Compiler/TMS320F28377S: FPU, execution time

Tool/software: TI C/C++ Compiler

Hi to all,

In my project I use FPU library to calculate a fir filter ( order 1023) on signal acquired from ADC and put the result on DAC.

In my test I would to measure the execution time of

hnd_firFP->calc(&firFP);

to do that I put a gipo High prior to call the calc function, and return to low state after the calc function, and use an oscilloscope to monitor the pin activity.

What I see is that the calc function take aboute 5,6 us but often it take about 10us.

How do you explain this beaviours?

I thought htat is a problem of variable allign, so I modify the linker command adding 3 line:

  firldb    ALIGN(0x800)	 > RAMGS10,PAGE = 1, fill=0x0400
  coefffilt ALIGN(0x800)	 > RAMGS11,PAGE = 1, fill=0x0400
  firfilt   				 > RAMLS5 ,PAGE = 1, fill=0x0100

But the problem is still here. It's correct my change in linker ommand?

Thanks!