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freeswitch/libs/spandsp/src/bert.c

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/*
* SpanDSP - a series of DSP components for telephony
*
* bert.c - Bit error rate tests.
*
* Written by Steve Underwood <steveu@coppice.org>
*
* Copyright (C) 2004 Steve Underwood
*
* All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License version 2.1,
* as published by the Free Software Foundation.
*
* 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#if defined(HAVE_CONFIG_H)
#include "config.h"
#endif
#include <inttypes.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <assert.h>
#include <time.h>
#include "spandsp/telephony.h"
#include "spandsp/logging.h"
#include "spandsp/async.h"
#include "spandsp/bert.h"
#include "spandsp/private/logging.h"
#include "spandsp/private/bert.h"
#define MEASUREMENT_STEP 100
static const char *qbf = "VoyeZ Le BricK GeanT QuE J'ExaminE PreS Du WharF 123 456 7890 + - * : = $ % ( )"
"ThE QuicK BrowN FoX JumpS OveR ThE LazY DoG 123 456 7890 + - * : = $ % ( )";
SPAN_DECLARE(const char *) bert_event_to_str(int event)
{
switch (event)
{
case BERT_REPORT_SYNCED:
return "synced";
case BERT_REPORT_UNSYNCED:
return "unsync'ed";
case BERT_REPORT_REGULAR:
return "regular";
case BERT_REPORT_GT_10_2:
return "error rate > 1 in 10^2";
case BERT_REPORT_LT_10_2:
return "error rate < 1 in 10^2";
case BERT_REPORT_LT_10_3:
return "error rate < 1 in 10^3";
case BERT_REPORT_LT_10_4:
return "error rate < 1 in 10^4";
case BERT_REPORT_LT_10_5:
return "error rate < 1 in 10^5";
case BERT_REPORT_LT_10_6:
return "error rate < 1 in 10^6";
case BERT_REPORT_LT_10_7:
return "error rate < 1 in 10^7";
}
return "???";
}
/*- End of function --------------------------------------------------------*/
SPAN_DECLARE(int) bert_get_bit(bert_state_t *s)
{
int bit;
if (s->limit && s->tx.bits >= s->limit)
return SIG_STATUS_END_OF_DATA;
bit = 0;
switch (s->pattern_class)
{
case 0:
bit = s->tx.reg & 1;
s->tx.reg = (s->tx.reg >> 1) | ((s->tx.reg & 1) << s->shift2);
break;
case 1:
bit = s->tx.reg & 1;
s->tx.reg = (s->tx.reg >> 1) | (((s->tx.reg ^ (s->tx.reg >> s->shift)) & 1) << s->shift2);
if (s->max_zeros)
{
/* This generator suppresses runs >s->max_zeros */
if (bit)
{
if (++s->tx.zeros > s->max_zeros)
{
s->tx.zeros = 0;
bit ^= 1;
}
}
else
{
s->tx.zeros = 0;
}
}
bit ^= s->invert;
break;
case 2:
if (s->tx.step_bit == 0)
{
s->tx.step_bit = 7;
s->tx.reg = qbf[s->tx.step++];
if (s->tx.reg == 0)
{
s->tx.reg = 'V';
s->tx.step = 1;
}
}
bit = s->tx.reg & 1;
s->tx.reg >>= 1;
s->tx.step_bit--;
break;
}
s->tx.bits++;
return bit;
}
/*- End of function --------------------------------------------------------*/
static void assess_error_rate(bert_state_t *s)
{
int i;
int j;
int sum;
int test;
/* We assess the error rate in decadic steps. For each decade we assess the error over 10 times
the number of bits, to smooth the result. This means we assess the 1 in 100 rate based on 1000 bits
(i.e. we look for >=10 errors in 1000 bits). We make an assessment every 100 bits, using a sliding
window over the last 1000 bits. We assess the 1 in 1000 rate over 10000 bits in a similar way, and
so on for the lower error rates. */
test = TRUE;
for (i = 2; i <= 7; i++)
{
if (++s->decade_ptr[i] < 10)
break;
/* This decade has reached 10 snapshots, so we need to touch the next decade */
s->decade_ptr[i] = 0;
/* Sum the last 10 snapshots from this decade, to see if we overflow into the next decade */
for (sum = 0, j = 0; j < 10; j++)
sum += s->decade_bad[i][j];
if (test && sum > 10)
{
/* We overflow into the next decade */
test = FALSE;
if (s->error_rate != i && s->reporter)
s->reporter(s->user_data, BERT_REPORT_GT_10_2 + i - 2, &s->results);
s->error_rate = i;
}
s->decade_bad[i][0] = 0;
if (i < 7)
s->decade_bad[i + 1][s->decade_ptr[i + 1]] = sum;
}
if (i > 7)
{
if (s->decade_ptr[i] >= 10)
s->decade_ptr[i] = 0;
if (test)
{
if (s->error_rate != i && s->reporter)
s->reporter(s->user_data, BERT_REPORT_GT_10_2 + i - 2, &s->results);
s->error_rate = i;
}
}
else
{
s->decade_bad[i][s->decade_ptr[i]] = 0;
}
}
/*- End of function --------------------------------------------------------*/
SPAN_DECLARE(void) bert_put_bit(bert_state_t *s, int bit)
{
if (bit < 0)
{
/* Special conditions */
printf("Status is %s (%d)\n", signal_status_to_str(bit), bit);
return;
}
bit = (bit & 1) ^ s->invert;
s->rx.bits++;
switch (s->pattern_class)
{
case 0:
if (s->rx.resync)
{
s->rx.reg = (s->rx.reg >> 1) | (bit << s->shift2);
s->rx.ref_reg = (s->rx.ref_reg >> 1) | ((s->rx.ref_reg & 1) << s->shift2);
if (s->rx.reg == s->rx.ref_reg)
{
if (++s->rx.resync > s->resync_time)
{
s->rx.resync = 0;
if (s->reporter)
s->reporter(s->user_data, BERT_REPORT_SYNCED, &s->results);
}
}
else
{
s->rx.resync = 2;
s->rx.ref_reg = s->rx.master_reg;
}
}
else
{
s->results.total_bits++;
if ((bit ^ s->rx.ref_reg) & 1)
s->results.bad_bits++;
s->rx.ref_reg = (s->rx.ref_reg >> 1) | ((s->rx.ref_reg & 1) << s->shift2);
}
break;
case 1:
if (s->rx.resync)
{
/* If we get a reasonable period for which we correctly predict the
next bit, we must be in sync. */
/* Don't worry about max. zeros tests when resyncing.
It might just extend the resync time a little. Trying
to include the test might affect robustness. */
if (bit == (int) ((s->rx.reg >> s->shift) & 1))
{
if (++s->rx.resync > s->resync_time)
{
s->rx.resync = 0;
if (s->reporter)
s->reporter(s->user_data, BERT_REPORT_SYNCED, &s->results);
}
}
else
{
s->rx.resync = 2;
s->rx.reg ^= s->mask;
}
}
else
{
s->results.total_bits++;
if (s->max_zeros)
{
/* This generator suppresses runs >s->max_zeros */
if ((s->rx.reg & s->mask))
{
if (++s->rx.zeros > s->max_zeros)
{
s->rx.zeros = 0;
bit ^= 1;
}
}
else
{
s->rx.zeros = 0;
}
}
if (bit != (int) ((s->rx.reg >> s->shift) & 1))
{
s->results.bad_bits++;
s->rx.resync_bad_bits++;
s->decade_bad[2][s->decade_ptr[2]]++;
}
if (--s->rx.measurement_step <= 0)
{
/* Every hundred bits we need to do the error rate measurement */
s->rx.measurement_step = MEASUREMENT_STEP;
assess_error_rate(s);
}
if (--s->rx.resync_cnt <= 0)
{
/* Check if there were enough bad bits during this period to
justify a resync. */
if (s->rx.resync_bad_bits >= (s->rx.resync_len*s->rx.resync_percent)/100)
{
s->rx.resync = 1;
s->results.resyncs++;
if (s->reporter)
s->reporter(s->user_data, BERT_REPORT_UNSYNCED, &s->results);
}
s->rx.resync_cnt = s->rx.resync_len;
s->rx.resync_bad_bits = 0;
}
}
s->rx.reg = (s->rx.reg >> 1) | (((s->rx.reg ^ (s->rx.reg >> s->shift)) & 1) << s->shift2);
break;
case 2:
s->rx.reg = (s->rx.reg >> 1) | (bit << 6);
/* TODO: There is no mechanism for synching yet. This only works if things start in sync. */
if (++s->rx.step_bit == 7)
{
s->rx.step_bit = 0;
if ((int) s->rx.reg != qbf[s->rx.step])
{
/* We need to work out the number of actual bad bits here. We need to look at the
error rate, and see it a resync is needed. etc. */
s->results.bad_bits++;
}
if (qbf[++s->rx.step] == '\0')
s->rx.step = 0;
}
s->results.total_bits++;
break;
}
if (s->report_frequency > 0)
{
if (--s->rx.report_countdown <= 0)
{
if (s->reporter)
s->reporter(s->user_data, BERT_REPORT_REGULAR, &s->results);
s->rx.report_countdown = s->report_frequency;
}
}
}
/*- End of function --------------------------------------------------------*/
SPAN_DECLARE(int) bert_result(bert_state_t *s, bert_results_t *results)
{
results->total_bits = s->results.total_bits;
results->bad_bits = s->results.bad_bits;
results->resyncs = s->results.resyncs;
return sizeof(*results);
}
/*- End of function --------------------------------------------------------*/
SPAN_DECLARE(void) bert_set_report(bert_state_t *s, int freq, bert_report_func_t reporter, void *user_data)
{
s->report_frequency = freq;
s->reporter = reporter;
s->user_data = user_data;
s->rx.report_countdown = s->report_frequency;
}
/*- End of function --------------------------------------------------------*/
SPAN_DECLARE(bert_state_t *) bert_init(bert_state_t *s, int limit, int pattern, int resync_len, int resync_percent)
{
int i;
int j;
if (s == NULL)
{
if ((s = (bert_state_t *) malloc(sizeof(*s))) == NULL)
return NULL;
}
memset(s, 0, sizeof(*s));
s->pattern = pattern;
s->limit = limit;
s->reporter = NULL;
s->user_data = NULL;
s->report_frequency = 0;
s->resync_time = 72;
s->invert = 0;
switch (s->pattern)
{
case BERT_PATTERN_ZEROS:
s->tx.reg = 0;
s->shift2 = 31;
s->pattern_class = 0;
break;
case BERT_PATTERN_ONES:
s->tx.reg = ~((uint32_t) 0);
s->shift2 = 31;
s->pattern_class = 0;
break;
case BERT_PATTERN_7_TO_1:
s->tx.reg = 0xFEFEFEFE;
s->shift2 = 31;
s->pattern_class = 0;
break;
case BERT_PATTERN_3_TO_1:
s->tx.reg = 0xEEEEEEEE;
s->shift2 = 31;
s->pattern_class = 0;
break;
case BERT_PATTERN_1_TO_1:
s->tx.reg = 0xAAAAAAAA;
s->shift2 = 31;
s->pattern_class = 0;
break;
case BERT_PATTERN_1_TO_3:
s->tx.reg = 0x11111111;
s->shift2 = 31;
s->pattern_class = 0;
break;
case BERT_PATTERN_1_TO_7:
s->tx.reg = 0x01010101;
s->shift2 = 31;
s->pattern_class = 0;
break;
case BERT_PATTERN_QBF:
s->tx.reg = 0;
s->pattern_class = 2;
break;
case BERT_PATTERN_ITU_O151_23:
s->pattern_class = 1;
s->tx.reg = 0x7FFFFF;
s->mask = 0x20;
s->shift = 5;
s->shift2 = 22;
s->invert = 1;
s->resync_time = 56;
s->max_zeros = 0;
break;
case BERT_PATTERN_ITU_O151_20:
s->pattern_class = 1;
s->tx.reg = 0xFFFFF;
s->mask = 0x8;
s->shift = 3;
s->shift2 = 19;
s->invert = 1;
s->resync_time = 50;
s->max_zeros = 14;
break;
case BERT_PATTERN_ITU_O151_15:
s->pattern_class = 1;
s->tx.reg = 0x7FFF;
s->mask = 0x2;
s->shift = 1;
s->shift2 = 14;
s->invert = 1;
s->resync_time = 40;
s->max_zeros = 0;
break;
case BERT_PATTERN_ITU_O152_11:
s->pattern_class = 1;
s->tx.reg = 0x7FF;
s->mask = 0x4;
s->shift = 2;
s->shift2 = 10;
s->invert = 0;
s->resync_time = 32;
s->max_zeros = 0;
break;
case BERT_PATTERN_ITU_O153_9:
s->pattern_class = 1;
s->tx.reg = 0x1FF;
s->mask = 0x10;
s->shift = 4;
s->shift2 = 8;
s->invert = 0;
s->resync_time = 28;
s->max_zeros = 0;
break;
}
s->tx.bits = 0;
s->tx.step = 0;
s->tx.step_bit = 0;
s->tx.zeros = 0;
s->rx.reg = s->tx.reg;
s->rx.ref_reg = s->rx.reg;
s->rx.master_reg = s->rx.ref_reg;
s->rx.bits = 0;
s->rx.step = 0;
s->rx.step_bit = 0;
s->rx.resync = 1;
s->rx.resync_cnt = resync_len;
s->rx.resync_bad_bits = 0;
s->rx.resync_len = resync_len;
s->rx.resync_percent = resync_percent;
s->results.total_bits = 0;
s->results.bad_bits = 0;
s->results.resyncs = 0;
s->rx.report_countdown = 0;
for (i = 0; i < 8; i++)
{
for (j = 0; j < 10; j++)
s->decade_bad[i][j] = 0;
s->decade_ptr[i] = 0;
}
s->error_rate = 8;
s->rx.measurement_step = MEASUREMENT_STEP;
span_log_init(&s->logging, SPAN_LOG_NONE, NULL);
span_log_set_protocol(&s->logging, "BERT");
return s;
}
/*- End of function --------------------------------------------------------*/
SPAN_DECLARE(int) bert_release(bert_state_t *s)
{
return 0;
}
/*- End of function --------------------------------------------------------*/
SPAN_DECLARE(int) bert_free(bert_state_t *s)
{
free(s);
return 0;
}
/*- End of function --------------------------------------------------------*/
/*- End of file ------------------------------------------------------------*/
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