Using DPI-C sin function

[saket]

Hi,

 

 I'm trying to use DPI-C to import sin function, but it doesn't work, as a workround i had used a sin approximative function which finally give a static value of 2.5 (the offset value) i think that the instanciation of the sin in the code does not work, and i did not know why, any help would be appreciable:

 

 package math_pkg;

  //import dpi task      C Name = SV function name

 //import "DPI-C" pure function real sin (input real rTheta);

 `define PI 3.14159265

 

  function real sin;

 

     input x;

 

     real x;

 

     real x1,y,y2,y3,y5,y7,sum,sign;

 

     begin

 

         sign = 1.0;

 

         x1 = x;

 

         if (x1<0)

 

           begin

 

               x1 = -x1;

 

               sign = -1.0;

 

           end

 

         while (x1 > `PI/2.0)        

 

           begin

 

               x1 = x1 - `PI;

 

               sign = -1.0*sign;

 

           end  

 

         y = x1*2/`PI;

 

         y2 = y*y;

 

         y3 = y*y2;

 

         y5 = y3*y2;

 

         y7 = y5*y2;

 

         sum = 1.570794*y - 0.645962*y3 +

 

               0.079692*y5 - 0.004681712*y7;

 

         sin = sign*sum;

 

     end

 

  endfunction // sin

 

 

endpackage : math_pkg

 

module sv_ams_sin_voltage_gen(output real sine_out);

import math_pkg::*;

parameter sampling_time = 5;

const real pi = 3.1416;

real time_us, time_s ;

bit sampling_clock;

real freq = 20;

real offset = 2.5;

real ampl = 2.5;

always sampling_clock = #(sampling_time) ~sampling_clock;

always @(sampling_clock) begin

time_us = $time/1000;

time_s = time_us/1000000;

end

assign sine_out = offset + (ampl * sin(2*pi*freq));

endmodule