flightgear/src/Network/generic.cxx

// generic.cxx -- generic protocal class
//
// Written by Curtis Olson, started November 1999.
//
// Copyright (C) 1999  Curtis L. Olson - http://www.flightgear.org/~curt
//
// 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 2 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, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
//
// $Id$

#ifdef HAVE_CONFIG_H
#  include "config.h"
#endif

#include <string.h>                // strstr()
#include <stdlib.h>                // strtod(), atoi()

#include <simgear/debug/logstream.hxx>
#include <simgear/io/iochannel.hxx>
#include <simgear/structure/exception.hxx>
#include <simgear/misc/sg_path.hxx>
#include <simgear/misc/stdint.hxx>
#include <simgear/props/props.hxx>
#include <simgear/props/props_io.hxx>

#include <Main/globals.hxx>
#include <Main/fg_props.hxx>

#include "generic.hxx"



FGGeneric::FGGeneric(string& config) {

    string file = config+".xml";

    SGPath path( globals->get_fg_root() );
    path.append("Protocol");
    path.append(file.c_str());
    SG_LOG(SG_GENERAL, SG_INFO, "Reading communication protocol from "
                                << path.str());

    SGPropertyNode root;
    try {
        readProperties(path.str(), &root);
     } catch (const sg_exception &e) {
        SG_LOG(SG_GENERAL, SG_ALERT,
         "Unable to load the protocol configuration file");
         return;
    }

    SGPropertyNode *output = root.getNode("generic/output");
    if (output)
        read_config(output, _out_message);

    SGPropertyNode *input = root.getNode("generic/input");
    if (input)
        read_config(input, _in_message);
}

FGGeneric::~FGGeneric() {
}


// generate the message
bool FGGeneric::gen_message() {
    string generic_sentence;
    char tmp[255];
    length = 0;

    double val;

    for (unsigned int i = 0; i < _out_message.size(); i++) {

        if (i > 0 && !binary_mode)
            generic_sentence += var_separator;

        switch (_out_message[i].type) {
        case FG_INT:
            val = _out_message[i].offset +
                  _out_message[i].prop->getIntValue() * _out_message[i].factor;
            if (binary_mode) {
                *((int32_t*)&buf[length]) = (int32_t)val;
                length += sizeof(int32_t);
            } else {
                snprintf(tmp, 255, _out_message[i].format.c_str(), (int)val);
            }
            break;

        case FG_BOOL:
            if (binary_mode) {
                *((int8_t*)&buf[length])
                          = _out_message[i].prop->getBoolValue() ? true : false;
                length += sizeof(int8_t);
            } else {
                snprintf(tmp, 255, _out_message[i].format.c_str(),
                                   _out_message[i].prop->getBoolValue());
            }
            break;

        case FG_DOUBLE:
            val = _out_message[i].offset +
                _out_message[i].prop->getFloatValue() * _out_message[i].factor;
            if (binary_mode) {
                *((double*)&buf[length]) = val;
                length += sizeof(double);
            } else {
                snprintf(tmp, 255, _out_message[i].format.c_str(), (float)val);
            }
            break;

        default: // SG_STRING
            if (binary_mode) {
                const char *strdata = _out_message[i].prop->getStringValue();
                int strlength = strlen(strdata);

                /* Format for strings is 
                 * [length as int, 4 bytes][ASCII data, length bytes]
                 */
                *((int32_t*)&buf[length]) = strlength;
                                length += sizeof(int32_t);
                                strncpy(&buf[length], strdata, strlength);
                                length += strlength; 
                /* FIXME padding for alignment? Something like: 
                 * length += (strlength % 4 > 0 ? sizeof(int32_t) - strlength % 4 : 0;
                 */
            } else {
                snprintf(tmp, 255, _out_message[i].format.c_str(),
                                   _out_message[i].prop->getStringValue());
            }
        }

        if (!binary_mode) {
            generic_sentence += tmp;
        }
    }

    if (!binary_mode) {
        /* After each lot of variables has been added, put the line separator
         * char/string
         */
        generic_sentence += line_separator;

        length =  generic_sentence.length();
        strncpy( buf, generic_sentence.c_str(), length );
    } else {
        // add the footer to the packet ("line")
        switch (binary_footer_type) {
            case FOOTER_LENGTH:
                binary_footer_value = length;
                break;

            case FOOTER_MAGIC:
                break;
        }
        if (binary_footer_type != FOOTER_NONE) {
            *((int32_t*)&buf[length]) = binary_footer_value;
            length += sizeof(int32_t);
        }
    }

    return true;
}

bool FGGeneric::parse_message() {
    char *p2, *p1 = buf;
    double val;
    int i = -1;

    if (binary_mode)
        SG_LOG( SG_IO, SG_ALERT,
                "generic protocol: binary mode input is not yet implemented.");
        
    while ((++i < (int)_in_message.size()) &&
            p1 && strcmp(p1, line_separator.c_str())) {

        p2 = strstr(p1, var_separator.c_str());
        if (p2) {
            *p2 = 0;
            p2 += var_separator.length();
        }

        switch (_in_message[i].type) {
        case FG_INT:
            val = _in_message[i].offset + atoi(p1) * _in_message[i].factor;
            _in_message[i].prop->setIntValue((int)val);
            break;

        case FG_BOOL:
            _in_message[i].prop->setBoolValue( atof(p1) != 0.0 );
            break;

        case FG_DOUBLE:
            val = _in_message[i].offset + strtod(p1, 0) * _in_message[i].factor;
            _in_message[i].prop->setFloatValue((float)val);
            break;

        default: // SG_STRING
             _in_message[i].prop->setStringValue(p1);
        }

        p1 = p2;
    }
    
    return true;
}



// open hailing frequencies
bool FGGeneric::open() {
    if ( is_enabled() ) {
        SG_LOG( SG_IO, SG_ALERT, "This shouldn't happen, but the channel " 
                << "is already in use, ignoring" );
        return false;
    }

    SGIOChannel *io = get_io_channel();

    if ( ! io->open( get_direction() ) ) {
        SG_LOG( SG_IO, SG_ALERT, "Error opening channel communication layer." );
        return false;
    }

    set_enabled( true );

    return true;
}


// process work for this port
bool FGGeneric::process() {
    SGIOChannel *io = get_io_channel();

    if ( get_direction() == SG_IO_OUT ) {
        gen_message();
        if ( ! io->write( buf, length ) ) {
            SG_LOG( SG_IO, SG_WARN, "Error writing data." );
            return false;
        }
    } else if ( get_direction() == SG_IO_IN ) {
        if ( (length = io->readline( buf, FG_MAX_MSG_SIZE )) > 0 ) {
            parse_message();
        } else {
            SG_LOG( SG_IO, SG_ALERT, "Error reading data." );
            return false;
        }
    }

    return true;
}


// close the channel
bool FGGeneric::close() {
    SGIOChannel *io = get_io_channel();

    set_enabled( false );

    if ( ! io->close() ) {
        return false;
    }

    return true;
}


void
FGGeneric::read_config(SGPropertyNode *root, vector<_serial_prot> &msg)
{
    if (root->hasValue("binary_mode"))
        binary_mode = root->getBoolValue("binary_mode");
    else 
        binary_mode = false;

    if (!binary_mode) {
        /* These variables specified in the $FG_ROOT/data/Protocol/xxx.xml
         * file for each format
         *
         * var_sep_string  = the string/charachter to place between variables
         * line_sep_string = the string/charachter to place at the end of each
         *                   lot of variables
         */
        var_sep_string = root->getStringValue("var_separator");
        line_sep_string = root->getStringValue("line_separator");

        if ( var_sep_string == "newline" )
                var_separator = '\n';
        else if ( var_sep_string == "tab" )
                var_separator = '\t';
        else if ( var_sep_string == "space" )
                var_separator = ' ';
        else if ( var_sep_string == "formfeed" )
                var_separator = '\f';
        else if ( var_sep_string == "carriagereturn" )
                var_sep_string = '\r';
        else if ( var_sep_string == "verticaltab" )
                var_separator = '\v';
        else
                var_separator = var_sep_string;

        if ( line_sep_string == "newline" )
                line_separator = '\n';
        else if ( line_sep_string == "tab" )
                line_separator = '\t';
        else if ( line_sep_string == "space" )
                line_separator = ' ';
        else if ( line_sep_string == "formfeed" )
                line_separator = '\f';
        else if ( line_sep_string == "carriagereturn" )
                line_separator = '\r';
        else if ( line_sep_string == "verticaltab" )
                line_separator = '\v';
        else
                line_separator = line_sep_string;
    } else {
        binary_footer_type = FOOTER_NONE; // default choice
        if ( root->hasValue("binary_footer") ) {
            string footer_type = root->getStringValue("binary_footer");
            if ( footer_type == "length" )
                binary_footer_type = FOOTER_LENGTH;
            else if ( footer_type.substr(0, 5) == "magic" ) {
                binary_footer_type = FOOTER_MAGIC;
                binary_footer_value = strtol(footer_type.substr(6, 
                            footer_type.length() - 6).c_str(), (char**)0, 0);
            } else if ( footer_type != "none" )
                SG_LOG(SG_IO, SG_ALERT,
                       "generic protocol: Undefined generic binary protocol"
                                           "footer, using no footer.");
        }
    }

    vector<SGPropertyNode_ptr> chunks = root->getChildren("chunk");
    for (unsigned int i = 0; i < chunks.size(); i++) {

        _serial_prot chunk;

     // chunk.name = chunks[i]->getStringValue("name");
        chunk.format = chunks[i]->getStringValue("format", "%d");
        chunk.offset = chunks[i]->getDoubleValue("offset");
        chunk.factor = chunks[i]->getDoubleValue("factor", 1.0);

        string node = chunks[i]->getStringValue("node");
        chunk.prop = fgGetNode(node.c_str(), true);

        string type = chunks[i]->getStringValue("type");
        if (type == "bool")
            chunk.type = FG_BOOL;
        else if (type == "float")
            chunk.type = FG_DOUBLE;
        else if (type == "string")
            chunk.type = FG_STRING;
        else
            chunk.type = FG_INT;

        msg.push_back(chunk);

    }

}