now printf is disabled if twiddles arrays are external. Now while used for emdedded there is no prfintf garbage in compiled code.

.project

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<projectDescription>
+	<name>Theta_fourier</name>
+	<comment></comment>
+	<projects>
+	</projects>
+	<buildSpec>
+	</buildSpec>
+	<natures>
+	</natures>
+</projectDescription>

C/FFT_FP_realisation.c

@@ -3,15 +3,28 @@
 #include <math.h>
 #include <stdio.h>
 
+#ifndef FFT_FP_EXTERNAL_TWIDDLES
 static int64_t twiddle_re[TWIDDLE_L] = {0,};
 static int64_t twiddle_im[TWIDDLE_L] = {0,};
+#define PRINTF
+#endif
 
-void fft_fp_prepare(void){
+
+
+void fft_twiddle_gen(int64_t* tw_re, int64_t* tw_im){
 	for (uint32_t k = 0; k < TWIDDLE_L; ++k){
 		double angle = 2.0 * PI * k / DATA_L;
-		twiddle_re[k] = lround(cos(angle) * FP_acc);
-		twiddle_im[k] = lround(-sin(angle) * FP_acc);
-		printf("k, angle, tw_re, tw_im: %u %g %lld %lld\n", k, angle, (long long)twiddle_re[k], (long long)twiddle_im[k]);
+		tw_re[k] = lround(cos(angle) * FP_acc);
+		tw_im[k] = lround(-sin(angle) * FP_acc);
+	}
+}
+
+void fft_fp_prepare(void){
+	fft_twiddle_gen(twiddle_re, twiddle_im);
+	for (uint32_t k = 0; k < TWIDDLE_L; ++k){
+#ifdef PRINTF
+		printf("k, angle, tw_re, tw_im: %u %g %lld %lld\n", k, 2.0 * PI * k / DATA_L, (long long)twiddle_re[k], (long long)twiddle_im[k]);
+#endif
 	}
 }
 
@@ -82,7 +95,10 @@ void FFT_fp(int64_t* inp, uint32_t inp_L, int64_t* buf){
 	    for (uint32_t ii = 0; ii < inp_L; ++ii){
 	    	buf[ii*2] /= inp_L;
 	    	buf[ii*2+1] /= inp_L;
+#ifdef PRINTF
 	    	printf("re,im: %lld, %lld\n", (long long)buf[ii*2], (long long)buf[ii*2 +1]);
+#endif
+
 	    }
 
 }

C/FFT_FP_realisation.h

@@ -19,6 +19,12 @@
 #define PI 3.141592653589793238462643383279502884197169399375105820974944
 #endif
 
+#ifdef FFT_FP_EXTERNAL_TWIDDLES
+extern volatile int64_t twiddle_re[TWIDDLE_L];
+extern volatile int64_t twiddle_im[TWIDDLE_L];
+#endif
+
+void fft_twiddle_gen(int64_t* twiddle_re, int64_t* twiddle_im);
 void fft_fp_prepare(void);
 void FFT_fp(int64_t* inp, uint32_t inp_L, int64_t* buf);
 

C/FP_math.c

@@ -5,7 +5,7 @@
 #include <math.h>
 
 #define DATA_L (1<<16)
-#define FP_acc 1000
+#define FP_acc (1<<16)
 
 #include "FFT_FP_realisation.h"