gps.c

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/*
 * File : gps.c
 * Project : WifiScanner (c) 2002-2007 Hervé Schauer Consultants
 * Usage : This utility is written for use with IEEE 802.11 adapters based
 * on Intersil's PRISM II chipset (PCMCIA).
 * 
 * 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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *
 * $Id: $
 */
#include <include.h>
#define DEFAULTHOST "localhost"
#define DEFAULTPORT "2947"
int GPSDsock;
float lat, lon, alt, spd, hed;
float last_lat, last_lon, last_hed;
struct sockaddr_in servaddr, localaddr;
int mode;

const char gpsd_command[] = "PAVMH\n";

int OpenGPSD(void)
{
  int save_mode;

  GPSDsock = -1;
  lat = lon = alt = spd = hed = 0;
  last_lat = last_lon = last_hed = 0;
  mode = -1;

  host = strdup(DEFAULTHOST);
  port = DEFAULTPORT;

  // Find the host
  h = gethostbyname(host);
  if (h == NULL) {
    return GPSD_UNKNOWN_HOST;
  }
  // Fill in the server
  servaddr.sin_family = h->h_addrtype;
  memcpy((char *) &servaddr.sin_addr.s_addr, h->h_addr_list[0],
         h->h_length);
  servaddr.sin_port = htons(port);

  // Create the socket
  if ((GPSDsock = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
    return GPSD_CANT_OPEN_SOCKET;
  }
  // Bind to any local port
  localaddr.sin_family = AF_INET;
  localaddr.sin_addr.s_addr = htonl(INADDR_ANY);
  localaddr.sin_port = htons(0);

  if (bind(sock, (struct sockaddr *) &localaddr, sizeof(localaddr)) < 0) {
    return GPSD_CANT_BIND_PORT;
  }
  // Connect
  if (connect(sock, (struct sockaddr *) &servaddr, sizeof(servaddr)) < 0) {
    return GPSD_CANT_CONNECT;
  }
  // Set nonblocking mode
  save_mode = fcntl(sock, F_GETFL, 0);
  fcntl(sock, F_SETFL, save_mode | O_NONBLOCK);

  }

  return 1;
}

GetGPSPos(float lat, float lon)
{
  const gpsd_command = "P";
  int result;

  // Kick a command off into the system, too
  if (write(sock, gpsd_command, sizeof(gpsd_command)) < 0) {
    if (errno != EAGAIN) {
      close(GPSDsock);
      GPSDsock = -1;
      return GPSD_WRITE_ERROR;
    }
  }
  result = read(sock, buf, 1024);
  return NO_ERROR;
}

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