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hwclock: add parameters for minimum/maximum number of samples

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Allocate the arrays which hold the samples dynamically and limit the
number of dropped samples to not fall below the minimum.
This commit is contained in:
Miroslav Lichvar
2018-08-08 13:22:30 +02:00
parent 159bd73f76
commit c0717a27f6
5 changed files with 33 additions and 17 deletions
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40
hwclock.c
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@@ -36,8 +36,9 @@
#include "regress.h"
#include "util.h"
/* Maximum number of samples per clock */
#define MAX_SAMPLES 16
/* Minimum and maximum number of samples per clock */
#define MIN_SAMPLES 2
#define MAX_SAMPLES 64
/* Maximum acceptable frequency offset of the clock */
#define MAX_FREQ_OFFSET (2.0 / 3.0)
@@ -49,10 +50,12 @@ struct HCL_Instance_Record {
/* Samples stored as intervals (uncorrected for frequency error)
relative to local_ref and hw_ref */
double x_data[MAX_SAMPLES];
double y_data[MAX_SAMPLES];
double *x_data;
double *y_data;
/* Number of samples */
/* Minimum, maximum and current number of samples */
int min_samples;
int max_samples;
int n_samples;
/* Maximum error of the last sample */
@@ -89,13 +92,21 @@ handle_slew(struct timespec *raw, struct timespec *cooked, double dfreq,
/* ================================================== */
HCL_Instance
HCL_CreateInstance(double min_separation)
HCL_CreateInstance(int min_samples, int max_samples, double min_separation)
{
HCL_Instance clock;
min_samples = CLAMP(MIN_SAMPLES, min_samples, MAX_SAMPLES);
max_samples = CLAMP(MIN_SAMPLES, max_samples, MAX_SAMPLES);
max_samples = MAX(min_samples, max_samples);
clock = MallocNew(struct HCL_Instance_Record);
clock->x_data[MAX_SAMPLES - 1] = 0.0;
clock->y_data[MAX_SAMPLES - 1] = 0.0;
clock->x_data = MallocArray(double, max_samples);
clock->y_data = MallocArray(double, max_samples);
clock->x_data[max_samples - 1] = 0.0;
clock->y_data[max_samples - 1] = 0.0;
clock->min_samples = min_samples;
clock->max_samples = max_samples;
clock->n_samples = 0;
clock->valid_coefs = 0;
clock->min_separation = min_separation;
@@ -110,6 +121,8 @@ HCL_CreateInstance(double min_separation)
void HCL_DestroyInstance(HCL_Instance clock)
{
LCL_RemoveParameterChangeHandler(handle_slew, clock);
Free(clock->y_data);
Free(clock->x_data);
Free(clock);
}
@@ -138,7 +151,7 @@ HCL_AccumulateSample(HCL_Instance clock, struct timespec *hw_ts,
/* Shift old samples */
if (clock->n_samples) {
if (clock->n_samples >= MAX_SAMPLES)
if (clock->n_samples >= clock->max_samples)
clock->n_samples--;
hw_delta = UTI_DiffTimespecsToDouble(hw_ts, &clock->hw_ref);
@@ -149,7 +162,7 @@ HCL_AccumulateSample(HCL_Instance clock, struct timespec *hw_ts,
DEBUG_LOG("HW clock reset interval=%f", local_delta);
}
for (i = MAX_SAMPLES - clock->n_samples; i < MAX_SAMPLES; i++) {
for (i = clock->max_samples - clock->n_samples; i < clock->max_samples; i++) {
clock->y_data[i - 1] = clock->y_data[i] - hw_delta;
clock->x_data[i - 1] = clock->x_data[i] - local_delta;
}
@@ -162,8 +175,8 @@ HCL_AccumulateSample(HCL_Instance clock, struct timespec *hw_ts,
/* Get new coefficients */
clock->valid_coefs =
RGR_FindBestRobustRegression(clock->x_data + MAX_SAMPLES - clock->n_samples,
clock->y_data + MAX_SAMPLES - clock->n_samples,
RGR_FindBestRobustRegression(clock->x_data + clock->max_samples - clock->n_samples,
clock->y_data + clock->max_samples - clock->n_samples,
clock->n_samples, 1.0e-10, &clock->offset, &raw_freq,
&n_runs, &best_start);
@@ -175,7 +188,8 @@ HCL_AccumulateSample(HCL_Instance clock, struct timespec *hw_ts,
clock->frequency = raw_freq / local_freq;
/* Drop unneeded samples */
clock->n_samples -= best_start;
if (clock->n_samples > clock->min_samples)
clock->n_samples -= MIN(best_start, clock->n_samples - clock->min_samples);
/* If the fit doesn't cross the error interval of the last sample,
or the frequency is not sane, drop all samples and start again */