blender-archive/source/blender/imbuf/intern/dds/PixelFormat.h

/*
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */

/** \file
 * \ingroup imbdds
 */

/*
 * This file is based on a similar file from the NVIDIA texture tools
 * (http://nvidia-texture-tools.googlecode.com/)
 *
 * Original license from NVIDIA follows.
 */

/* Copyright NVIDIA Corporation 2007 -- Ignacio Castano <icastano@nvidia.com>
 *
 * Permission is hereby granted, free of charge, to any person
 * obtaining a copy of this software and associated documentation
 * files (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use,
 * copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following
 * conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 */

#pragma once

#include "Common.h"

namespace PixelFormat {

/** Convert component \a c having \a inbits to the returned value having \a outbits. */
inline uint convert(uint c, uint inbits, uint outbits)
{
  if (inbits == 0) {
    return 0;
  }
  else if (inbits >= outbits) {
    /* truncate */
    return c >> (inbits - outbits);
  }
  else {
    /* bitexpand */
    return (c << (outbits - inbits)) | convert(c, inbits, outbits - inbits);
  }
}

/* Get pixel component shift and size given its mask. */
inline void maskShiftAndSize(uint mask, uint *shift, uint *size)
{
  if (!mask) {
    *shift = 0;
    *size = 0;
    return;
  }

  *shift = 0;
  while ((mask & 1) == 0) {
    ++(*shift);
    mask >>= 1;
  }

  *size = 0;
  while ((mask & 1) == 1) {
    ++(*size);
    mask >>= 1;
  }
}

inline float quantizeCeil(float f, int inbits, int outbits)
{
#if 0
  uint i = f * (float(1 << inbits) - 1);
  i = convert(i, inbits, outbits);
  float result = float(i) / (float(1 << outbits) - 1);
  nvCheck(result >= f);
#endif
  float result;

  int offset = 0;
  do {
    uint i = offset + uint(f * (float(1 << inbits) - 1));
    i = convert(i, inbits, outbits);
    result = float(i) / (float(1 << outbits) - 1);
    offset++;
  } while (result < f);

  return result;
}

#if 0
inline float quantizeRound(float f, int bits)
{
  float scale = float(1 << bits);
  return fround(f * scale) / scale;
}

inline float quantizeFloor(float f, int bits)
{
  float scale = float(1 << bits);
  return floor(f * scale) / scale;
}
#endif

} /* namespace PixelFormat */