/* SPDX-License-Identifier: GPL-2.0-or-later */

/** \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. */

#include <BLI_sys_types.h> /* For `uint`. */

#include <BlockDXT.h>
#include <ColorBlock.h>
#include <Common.h>
#include <Stream.h>

/* ---------------------------------------------------------------------------
 * BlockDXT1
 * --------------------------------------------------------------------------*/

uint BlockDXT1::evaluatePalette(Color32 color_array[4]) const
{
  /* Does bit expansion before interpolation. */
  color_array[0].b = (col0.b << 3) | (col0.b >> 2);
  color_array[0].g = (col0.g << 2) | (col0.g >> 4);
  color_array[0].r = (col0.r << 3) | (col0.r >> 2);
  color_array[0].a = 0xFF;

  /* @@ Same as above, but faster?
   *  Color32 c;
   *  c.u = ((col0.u << 3) & 0xf8) | ((col0.u << 5) & 0xfc00) | ((col0.u << 8) & 0xf80000);
   *  c.u |= (c.u >> 5) & 0x070007;
   *  c.u |= (c.u >> 6) & 0x000300;
   *  color_array[0].u = c.u; */

  color_array[1].r = (col1.r << 3) | (col1.r >> 2);
  color_array[1].g = (col1.g << 2) | (col1.g >> 4);
  color_array[1].b = (col1.b << 3) | (col1.b >> 2);
  color_array[1].a = 0xFF;

  /* @@ Same as above, but faster?
   *  c.u = ((col1.u << 3) & 0xf8) | ((col1.u << 5) & 0xfc00) | ((col1.u << 8) & 0xf80000);
   *  c.u |= (c.u >> 5) & 0x070007;
   *  c.u |= (c.u >> 6) & 0x000300;
   *  color_array[1].u = c.u; */

  if (col0.u > col1.u) {
    /* Four-color block: derive the other two colors. */
    color_array[2].r = (2 * color_array[0].r + color_array[1].r) / 3;
    color_array[2].g = (2 * color_array[0].g + color_array[1].g) / 3;
    color_array[2].b = (2 * color_array[0].b + color_array[1].b) / 3;
    color_array[2].a = 0xFF;

    color_array[3].r = (2 * color_array[1].r + color_array[0].r) / 3;
    color_array[3].g = (2 * color_array[1].g + color_array[0].g) / 3;
    color_array[3].b = (2 * color_array[1].b + color_array[0].b) / 3;
    color_array[3].a = 0xFF;

    return 4;
  }

  /* Three-color block: derive the other color. */
  color_array[2].r = (color_array[0].r + color_array[1].r) / 2;
  color_array[2].g = (color_array[0].g + color_array[1].g) / 2;
  color_array[2].b = (color_array[0].b + color_array[1].b) / 2;
  color_array[2].a = 0xFF;

  /* Set all components to 0 to match DXT specs. */
  color_array[3].r = 0x00; /* color_array[2].r; */
  color_array[3].g = 0x00; /* color_array[2].g; */
  color_array[3].b = 0x00; /* color_array[2].b; */
  color_array[3].a = 0x00;

  return 3;
}

uint BlockDXT1::evaluatePaletteNV5x(Color32 color_array[4]) const
{
  /* Does bit expansion before interpolation. */
  color_array[0].b = (3 * col0.b * 22) / 8;
  color_array[0].g = (col0.g << 2) | (col0.g >> 4);
  color_array[0].r = (3 * col0.r * 22) / 8;
  color_array[0].a = 0xFF;

  color_array[1].r = (3 * col1.r * 22) / 8;
  color_array[1].g = (col1.g << 2) | (col1.g >> 4);
  color_array[1].b = (3 * col1.b * 22) / 8;
  color_array[1].a = 0xFF;

  int gdiff = color_array[1].g - color_array[0].g;

  if (col0.u > col1.u) {
    /* Four-color block: derive the other two colors. */
    color_array[2].r = ((2 * col0.r + col1.r) * 22) / 8;
    color_array[2].g = (256 * color_array[0].g + gdiff / 4 + 128 + gdiff * 80) / 256;
    color_array[2].b = ((2 * col0.b + col1.b) * 22) / 8;
    color_array[2].a = 0xFF;

    color_array[3].r = ((2 * col1.r + col0.r) * 22) / 8;
    color_array[3].g = (256 * color_array[1].g - gdiff / 4 + 128 - gdiff * 80) / 256;
    color_array[3].b = ((2 * col1.b + col0.b) * 22) / 8;
    color_array[3].a = 0xFF;

    return 4;
  }

  /* Three-color block: derive the other color. */
  color_array[2].r = ((col0.r + col1.r) * 33) / 8;
  color_array[2].g = (256 * color_array[0].g + gdiff / 4 + 128 + gdiff * 128) / 256;
  color_array[2].b = ((col0.b + col1.b) * 33) / 8;
  color_array[2].a = 0xFF;

  /* Set all components to 0 to match DXT specs. */
  color_array[3].r = 0x00; /* color_array[2].r; */
  color_array[3].g = 0x00; /* color_array[2].g; */
  color_array[3].b = 0x00; /* color_array[2].b; */
  color_array[3].a = 0x00;

  return 3;
}

void BlockDXT1::evaluatePalette3(Color32 color_array[4]) const
{
  color_array[0].b = (col0.b << 3) | (col0.b >> 2);
  color_array[0].g = (col0.g << 2) | (col0.g >> 4);
  color_array[0].r = (col0.r << 3) | (col0.r >> 2);
  color_array[0].a = 0xFF;

  color_array[1].r = (col1.r << 3) | (col1.r >> 2);
  color_array[1].g = (col1.g << 2) | (col1.g >> 4);
  color_array[1].b = (col1.b << 3) | (col1.b >> 2);
  color_array[1].a = 0xFF;

  /* Three-color block: derive the other color. */
  color_array[2].r = (color_array[0].r + color_array[1].r) / 2;
  color_array[2].g = (color_array[0].g + color_array[1].g) / 2;
  color_array[2].b = (color_array[0].b + color_array[1].b) / 2;
  color_array[2].a = 0xFF;

  /* Set all components to 0 to match DXT specs. */
  color_array[3].r = 0x00; /* color_array[2].r; */
  color_array[3].g = 0x00; /* color_array[2].g; */
  color_array[3].b = 0x00; /* color_array[2].b; */
  color_array[3].a = 0x00;
}

void BlockDXT1::evaluatePalette4(Color32 color_array[4]) const
{
  color_array[0].b = (col0.b << 3) | (col0.b >> 2);
  color_array[0].g = (col0.g << 2) | (col0.g >> 4);
  color_array[0].r = (col0.r << 3) | (col0.r >> 2);
  color_array[0].a = 0xFF;

  color_array[1].r = (col1.r << 3) | (col1.r >> 2);
  color_array[1].g = (col1.g << 2) | (col1.g >> 4);
  color_array[1].b = (col1.b << 3) | (col1.b >> 2);
  color_array[1].a = 0xFF;

  /* Four-color block: derive the other two colors. */
  color_array[2].r = (2 * color_array[0].r + color_array[1].r) / 3;
  color_array[2].g = (2 * color_array[0].g + color_array[1].g) / 3;
  color_array[2].b = (2 * color_array[0].b + color_array[1].b) / 3;
  color_array[2].a = 0xFF;

  color_array[3].r = (2 * color_array[1].r + color_array[0].r) / 3;
  color_array[3].g = (2 * color_array[1].g + color_array[0].g) / 3;
  color_array[3].b = (2 * color_array[1].b + color_array[0].b) / 3;
  color_array[3].a = 0xFF;
}

void BlockDXT1::decodeBlock(ColorBlock *block) const
{
  /* Decode color block. */
  Color32 color_array[4];
  evaluatePalette(color_array);

  /* Write color block. */
  for (uint j = 0; j < 4; j++) {
    for (uint i = 0; i < 4; i++) {
      uint idx = (row[j] >> (2 * i)) & 3;
      block->color(i, j) = color_array[idx];
    }
  }
}

void BlockDXT1::decodeBlockNV5x(ColorBlock *block) const
{
  /* Decode color block. */
  Color32 color_array[4];
  evaluatePaletteNV5x(color_array);

  /* Write color block. */
  for (uint j = 0; j < 4; j++) {
    for (uint i = 0; i < 4; i++) {
      uint idx = (row[j] >> (2 * i)) & 3;
      block->color(i, j) = color_array[idx];
    }
  }
}

void BlockDXT1::setIndices(const int *idx)
{
  indices = 0;
  for (uint i = 0; i < 16; i++) {
    indices |= (idx[i] & 3) << (2 * i);
  }
}

inline void BlockDXT1::flip4()
{
  swap(row[0], row[3]);
  swap(row[1], row[2]);
}

inline void BlockDXT1::flip2()
{
  swap(row[0], row[1]);
}

/* ---------------------------------------------------------------------------
 * BlockDXT3
 * ---------------------------------------------------------------------------*/

void BlockDXT3::decodeBlock(ColorBlock *block) const
{
  /* Decode color. */
  color.decodeBlock(block);

  /* Decode alpha. */
  alpha.decodeBlock(block);
}

void BlockDXT3::decodeBlockNV5x(ColorBlock *block) const
{
  color.decodeBlockNV5x(block);
  alpha.decodeBlock(block);
}

void AlphaBlockDXT3::decodeBlock(ColorBlock *block) const
{
  block->color(0x0).a = (alpha0 << 4) | alpha0;
  block->color(0x1).a = (alpha1 << 4) | alpha1;
  block->color(0x2).a = (alpha2 << 4) | alpha2;
  block->color(0x3).a = (alpha3 << 4) | alpha3;
  block->color(0x4).a = (alpha4 << 4) | alpha4;
  block->color(0x5).a = (alpha5 << 4) | alpha5;
  block->color(0x6).a = (alpha6 << 4) | alpha6;
  block->color(0x7).a = (alpha7 << 4) | alpha7;
  block->color(0x8).a = (alpha8 << 4) | alpha8;
  block->color(0x9).a = (alpha9 << 4) | alpha9;
  block->color(0xA).a = (alphaA << 4) | alphaA;
  block->color(0xB).a = (alphaB << 4) | alphaB;
  block->color(0xC).a = (alphaC << 4) | alphaC;
  block->color(0xD).a = (alphaD << 4) | alphaD;
  block->color(0xE).a = (alphaE << 4) | alphaE;
  block->color(0xF).a = (alphaF << 4) | alphaF;
}

void AlphaBlockDXT3::flip4()
{
  swap(row[0], row[3]);
  swap(row[1], row[2]);
}

void AlphaBlockDXT3::flip2()
{
  swap(row[0], row[1]);
}

void BlockDXT3::flip4()
{
  alpha.flip4();
  color.flip4();
}

void BlockDXT3::flip2()
{
  alpha.flip2();
  color.flip2();
}

/* ---------------------------------------------------------------------------
 * BlockDXT5
 * ---------------------------------------------------------------------------*/

void AlphaBlockDXT5::evaluatePalette(uint8 alpha[8]) const
{
  if (alpha0() > alpha1()) {
    evaluatePalette8(alpha);
  }
  else {
    evaluatePalette6(alpha);
  }
}

void AlphaBlockDXT5::evaluatePalette8(uint8 alpha[8]) const
{
  /* 8-alpha block:  derive the other six alphas.
   * Bit code 000 = alpha0, 001 = alpha1, others are interpolated. */
  alpha[0] = alpha0();
  alpha[1] = alpha1();
  alpha[2] = (6 * alpha[0] + 1 * alpha[1]) / 7; /* bit code 010 */
  alpha[3] = (5 * alpha[0] + 2 * alpha[1]) / 7; /* bit code 011 */
  alpha[4] = (4 * alpha[0] + 3 * alpha[1]) / 7; /* bit code 100 */
  alpha[5] = (3 * alpha[0] + 4 * alpha[1]) / 7; /* bit code 101 */
  alpha[6] = (2 * alpha[0] + 5 * alpha[1]) / 7; /* bit code 110 */
  alpha[7] = (1 * alpha[0] + 6 * alpha[1]) / 7; /* bit code 111 */
}

void AlphaBlockDXT5::evaluatePalette6(uint8 alpha[8]) const
{
  /* 6-alpha block.
   * Bit code 000 = alpha0, 001 = alpha1, others are interpolated. */
  alpha[0] = alpha0();
  alpha[1] = alpha1();
  alpha[2] = (4 * alpha[0] + 1 * alpha[1]) / 5; /* Bit code 010 */
  alpha[3] = (3 * alpha[0] + 2 * alpha[1]) / 5; /* Bit code 011 */
  alpha[4] = (2 * alpha[0] + 3 * alpha[1]) / 5; /* Bit code 100 */
  alpha[5] = (1 * alpha[0] + 4 * alpha[1]) / 5; /* Bit code 101 */
  alpha[6] = 0x00;                              /* Bit code 110 */
  alpha[7] = 0xFF;                              /* Bit code 111 */
}

void AlphaBlockDXT5::indices(uint8 index_array[16]) const
{
  index_array[0x0] = bits0();
  index_array[0x1] = bits1();
  index_array[0x2] = bits2();
  index_array[0x3] = bits3();
  index_array[0x4] = bits4();
  index_array[0x5] = bits5();
  index_array[0x6] = bits6();
  index_array[0x7] = bits7();
  index_array[0x8] = bits8();
  index_array[0x9] = bits9();
  index_array[0xA] = bitsA();
  index_array[0xB] = bitsB();
  index_array[0xC] = bitsC();
  index_array[0xD] = bitsD();
  index_array[0xE] = bitsE();
  index_array[0xF] = bitsF();
}

uint AlphaBlockDXT5::index(uint index) const
{
  int offset = (3 * index + 16);
  return uint((this->u >> offset) & 0x7);
}

void AlphaBlockDXT5::setIndex(uint index, uint value)
{
  int offset = (3 * index + 16);
  uint64 mask = uint64(0x7) << offset;
  this->u = (this->u & ~mask) | (uint64(value) << offset);
}

void AlphaBlockDXT5::decodeBlock(ColorBlock *block) const
{
  uint8 alpha_array[8];
  evaluatePalette(alpha_array);

  uint8 index_array[16];
  indices(index_array);

  for (uint i = 0; i < 16; i++) {
    block->color(i).a = alpha_array[index_array[i]];
  }
}

void AlphaBlockDXT5::flip4()
{
  uint64 *b = (uint64 *)this;

  /* @@ The masks might have to be byte swapped. */
  uint64 tmp = (*b & (uint64)(0x000000000000FFFFLL));
  tmp |= (*b & (uint64)(0x000000000FFF0000LL)) << 36;
  tmp |= (*b & (uint64)(0x000000FFF0000000LL)) << 12;
  tmp |= (*b & (uint64)(0x000FFF0000000000LL)) >> 12;
  tmp |= (*b & (uint64)(0xFFF0000000000000LL)) >> 36;

  *b = tmp;
}

void AlphaBlockDXT5::flip2()
{
  uint *b = (uint *)this;

  /* @@ The masks might have to be byte swapped. */
  uint tmp = (*b & 0xFF000000);
  tmp |= (*b & 0x00000FFF) << 12;
  tmp |= (*b & 0x00FFF000) >> 12;

  *b = tmp;
}

void BlockDXT5::decodeBlock(ColorBlock *block) const
{
  /* Decode color. */
  color.decodeBlock(block);

  /* Decode alpha. */
  alpha.decodeBlock(block);
}

void BlockDXT5::decodeBlockNV5x(ColorBlock *block) const
{
  /* Decode color. */
  color.decodeBlockNV5x(block);

  /* Decode alpha. */
  alpha.decodeBlock(block);
}

void BlockDXT5::flip4()
{
  alpha.flip4();
  color.flip4();
}

void BlockDXT5::flip2()
{
  alpha.flip2();
  color.flip2();
}

void BlockATI1::decodeBlock(ColorBlock *block) const
{
  uint8 alpha_array[8];
  alpha.evaluatePalette(alpha_array);

  uint8 index_array[16];
  alpha.indices(index_array);

  for (uint i = 0; i < 16; i++) {
    Color32 &c = block->color(i);
    c.b = c.g = c.r = alpha_array[index_array[i]];
    c.a = 255;
  }
}

void BlockATI1::flip4()
{
  alpha.flip4();
}

void BlockATI1::flip2()
{
  alpha.flip2();
}

void BlockATI2::decodeBlock(ColorBlock *block) const
{
  uint8 alpha_array[8];
  uint8 index_array[16];

  x.evaluatePalette(alpha_array);
  x.indices(index_array);

  for (uint i = 0; i < 16; i++) {
    Color32 &c = block->color(i);
    c.r = alpha_array[index_array[i]];
  }

  y.evaluatePalette(alpha_array);
  y.indices(index_array);

  for (uint i = 0; i < 16; i++) {
    Color32 &c = block->color(i);
    c.g = alpha_array[index_array[i]];
    c.b = 0;
    c.a = 255;
  }
}

void BlockATI2::flip4()
{
  x.flip4();
  y.flip4();
}

void BlockATI2::flip2()
{
  x.flip2();
  y.flip2();
}

void BlockCTX1::evaluatePalette(Color32 color_array[4]) const
{
  /* Does bit expansion before interpolation. */
  color_array[0].b = 0x00;
  color_array[0].g = col0[1];
  color_array[0].r = col0[0];
  color_array[0].a = 0xFF;

  color_array[1].r = 0x00;
  color_array[1].g = col0[1];
  color_array[1].b = col1[0];
  color_array[1].a = 0xFF;

  color_array[2].r = 0x00;
  color_array[2].g = (2 * color_array[0].g + color_array[1].g) / 3;
  color_array[2].b = (2 * color_array[0].b + color_array[1].b) / 3;
  color_array[2].a = 0xFF;

  color_array[3].r = 0x00;
  color_array[3].g = (2 * color_array[1].g + color_array[0].g) / 3;
  color_array[3].b = (2 * color_array[1].b + color_array[0].b) / 3;
  color_array[3].a = 0xFF;
}

void BlockCTX1::decodeBlock(ColorBlock *block) const
{
  /* Decode color block. */
  Color32 color_array[4];
  evaluatePalette(color_array);

  /* Write color block. */
  for (uint j = 0; j < 4; j++) {
    for (uint i = 0; i < 4; i++) {
      uint idx = (row[j] >> (2 * i)) & 3;
      block->color(i, j) = color_array[idx];
    }
  }
}

void BlockCTX1::setIndices(const int *idx)
{
  indices = 0;
  for (uint i = 0; i < 16; i++) {
    indices |= (idx[i] & 3) << (2 * i);
  }
}

inline void BlockCTX1::flip4()
{
  swap(row[0], row[3]);
  swap(row[1], row[2]);
}

inline void BlockCTX1::flip2()
{
  swap(row[0], row[1]);
}

void mem_read(Stream &mem, BlockDXT1 &block)
{
  mem_read(mem, block.col0.u);
  mem_read(mem, block.col1.u);
  mem_read(mem, block.indices);
}

void mem_read(Stream &mem, AlphaBlockDXT3 &block)
{
  for (ushort &alpha : block.row) {
    mem_read(mem, alpha);
  }
}

void mem_read(Stream &mem, BlockDXT3 &block)
{
  mem_read(mem, block.alpha);
  mem_read(mem, block.color);
}

void mem_read(Stream &mem, AlphaBlockDXT5 &block)
{
  mem_read(mem, block.u);
}

void mem_read(Stream &mem, BlockDXT5 &block)
{
  mem_read(mem, block.alpha);
  mem_read(mem, block.color);
}

void mem_read(Stream &mem, BlockATI1 &block)
{
  mem_read(mem, block.alpha);
}

void mem_read(Stream &mem, BlockATI2 &block)
{
  mem_read(mem, block.x);
  mem_read(mem, block.y);
}

void mem_read(Stream &mem, BlockCTX1 &block)
{
  mem_read(mem, block.col0[0]);
  mem_read(mem, block.col0[1]);
  mem_read(mem, block.col1[0]);
  mem_read(mem, block.col1[1]);
  mem_read(mem, block.indices);
}