// SPDX-License-Identifier: Apache-2.0

// ----------------------------------------------------------------------------

// Copyright 2011-2026 Arm Limited

//

// Licensed under the Apache License, Version 2.0 (the "License"); you may not

// use this file except in compliance with the License. You may obtain a copy

// of the License at:

//

//     http://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing, software

// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT

// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the

// License for the specific language governing permissions and limitations

// under the License.

// ----------------------------------------------------------------------------

/**

 * @brief Functions for creating in-memory ASTC image structures.

 */

#include <cassert>

#include <cstring>

#include "astcenc_internal.h"

/**

 * @brief Loader pipeline function type for data fetch from memory.

 */

using pixel_loader = vfloat4(*)(const void*, size_t);

/**

 * @brief Loader pipeline function type for swizzling data in a vector.

 */

using pixel_swizzler = vfloat4(*)(vfloat4, const astcenc_swizzle&);

/**

 * @brief Loader pipeline function type for converting data in a vector to LNS.

 */

using pixel_converter = vfloat4(*)(vfloat4, vmask4);

/**

 * @brief Load an 8-bit UNORM texel from a data array.

 *

 * @param data          The data pointer.

 * @param base_offset   The index offset to the start of the pixel.

 */

static vfloat4 load_texel_u8(

  const void* data,

  size_t base_offset

) {

  const uint8_t* data8 = static_cast<const uint8_t*>(data);

  return int_to_float(vint4(data8 + base_offset)) / 255.0f;

}

/**

 * @brief Load a 16-bit fp16 texel from a data array.

 *

 * @param data          The data pointer.

 * @param base_offset   The index offset to the start of the pixel.

 */

static vfloat4 load_texel_f16(

  const void* data,

  size_t base_offset

) {

  const uint16_t* data16 = static_cast<const uint16_t*>(data);

  int r = data16[base_offset    ];

  int g = data16[base_offset + 1];

  int b = data16[base_offset + 2];

  int a = data16[base_offset + 3];

  return float16_to_float(vint4(r, g, b, a));

}

/**

 * @brief Load a 32-bit float texel from a data array.

 *

 * @param data          The data pointer.

 * @param base_offset   The index offset to the start of the pixel.

 */

static vfloat4 load_texel_f32(

  const void* data,

  size_t base_offset

) {

  const float* data32 = static_cast<const float*>(data);

  return vfloat4(data32 + base_offset);

}

/**

 * @brief Dummy no-op swizzle function.

 *

 * @param data   The source RGBA vector to swizzle.

 * @param swz    The swizzle to use.

 */

static vfloat4 swz_texel_skip(

  vfloat4 data,

  const astcenc_swizzle& swz

) {

  (void)swz;

  return data;

}

/**

 * @brief Swizzle a texel into a new arrangement.

 *

 * @param data   The source RGBA vector to swizzle.

 * @param swz    The swizzle to use.

 */

static vfloat4 swz_texel(

  vfloat4 data,

  const astcenc_swizzle& swz

) {

  ASTCENC_ALIGNAS float datas[6];

  storea(data, datas);

  datas[ASTCENC_SWZ_0] = 0.0f;

  datas[ASTCENC_SWZ_1] = 1.0f;

  return vfloat4(datas[swz.r], datas[swz.g], datas[swz.b], datas[swz.a]);

}

/**

 * @brief Encode a texel that is entirely LDR linear.

 *

 * Out-of-range inputs will be clamped to the valid UNORM range.

 *

 * @param data       The RGBA data to encode.

 * @param lns_mask   The mask for the HDR channels that need LNS encoding.

 */

static vfloat4 encode_texel_unorm(

  vfloat4 data,

  vmask4 lns_mask

) {

  (void)lns_mask;

  vfloat4 raw_value = data * 65535.0f;

  // Unorm data must be in 0-1 range, so clamp because data can come from an

  // unconstrained float. This will replace NaNs with zero.

  return clamp(0.0f, 65535.0f, raw_value);

}

/**

 * @brief Encode a texel that includes at least some HDR LNS texels.

 *

 * Out-of-range inputs will be clamped to the valid LNS or UNORM range,

 * depending on @c lns_mask.

 *

 * @param data       The RGBA data to encode.

 * @param lns_mask   The mask for the HDR channels that need LNS encoding.

 */

static vfloat4 encode_texel_lns(

  vfloat4 data,

  vmask4 lns_mask

) {

  vfloat4 datav_unorm = encode_texel_unorm(data, lns_mask);

  // Out-of-range inputs are clamped inside float_to_lns

  vfloat4 datav_lns = float_to_lns(data);

  return select(datav_unorm, datav_lns, lns_mask);

}

/* See header for documentation. */

void load_image_block(

  astcenc_profile decode_mode,

  const astcenc_image& img,

  image_block& blk,

  const block_size_descriptor& bsd,

  size_t pos_x,

  size_t pos_y,

  size_t pos_z,

  const astcenc_swizzle& swz

) {

  size_t size_x = img.dim_x;

  size_t size_y = img.dim_y;

  size_t size_z = img.dim_z;

  blk.pos_x = pos_x;

  blk.pos_y = pos_y;

  blk.pos_z = pos_z;

  // True if any non-identity swizzle

  bool needs_swz = (swz.r != ASTCENC_SWZ_R) || (swz.g != ASTCENC_SWZ_G) ||

                   (swz.b != ASTCENC_SWZ_B) || (swz.a != ASTCENC_SWZ_A);

  vfloat4 data_min(1e38f);

  vfloat4 data_mean(0.0f);

  vfloat4 data_mean_scale(1.0f / static_cast<float>(bsd.texel_count));

  vfloat4 data_max(-1e38f);

  vmask4 grayscalev(true);

  size_t idx = 0;

  // This works because we impose the same choice everywhere during encode

  uint8_t rgb_lns = (decode_mode == ASTCENC_PRF_HDR) ||

                    (decode_mode == ASTCENC_PRF_HDR_RGB_LDR_A) ? 1 : 0;

  uint8_t a_lns = decode_mode == ASTCENC_PRF_HDR ? 1 : 0;

  vint4 use_lns(rgb_lns, rgb_lns, rgb_lns, a_lns);

  vmask4 lns_mask = use_lns != vint4::zero();

  // Set up the function pointers for loading pipeline as needed

  pixel_loader loader = load_texel_u8;

  if (img.data_type == ASTCENC_TYPE_F16)

  {

    loader = load_texel_f16;

  }

  else if  (img.data_type == ASTCENC_TYPE_F32)

  {

    loader = load_texel_f32;

  }

  pixel_swizzler swizzler = swz_texel_skip;

  if (needs_swz)

  {

    swizzler = swz_texel;

  }

  pixel_converter converter = encode_texel_unorm;

  if (any(lns_mask))

  {

    converter = encode_texel_lns;

  }

  for (size_t z = 0; z < bsd.dim_z; z++)

  {

    size_t zi = astc::min(pos_z + z, size_z - 1);

    void* plane = img.data[zi];

    for (size_t y = 0; y < bsd.dim_y; y++)

    {

      size_t yi = astc::min(pos_y + y, size_y - 1);

      for (size_t x = 0; x < bsd.dim_x; x++)

      {

        size_t xi = astc::min(pos_x + x, size_x - 1);

        vfloat4 datav = loader(plane, (4 * size_x * yi) + (4 * xi));

        datav = swizzler(datav, swz);

        datav = converter(datav, lns_mask);

        // Compute block metadata

        data_min = min(data_min, datav);

        data_mean += datav * data_mean_scale;

        data_max = max(data_max, datav);

        grayscalev = grayscalev & (datav.swz<0,0,0,0>() == datav.swz<1,1,2,2>());

        blk.data_r[idx] = datav.lane<0>();

        blk.data_g[idx] = datav.lane<1>();

        blk.data_b[idx] = datav.lane<2>();

        blk.data_a[idx] = datav.lane<3>();

        blk.rgb_lns[idx] = rgb_lns;

        blk.alpha_lns[idx] = a_lns;

        idx++;

      }

    }

  }

  // Reverse the encoding so we store origin block in the original format

  vfloat4 data_enc = blk.texel(0);

  vfloat4 data_enc_unorm = data_enc / 65535.0f;

  vfloat4 data_enc_lns = vfloat4::zero();

  if (rgb_lns || a_lns)

  {

    data_enc_lns = float16_to_float(lns_to_sf16(float_to_int(data_enc)));

  }

  blk.origin_texel = select(data_enc_unorm, data_enc_lns, lns_mask);

  // Store block metadata

  blk.data_min = data_min;

  blk.data_mean = data_mean;

  blk.data_max = data_max;

  blk.grayscale = all(grayscalev);

}

/* See header for documentation. */

void load_image_block_fast_ldr(

  astcenc_profile decode_mode,

  const astcenc_image& img,

  image_block& blk,

  const block_size_descriptor& bsd,

  size_t pos_x,

  size_t pos_y,

  size_t pos_z,

  const astcenc_swizzle& swz

) {

  (void)swz;

  (void)decode_mode;

  size_t size_x = img.dim_x;

  size_t size_y = img.dim_y;

  blk.pos_x = pos_x;

  blk.pos_y = pos_y;

  blk.pos_z = pos_z;

  vfloat4 data_min(1e38f);

  vfloat4 data_mean = vfloat4::zero();

  vfloat4 data_max(-1e38f);

  vmask4 grayscalev(true);

  size_t idx = 0;

  const uint8_t* plane = static_cast<const uint8_t*>(img.data[0]);

  for (size_t y = pos_y; y < pos_y + bsd.dim_y; y++)

  {

    size_t yi = astc::min(y, size_y - 1);

    for (size_t x = pos_x; x < pos_x + bsd.dim_x; x++)

    {

      size_t xi = astc::min(x, size_x - 1);

      vint4 datavi = vint4(plane + (4 * size_x * yi) + (4 * xi));

      vfloat4 datav = int_to_float(datavi) * (65535.0f / 255.0f);

      // Compute block metadata

      data_min = min(data_min, datav);

      data_mean += datav;

      data_max = max(data_max, datav);

      grayscalev = grayscalev & (datav.swz<0,0,0,0>() == datav.swz<1,1,2,2>());

      blk.data_r[idx] = datav.lane<0>();

      blk.data_g[idx] = datav.lane<1>();

      blk.data_b[idx] = datav.lane<2>();

      blk.data_a[idx] = datav.lane<3>();

      idx++;

    }

  }

  // Reverse the encoding so we store origin block in the original format

  blk.origin_texel = blk.texel(0) / 65535.0f;

  // Store block metadata

  blk.rgb_lns[0] = 0;

  blk.alpha_lns[0] = 0;

  blk.data_min = data_min;

  blk.data_mean = data_mean / static_cast<float>(bsd.texel_count);

  blk.data_max = data_max;

  blk.grayscale = all(grayscalev);

}

/* See header for documentation. */

void store_image_block(

  astcenc_image& img,

  const image_block& blk,

  const block_size_descriptor& bsd,

  size_t pos_x,

  size_t pos_y,

  size_t pos_z,

  const astcenc_swizzle& swz

) {

  size_t size_x = img.dim_x;

  size_t start_x = pos_x;

  size_t end_x = astc::min(size_x, pos_x + bsd.dim_x);

  size_t count_x = end_x - start_x;

  size_t nudge_x = bsd.dim_x - count_x;

  size_t size_y = img.dim_y;

  size_t start_y = pos_y;

  size_t end_y = astc::min(size_y, pos_y + bsd.dim_y);

  size_t count_y = end_y - start_y;

  size_t nudge_y = (bsd.dim_y - count_y) * bsd.dim_x;

  size_t size_z = img.dim_z;

  size_t start_z = pos_z;

  size_t end_z = astc::min(size_z, pos_z + bsd.dim_z);

  size_t idx = 0;

  // True if any non-identity swizzle

  bool needs_swz = (swz.r != ASTCENC_SWZ_R) || (swz.g != ASTCENC_SWZ_G) ||

                   (swz.b != ASTCENC_SWZ_B) || (swz.a != ASTCENC_SWZ_A);

  // True if any swizzle uses Z reconstruct

  bool needs_z = (swz.r == ASTCENC_SWZ_Z) || (swz.g == ASTCENC_SWZ_Z) ||

                 (swz.b == ASTCENC_SWZ_Z) || (swz.a == ASTCENC_SWZ_Z);

  if (img.data_type == ASTCENC_TYPE_U8)

  {

    for (size_t z = start_z; z < end_z; z++)

    {

      // Fetch the image plane

      uint8_t* data8 = static_cast<uint8_t*>(img.data[z]);

      for (size_t y = start_y; y < end_y; y++)

      {

        uint8_t* data8_row = data8 + (4 * size_x * y) + (4 * start_x);

        for (size_t x = 0; x < count_x; x += ASTCENC_SIMD_WIDTH)

        {

          size_t max_texels = ASTCENC_SIMD_WIDTH;

          size_t used_texels = astc::min(count_x - x, max_texels);

          // Unaligned load as rows are not always SIMD_WIDTH long

          vfloat data_r(blk.data_r + idx);

          vfloat data_g(blk.data_g + idx);

          vfloat data_b(blk.data_b + idx);

          vfloat data_a(blk.data_a + idx);

          // Clamp values to [0.0, 1.0] range before unorm conversion

          //   - Values > 1.0 are possible for all HDR blocks

          //   - Values < 0.0 are possible for HDR void-extent blocks

          vint data_ri = float_to_int_rtn(clampzo(data_r) * 255.0f);

          vint data_gi = float_to_int_rtn(clampzo(data_g) * 255.0f);

          vint data_bi = float_to_int_rtn(clampzo(data_b) * 255.0f);

          vint data_ai = float_to_int_rtn(clampzo(data_a) * 255.0f);

          if (needs_swz)

          {

            vint swizzle_table[7];

            swizzle_table[ASTCENC_SWZ_0] = vint(0);

            swizzle_table[ASTCENC_SWZ_1] = vint(255);

            swizzle_table[ASTCENC_SWZ_R] = data_ri;

            swizzle_table[ASTCENC_SWZ_G] = data_gi;

            swizzle_table[ASTCENC_SWZ_B] = data_bi;

            swizzle_table[ASTCENC_SWZ_A] = data_ai;

            if (needs_z)

            {

              vfloat data_x = (data_r * vfloat(2.0f)) - vfloat(1.0f);

              vfloat data_y = (data_a * vfloat(2.0f)) - vfloat(1.0f);

              vfloat data_z = vfloat(1.0f) - (data_x * data_x) - (data_y * data_y);

              data_z = max(data_z, 0.0f);

              data_z = (sqrt(data_z) * vfloat(0.5f)) + vfloat(0.5f);

              swizzle_table[ASTCENC_SWZ_Z] = float_to_int_rtn(min(data_z, 1.0f) * 255.0f);

            }

            data_ri = swizzle_table[swz.r];

            data_gi = swizzle_table[swz.g];

            data_bi = swizzle_table[swz.b];

            data_ai = swizzle_table[swz.a];

          }

          // Errors are NaN encoded - convert to magenta error color

          // Branch is OK here - it is almost never true so predicts well

          vmask nan_mask = data_r != data_r;

          if (any(nan_mask))

          {

            data_ri = select(data_ri, vint(0xFF), nan_mask);

            data_gi = select(data_gi, vint(0x00), nan_mask);

            data_bi = select(data_bi, vint(0xFF), nan_mask);

            data_ai = select(data_ai, vint(0xFF), nan_mask);

          }

          vint data_rgbai = interleave_rgba8(data_ri, data_gi, data_bi, data_ai);

          // Static cast must be safe, as used_texels must be less than vector length

          vmask store_mask = vint::lane_id() < vint(static_cast<int>(used_texels));

          store_lanes_masked(data8_row, data_rgbai, store_mask);

          data8_row += ASTCENC_SIMD_WIDTH * 4;

          idx += used_texels;

        }

        idx += nudge_x;

      }

      idx += nudge_y;

    }

  }

  else if (img.data_type == ASTCENC_TYPE_F16)

  {

    for (size_t z = start_z; z < end_z; z++)

    {

      // Fetch the image plane

      uint16_t* data16 = static_cast<uint16_t*>(img.data[z]);

      for (size_t y = start_y; y < end_y; y++)

      {

        uint16_t* data16_row = data16 + (4 * size_x * y) + (4 * start_x);

        for (size_t x = 0; x < count_x; x++)

        {

          vint4 color;

          // NaNs are handled inline - no need to special case

          if (needs_swz)

          {

            float data[7];

            data[ASTCENC_SWZ_0] = 0.0f;

            data[ASTCENC_SWZ_1] = 1.0f;

            data[ASTCENC_SWZ_R] = blk.data_r[idx];

            data[ASTCENC_SWZ_G] = blk.data_g[idx];

            data[ASTCENC_SWZ_B] = blk.data_b[idx];

            data[ASTCENC_SWZ_A] = blk.data_a[idx];

            if (needs_z)

            {

              float xN = (data[0] * 2.0f) - 1.0f;

              float yN = (data[3] * 2.0f) - 1.0f;

              float zN = 1.0f - xN * xN - yN * yN;

              if (zN < 0.0f)

              {

                zN = 0.0f;

              }

              data[ASTCENC_SWZ_Z] = (astc::sqrt(zN) * 0.5f) + 0.5f;

            }

            vfloat4 colorf(data[swz.r], data[swz.g], data[swz.b], data[swz.a]);

            color = float_to_float16(colorf);

          }

          else

          {

            vfloat4 colorf = blk.texel(idx);

            color = float_to_float16(colorf);

          }

          // TODO: Vectorize with store N shorts?

          data16_row[0] = static_cast<uint16_t>(color.lane<0>());

          data16_row[1] = static_cast<uint16_t>(color.lane<1>());

          data16_row[2] = static_cast<uint16_t>(color.lane<2>());

          data16_row[3] = static_cast<uint16_t>(color.lane<3>());

          data16_row += 4;

          idx++;

        }

        idx += nudge_x;

      }

      idx += nudge_y;

    }

  }

  else // if (img.data_type == ASTCENC_TYPE_F32)

  {

    assert(img.data_type == ASTCENC_TYPE_F32);

    for (size_t z = start_z; z < end_z; z++)

    {

      // Fetch the image plane

      float* data32 = static_cast<float*>(img.data[z]);

      for (size_t y = start_y; y < end_y; y++)

      {

        float* data32_row = data32 + (4 * size_x * y) + (4 * start_x);

        for (size_t x = 0; x < count_x; x++)

        {

          vfloat4 color = blk.texel(idx);

          // NaNs are handled inline - no need to special case

          if (needs_swz)

          {

            float data[7];

            data[ASTCENC_SWZ_0] = 0.0f;

            data[ASTCENC_SWZ_1] = 1.0f;

            data[ASTCENC_SWZ_R] = color.lane<0>();

            data[ASTCENC_SWZ_G] = color.lane<1>();

            data[ASTCENC_SWZ_B] = color.lane<2>();

            data[ASTCENC_SWZ_A] = color.lane<3>();

            if (needs_z)

            {

              float xN = (data[0] * 2.0f) - 1.0f;

              float yN = (data[3] * 2.0f) - 1.0f;

              float zN = 1.0f - xN * xN - yN * yN;

              if (zN < 0.0f)

              {

                zN = 0.0f;

              }

              data[ASTCENC_SWZ_Z] = (astc::sqrt(zN) * 0.5f) + 0.5f;

            }

            color = vfloat4(data[swz.r], data[swz.g], data[swz.b], data[swz.a]);

          }

          store(color, data32_row);

          data32_row += 4;

          idx++;

        }

        idx += nudge_x;

      }

      idx += nudge_y;

    }

  }

}