Fixed versus Floating Point ?

smeil smaili,

If you require a lot of floating point operations, then you may want to consider the new C66x family of multi-core DSPs. The C66x DSP core has all of the advanced operational features of the C64x+ core in the C6474 and then adds native floating point instructions.

But if you want to do just a few floating point operations, then it may be a perfect solution to stay with the C6474 and use its Run-Time Support library which provides floating point support through function calls.

I do not know the number of cycles for each of the floating point functions or operations, but you can easily write a test program that will tell you how many cycles. The following test program has a place where you can insert any instructions and then read the ullTime1 variable to determine how long something takes. Remember that you are benchmarking the Compiler Configuration (Debug vs. Release) as well as the individual operations. Your final project should use the Release configuration, so benchmarking in the Debug Configuration may give misleading results.

Sample Benchmarking main.c said:

#include <c6x.h>
#include <stdio.h>

unsigned long long ullStart, ullEnd, ullCal, ullTime1, ullTime2;

void main()
{
    int s32_Val1 = 0;    // an integer variable.
    double d_Val2 = 0; // a double variable
   
    TSCL = 0;
    ullStart = _itoll( TSCH, TSCL );
    ullEnd = _itoll( TSCH, TSCL );
    ullCal = ullEnd - ullStart;
   
    ullStart = _itoll( TSCH, TSCL );
    s32_Val1  = (int) (d_Val2* 256);  // replace this line with whatever you wish to benchmark, then read ullTime1 after you run to the end of main()
    ullEnd = _itoll( TSCH, TSCL );
    ullTime1 = ullEnd - ullStart - ullCal;

}

Please try this and let us know if this gets the information you want. Please report your findings here, too.

Regards,
RandyP

If you need more help, please reply back. If this answers the question, please click  Verify Answer  , below.

Hi  RandyP,

Thank you for the example... i made some changes to execute an example of integer/float multiplication

so i found that :

Multiplication of two 'int' consumes  1 cycle 

Multiplication of two 'float' consumes 11 cycles.