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C:/temp/src/j2k/nto/bakJuly/speed.cpp

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#include <j2k/Fred/Standard.hpp>

//  -1  Emergency stop
//   0  Stop
//   1   1st speed step:  1/14 * MAX
//   2   2nd speed step:  2/14 * MAX
//   3   3rd speed step:  3/14 * MAX
//   4   4th speed step:  4/14 * MAX
//   5   5th speed step:  5/14 * MAX
//   6   6th speed step:  6/14 * MAX
//   7   7th speed step:  7/14 * MAX
//   8   8th speed step:  8/14 * MAX
//   9   9th speed step:  9/14 * MAX
//  10  10th speed step: 10/14 * MAX
//  11  11th speed step: 11/14 * MAX
//  12  12th speed step: 12/14 * MAX
//  13  13th speed step: 13/14 * MAX
//  14  14th speed step: 14/14 * MAX


// If you don't understand look at the HEX value table at p.123 !
// 0x00 = Stop
// 0x01 = Emergency Stop
// 0x11 = Emergency Stop
// 0x02 =  1/14
// 0x12 =  2/14
// 0x03 =  3/14
// 0x13 =  4/14
// 0x04 =  5/14
// 0x14 =  6/14
// 0x05 =  7/14
// 0x15 =  8/14
// 0x06 =  9/14
// 0x16 = 10/14
// 0x07 = 11/14
// 0x17 = 12/14
// 0x08 = 13/14
// 0x18 = 14/14

UCHAR getSpeedHex( int spd )
{
  //
  // Emergency stop
  //
  if ( spd <  0 ) return 0x01;

  //
  // Stop the train
  //
  if ( spd == 0 ) return 0x00;

  assert( spd <= 28 );

  // 
  // if ( spd ) { even = 0x00; } else { even = 0x10; }
  //
  register UCHAR even = ( (spd & 0x01) ? 0x00 : 0x10 );


  //
  // Same as: val = (spd+1)/2  + 1;
  //
  register UCHAR val  = spd;


  val++;
  val >>= 1;  // Shift Right by 1  _OR_  Divide by 2
  val++;

  return even + val;  
}

char* setSpeed( UCHAR trainid, int speed, BOOL clockwise, BOOL lights )
{
  char buf[13];
  memset( buf, 0, 13 );

  register UCHAR checksum = trainid;
  register UCHAR command  = 0x40;      // Set Speed 14 speed steps

  if ( clockwise ) command += 0x20;
  if ( lights    ) command += 0x10;
  
  command += getSpeedHex( speed );

  // XOR the parameters to get checksum = trainid ^ command.
  checksum ^= command;

  sprintf( buf, "Q %02X %02X %02X%c%c", trainid, command, checksum, 13, 0 ); 

  printf( "Train #%d is going at speed %d ", trainid, speed );

  if ( clockwise ) {
    printf( "in the forward direction " );
  } else {
    printf( "in the reverse direction " );
  }

  if ( lights ) {
    printf( "with the lights ON \n" );
  } else {
    printf( "with the lights OFF \n" );
  }

  printf( "\t%s\n", buf );
  fflush( stdout );

  return strdup( buf );
}

/*
void setInfo( UCHAR trainid, int speed, BOOL clockwise, BOOL lights )
{
    char buf[12];
    char* cmd = setSpeed( trainid, speed, clockwise, lights );
    memset( buf, 0, 12 );

    int done = 0;
    int loop = 1;
    while( !done )
    {
       loop++;
   if ( loop > 10 ) exit( 1 );
  
       write( cmd, strlen( cmd ) );
       size_t size_read = read( buf, 12 );      
       if ( buf[0] != 'O' ) 
       { 
         // error 
         cmd = setSpeed( trainid, speed, clockwise, lights );
       } else {
         done = 1;
       } 
    }
} 

*/

void test()
{
  UCHAR trainid  = 7;

  for( int l =  0; l <= 1; l++ ) 
  for( int d =  0; d <= 1; d++ ) 
  for( int i = -1; i <= 14; i++ ) 
  {
    char* b = setSpeed( trainid, i, d==1, l==1 );
    printf( "Command: %s", b );
  }
}


int main()
{
  test();

  return 0;
}

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