/*
Looking Glass
Copyright (C) 2017-2021 The Looking Glass Authors
https://looking-glass.io

This program is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
Foundation; either version 2 of the License, or (at your option) any later
version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with
this program; if not, write to the Free Software Foundation, Inc., 59 Temple
Place, Suite 330, Boston, MA 02111-1307 USA
*/

#include "common/runningavg.h"

#include <stdlib.h>

struct RunningAvg
{
  int       length, samples;
  int       pos;
  int       value;
  int64_t   values[0];
};

RunningAvg runningavg_new(int length)
{
  struct RunningAvg * ra = calloc(1, sizeof(*ra) + sizeof(*ra->values) * length);
  ra->length = length;
  return ra;
}

void runningavg_free(RunningAvg * ra)
{
  free(*ra);
  *ra = NULL;
}

void runningavg_push(RunningAvg ra, int64_t value)
{
  if (ra->samples == ra->length)
    ra->value -= ra->values[ra->pos];
  else
    ++ra->samples;

  ra->value += value;
  ra->values[ra->pos++] = value;

  if (ra->pos == ra->length)
    ra->pos = 0;
}

void runningavg_reset(RunningAvg ra)
{
  ra->samples = 0;
  ra->pos     = 0;
  ra->value   = 0;
}

double runningavg_calc(RunningAvg ra)
{
  return (double)ra->value / ra->samples;
}