/********************************************************************
** @source JEEPS packet construction, sending and ack functions
**
** @author Copyright (C) 1999 Alan Bleasby
** @version 1.0
** @modified Dec 28 1999 Alan Bleasby. First version
** @modified Copyright (C) 2006 Robert Lipe
** @@
**
** This library is free software; you can redistribute it and/or
** modify it under the terms of the GNU Library General Public
** License as published by the Free Software Foundation; either
** version 2 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
** Library General Public License for more details.
**
** You should have received a copy of the GNU Library General Public
** License along with this library; if not, write to the
** Free Software Foundation, Inc., 59 Temple Place - Suite 330,
** Boston, MA  02111-1307, USA.
********************************************************************/
#include "gps.h"
#include "gpsserial.h"

#include <stdio.h>
#include <errno.h>
#include <ctype.h>


/* @funcstatic Build_Serial_Packet *************************************
**
** Forms a complete packet to send on serial port
*
** @param [r] in [GPS_PPacket *] packet string with portable packet data
** @param [w] out [GPS_Serial_PPacket *] packet string suitable for serial port
**
** @return [US] number of data bytes to send
************************************************************************/
static US
Build_Serial_Packet(GPS_PPacket in, GPS_Serial_PPacket out)
{
  UC* p;
  UC* q;

  int32 i;
  UC  chk=0;
  US  bytes=0;

  p = in->data;
  q = out->data;

  out->dle   = DLE;
  out->edle  = DLE;
  out->etx   = ETX;
  out->n     = in->n;
  out->type  = in->type;

  chk -= in->type;

  if (in->n == DLE) {
    ++bytes;
    *q++ = DLE;
  }

  chk -= in->n;

  for (i = 0; i < in->n; ++i) {
    if (*p == DLE) {
      ++bytes;
      *q++ = DLE;
    }
    chk -= *p;
    *q++ = *p++;
    ++bytes;
  }

  if (chk == DLE) {
    *q++ = DLE;
    ++bytes;
  }

  out->chk = chk;

  return bytes;
}


void
Diag(void* buf, size_t sz)
{
  unsigned char* cbuf = (unsigned char*) buf;
  while (sz--) {
    GPS_Diag("%02x ", *cbuf++);
  }
}

void
DiagS(void* buf, size_t sz)
{
  unsigned char* cbuf = (unsigned char*) buf;

  while (sz--) {
    unsigned char c = *cbuf++;
    GPS_Diag("%c", isalnum(c) ? c : '.');
  }
}

/* @func GPS_Write_Packet ***********************************************
**
** Forms a complete packet to send
**
** @param [w] fd [int32] file descriptor
** @param [r] packet [GPS_PPacket] packet
**
** @return [int32] number of bytes in the packet
************************************************************************/

int32 GPS_Serial_Write_Packet(gpsdevh* fd, GPS_PPacket packet)
{
  size_t ret;
  const char* m1, *m2;
  GPS_Serial_OPacket ser_pkt;
  UC ser_pkt_data[MAX_GPS_PACKET_SIZE * sizeof(UC)];
  US bytes;

  if (packet->type >= 0xff || packet->n >= 0xff) {
    GPS_Error("SEND: Unsupported packet type/size for serial protocol");
    return 0;
  }

  ser_pkt.data = ser_pkt_data;
  bytes = Build_Serial_Packet(packet, &ser_pkt);

  GPS_Diag("Tx Data:");
  Diag(&ser_pkt.dle, 3);
  if ((ret=GPS_Serial_Write(fd,(const void*) &ser_pkt.dle,(size_t)3)) == -1) {
    perror("write");
    GPS_Error("SEND: Write to GPS failed");
    return 0;
  }
  if (ret!=3) {
    GPS_Error("SEND: Incomplete write to GPS");
    return 0;
  }

  Diag(ser_pkt.data, bytes);
  if ((ret=GPS_Serial_Write(fd,(const void*)ser_pkt.data,(size_t)bytes)) == -1) {
    perror("write");
    GPS_Error("SEND: Write to GPS failed");
    return 0;
  }
  if (ret!=bytes) {
    GPS_Error("SEND: Incomplete write to GPS");
    return 0;
  }


  Diag(&ser_pkt.chk, 3);

  GPS_Diag(": ");
  DiagS(ser_pkt.data, bytes);
  DiagS(&ser_pkt.chk, 3);
  m1 = Get_Pkt_Type(ser_pkt.type, ser_pkt.data[0], &m2);
  GPS_Diag("(%-8s%s)\n", m1, m2 ? m2 : "");

  if ((ret=GPS_Serial_Write(fd,(const void*)&ser_pkt.chk,(size_t)3)) == -1) {
    perror("write");
    GPS_Error("SEND: Write to GPS failed");
    return 0;
  }
  if (ret!=3) {
    GPS_Error("SEND: Incomplete write to GPS");
    return 0;
  }


  return 1;
}


/* @func GPS_Send_Ack ***********************************************
**
** Send an acknowledge packet
**
** @param [w] fd [int32] file descriptor
** @param [r] tra [GPS_PPacket *] packet to transmit
** @param [r] rec [GPS_PPacket *] last packet received
**
** @return [int32] success
************************************************************************/

int32 GPS_Serial_Send_Ack(gpsdevh* fd, GPS_PPacket* tra, GPS_PPacket* rec)
{
  UC data[2];

  GPS_Util_Put_Short(data,(US)(*rec)->type);
  GPS_Make_Packet(tra,LINK_ID[0].Pid_Ack_Byte,data,2);
  if (!GPS_Write_Packet(fd,*tra)) {
    GPS_Error("Error acknowledging packet");
    gps_errno = SERIAL_ERROR;
    return 0;
  }

  return 1;
}
