Maixduino/libraries/NS2009/src/mean.c

/*
 * libc/filter/mean.c
 */

#include <math.h>
#include <stddef.h>
#include <mean.h>
#include "stdlib.h"

#define touchscreen_malloc(p) malloc(p)
#define touchscreen_free(p) free(p)

struct mean_filter_t *mean_alloc(int length)
{
    struct mean_filter_t *filter;
    int i;
    if (length <= 0)
        return NULL;

    filter = touchscreen_malloc(sizeof(struct mean_filter_t));
    if (!filter)
        return NULL;

    filter->buffer = touchscreen_malloc(sizeof(int) * length);
    if (!filter->buffer)
    {
        touchscreen_free(filter);
        return NULL;
    }
    for (i = 0; i < length; i++)
        filter->buffer[i] = 0;
    filter->length = length;
    filter->index = 0;
    filter->count = 0;
    filter->sum = 0;

    return filter;
}

void mean_free(struct mean_filter_t *filter)
{
    if (filter)
    {
        if (filter->buffer)
            touchscreen_free(filter->buffer);
        touchscreen_free(filter);
    }
}

int mean_update(struct mean_filter_t *filter, int value)
{
    filter->sum -= filter->buffer[filter->index];
    filter->sum += value;
    filter->buffer[filter->index] = value;
    filter->index = (filter->index + 1) % filter->length;

    if (filter->count < filter->length)
        filter->count++;
    return filter->sum / filter->count;
}

void mean_clear(struct mean_filter_t *filter)
{
    int i;

    if (filter)
    {
        for (i = 0; i < filter->length; i++)
            filter->buffer[i] = 0;
        filter->index = 0;
        filter->count = 0;
        filter->sum = 0;
    }
}