/*
 * Copyright (C) 2013-2019 Red Hat
 * Copyright (c) 2018 DisplayLink (UK) Ltd.
 *
 * 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, see <http://www.gnu.org/licenses/>.
 */

#include "config.h"

#include "backends/native/meta-kms-utils.h"

#include <glib.h>

float
meta_calculate_drm_mode_refresh_rate (const drmModeModeInfo *drm_mode)
{
  double numerator;
  double denominator;

  if (drm_mode->htotal <= 0 || drm_mode->vtotal <= 0)
    return 0.0;

  numerator = drm_mode->clock * 1000.0;
  denominator = (double) drm_mode->vtotal * drm_mode->htotal;
  if (drm_mode->vscan > 1)
    denominator *= drm_mode->vscan;

  return (float) (numerator / denominator);
}

int64_t
meta_calculate_drm_mode_vblank_duration_us (const drmModeModeInfo *drm_mode)
{
  int64_t value;

  if (drm_mode->htotal <= 0 || drm_mode->vtotal <= 0)
    return 0;

  /* Convert to int64_t early. */
  value = drm_mode->vtotal - drm_mode->vdisplay;
  value *= drm_mode->htotal;

  if (drm_mode->flags & DRM_MODE_FLAG_DBLSCAN)
    value *= 2;

  /* Round the duration up as it is used for buffer swap deadline computation. */
  value = (value * 1000 + drm_mode->clock - 1) / drm_mode->clock;

  return value;
}