diff options
Diffstat (limited to 'controller/fw/src/ldpc_decoder.c')
| -rw-r--r-- | controller/fw/src/ldpc_decoder.c | 267 |
1 files changed, 0 insertions, 267 deletions
diff --git a/controller/fw/src/ldpc_decoder.c b/controller/fw/src/ldpc_decoder.c deleted file mode 100644 index fe59d77..0000000 --- a/controller/fw/src/ldpc_decoder.c +++ /dev/null @@ -1,267 +0,0 @@ - -#include <stdint.h> -#include <unistd.h> -#include <stdbool.h> -#include <math.h> -#include <stdio.h> - - -void gausselimination(size_t n, size_t k, int8_t *A, int8_t *b); - -void inner_logbp( - size_t m, size_t n, - size_t bits_count, size_t nodes_count, const uint32_t bits_values[], const uint32_t nodes_values[], - int8_t Lc[], - float Lq[], float Lr[], - unsigned int n_iter, - float L_posteriori_out[]); - -//decode(384, 6, 8, ...) -int decode(size_t n, size_t nodes_count, size_t bits_count, uint32_t bits[], int8_t y[], int8_t out[], unsigned int maxiter) { - const size_t m = n * nodes_count / bits_count; - float Lq[m*n]; - float Lr[m*n]; - float L_posteriori[n]; - - /* Calculate column bit positions from row bit positions */ - int32_t bits_transposed[nodes_count * n]; - for (size_t i=0; i<nodes_count * n; i++) - bits_transposed[i] = -1; - - for (size_t i=0; i<m; i++) { - for (size_t j=0; j<bits_count; j++) { - int32_t *base = bits_transposed + bits[i*bits_count + j] * nodes_count; - for (; *base != -1; base++) - ; - *base = i; - } - } - - /* - printf("Row positions: ["); - for (size_t i=0; i<m*bits_count; i++) { - if (i) - printf(", "); - if (i%32 == 0) - printf("\n "); - printf("%4d", bits[i]); - } - printf("\n]\n"); - - printf("Column positions: ["); - for (size_t i=0; i<n*nodes_count; i++) { - if (i) - printf(", "); - if (i%32 == 0) - printf("\n "); - printf("%4d", bits_transposed[i]); - } - printf("\n]\n"); - */ - - /* Run iterative optimization algorithm */ - for (unsigned int n_iter=0; n_iter<maxiter; n_iter++) { - inner_logbp(m, n, bits_count, nodes_count, bits, (uint32_t*)bits_transposed, y, Lq, Lr, n_iter, L_posteriori); - - /* - float *arrs[3] = {Lq, Lr, L_posteriori}; - const char *names[3] = {"Lq", "Lr", "L_posteriori"}; - size_t lens[3] = {m*n, m*n, n}; - const size_t head_tail = 10; - for (int j=0; j<3; j++) { - printf("%s=[", names[j]); - bool ellipsis = false; - const int w = 16; - for (size_t i=0; i<lens[j]; i++) { - if (lens[j] > 1000 && i/w > head_tail && i/w < m*n/w-head_tail) { - if (!ellipsis) { - ellipsis = true; - printf("\n ..."); - } - continue; - } - if (i) - printf(", "); - if (i%w == 0) - printf("\n "); - float outf = arrs[j][i]; - char *s = outf < 0 ? "\033[91m" : (outf > 0 ? "\033[92m" : "\033[94m"); - printf("%s% 012.6g\033[38;5;240m", s, outf); - } - printf("\n]\n"); - } - */ - - for (size_t i=0; i<n; i++) - out[i] = L_posteriori[i] <= 0.0f; - - for (size_t i=0; i<m; i++) { - bool sum = 0; - for (size_t j=0; j<bits_count; j++) - sum ^= out[bits[i*bits_count + j]]; - if (sum) - continue; - } - - fflush(stdout); - return n_iter; - } - - fflush(stdout); - return -1; -} - -/* Perform inner ext LogBP solver */ -void inner_logbp( - size_t m, size_t n, - size_t bits_count, size_t nodes_count, uint32_t const bits_values[], const uint32_t nodes_values[], - int8_t Lc[], - float Lq[], float Lr[], - unsigned int n_iter, - float L_posteriori_out[]) { - - /* - printf("Input data: ["); - for (size_t i=0; i<n; i++) { - if (i) - printf(", "); - if (i%32 == 0) - printf("\n "); - printf("%4d", Lc[i]); - } - printf("\n]\n"); - */ - - /* step 1 : Horizontal */ - unsigned int bits_counter = 0; - for (size_t i=0; i<m; i++) { - //printf("=== i=%zu\n", i); - for (size_t p=bits_counter; p<bits_counter+bits_count; p++) { - size_t j = bits_values[p]; - //printf("\033[38;5;240mj=%04zd ", j); - - float x = 1; - if (n_iter == 0) { - for (size_t q=bits_counter; q<bits_counter+bits_count; q++) { - if (bits_values[q] != j) { - //int lcv = Lc[bits_values[q]]; - //char *s = lcv < 0 ? "\033[91m" : (lcv > 0 ? "\033[92m" : "\033[94m"); - //printf("nij=%04u Lc=%s%3d\033[38;5;240m ", bits_values[q], s, lcv); - x *= tanhf(0.5f * Lc[bits_values[q]]); - } - } - - } else { - for (size_t q=bits_counter; q<bits_counter+bits_count; q++) { - if (bits_values[q] != j) - x *= tanhf(0.5f * Lq[i*n + bits_values[q]]); - } - } - - //printf("\n==== i=%03zd p=%01zd x=%08f\n", i, p-bits_counter, x); - - float num = 1 + x; - float denom = 1 - x; - if (num == 0) - Lr[i*n + j] = -1.0f; - else if (denom == 0) - Lr[i*n + j] = 1.0f; - else - Lr[i*n + j] = logf(num/denom); - } - - bits_counter += bits_count; - } - - /* step 2 : Vertical */ - unsigned int nodes_counter = 0; - for (size_t j=0; j<n; j++) { - for (size_t p=bits_counter; p<nodes_counter+nodes_count; p++) { - size_t i = nodes_values[p]; - - Lq[i*n + j] = Lc[j]; - - for (size_t q=bits_counter; q<nodes_counter+nodes_count; q++) { - if (nodes_values[q] != i) - Lq[i*n + j] += Lr[nodes_values[q]*n + j]; - } - } - - nodes_counter += nodes_count; - } - - /* LLR a posteriori */ - nodes_counter = 0; - for (size_t j=0; j<n; j++) { - float sum = 0; - for (size_t k=bits_counter; k<nodes_counter+nodes_count; k++) - sum += Lr[nodes_values[k]*n + j]; - nodes_counter += nodes_count; - - L_posteriori_out[j] = Lc[j] + sum; - } -} - -/* Compute the original (k) bit message from a (n) bit codeword x. - * - * tG: (n, k)-matrix - * x: (n)-vector - * out: (k)-vector - */ -void get_message(size_t n, size_t k, int8_t *tG, int8_t *x, int8_t *out) { - - gausselimination(n, k, tG, x); - - out[k - 1] = x[k - 1]; - for (ssize_t i=k-2; i>=0; i--) { - out[i] = x[i]; - - uint8_t sum = 0; - for (size_t j=i+1; j<k; j++) - sum ^= tG[i*k + j] * out[j]; - - out[i] = !!(out[i] - sum); - } -} - -/* Solve linear system in Z/2Z via Gauss Gauss elimination. - * - * A: (n, k)-matrix - * b: (n)-vector - */ -void gausselimination(size_t n, size_t k, int8_t *A, int8_t *b) { - ssize_t d = k<n ? k : n; - for (ssize_t j=0; j<d; j++) { - - ssize_t pivot = -1; - for (size_t i=j; i<n; i++) { - if (A[i*k + j]) { - pivot = i; - break; - } - } - if (pivot == -1) - continue; - - if (pivot != j) { - for (size_t i=0; i<k; i++) { - int8_t tmp = A[j*k + i]; - A[j*k + i] = A[pivot*k + i]; - A[pivot*k + i] = tmp; - } - - int8_t tmp = b[j]; - b[j] = b[pivot]; - b[pivot] = tmp; - } - - for (size_t i=j+1; i<n; i++) { - if (A[i*k + j]) { - for (size_t p=0; p<k; p++) - A[i*k + p] = !!(A[i*k + p] - A[j*k + p]); - b[i] = !!(b[i] - b[j]); - } - } - } -} - |