replaced huge 2d twiddle arrays by smaller 1d arrays. Now it uses very low memory

C/FP_math.c_backup

@@ -0,0 +1,152 @@
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <math.h>
+
+#define DATA_L 1024
+#define FP_acc 1000
+
+#define PI 3.141592653589793238462643383279502884197169399375105820974944
+
+
+
+int cos_delta_FP_arr[DATA_L] = {0,};
+int sin_delta_FP_arr[DATA_L] = {0,};
+
+void FFT_fp(uint32_t* inp, uint32_t inp_L, uint32_t* buf){
+
+	    // buf имеет длину inp_L * 2 (Re, Im, Re, Im, ...)
+	    // inp содержит inp_L значений uint32_t
+
+	    uint32_t i, j, bit;
+//	    uint32_t N = inp_L / 2;  // длина комплексного массива (inp содержит только Re-часть)
+	    uint32_t N = inp_L;  // длина комплексного массива (inp содержит только Re-часть)
+
+	    // --- копирование входных данных в буфер ---
+	    for (i = 0; i < inp_L; i++) {
+	        buf[i * 2]     = (int)inp[i];  // Re
+	        buf[i * 2 + 1] = 0;            // Im = 0
+	    }
+
+	    // --- bit-reversal перестановка ---
+	    j = 0;
+	    for (i = 1; i < N; i++) {
+	        bit = N >> 1;
+	        while (j & bit) {
+	            j ^= bit;
+	            bit >>= 1;
+	        }
+	        j |= bit;
+	        if (i < j) {
+	            int tmp_re = buf[i * 2];
+	            int tmp_im = buf[i * 2 + 1];
+	            buf[i * 2]     = buf[j * 2];
+	            buf[i * 2 + 1] = buf[j * 2 + 1];
+	            buf[j * 2]     = tmp_re;
+	            buf[j * 2 + 1] = tmp_im;
+	        }
+	    }
+
+	    // --- уровни бабочек ---
+	    uint32_t m = 2;
+	    while (m <= N) {
+	        uint32_t half = m >> 1;
+
+	        int c_delta_FP = cos_delta_FP_arr[m - 2];
+	        int s_delta_FP = sin_delta_FP_arr[m - 2];
+
+	        for (uint32_t start = 0; start < N; start += m) {
+	            int wr = FP_acc;
+	            int wi = 0;
+
+	            for (uint32_t k = 0; k < half; k++) {
+	                int u_re = buf[(start + k) * 2];
+	                int u_im = buf[(start + k) * 2 + 1];
+	                int v_re = buf[(start + k + half) * 2];
+	                int v_im = buf[(start + k + half) * 2 + 1];
+
+	                // t = w * v  (в фиксированной точке)
+	                int64_t t_re = ((int64_t)wr * v_re - (int64_t)wi * v_im) / FP_acc;
+	                int64_t t_im = ((int64_t)wr * v_im + (int64_t)wi * v_re) / FP_acc;
+
+	                // верх/низ
+	                buf[(start + k) * 2]              = u_re + (int)t_re;
+	                buf[(start + k) * 2 + 1]          = u_im + (int)t_im;
+	                buf[(start + k + half) * 2]       = u_re - (int)t_re;
+	                buf[(start + k + half) * 2 + 1]   = u_im - (int)t_im;
+
+	                // w *= w_m (обновление twiddle)
+	                int64_t wr_new = ((int64_t)wr * c_delta_FP - (int64_t)wi * s_delta_FP) / FP_acc;
+	                int64_t wi_new = ((int64_t)wr * s_delta_FP + (int64_t)wi * c_delta_FP) / FP_acc;
+	                wr = (int)wr_new;
+	                wi = (int)wi_new;
+	            }
+	        }
+	        m <<= 1;
+	    }
+	    for (uint32_t i = 0; i < inp_L; ++i){
+	    	//buf[i*2] /= inp_L;
+	    	//buf[i*2+1] /= inp_L;
+	    	printf("re,im: %d, %d\n", buf[i*2], buf[i*2 +1]);
+	    }
+
+}
+
+void imagery2abs(uint32_t* inp, uint32_t inp_L, uint32_t *out){
+	printf("+++++++++++++++++++++\n");
+	printf("calculating abs^2\n");
+	for (uint32_t i = 0; i < inp_L; ++i){
+		int val = (inp[i*2]*inp[i*2] + inp[i*2 +1]*inp[i*2 +1])/FP_acc;
+		printf("%d\n", val);
+		out[i] = val;
+	}
+}
+
+
+
+void sin_cos_filler(int* sin_arr, int* cos_arr, uint32_t L){
+	//[int(-sin(2.0 * pi / m) * FP_acc) for m in range(2,inp_L//2 + 2)]
+	for (uint32_t i = 0; i < L; ++i){
+		int m = i + 2;
+		double angle = 2.0* PI/m;
+		sin_arr[i] = lround(-sin(angle) * FP_acc);
+		cos_arr[i] = lround(cos(angle) * FP_acc);
+		printf("i, angle, sin, cos: %d %g %d %d\n", i, angle, sin_arr[i], cos_arr[i]);
+	}
+}
+
+void data_generator(uint32_t* X, uint32_t* Y, uint32_t N){
+	for (int i = 0; i < N; ++i){
+		X[i] = (int) i;
+		Y[i] = lround(sin(((double)i)*2.0* PI/(N/10))*FP_acc);
+//		Y[I] += 10*FP_acc;
+	}
+}
+
+void main(){
+	char* logfilename = "tmp";
+	uint32_t data_X[DATA_L] = {0,};
+	uint32_t data_Y[DATA_L] = {0,};
+	uint32_t data_res_FFT_imag[DATA_L*2] = {0,};
+	uint32_t data_res_FFT_abs[DATA_L] = {0,};
+
+	sin_cos_filler(sin_delta_FP_arr, cos_delta_FP_arr, DATA_L);
+
+	data_generator(data_X, data_Y, DATA_L);
+
+
+	FFT_fp(data_Y, DATA_L, data_res_FFT_imag);
+
+
+	imagery2abs(data_res_FFT_imag, DATA_L, data_res_FFT_abs);
+
+	FILE *logfile_ptr;
+    logfile_ptr = fopen(logfilename, "w");
+    fprintf(logfile_ptr, "X, Y, FFT\n");
+	for (uint32_t i = 0; i < DATA_L; ++i){
+		fprintf(logfile_ptr, "%d, %d, %d \n", data_X[i], data_Y[i],data_res_FFT_abs[i]);
+	}
+	fclose(logfile_ptr);
+}
+