basic_verilog/Advanced Synthesis Cookbook/arithmetic/cordic_angle_table.cpp

// Copyright 2008 Altera Corporation. All rights reserved.  
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//
// This reference design file, and your use thereof, is subject to and governed
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/////////////////////////////////////////////////////////////////////////////

// baeckler - 08-06-2008

#include <math.h>
#include <stdio.h>

////////////////////////////////////////
// convert float to fixed point signed binary
// values must be in the range -2..2
////////////////////////////////////////
void conv_binary (double val, int bits)
{
	double f;
	int n = 0;

	fprintf (stdout,"%d'b",bits);
	
	// handle the top bit to become positive
	if (val < 0.0) 
	{
		fprintf (stdout,"1");
		val += 2.0;		
	}
	else 
	{
		fprintf (stdout,"0");
	}
	
	// handle remaining bits
	for (n=0; n<bits-1; n++)
	{
		f = 1.0;
		f /= (1 << n);

		if (val >= f) 
		{
			fprintf (stdout,"1");
			val -= f;
		}		
		else 
		{
			fprintf (stdout,"0");			
		}
	}	
}

////////////////////////////////////////
// generate an arctan table for CORDIC
////////////////////////////////////////
int main (void)
{
	double f = 1.0, at=0.0;
	double pi = 3.14159265358979;
	double gain = 1.0, gain_term;

	int const bits = 16;
	int const rounds = 16;

	int n = 0;

	// ROM content
	for (n=0; n<rounds; n++)
	{
		f = 1.0;
		f /= (1 << n);
		
		gain_term = 1.0 + f*f;
		gain_term = sqrt(gain_term);
		gain *= gain_term;

		at = atan(f);
		fprintf (stdout,"  4'h%x : zrom <= ",n);
		conv_binary (at,bits);
		fprintf (stdout,"; // %1.8f\n",at);
	}

	// handy constants for use in testing
	fprintf (stdout,"\n\n");

	fprintf (stdout,"gain = ");
	conv_binary (gain,bits);
	fprintf (stdout," // %1.8f\n",gain);
	
	fprintf (stdout,"inv_gain = ");
	conv_binary (1.0/gain,bits);
	fprintf (stdout," // %1.8f\n",1.0/gain);
	
	f = pi / 8.0;
	fprintf (stdout,"pi_over_8 = ");
	conv_binary (f,bits);
	fprintf (stdout,"; // %1.8f\n",f);

	f = pi / 8.0;
	f = sin(f);
	fprintf (stdout,"sin_pi_over_8 = ");
	conv_binary (f,bits);
	fprintf (stdout,"; // %1.8f\n",f);

	f = pi / 8.0;
	f = cos(f);
	fprintf (stdout,"cos_pi_over_8 = ");
	conv_binary (f,bits);
	fprintf (stdout,"; // %1.8f\n",f);
	
	f = -pi / 3.0;
	fprintf (stdout,"neg_pi_over_3 = ");
	conv_binary (f,bits);
	fprintf (stdout,"; // %1.8f\n",f);

	f = -pi / 3.0;
	f = sin(f);
	fprintf (stdout,"sin_neg_pi_over_3 = ");
	conv_binary (f,bits);
	fprintf (stdout,"; // %1.8f\n",f);

	f = -pi / 3.0;
	f = cos(f);
	fprintf (stdout,"cos_neg_pi_over_3 = ");
	conv_binary (f,bits);
	fprintf (stdout,"; // %1.8f\n",f);

	f = pi / 4.0;
	fprintf (stdout,"pi_over_4 = ");
	conv_binary (f,bits);
	fprintf (stdout,"; // %1.8f\n",f);

	f = -pi / 4.0;
	fprintf (stdout,"neg_pi_over_4 = ");
	conv_binary (f,bits);
	fprintf (stdout,"; // %1.8f\n",f);

	f = (0.25*0.25) + (0.25*0.25);
	f = sqrt(f) * gain;
	fprintf (stdout,"gained_vec_len = ");
	conv_binary (f,bits);
	fprintf (stdout,"; // %1.8f\n",f);


	return (0);
}