simulator/mapping.cpp (b320fb0) - libetherpix · BlinkenArea

mapping.cpp

/*
 * EtherPix simulator
 *
 * Copyright 2017 Stefan Schuermans <stefan schuermans info>
 *
 * 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, version 3 of the License.
 *
 *
 * 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 Lesser General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */

#include <math.h>
#include <stdint.h>

#include "mapping.h"

/// default constructor
Mapping::Mapping():
  m_base(1.0),
  m_factor(0.0),
  m_gamma(1.0)
{
  update();
}

/// constructor based on parameters
Mapping::Mapping(double base, double factor, double gamma):
  m_base(base),
  m_factor(factor),
  m_gamma(gamma)
{
  update();
}

/// update internal mapping table based on parameters
void Mapping::update()
{
  /* mapping formula:
   *   display := base + factor * video ** (1.0 / gamma)
   * display values are coming in via IPv4/UDP
   * simulator needs to show video values
   *   video := ((display - base) / factor) ** gamma
   */
  for (unsigned int display_i = 0; display_i < 256; ++display_i) {
    double display = (double)display_i / 255.0;
    double video = pow((display - m_base) / m_factor, m_gamma);
    uint8_t video_u8;
    if (video < 0.0) {
      video_u8 = 0;
    } else if (video > 1.0) {
      video_u8 = 255;
    } else {
      video_u8 = (uint8_t)round(255.0 * video);
    }
    m_display2video[display_i] = video_u8;
  }
}

libetherpix

implement mapping table