text: /*
   * Texture block decompression
   * Copyright (C) 2009 Benjamin Dobell, Glass Echidna
   * Copyright (C) 2012 Matthäus G. "Anteru" Chajdas (http://anteru.net)
   * Copyright (C) 2015 Vittorio Giovara <vittorio.giovara@gmail.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 <stddef.h>
  #include <stdint.h>
  
  #include "libavutil/attributes.h"
  #include "libavutil/common.h"
  #include "libavutil/intreadwrite.h"
  #include "libavutil/libm.h"
  
  #include "texturedsp.h"
  
  #define RGBA(r, g, b, a) (((uint8_t)(r) <<  0) | \
                            ((uint8_t)(g) <<  8) | \
                            ((uint8_t)(b) << 16) | \
                            ((unsigned)(uint8_t)(a) << 24))
  
  static av_always_inline void extract_color(uint32_t colors[4],
                                             uint16_t color0,
                                             uint16_t color1,
                                             int dxtn, int alpha)
  {
      int tmp;
      uint8_t r0, g0, b0, r1, g1, b1;
      uint8_t a = dxtn ? 0 : 255;
  
      tmp = (color0 >> 11) * 255 + 16;
      r0  = (uint8_t) ((tmp / 32 + tmp) / 32);
      tmp = ((color0 & 0x07E0) >> 5) * 255 + 32;
      g0  = (uint8_t) ((tmp / 64 + tmp) / 64);
      tmp = (color0 & 0x001F) * 255 + 16;
      b0  = (uint8_t) ((tmp / 32 + tmp) / 32);
  
      tmp = (color1 >> 11) * 255 + 16;
      r1  = (uint8_t) ((tmp / 32 + tmp) / 32);
      tmp = ((color1 & 0x07E0) >> 5) * 255 + 32;
      g1  = (uint8_t) ((tmp / 64 + tmp) / 64);
      tmp = (color1 & 0x001F) * 255 + 16;
      b1  = (uint8_t) ((tmp / 32 + tmp) / 32);
  
      if (dxtn || color0 > color1) {
          colors[0] = RGBA(r0, g0, b0, a);
          colors[1] = RGBA(r1, g1, b1, a);
          colors[2] = RGBA((2 * r0 + r1) / 3,
                           (2 * g0 + g1) / 3,
                           (2 * b0 + b1) / 3,
                           a);
          colors[3] = RGBA((2 * r1 + r0) / 3,
                           (2 * g1 + g0) / 3,
                           (2 * b1 + b0) / 3,
                           a);
      } else {
          colors[0] = RGBA(r0, g0, b0, a);
          colors[1] = RGBA(r1, g1, b1, a);
          colors[2] = RGBA((r0 + r1) / 2,
                           (g0 + g1) / 2,
                           (b0 + b1) / 2,
                           a);
          colors[3] = RGBA(0, 0, 0, alpha);
      }
  }
  
  static inline void dxt1_block_internal(uint8_t *dst, ptrdiff_t stride,
                                         const uint8_t *block, uint8_t alpha)
  {
      int x, y;
      uint32_t colors[4];
      uint16_t color0 = AV_RL16(block + 0);
      uint16_t color1 = AV_RL16(block + 2);
      uint32_t code   = AV_RL32(block + 4);
  
      extract_color(colors, color0, color1, 0, alpha);
  
      for (y = 0; y < 4; y++) {
          for (x = 0; x < 4; x++) {
              uint32_t pixel = colors[code & 3];
              code >>= 2;
              AV_WL32(dst + x * 4, pixel);
          }
          dst += stride;
      }
  }
  
  /**
   * Decompress one block of a DXT1 texture and store the resulting
   * RGBA pixels in 'dst'. Alpha component is fully opaque.
   *
   * @param dst    output buffer.
   * @param stride scanline in bytes.
   * @param block  block to decompress.
   * @return how much texture data has been consumed.
   */
  static int dxt1_block(uint8_t *dst, ptrdiff_t stride, const uint8_t *block)
  {
      dxt1_block_internal(dst, stride, block, 255);
  
      return 8;
  }
  
  /**
   * Decompress one block of a DXT1 with 1-bit alpha texture and store
   * the resulting RGBA pixels in 'dst'. Alpha is either fully opaque or
   * fully transparent.
   *
   * @param dst    output buffer.
   * @param stride scanline in bytes.
   * @param block  block to decompress.
   * @return how much texture data has been consumed.
   */
  static int dxt1a_block(uint8_t *dst, ptrdiff_t stride, const uint8_t *block)
  {
      dxt1_block_internal(dst, stride, block, 0);
  
      return 8;
  }
  
  static inline void dxt3_block_internal(uint8_t *dst, ptrdiff_t stride,
                                         const uint8_t *block)
  {
      int x, y;
      uint32_t colors[4];
      uint16_t color0 = AV_RL16(block +  8);
      uint16_t color1 = AV_RL16(block + 10);
      uint32_t code   = AV_RL32(block + 12);
  
      extract_color(colors, color0, color1, 1, 0);
  
      for (y = 0; y < 4; y++) {
          const uint16_t alpha_code = AV_RL16(block + 2 * y);
          uint8_t alpha_values[4];
  
          alpha_values[0] = ((alpha_code >>  0) & 0x0F) * 17;
          alpha_values[1] = ((alpha_code >>  4) & 0x0F) * 17;
          alpha_values[2] = ((alpha_code >>  8) & 0x0F) * 17;
          alpha_values[3] = ((alpha_code >> 12) & 0x0F) * 17;
  
          for (x = 0; x < 4; x++) {
              uint8_t alpha = alpha_values[x];
              uint32_t pixel = colors[code & 3] | ((unsigned)alpha << 24);
              code >>= 2;
  
              AV_WL32(dst + x * 4, pixel);
          }
          dst += stride;
      }
  }
  
  /** Convert a premultiplied alpha pixel to a straight alpha pixel. */
  static av_always_inline void premult2straight(uint8_t *src)
  {
      int r = src[0];
      int g = src[1];
      int b = src[2];
      int a = src[3]; /* unchanged */
  
      src[0] = (uint8_t) r * a / 255;
      src[1] = (uint8_t) g * a / 255;
      src[2] = (uint8_t) b * a / 255;
  }
  
  /**
   * Decompress one block of a DXT2 texture and store the resulting
   * RGBA pixels in 'dst'.
   *
   * @param dst    output buffer.
   * @param stride scanline in bytes.
   * @param block  block to decompress.
   * @return how much texture data has been consumed.
   */
  static int dxt2_block(uint8_t *dst, ptrdiff_t stride, const uint8_t *block)
  {
      int x, y;
  
      dxt3_block_internal(dst, stride, block);
  
      /* This format is DXT3, but returns premultiplied alpha. It needs to be
       * converted because it's what lavc outputs (and swscale expects). */
      for (y = 0; y < 4; y++)
          for (x = 0; x < 4; x++)
              premult2straight(dst + x * 4 + y * stride);
  
      return 16;
  }
  
  /**
   * Decompress one block of a DXT3 texture and store the resulting
   * RGBA pixels in 'dst'.
   *
   * @param dst    output buffer.
   * @param stride scanline in bytes.
   * @param block  block to decompress.
   * @return how much texture data has been consumed.
   */
  static int dxt3_block(uint8_t *dst, ptrdiff_t stride, const uint8_t *block)
  {
      dxt3_block_internal(dst, stride, block);
  
      return 16;
  }
  
  /**
   * Decompress a BC 16x3 index block stored as
   *   h g f e
   *   d c b a
   *   p o n m
   *   l k j i
   *
   * Bits packed as
   *  | h | g | f | e | d | c | b | a | // Entry
   *  |765 432 107 654 321 076 543 210| // Bit
   *  |0000000000111111111112222222222| // Byte
   *
   * into 16 8-bit indices.
   */
  static void decompress_indices(uint8_t *dst, const uint8_t *src)
  {
      int block, i;
  
      for (block = 0; block < 2; block++) {
          int tmp = AV_RL24(src);
  
          /* Unpack 8x3 bit from last 3 byte block */
          for (i = 0; i < 8; i++)
              dst[i] = (tmp >> (i * 3)) & 0x7;
  
          src += 3;
          dst += 8;
      }
  }
  
  static inline void dxt5_block_internal(uint8_t *dst, ptrdiff_t stride,
                                         const uint8_t *block)
  {
      int x, y;
      uint32_t colors[4];
      uint8_t alpha_indices[16];
      uint16_t color0 = AV_RL16(block + 8);
      uint16_t color1 = AV_RL16(block + 10);
      uint32_t code   = AV_RL32(block + 12);
      uint8_t alpha0  = *(block);
      uint8_t alpha1  = *(block + 1);
  
      decompress_indices(alpha_indices, block + 2);
  
      extract_color(colors, color0, color1, 1, 0);
  
      for (y = 0; y < 4; y++) {
          for (x = 0; x < 4; x++) {
              int alpha_code = alpha_indices[x + y * 4];
              uint32_t pixel;
              uint8_t alpha;
  
              if (alpha_code == 0) {
                  alpha = alpha0;
              } else if (alpha_code == 1) {
                  alpha = alpha1;
              } else {
                  if (alpha0 > alpha1) {
                      alpha = (uint8_t) (((8 - alpha_code) * alpha0 +
                                          (alpha_code - 1) * alpha1) / 7);
                  } else {
                      if (alpha_code == 6) {
                          alpha = 0;
                      } else if (alpha_code == 7) {
                          alpha = 255;
                      } else {
                          alpha = (uint8_t) (((6 - alpha_code) * alpha0 +
                                              (alpha_code - 1) * alpha1) / 5);
                      }
                  }
              }
              pixel = colors[code & 3] | ((unsigned)alpha << 24);
              code >>= 2;
              AV_WL32(dst + x * 4, pixel);
          }
          dst += stride;
      }
  }
  
  /**
   * Decompress one block of a DXT4 texture and store the resulting
   * RGBA pixels in 'dst'.
   *
   * @param dst    output buffer.
   * @param stride scanline in bytes.
   * @param block  block to decompress.
   * @return how much texture data has been consumed.
   */
  static int dxt4_block(uint8_t *dst, ptrdiff_t stride, const uint8_t *block)
  {
      int x, y;
  
      dxt5_block_internal(dst, stride, block);
  
      /* This format is DXT5, but returns premultiplied alpha. It needs to be
       * converted because it's what lavc outputs (and swscale expects). */
      for (y = 0; y < 4; y++)
          for (x = 0; x < 4; x++)
              premult2straight(dst + x * 4 + y * stride);
  
      return 16;
  }
  
  /**
   * Decompress one block of a DXT5 texture and store the resulting
   * RGBA pixels in 'dst'.
   *
   * @param dst    output buffer.
   * @param stride scanline in bytes.
   * @param block  block to decompress.
   * @return how much texture data has been consumed.
   */
  static int dxt5_block(uint8_t *dst, ptrdiff_t stride, const uint8_t *block)
  {
      dxt5_block_internal(dst, stride, block);
  
      return 16;
  }
  
  /**
   * Convert a YCoCg buffer to RGBA.
   *
   * @param src    input buffer.
   * @param scaled variant with scaled chroma components and opaque alpha.
   */
  static av_always_inline void ycocg2rgba(uint8_t *src, int scaled)
  {
      int r = src[0];
      int g = src[1];
      int b = src[2];
      int a = src[3];
  
      int s  = scaled ? (b >> 3) + 1 : 1;
      int y  = a;
      int co = (r - 128) / s;
      int cg = (g - 128) / s;
  
      src[0] = av_clip_uint8(y + co - cg);
      src[1] = av_clip_uint8(y + cg);
      src[2] = av_clip_uint8(y - co - cg);
      src[3] = scaled ? 255 : b;
  }
  
  /**
   * Decompress one block of a DXT5 texture with classic YCoCg and store
   * the resulting RGBA pixels in 'dst'. Alpha component is fully opaque.
   *
   * @param dst    output buffer.
   * @param stride scanline in bytes.
   * @param block  block to decompress.
   * @return how much texture data has been consumed.
   */
  static int dxt5y_block(uint8_t *dst, ptrdiff_t stride, const uint8_t *block)
  {
      int x, y;
  
      /* This format is basically DXT5, with luma stored in alpha.
       * Run a normal decompress and then reorder the components. */
      dxt5_block_internal(dst, stride, block);
  
      for (y = 0; y < 4; y++)
          for (x = 0; x < 4; x++)
              ycocg2rgba(dst + x * 4 + y * stride, 0);
  
      return 16;
  }
  
  /**
   * Decompress one block of a DXT5 texture with scaled YCoCg and store
   * the resulting RGBA pixels in 'dst'. Alpha component is fully opaque.
   *
   * @param dst    output buffer.
   * @param stride scanline in bytes.
   * @param block  block to decompress.
   * @return how much texture data has been consumed.
   */
  static int dxt5ys_block(uint8_t *dst, ptrdiff_t stride, const uint8_t *block)
  {
      int x, y;
  
      /* This format is basically DXT5, with luma stored in alpha.
       * Run a normal decompress and then reorder the components. */
      dxt5_block_internal(dst, stride, block);
  
      for (y = 0; y < 4; y++)
          for (x = 0; x < 4; x++)
              ycocg2rgba(dst + x * 4 + y * stride, 1);
  
      return 16;
  }
  
  static inline void rgtc_block_internal(uint8_t *dst, ptrdiff_t stride,
                                         const uint8_t *block,
                                         const int *color_tab, int mono, int offset, int pix_size)
  {
      uint8_t indices[16];
      int x, y;
  
      decompress_indices(indices, block + 2);
  
      /* Only one or two channels are stored at most, since it only used to
       * compress specular (black and white) or normal (red and green) maps.
       * Although the standard says to zero out unused components, many
       * implementations fill all of them with the same value. */
      for (y = 0; y < 4; y++) {
          for (x = 0; x < 4; x++) {
              int i = indices[x + y * 4];
              /* Interval expansion from [-1 1] or [0 1] to [0 255]. */
              int c = color_tab[i];
  
              if (mono){
                  dst [x * pix_size + y * stride + offset] = (uint8_t)c;
              }
              else{
                  uint32_t pixel = RGBA(c, c, c, 255U);
                  AV_WL32(dst + x * pix_size + y * stride, pixel);
              }
          }
      }
  }
  
  static inline void rgtc1_block_internal(uint8_t *dst, ptrdiff_t stride,
                                          const uint8_t *block, int sign, int mono, int offset, int pix_size)
  {
      int color_table[8];
      int r0, r1;
  
      if (sign) {
          /* signed data is in [-128 127] so just offset it to unsigned
           * and it can be treated exactly the same */
          r0 = ((int8_t) block[0]) + 128;
          r1 = ((int8_t) block[1]) + 128;
      } else {
          r0 = block[0];
          r1 = block[1];
      }
  
      color_table[0] = r0;
      color_table[1] = r1;
  
      if (r0 > r1) {
          /* 6 interpolated color values */
          color_table[2] = (6 * r0 + 1 * r1) / 7; // bit code 010
          color_table[3] = (5 * r0 + 2 * r1) / 7; // bit code 011
          color_table[4] = (4 * r0 + 3 * r1) / 7; // bit code 100
          color_table[5] = (3 * r0 + 4 * r1) / 7; // bit code 101
          color_table[6] = (2 * r0 + 5 * r1) / 7; // bit code 110
          color_table[7] = (1 * r0 + 6 * r1) / 7; // bit code 111
      } else {
          /* 4 interpolated color values */
          color_table[2] = (4 * r0 + 1 * r1) / 5; // bit code 010
          color_table[3] = (3 * r0 + 2 * r1) / 5; // bit code 011
          color_table[4] = (2 * r0 + 3 * r1) / 5; // bit code 100
          color_table[5] = (1 * r0 + 4 * r1) / 5; // bit code 101
          color_table[6] = 0;    /* min range */  // bit code 110
          color_table[7] = 255;  /* max range */  // bit code 111
      }
  
      rgtc_block_internal(dst, stride, block, color_table, mono, offset, pix_size);
  }
  
  /**
   * Decompress one block of a RGRC1 texture with signed components
   * and store the resulting RGBA pixels in 'dst'.
   *
   * @param dst    output buffer.
   * @param stride scanline in bytes.
   * @param block  block to decompress.
   * @return how much texture data has been consumed.
   */
  static int rgtc1s_block(uint8_t *dst, ptrdiff_t stride, const uint8_t *block)
  {
      rgtc1_block_internal(dst, stride, block, 1, 0, 0, 4);
  
      return 8;
  }
  
  /**
   * Decompress one block of a RGRC1 texture with unsigned components
   * and store the resulting RGBA pixels in 'dst'.
   *
   * @param dst    output buffer.
   * @param stride scanline in bytes.
   * @param block  block to decompress.
   * @return how much texture data has been consumed.
   */
  static int rgtc1u_block(uint8_t *dst, ptrdiff_t stride, const uint8_t *block)
  {
      rgtc1_block_internal(dst, stride, block, 0, 0, 0, 4);
  
      return 8;
  }
  
  /**
   * Decompress one block of a RGTC1 texture with unsigned components
   * and overwrite the alpha component in 'dst' (RGBA data).
   *
   * @param dst    output buffer.
   * @param stride scanline in bytes.
   * @param block  block to decompress.
   * @return how much texture data has been consumed.
   */
  static int rgtc1u_alpha_block(uint8_t *dst, ptrdiff_t stride, const uint8_t *block)
  {
      rgtc1_block_internal(dst, stride, block, 0, 1, 3, 4);
  
      return 8;
  }
  
  /**
   * Decompress one block of a RGTC1 texture with unsigned components
   * to Gray 8.
   *
   * @param dst    output buffer.
   * @param stride scanline in bytes.
   * @param block  block to decompress.
   * @return how much texture data has been consumed.
   */
  static int rgtc1u_gray_block(uint8_t *dst, ptrdiff_t stride, const uint8_t *block)
  {
      rgtc1_block_internal(dst, stride, block, 0, 1, 0, 1);
  
      return 8;
  }
  
  static inline void rgtc2_block_internal(uint8_t *dst, ptrdiff_t stride,
                                          const uint8_t *block, int sign)
  {
      /* 4x4 block containing 4 component pixels. */
      uint8_t c0[4 * 4 * 4];
      uint8_t c1[4 * 4 * 4];
      int x, y;
  
      /* Decompress the two channels separately and interleave them afterwards. */
      rgtc1_block_internal(c0, 16, block, sign, 0, 0, 4);
      rgtc1_block_internal(c1, 16, block + 8, sign, 0, 0, 4);
  
      /* B is rebuilt exactly like a normal map. */
      for (y = 0; y < 4; y++) {
          for (x = 0; x < 4; x++) {
              uint8_t *p = dst + x * 4 + y * stride;
              int r = c0[x * 4 + y * 16];
              int g = c1[x * 4 + y * 16];
              int b = 127;
  
              int d = (255 * 255 - r * r - g * g) / 2;
              if (d > 0)
                  b = lrint(sqrtf(d));
  
              p[0] = r;
              p[1] = g;
              p[2] = b;
              p[3] = 255;
          }
      }
  }
  
  /**
   * Decompress one block of a RGRC2 texture with signed components
   * and store the resulting RGBA pixels in 'dst'. Alpha is fully opaque.
   *
   * @param dst    output buffer.
   * @param stride scanline in bytes.
   * @param block  block to decompress.
   * @return how much texture data has been consumed.
   */
  static int rgtc2s_block(uint8_t *dst, ptrdiff_t stride, const uint8_t *block)
  {
      rgtc2_block_internal(dst, stride, block, 1);
  
      return 16;
  }
  
  /**
   * Decompress one block of a RGRC2 texture with unsigned components
   * and store the resulting RGBA pixels in 'dst'. Alpha is fully opaque.
   *
   * @param dst    output buffer.
   * @param stride scanline in bytes.
   * @param block  block to decompress.
   * @return how much texture data has been consumed.
   */
  static int rgtc2u_block(uint8_t *dst, ptrdiff_t stride, const uint8_t *block)
  {
      rgtc2_block_internal(dst, stride, block, 0);
  
      return 16;
  }
  
  /**
   * Decompress one block of a 3Dc texture with unsigned components
   * and store the resulting RGBA pixels in 'dst'. Alpha is fully opaque.
   *
   * @param dst    output buffer.
   * @param stride scanline in bytes.
   * @param block  block to decompress.
   * @return how much texture data has been consumed.
   */
  static int dxn3dc_block(uint8_t *dst, ptrdiff_t stride, const uint8_t *block)
  {
      int x, y;
      rgtc2_block_internal(dst, stride, block, 0);
  
      /* This is the 3Dc variant of RGTC2, with swapped R and G. */
      for (y = 0; y < 4; y++) {
          for (x = 0; x < 4; x++) {
              uint8_t *p = dst + x * 4 + y * stride;
              FFSWAP(uint8_t, p[0], p[1]);
          }
      }
  
      return 16;
  }
  
  av_cold void ff_texturedsp_init(TextureDSPContext *c)
  {
      c->dxt1_block         = dxt1_block;
      c->dxt1a_block        = dxt1a_block;
      c->dxt2_block         = dxt2_block;
      c->dxt3_block         = dxt3_block;
      c->dxt4_block         = dxt4_block;
      c->dxt5_block         = dxt5_block;
      c->dxt5y_block        = dxt5y_block;
      c->dxt5ys_block       = dxt5ys_block;
      c->rgtc1s_block       = rgtc1s_block;
      c->rgtc1u_block       = rgtc1u_block;
      c->rgtc1u_gray_block  = rgtc1u_gray_block;
      c->rgtc1u_alpha_block = rgtc1u_alpha_block;
      c->rgtc2s_block       = rgtc2s_block;
      c->rgtc2u_block       = rgtc2u_block;
      c->dxn3dc_block       = dxn3dc_block;
  }
  