/*
          file: alt.c
       project: oLogic
   description: Alternate line display mode
   written by : Michael Bradley

   Changelog:
      08/01/09 separate chop/alt source files
      
*/

void showTracesAlt(void)
{
     portData = input_b();   // read data from port B

     traceData = 0;
     if (bit_test(portData,altCurTrace) == 1){
       traceData = TRACE_HEIGHT;
       }

     tracePos = altCurTrace * TRACE_SPACING;
     output_c(tracePos + traceData);
     delay_us(traceWidth);

     if ( (input(SYNC_IN) == 0) && (syncInState == 1) )
       {
       syncInState = 0;
       output_low(SYNC_OUT);
       }
       

     if ( (input(SYNC_IN) == 1) && (syncInState == 0) )
       {
       syncInState = 1;
       altCurTrace++;
       if (altCurTrace == showTraces)
         {
         altCurTrace = 0;
         tracePos = TRACE_BEGIN;
         }
       output_high(SYNC_OUT);
       }


}