m_filter_fifo.h

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// Copyright 2020, Collabora, Ltd.
// SPDX-License-Identifier: BSL-1.0
/*!
 * @file
 * @brief  A fifo that also allows you to dynamically filter.
 * @author Jakob Bornecrantz <jakob@collabora.com>
 * @ingroup aux_math
 */

#pragma once

#include "xrt/xrt_defines.h"

#ifdef __cplusplus
extern "C" {
#endif


struct m_ff_vec3_f32;

/*!
 * Allocates a filter fifo tracking @p num samples and fills it with @p num
 * samples at timepoint zero.
 */
void
m_ff_vec3_f32_alloc(struct m_ff_vec3_f32 **ff_out, size_t num);

/*!
 * Frees the given filter fifo and all it's samples.
 */
void
m_ff_vec3_f32_free(struct m_ff_vec3_f32 **ff_ptr);

/*!
 * Pushes a sample at the given timepoint, pushing samples out of order yields
 * unspecified behaviour, so samples must be pushed in time order.
 */
void
m_ff_vec3_f32_push(struct m_ff_vec3_f32 *ff,
                   const struct xrt_vec3 *sample,
                   uint64_t timestamp_ns);

/*!
 * Return the sample at the index, zero means the last sample push, one second
 * last and so on.
 */
void
m_ff_vec3_f32_get(struct m_ff_vec3_f32 *ff,
                  size_t num,
                  struct xrt_vec3 *out_sample,
                  uint64_t *out_timestamp_ns);

/*!
 * Averages all samples in the fifo between the two timepoints, returns number
 * of samples sampled, if no samples was found between the timpoints returns 0
 * and sets @p out_average to all zeros.
 *
 * @param ff          Filter fifo to search in.
 * @param start_ns    Timepoint furthest in the past, to start searching for
 *                    samples.
 * @param stop_ns     Timepoint closest in the past, or now, to stop searching
 *                    for samples.
 * @param out_average Average of all samples in the given timeframe.
 */
size_t
m_ff_vec3_f32_filter(struct m_ff_vec3_f32 *ff,
                     uint64_t start_ns,
                     uint64_t stop_ns,
                     struct xrt_vec3 *out_average);


#ifdef __cplusplus
}

/*!
 * Helper class to wrap a C filter fifo.
 */
class FilterFifo3F
{
private:
        struct m_ff_vec3_f32 *ff;


public:
        FilterFifo3F() = delete;

        FilterFifo3F(size_t size)
        {
                m_ff_vec3_f32_alloc(&ff, size);
        }

        ~FilterFifo3F()
        {
                m_ff_vec3_f32_free(&ff);
        }

        inline void
        push(const xrt_vec3 &sample, uint64_t timestamp_ns)
        {
                m_ff_vec3_f32_push(ff, &sample, timestamp_ns);
        }

        inline void
        get(size_t num, xrt_vec3 *out_sample, uint64_t *out_timestamp_ns)
        {
                m_ff_vec3_f32_get(ff, num, out_sample, out_timestamp_ns);
        }

        inline size_t
        filter(uint64_t start_ns,
               uint64_t stop_ns,
               struct xrt_vec3 *out_average)
        {
                return m_ff_vec3_f32_filter(ff, start_ns, stop_ns, out_average);
        }
};
#endif