Python Library)

#

# Copyright (C) 2006 Isaac Barona <ibarona@gmail.com>

# 

# This library is free software; you can redistribute it and/or

# modify it under the terms of the GNU Lesser General Public

# License as published by the Free Software Foundation; either

# version 2.1 of the License, or (at your option) any later version.

# 

# This library 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

# Lesser General Public License for more details.

# You should have received a copy of the GNU Lesser General Public

# License along with this library; if not, write to the Free Software

# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

##########################################################################

#------------------------------------------------------------------------

# Project:   USPP Library (Universal Serial Port Python Library)

# Name:      SerialPort_linux.py

# Purpose:   Handle low level access to serial port in linux.

#

# Author:    Isaac Barona Martinez <ibarona@gmail.com>

# Copyright: (c) 2006 by Isaac Barona Martínez

# Licence:   LGPL

#

# Created:   26 June 2001

# History:

# 20 January 2002 : Damien Geranton <dgeranton@voila.fr>

#  - NCCS worry fixed. We must not use TERMIOS

#  - inWaiting call fixed.

# 09 Sept 2005: Douglas Jones <dfj23@drexel.edu>

#  - readline method.

#

#-------------------------------------------------------------------------

"""

SerialPort_linux.py - Handle low level access to serial port in linux.

See also uspp module docstring.

"""

import os

from termios import *

from struct import *

import fcntl

import exceptions

import struct

import array

import time

class SerialPortException(exceptions.Exception):

    """Exception raise in the SerialPort methods"""

    def __init__(self, args=None):

        self.args=args

    def __str__(self):

        return repr(self.args)

class SerialPort:

    """Encapsulate methods for accesing to a serial port."""

    BaudRatesDic={

        110: B110,

        300: B300,

        600: B600,

        1200: B1200,

        2400: B2400,

        4800: B4800,

        9600: B9600,

        19200: B19200,

        38400: B38400,

        57600: B57600,

        115200: B115200

        }

    buf = array.array('h', '\000'*4)

    def __init__(self, dev, timeout=None, speed=115200, mode='232', params=None):

        """Open the serial port named by the string 'dev'

        'dev' can be any of the following strings: '/dev/ttyS0', '/dev/ttyS1',

        ..., '/dev/ttySX' or '/dev/cua0', '/dev/cua1', ..., '/dev/cuaX'.

        'timeout' specifies the inter-byte timeout or first byte timeout

        (in miliseconds) for all subsequent reads on SerialPort.

        If we specify None time-outs are not used for reading operations

        (blocking reading).

        If 'timeout' is 0 then reading operations are non-blocking. It

        specifies that the reading operation is to return inmediately

        with the bytes that have already been received, even if

        no bytes have been received.

        'speed' is an integer that specifies the input and output baud rate to

        use. Possible values are: 110, 300, 600, 1200, 2400, 4800, 9600,

        19200, 38400, 57600 and 115200.

        If None a default speed of 9600 bps is selected.

        'mode' specifies if we are using RS-232 or RS-485. The RS-485 mode

        is half duplex and use the RTS signal to indicate the

        direction of the communication (transmit or recive).

        Default to RS232 mode (at moment, only the RS-232 mode is

        implemented).

        'params' is a list that specifies properties of the serial

        communication.

        If params=None it uses default values for the number of bits

        per byte (8), the parity (NOPARITY) and the number of stop bits (1)

        else params is the termios package mode array to use for

        initialization.

        """

        self.__devName, self.__timeout, self.__speed=dev, timeout, speed

        self.__mode=mode

        self.__params=params

        self.__speed = 0

        self.__reopen = 0

        while 1:

            try:

                self.__handle=os.open(dev, os.O_RDWR)

                break

            except:

                n=0

                while (n < 2000000):

                    n += 1;

                self.__reopen = self.__reopen + 1

            if self.__reopen > 32:

                print "Port does not exist..."

                raise SerialPortException('Port does not exist...')

                break

        self.__configure()

    def __del__(self):

        """Close the serial port and restore its initial configuration

        To close the serial port we have to do explicity: del s

        (where s is an instance of SerialPort)

        """

        if self.__speed:

            tcsetattr(self.__handle, TCSANOW, self.__oldmode)

            try:

                os.close(self.__handle)

            except IOError:

                raise SerialPortException('Unable to close port')

    def __configure(self):

        """Configure the serial port.

        Private method called in the class constructor that configure the

        serial port with the characteristics given in the constructor.

        """

        if not self.__speed:

            self.__speed=115200

        # Save the initial port configuration

        self.__oldmode=tcgetattr(self.__handle)

        if not self.__params:

            # self.__params is a list of attributes of the file descriptor

            # self.__handle as follows:

            # [c_iflag, c_oflag, c_cflag, c_lflag, c_ispeed, c_ospeed, cc]

            # where cc is a list of the tty special characters.

            self.__params=[]

            # c_iflag

            self.__params.append(IGNPAR)

            # c_oflag

            self.__params.append(0)

            # c_cflag

            self.__params.append(CS8|CLOCAL|CREAD)

            # c_lflag

            self.__params.append(0)

            # c_ispeed

            self.__params.append(SerialPort.BaudRatesDic[self.__speed])

            # c_ospeed

            self.__params.append(SerialPort.BaudRatesDic[self.__speed])

            cc=[0]*NCCS

        if self.__timeout==None:

            # A reading is only complete when VMIN characters have

            # been received (blocking reading)

            cc[VMIN]=1

            cc[VTIME]=0

        elif self.__timeout==0:

            # Non-blocking reading. The reading operation returns

            # inmeditately, returning the characters waiting to 

            # be read.

            cc[VMIN]=0

            cc[VTIME]=0

        else:

            # Time-out reading. For a reading to be correct

            # a character must be recieved in VTIME*100 seconds.

            cc[VMIN]=0

            cc[VTIME]=self.__timeout/100

        self.__params.append(cc)               # c_cc

        tcsetattr(self.__handle, TCSANOW, self.__params)

    def fileno(self):

        """Return the file descriptor for opened device.

        This information can be used for example with the

        select funcion.

        """

        return self.__handle

    def __read1(self):

        """Read 1 byte from the serial port.

        Generate an exception if no byte is read and self.timeout!=0

        because a timeout has expired.

        """

        byte = os.read(self.__handle, 1)

        if len(byte)==0 and self.__timeout!=0: # Time-out

            raise SerialPortException('Timeout')

        else:

            return byte

    def read(self, num=1):

        """Read num bytes from the serial port.

        Uses the private method __read1 to read num bytes. If an exception

        is generated in any of the calls to __read1 the exception is reraised.

        """

        s=''

        for i in range(num):

            s=s+SerialPort.__read1(self)

        return s

    def readline(self):

        """Read a line from the serial port.  Returns input once a '\n'

        character is found.

        Douglas Jones (dfj23@drexel.edu) 09/09/2005.

        """

        s = ''

        while not '\n' in s:

            s = s+SerialPort.__read1(self)

        return s

    def write(self, s):

        """Write the string s to the serial port"""

        os.write(self.__handle, s)

    def inWaiting(self):

        """Returns the number of bytes waiting to be read"""

        data = struct.pack("L", 0)

        data=fcntl.ioctl(self.__handle, TIOCINQ, data)

        return struct.unpack("L", data)[0]

    def outWaiting(self):

        """Returns the number of bytes waiting to be write

        mod. by J.Grauheding

        result needs some finetunning

        """

        rbuf=fcntl.ioctl(self.__handle, TIOCOUTQ, self.buf)

        return rbuf

    def getlsr(self):

        """Returns the status of the UART LSR Register

        J.Grauheding

        """

        rbuf=fcntl.ioctl(self.__handle, TIOCSERGETLSR, self.buf)

        return ord(rbuf[0])

    def get_temt(self):

        """Returns the Tranmitterbuffer Empty Bit of LSR Register

        J.Grauheding

        test result against TIOCSER_TEMT

        """

        rbuf=fcntl.ioctl(self.__handle, TIOCSERGETLSR, self.buf)

        return ord(rbuf[0]) & TIOSER_TEMT

    def flush(self):

        """Discards all bytes from the output or input buffer"""

        tcflush(self.__handle, TCIOFLUSH)

    def rts_on(self):

        """ J.Grauheding """

        rbuf = fcntl.ioctl(self.__handle, TIOCMGET, SerialPort.buf)

        SerialPort.buf[1] = ord(rbuf[3]) | TIOCM_RTS

        rbuf = fcntl.ioctl(self.__handle, TIOCMSET, SerialPort.buf)

        return rbuf

    def rts_off(self):

        """ J.Grauheding """

        rbuf = fcntl.ioctl(self.__handle, TIOCMGET, self.buf)

        self.buf[1]=ord(rbuf[3]) & ~TIOCM_RTS

        rbuf = fcntl.ioctl(self.__handle, TIOCMSET, self.buf)

        return rbuf

    def dtr_on(self):

        """ J.Grauheding """

        rbuf = fcntl.ioctl(self.__handle, TIOCMGET, SerialPort.buf)

        SerialPort.buf[1] = ord(rbuf[3]) | TIOCM_DTR

        rbuf = fcntl.ioctl(self.__handle, TIOCMSET, SerialPort.buf)

        return rbuf

    def dtr_off(self):

        """ J.Grauheding """

        rbuf = fcntl.ioctl(self.__handle, TIOCMGET, self.buf)

        self.buf[1]=ord(rbuf[3]) & ~TIOCM_DTR

        rbuf = fcntl.ioctl(self.__handle, TIOCMSET, self.buf)

        return rbuf

    def cts(self):

        """ J.Grauheding """

        rbuf = fcntl.ioctl(self.__handle, TIOCMGET, self.buf)

        return ord(rbuf[3]) & TIOCM_CTS

    def cd(self):

        """ J.Grauheding """

        rbuf = fcntl.ioctl(self.__handle, TIOCMGET, self.buf)

        return ord(rbuf[3]) & TIOCM_CAR

    def dsr(self):

        """ J.Grauheding """

        rbuf = fcntl.ioctl(self.__handle, TIOCMGET, self.buf)

        return ord(rbuf[2]) & (TIOCM_DSR>>8)

    def ri(self):

        """ J.Grauheding """

        rbuf = fcntl.ioctl(self.__handle, TIOCMGET, self.buf)

        return ord(rbuf[3]) & TIOCM_RNG