DSP Hardware Timer Test 
Tony Denault
1.5.98

There are some timing measurement with the ixthos board. I am using
the timer_delay() function which is using the DSP interrupt timer
for a sleep function.
1rev - was variable because I have a delay(20,1) in the loop.
2rev - is my fixed: changed to delay(3,1). 
Time were measure using a logic analyzer & Oscilloscope off
of the ixi32g using this code:

   for( i=0; i<loops;i++ )
	{
		m = ~m & 0x040;
		*ixi = m;
		timer_delay( usec, reps);
	}


Results
-----------------------------------------------------------------

                    usec   1rev.        2rev.

                      5                 20.0
 0.01 ms             10                 21.8
							50                 60.6

                    100    113         111.2
		              200    215.5
						  250                260.6
		              300    318.0
		              400    421.0
 0.5 ms             500    523.0       512.0
		              600    625.0
                    700    728.0
		              800    830.0
		              900    912.0       912.0
 
   1 ms            1000   1016        1011
                   2000   2019
                   5000   5008        5011
  10 ms           10000  1001x       1001x
                  50000  5001x   
 100 ms          100000 1000xx      1000xx 
                 500000 5996xx  

  1 sec         1000000 9996xx 
  5 sec         5000000 5000xx

--------------------------------------------------------------------

Using the timer_delay function seem to have a constant overhead
of about 11.5 usec (460 clock cycle) with usec.  I wouldn't used it for 
delay < 10 ms.

The spex clocking dsp code only uses this function for integration time
greater that 50000 usec (50ms).