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