#include <hardware/sensors.h>
#include <math.h>
#include <pthread.h>
+#include <utils/Log.h>
#include "common.h"
#include "filtering.h"
-void add_to_buff(struct circ_buff* circ_buff, float val)
+
+struct filter_median_t
{
- if (circ_buff->count < circ_buff->size)
- {
- circ_buff->buff[circ_buff->count] = val;
- circ_buff->count++;
- return;
- }
+ float* buff;
+ unsigned int idx;
+ unsigned int count;
+ unsigned int sample_size;
+};
- circ_buff->idx = circ_buff->idx % circ_buff->size;
- circ_buff->buff[circ_buff->idx] = val;
- circ_buff->idx++;
- return;
-}
-static unsigned int partition(float* list, unsigned int left,
- unsigned int right, unsigned int pivot_index)
+static unsigned int partition ( float* list, unsigned int left,
+ unsigned int right, unsigned int pivot_index)
{
unsigned int i;
unsigned int store_index = left;
float aux;
float pivot_value = list[pivot_index];
- // swap list[pivotIndex] and list[right]
+ /* Swap list[pivotIndex] and list[right] */
aux = list[pivot_index];
list[pivot_index] = list[right];
list[right] = aux;
{
if (list[i] < pivot_value)
{
- // swap list[store_index] and list[i]
+ /* Swap list[store_index] and list[i] */
aux = list[store_index];
list[store_index] = list[i];
list[i] = aux;
store_index++;
}
}
- //swap list[right] and list[store_index]
+
+ /* Swap list[right] and list[store_index] */
aux = list[right];
list[right] = list[store_index];
list[store_index] = aux;
return store_index;
}
-/* http://en.wikipedia.org/wiki/Quickselect */
-float median(float* queue, unsigned int size)
+
+static float median (float* queue, unsigned int size)
{
+ /* http://en.wikipedia.org/wiki/Quickselect */
+
unsigned int left = 0;
unsigned int right = size - 1;
unsigned int pivot_index;
return temp[left];
}
-void denoise_median(struct sensors_event_t* data, struct sensor_info_t* info)
+
+static void denoise_median_init(int s, unsigned int num_fields,
+ unsigned int max_samples)
+{
+ struct filter_median_t* f_data = (struct filter_median_t*)
+ malloc(sizeof(struct filter_median_t));
+
+ f_data->buff = (float*) calloc(max_samples, sizeof(float) * num_fields);
+ f_data->sample_size = max_samples;
+ f_data->count = 0;
+ f_data->idx = 0;
+ sensor[s].filter = f_data;
+}
+
+
+static void denoise_median_reset (struct sensor_info_t* info)
+{
+ struct filter_median_t* f_data = (struct filter_median_t*) info->filter;
+
+ if (!f_data)
+ return;
+
+ f_data->count = 0;
+ f_data->idx = 0;
+}
+
+
+static void denoise_median ( struct sensor_info_t* info,
+ struct sensors_event_t* data,
+ unsigned int num_fields)
{
float x, y, z;
float scale;
+ unsigned int field, offset;
- struct filter* f_data = (struct filter*) info->filter;
+ struct filter_median_t* f_data = (struct filter_median_t*) info->filter;
if (!f_data)
return;
- x = data->data[0];
- y = data->data[1];
- z = data->data[2];
+ /* If we are at event count 1 reset the indices */
+ if (info->event_count == 1)
+ denoise_median_reset(info);
+
+ if (f_data->count < f_data->sample_size)
+ f_data->count++;
+
+ for (field = 0; field < num_fields; field++) {
+ offset = f_data->sample_size * field;
+ f_data->buff[offset + f_data->idx] = data->data[field];
+
+ data->data[field] = median(f_data->buff + offset, f_data->count);
+ }
+
+ f_data->idx = (f_data->idx + 1) % f_data->sample_size;
+}
+
+
+static void denoise_average ( struct sensor_info_t* si,
+ struct sensors_event_t* data,
+ int num_fields, int max_samples)
+{
+ /*
+ * Smooth out incoming data using a moving average over a number of
+ * samples. We accumulate one second worth of samples, or max_samples,
+ * depending on which is lower.
+ */
+
+ int i;
+ int f;
+ int sampling_rate = (int) si->sampling_rate;
+ int history_size;
+ int history_full = 0;
+
+ /* Don't denoise anything if we have less than two samples per second */
+ if (sampling_rate < 2)
+ return;
+
+ /* Restrict window size to the min of sampling_rate and max_samples */
+ if (sampling_rate > max_samples)
+ history_size = max_samples;
+ else
+ history_size = sampling_rate;
+
+ /* Reset history if we're operating on an incorrect window size */
+ if (si->history_size != history_size) {
+ si->history_size = history_size;
+ si->history_entries = 0;
+ si->history_index = 0;
+ si->history = (float*) realloc(si->history,
+ si->history_size * num_fields * sizeof(float));
+ if (si->history) {
+ si->history_sum = (float*) realloc(si->history_sum,
+ num_fields * sizeof(float));
+ if (si->history_sum)
+ memset(si->history_sum, 0, num_fields * sizeof(float));
+ }
+ }
+
+ if (!si->history || !si->history_sum)
+ return; /* Unlikely, but still... */
+
+ /* Update initialized samples count */
+ if (si->history_entries < si->history_size)
+ si->history_entries++;
+ else
+ history_full = 1;
+
+ /* Record new sample and calculate the moving sum */
+ for (f=0; f < num_fields; f++) {
+ /**
+ * A field is going to be overwritten if
+ * history is full, so decrease the history sum
+ */
+ if (history_full)
+ si->history_sum[f] -=
+ si->history[si->history_index * num_fields + f];
- add_to_buff(f_data->x_buff, x);
- add_to_buff(f_data->y_buff, y);
- add_to_buff(f_data->z_buff, z);
+ si->history[si->history_index * num_fields + f] = data->data[f];
+ si->history_sum[f] += data->data[f];
- x = median(f_data->x_buff->buff, f_data->x_buff->count);
- y = median(f_data->y_buff->buff, f_data->y_buff->count);
- z = median(f_data->z_buff->buff, f_data->z_buff->count);
+ /* For now simply compute a mobile mean for each field */
+ /* and output filtered data */
+ data->data[f] = si->history_sum[f] / si->history_entries;
+ }
+
+ /* Update our rolling index (next evicted cell) */
+ si->history_index = (si->history_index + 1) % si->history_size;
+}
- data->data[0] = x;
- data->data[1] = y;
- data->data[2] = z;
+
+void setup_noise_filtering (int s)
+{
+ switch (sensor[s].type) {
+ case SENSOR_TYPE_GYROSCOPE:
+ denoise_median_init(s, 3, 5);
+ break;
+ }
}
+
+void denoise (int s, struct sensors_event_t* data)
+{
+ switch (sensor[s].type) {
+ case SENSOR_TYPE_GYROSCOPE:
+ denoise_median(&sensor[s], data, 3);
+ break;
+
+ case SENSOR_TYPE_MAGNETIC_FIELD:
+ denoise_average(&sensor[s], data, 3 , 20);
+ break;
+ }
+}
+
+
+void release_noise_filtering_data (int s)
+{
+ void *buff;
+
+ /* Delete moving average structures */
+ if (sensor[s].history) {
+ free(sensor[s].history);
+ sensor[s].history = NULL;
+ sensor[s].history_size = 0;
+ if (sensor[s].history_sum) {
+ free(sensor[s].history_sum);
+ sensor[s].history_sum = NULL;
+ }
+ }
+
+ /* Delete median filter structures */
+ if (sensor[s].filter) {
+ buff = ((struct filter_median_t*)sensor[s].filter)->buff;
+
+ if (buff)
+ free(buff);
+
+ free(sensor[s].filter);
+ sensor[s].filter = NULL;
+ }
+}
+
+
+#define GLOBAL_HISTORY_SIZE 100
+
+struct recorded_sample_t
+{
+ int sensor;
+ int motion_trigger;
+ sensors_event_t data;
+};
+
+/*
+ * This is a circular buffer holding the last GLOBAL_HISTORY_SIZE events,
+ * covering the entire sensor collection. It is intended as a way to correlate
+ * data coming from active sensors, no matter the sensor type, over a recent
+ * window of time. The array is not sorted ; we simply evict the oldest cell
+ * (by insertion time) and replace its contents. Timestamps don't necessarily
+ * grow monotonically as they tell the data acquisition type, and that there can
+ * be a delay between acquisition and insertion into this table.
+ */
+
+static struct recorded_sample_t global_history[GLOBAL_HISTORY_SIZE];
+
+static int initialized_entries; /* How many of these are initialized */
+static int insertion_index; /* Index of sample to evict next time */
+
+
+void record_sample (int s, const struct sensors_event_t* event)
+{
+ struct recorded_sample_t *cell;
+ int i;
+
+ /* Don't record duplicate samples, as they are not useful for filters */
+ if (sensor[s].report_pending == DATA_DUPLICATE)
+ return;
+
+ if (initialized_entries == GLOBAL_HISTORY_SIZE) {
+ i = insertion_index;
+ insertion_index = (insertion_index+1) % GLOBAL_HISTORY_SIZE;
+ } else {
+ i = initialized_entries;
+ initialized_entries++;
+ }
+
+ cell = &global_history[i];
+
+ cell->sensor = s;
+
+ cell->motion_trigger = (sensor[s].selected_trigger ==
+ sensor[s].motion_trigger_name);
+
+ memcpy(&cell->data, event, sizeof(sensors_event_t));
+}
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