--- /dev/null
+/*
+ * Copyright © 2012 Keith Packard <keithp@keithp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+ */
+
+#include <ao_fec.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+#include <string.h>
+
+#ifndef RANDOM_MAX
+#define RANDOM_MAX 0x7fffffff
+#endif
+
+static double
+rand_real(void) {
+ return (double) random() / (double) RANDOM_MAX;
+}
+
+static double
+gaussian_random(double mean, double dev)
+{
+ static int save_x_valid = 0;
+ static double save_x;
+ double x;
+
+ if (save_x_valid)
+ {
+ x = save_x;
+ save_x_valid = 0;
+ }
+ else
+ {
+ double w;
+ double normal_x1, normal_x2;
+
+ do {
+ normal_x1 = 2 * rand_real () - 1;
+ normal_x2 = 2 * rand_real () - 1;
+ w = normal_x1*normal_x1 + normal_x2*normal_x2;
+ } while (w >= 1 || w < 1E-30);
+
+ w = sqrt(log(w)*(-2./w));
+
+ /*
+ * normal_x1 and normal_x2 are independent normally
+ * distributed variates
+ */
+
+ x = normal_x1 * w;
+ /* save normal_x2 for next call */
+ save_x = normal_x2 * w;
+ save_x_valid = 1;
+ }
+ return x * dev + mean;
+}
+
+#define PREPARE_LEN(input_len) ((input_len) + AO_FEC_PREPARE_EXTRA)
+#define ENCODE_LEN(input_len) (PREPARE_LEN(input_len) * 2)
+#define DECODE_LEN(input_len) ((input_len) + AO_FEC_PREPARE_EXTRA)
+#define EXPAND_LEN(input_len) (ENCODE_LEN(input_len) * 8)
+
+static int
+ao_expand(uint8_t *bits, int bits_len, uint8_t *bytes)
+{
+ int i, bit;
+ uint8_t b;
+
+ for (i = 0; i < bits_len; i++) {
+ b = bits[i];
+ for (bit = 7; bit >= 0; bit--)
+ *bytes++ = ((b >> bit) & 1) * 0xff;
+ }
+
+ return bits_len * 8;
+}
+
+static int
+ao_fuzz (uint8_t *in, int in_len, uint8_t *out, double dev)
+{
+ int i;
+ int errors = 0;
+
+ for (i = 0; i < in_len; i++) {
+ double error = gaussian_random(0, dev);
+ uint8_t byte = in[i];
+
+ if (error > 0) {
+ if (error > 0xff)
+ error = 0xff;
+ if (error >= 0x80)
+ errors++;
+ if (byte < 0x80)
+ byte += error;
+ else
+ byte -= error;
+ }
+ out[i] = byte;
+ }
+ return errors;
+}
+
+static uint8_t
+ao_random_data(uint8_t *out, uint8_t out_len)
+{
+ uint8_t len = random() % (out_len + 1);
+ uint8_t i;
+
+ for (i = 0; i < len; i++)
+ out[i] = random();
+ return len;
+}
+
+
+int
+main(int argc, char **argv)
+{
+ int trial;
+
+ uint8_t original[120];
+ uint8_t original_len;
+
+ uint8_t encode[ENCODE_LEN(sizeof(original))];
+ int encode_len;
+
+ uint8_t transmit[EXPAND_LEN(sizeof(original))];
+ int transmit_len;
+
+ uint8_t receive[EXPAND_LEN(sizeof(original))];
+ int receive_len, receive_errors;
+
+ uint8_t decode[DECODE_LEN(sizeof(original))];
+ int decode_len;
+
+ int errors = 0;
+ int error;
+
+ srandom(0);
+ for (trial = 0; trial < 10000; trial++) {
+
+ /* Compute some random data */
+ original_len = ao_random_data(original, sizeof(original));
+
+ /* Encode it */
+ encode_len = ao_fec_encode(original, original_len, encode);
+
+ /* Expand from 1-bit-per-symbol to 1-byte-per-symbol */
+ transmit_len = ao_expand(encode, encode_len, transmit);
+
+ /* Add gaussian noise to the signal */
+ receive_errors = ao_fuzz(transmit, transmit_len, receive, 0x30);
+ receive_len = transmit_len;
+
+ /* Decode it */
+ decode_len = ao_fec_decode(receive, receive_len, decode);
+
+ /* Check to see if we received the right data */
+ error = 0;
+
+ if (decode_len < original_len + 2) {
+ printf ("len mis-match\n");
+ error++;
+ }
+
+ if (!ao_fec_check_crc(decode, original_len)) {
+ printf ("crc mis-match\n");
+ error++;
+ }
+
+ if (memcmp(original, decode, original_len) != 0) {
+ printf ("data mis-match\n");
+ error++;
+ }
+ if (error) {
+ printf ("Errors: %d\n", receive_errors);
+ ao_fec_dump_bytes(original, original_len, "Input");
+ ao_fec_dump_bytes(decode, original_len, "Decode");
+ errors += error;
+ }
+ }
+ return errors;
+}
+
+
projects / fw / altos / blobdiff