u_frame_times_widget.h

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// Copyright 2019, Collabora, Ltd.
// SPDX-License-Identifier: BSL-1.0
/*!
 * @file
 * @brief Shared code for visualizing frametimes.
 * @author Moses Turner <moses@collabora.com>
 * @ingroup aux_util
 */
 
#pragma once
 
#include "xrt/xrt_defines.h"
 
#include "os/os_time.h"
#include "util/u_var.h"
#include "util/u_logging.h"
#include "util/u_misc.h"
 
#include <assert.h>
 
#define FPS_WIDGET_NUM_FRAME_TIMES 50
 
struct u_frame_times_widget
{
        //! Current Index for times_ns.
        int index;
 
        //! Timestamps of last-pushed frames.
        int64_t times_ns[FPS_WIDGET_NUM_FRAME_TIMES];
 
        //! Frametimes between last-pushed frames.
        float timings_ms[FPS_WIDGET_NUM_FRAME_TIMES];
 
        //! Average FPS of last NUM_FRAME_TIMES pushed frames.
        float fps;
 
        struct u_var_timing *debug_var;
};
 
static inline void
u_frame_times_widget_push_sample(struct u_frame_times_widget *widget, uint64_t new_frame_time)
{
        int last_index = widget->index;
 
        widget->index++;
        widget->index %= FPS_WIDGET_NUM_FRAME_TIMES;
 
        // update fps only once every FPS_NUM_TIMINGS
        if (widget->index == 0) {
                float total_ms = 0;
 
                // frame *timings* are durations between *times*
                int NUM_FRAME_TIMINGS = FPS_WIDGET_NUM_FRAME_TIMES - 1;
 
                for (int i = 0; i < NUM_FRAME_TIMINGS; i++) {
                        total_ms += widget->timings_ms[i];
                }
                float avg_frametime_ms = total_ms / ((float)NUM_FRAME_TIMINGS);
                widget->fps = 1000.f / avg_frametime_ms;
        }
 
        widget->times_ns[widget->index] = new_frame_time;
 
        assert(widget->index >= 0);
        assert(widget->index < FPS_WIDGET_NUM_FRAME_TIMES);
        assert(last_index >= 0);
        assert(last_index < FPS_WIDGET_NUM_FRAME_TIMES);
 
        uint64_t diff = widget->times_ns[widget->index] - widget->times_ns[last_index];
        widget->timings_ms[widget->index] = (float)time_ns_to_ms_f(diff);
}
 
static inline void
u_frame_times_widget_init(struct u_frame_times_widget *widget, float target_frame_time_ms, float range)
{
        uint64_t now = os_monotonic_get_ns();
        for (int i = 0; i < FPS_WIDGET_NUM_FRAME_TIMES; i++) {
                widget->times_ns[i] = now + i;
        }
 
        struct u_var_timing *ft = U_TYPED_CALLOC(struct u_var_timing);
 
 
        ft->values.data = widget->timings_ms;
        ft->values.length = FPS_WIDGET_NUM_FRAME_TIMES;
        ft->values.index_ptr = &widget->index;
 
 
        ft->reference_timing = target_frame_time_ms;
        ft->range = range;
        ft->unit = "ms";
        ft->dynamic_rescale = false;
        ft->center_reference_timing = true;
        widget->debug_var = ft;
        widget->index = 0;
}
 
// Call u_var_remove_root first!
static inline void
u_frame_times_widget_teardown(struct u_frame_times_widget *widget)
{
        free(widget->debug_var);
}