/src/astc-encoder/Source/astcenc_entry.cpp

Source
// 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 the library entrypoint.
 */

#include <array>
#include <cstring>
#include <new>

#include "astcenc.h"
#include "astcenc_diagnostic_trace.h"
#include "astcenc_internal_entry.h"
#include "astcenc_mathlib.h"

/**
 * @brief Record of the quality tuning parameter values.
 *
 * See the @c astcenc_config structure for detailed parameter documentation.
 *
 * Note that the mse_overshoot entries are scaling factors relative to the base MSE to hit db_limit.
 * A 20% overshoot is harder to hit for a higher base db_limit, so we may actually use lower ratios
 * for the more through search presets because the underlying db_limit is so much higher.
 */
struct astcenc_preset_config
{
  float quality;
  unsigned int tune_partition_count_limit;
  unsigned int tune_2partition_index_limit;
  unsigned int tune_3partition_index_limit;
  unsigned int tune_4partition_index_limit;
  unsigned int tune_block_mode_limit;
  unsigned int tune_refinement_limit;
  unsigned int tune_candidate_limit;
  unsigned int tune_2partitioning_candidate_limit;
  unsigned int tune_3partitioning_candidate_limit;
  unsigned int tune_4partitioning_candidate_limit;
  float tune_db_limit_a_base;
  float tune_db_limit_b_base;
  float tune_mse_overshoot;
  float tune_2partition_early_out_limit_factor;
  float tune_3partition_early_out_limit_factor;
  float tune_2plane_early_out_limit_correlation;
  float tune_search_mode0_enable;
};

/**
 * @brief The static presets for high bandwidth encodings (x < 25 texels per block).
 */
static const std::array<astcenc_preset_config, 6> preset_configs_high {{
  {
    ASTCENC_PRE_FASTEST,
    2,  10,   6,   4,  43, 2, 2, 2, 2, 2,  85.2f,  63.2f,  3.5f, 1.00f, 1.00f, 0.85f, 0.0f
  }, {
    ASTCENC_PRE_FAST,
    3,  18,  10,   8,  55, 3, 3, 2, 2, 2,  85.2f,  63.2f,  3.5f, 1.00f, 1.00f, 0.90f, 0.0f
  }, {
    ASTCENC_PRE_MEDIUM,
    4,  34,  28,  16,  77, 3, 3, 2, 2, 2,  95.0f,  70.0f,  2.5f, 1.10f, 1.05f, 0.95f, 0.0f
  }, {
    ASTCENC_PRE_THOROUGH,
    4,  82,  60,  30,  94, 4, 4, 3, 2, 2, 105.0f,  77.0f, 10.0f, 1.35f, 1.15f, 0.97f, 0.0f
  }, {
    ASTCENC_PRE_VERYTHOROUGH,
    4, 256, 128,  64,  98, 4, 6, 8, 6, 4, 200.0f, 200.0f, 10.0f, 1.60f, 1.40f, 0.98f, 0.0f
  }, {
    ASTCENC_PRE_EXHAUSTIVE,
    4, 512, 512, 512, 100, 4, 8, 8, 8, 8, 200.0f, 200.0f, 10.0f, 2.00f, 2.00f, 0.99f, 0.0f
  }
}};

/**
 * @brief The static presets for medium bandwidth encodings (25 <= x < 64 texels per block).
 */
static const std::array<astcenc_preset_config, 6> preset_configs_mid {{
  {
    ASTCENC_PRE_FASTEST,
    2,  10,   6,   4,  43, 2, 2, 2, 2, 2,  85.2f,  63.2f,  3.5f, 1.00f, 1.00f, 0.80f, 1.0f
  }, {
    ASTCENC_PRE_FAST,
    3,  18,  12,  10,  55, 3, 3, 2, 2, 2,  85.2f,  63.2f,  3.5f, 1.00f, 1.00f, 0.85f, 1.0f
  }, {
    ASTCENC_PRE_MEDIUM,
    3,  34,  28,  16,  77, 3, 3, 2, 2, 2,  95.0f,  70.0f,  3.0f, 1.10f, 1.05f, 0.90f, 1.0f
  }, {
    ASTCENC_PRE_THOROUGH,
    4,  82,  60,  30,  94, 4, 4, 3, 2, 2, 105.0f,  77.0f, 10.0f, 1.40f, 1.20f, 0.95f, 0.0f
  }, {
    ASTCENC_PRE_VERYTHOROUGH,
    4, 256, 128,  64,  98, 4, 6, 8, 6, 3, 200.0f, 200.0f, 10.0f, 1.60f, 1.40f, 0.98f, 0.0f
  }, {
    ASTCENC_PRE_EXHAUSTIVE,
    4, 256, 256, 256, 100, 4, 8, 8, 8, 8, 200.0f, 200.0f, 10.0f, 2.00f, 2.00f, 0.99f, 0.0f
  }
}};

/**
 * @brief The static presets for low bandwidth encodings (64 <= x texels per block).
 */
static const std::array<astcenc_preset_config, 6> preset_configs_low {{
  {
    ASTCENC_PRE_FASTEST,
    2,  10,   6,   4,  40, 2, 2, 2, 2, 2,  85.0f,  63.0f,  3.5f, 1.00f, 1.00f, 0.80f, 1.0f
  }, {
    ASTCENC_PRE_FAST,
    2,  18,  12,  10,  55, 3, 3, 2, 2, 2,  85.0f,  63.0f,  3.5f, 1.00f, 1.00f, 0.85f, 1.0f
  }, {
    ASTCENC_PRE_MEDIUM,
    3,  34,  28,  16,  77, 3, 3, 2, 2, 2,  95.0f,  70.0f,  3.5f, 1.10f, 1.05f, 0.90f, 1.0f
  }, {
    ASTCENC_PRE_THOROUGH,
    4,  82,  60,  30,  93, 4, 4, 3, 2, 2, 105.0f,  77.0f, 10.0f, 1.30f, 1.20f, 0.97f, 1.0f
  }, {
    ASTCENC_PRE_VERYTHOROUGH,
    4, 256, 128,  64,  98, 4, 6, 8, 5, 2, 200.0f, 200.0f, 10.0f, 1.60f, 1.40f, 0.98f, 1.0f
  }, {
    ASTCENC_PRE_EXHAUSTIVE,
    4, 256, 256, 256, 100, 4, 8, 8, 8, 8, 200.0f, 200.0f, 10.0f, 2.00f, 2.00f, 0.99f, 1.0f
  }
}};

/**
 * @brief Get the total number of texels in an image.
 *
 * This function validates that the total size would fit in a size_t and returns
 * 0 if it does not.
 *
 * @param texels_x   Number of texels in the X axis.
 * @param texels_y   Number of texels in the Y axis.
 * @param texels_z   Number of texels in the Z axis.
 *
 * @return The number of texels in the image, or zero if total size would not
 *         fit into a size_t.
 */
static size_t get_texels_count(
  size_t texels_x,
  size_t texels_y,
  size_t texels_z
) {
  bool overflow { false };

  // Compute texel count
  size_t texels_count = astc::mul_safe(texels_x, texels_y, overflow);
  texels_count = astc::mul_safe(texels_count, texels_z, overflow);

  if (overflow)
  {
    return 0;
  }

  return texels_count;
}

/**
 * @brief Get the total number of blocks in an image.
 *
 * This function also validates that the total size of the compressed image,
 * in bytes, would fit in a size_t.
 *
 * @param blocks_x   Number of blocks in the X axis.
 * @param blocks_y   Number of blocks in the Y axis.
 * @param blocks_z   Number of blocks in the Z axis.
 *
 * @return The number of blocks in the image, or zero if total size would not
 *         fit into a size_t.
 */
static size_t get_blocks_count(
  size_t blocks_x,
  size_t blocks_y,
  size_t blocks_z
) {
  bool overflow { false };

  // Compute block count
  size_t blocks_count = astc::mul_safe(blocks_x, blocks_y, overflow);
  blocks_count = astc::mul_safe(blocks_count, blocks_z, overflow);

  // Also compute byte count, but we only use overflow and not the result
  astc::mul_safe(blocks_count, 16, overflow);

  if (overflow)
  {
    return 0;
  }

  return blocks_count;
}

/**
 * @brief Validate CPU floating point meets assumptions made in the codec.
 *
 * The codec is written with the assumption that float bit patterns are valid
 * IEEE754 values that are stored and reloaded with round-to-nearest rounding.
 * This is always the case in an IEEE-754 compliant system, however not every
 * system or compilation mode is actually IEEE-754 compliant. This normally
 * fails if the code is compiled with fast math enabled, for example.
 *
 * @return Return @c ASTCENC_SUCCESS if validated, an error on failure.
 */
static astcenc_error validate_cpu_float()
{
  volatile float xprec_testval = 2.51f;
  float store = xprec_testval + 12582912.0f;
  float q = store - 12582912.0f;

  if (q != 3.0f)
  {
    return ASTCENC_ERR_BAD_CPU_FLOAT;
  }

  return ASTCENC_SUCCESS;
}

/**
 * @brief Validate config profile.
 *
 * @param profile   The profile to check.
 *
 * @return Return @c ASTCENC_SUCCESS if validated, otherwise an error on failure.
 */
static astcenc_error validate_profile(
  astcenc_profile profile
) {
  // Values in this enum are from an external user, so not guaranteed to be
  // bounded to the enum values
  switch (static_cast<int>(profile))
  {
  case ASTCENC_PRF_LDR_SRGB:
  case ASTCENC_PRF_LDR:
  case ASTCENC_PRF_HDR_RGB_LDR_A:
  case ASTCENC_PRF_HDR:
    return ASTCENC_SUCCESS;
  default:
    return ASTCENC_ERR_BAD_PROFILE;
  }
}

/**
 * @brief Validate block size.
 *
 * @param block_x   The block x dimensions.
 * @param block_y   The block y dimensions.
 * @param block_z   The block z dimensions.
 *
 * @return Return @c ASTCENC_SUCCESS if validated, otherwise an error on failure.
 */
static astcenc_error validate_block_size(
  unsigned int block_x,
  unsigned int block_y,
  unsigned int block_z
) {
  // Test if this is a legal block size at all
  bool is_legal = (((block_z <= 1) && is_legal_2d_block_size(block_x, block_y)) ||
                   ((block_z >= 2) && is_legal_3d_block_size(block_x, block_y, block_z)));
  if (!is_legal)
  {
    return ASTCENC_ERR_BAD_BLOCK_SIZE;
  }

  // Test if this build has sufficient capacity for this block size
  bool have_capacity = (block_x * block_y * block_z) <= BLOCK_MAX_TEXELS;
  if (!have_capacity)
  {
    return ASTCENC_ERR_NOT_IMPLEMENTED;
  }

  return ASTCENC_SUCCESS;
}

/**
 * @brief Validate flags.
 *
 * @param profile   The profile to check.
 * @param flags     The flags to check.
 *
 * @return Return @c ASTCENC_SUCCESS if validated, otherwise an error on failure.
 */
static astcenc_error validate_flags(
  astcenc_profile profile,
  unsigned int flags
) {
  // Flags field must not contain any unknown flag bits
  unsigned int exMask = ~ASTCENC_ALL_FLAGS;
  if (popcount(flags & exMask) != 0)
  {
    return ASTCENC_ERR_BAD_FLAGS;
  }

  // Flags field must only contain at most a single map type
  exMask = ASTCENC_FLG_MAP_NORMAL
         | ASTCENC_FLG_MAP_RGBM;
  if (popcount(flags & exMask) > 1)
  {
    return ASTCENC_ERR_BAD_FLAGS;
  }

  // Decode_unorm8 must only be used with an LDR profile
  bool is_unorm8 = flags & ASTCENC_FLG_USE_DECODE_UNORM8;
  bool is_hdr = (profile == ASTCENC_PRF_HDR) || (profile == ASTCENC_PRF_HDR_RGB_LDR_A);
  if (is_unorm8 && is_hdr)
  {
    return ASTCENC_ERR_BAD_DECODE_MODE;
  }

  return ASTCENC_SUCCESS;
}

#if !defined(ASTCENC_DECOMPRESS_ONLY)

/**
 * @brief Validate single channel compression swizzle.
 *
 * @param swizzle   The swizzle to check.
 *
 * @return Return @c ASTCENC_SUCCESS if validated, otherwise an error on failure.
 */
static astcenc_error validate_compression_swz(
  astcenc_swz swizzle
) {
  // Not all enum values are handled; SWZ_Z is invalid for compression
  switch (static_cast<int>(swizzle))
  {
  case ASTCENC_SWZ_R:
  case ASTCENC_SWZ_G:
  case ASTCENC_SWZ_B:
  case ASTCENC_SWZ_A:
  case ASTCENC_SWZ_0:
  case ASTCENC_SWZ_1:
    return ASTCENC_SUCCESS;
  default:
    return ASTCENC_ERR_BAD_SWIZZLE;
  }
}

/**
 * @brief Validate overall compression swizzle.
 *
 * @param swizzle   The swizzle to check.
 *
 * @return Return @c ASTCENC_SUCCESS if validated, otherwise an error on failure.
 */
static astcenc_error validate_compression_swizzle(
  const astcenc_swizzle& swizzle
) {
  if (validate_compression_swz(swizzle.r) ||
      validate_compression_swz(swizzle.g) ||
      validate_compression_swz(swizzle.b) ||
      validate_compression_swz(swizzle.a))
  {
    return ASTCENC_ERR_BAD_SWIZZLE;
  }

  return ASTCENC_SUCCESS;
}
#endif

/**
 * @brief Validate single channel decompression swizzle.
 *
 * @param swizzle   The swizzle to check.
 *
 * @return Return @c ASTCENC_SUCCESS if validated, otherwise an error on failure.
 */
static astcenc_error validate_decompression_swz(
  astcenc_swz swizzle
) {
  // Values in this enum are from an external user, so not guaranteed to be
  // bounded to the enum values
  switch (static_cast<int>(swizzle))
  {
  case ASTCENC_SWZ_R:
  case ASTCENC_SWZ_G:
  case ASTCENC_SWZ_B:
  case ASTCENC_SWZ_A:
  case ASTCENC_SWZ_0:
  case ASTCENC_SWZ_1:
  case ASTCENC_SWZ_Z:
    return ASTCENC_SUCCESS;
  default:
    return ASTCENC_ERR_BAD_SWIZZLE;
  }
}

/**
 * @brief Validate overall decompression swizzle.
 *
 * @param swizzle   The swizzle to check.
 *
 * @return Return @c ASTCENC_SUCCESS if validated, otherwise an error on failure.
 */
static astcenc_error validate_decompression_swizzle(
  const astcenc_swizzle& swizzle
) {
  if (validate_decompression_swz(swizzle.r) ||
      validate_decompression_swz(swizzle.g) ||
      validate_decompression_swz(swizzle.b) ||
      validate_decompression_swz(swizzle.a))
  {
    return ASTCENC_ERR_BAD_SWIZZLE;
  }

  return ASTCENC_SUCCESS;
}

/**
 * Validate that an incoming configuration is in-spec.
 *
 * This function can respond in two ways:
 *
 *   * Numerical inputs that have valid ranges are clamped to those valid ranges. No error is thrown
 *     for out-of-range inputs in this case.
 *   * Numerical inputs and logic inputs are are logically invalid and which make no sense
 *     algorithmically will return an error.
 *
 * @param[in,out] config   The input compressor configuration.
 *
 * @return Return @c ASTCENC_SUCCESS if validated, otherwise an error on failure.
 */
static astcenc_error validate_config(
  astcenc_config &config
) {
  astcenc_error status;

  status = validate_profile(config.profile);
  if (status != ASTCENC_SUCCESS)
  {
    return status;
  }

  status = validate_flags(config.profile, config.flags);
  if (status != ASTCENC_SUCCESS)
  {
    return status;
  }

  status = validate_block_size(config.block_x, config.block_y, config.block_z);
  if (status != ASTCENC_SUCCESS)
  {
    return status;
  }

#if defined(ASTCENC_DECOMPRESS_ONLY)
  // Decompress-only builds only support decompress-only contexts
  if (!(config.flags & ASTCENC_FLG_DECOMPRESS_ONLY))
  {
    return ASTCENC_ERR_BAD_PARAM;
  }
#endif

  config.rgbm_m_scale = astc::max(config.rgbm_m_scale, 1.0f);

  config.tune_partition_count_limit = astc::clamp(config.tune_partition_count_limit, 1u, 4u);
  config.tune_2partition_index_limit = astc::clamp(config.tune_2partition_index_limit, 1u, BLOCK_MAX_PARTITIONINGS);
  config.tune_3partition_index_limit = astc::clamp(config.tune_3partition_index_limit, 1u, BLOCK_MAX_PARTITIONINGS);
  config.tune_4partition_index_limit = astc::clamp(config.tune_4partition_index_limit, 1u, BLOCK_MAX_PARTITIONINGS);
  config.tune_block_mode_limit = astc::clamp(config.tune_block_mode_limit, 1u, 100u);
  config.tune_refinement_limit = astc::max(config.tune_refinement_limit, 1u);
  config.tune_candidate_limit = astc::clamp(config.tune_candidate_limit, 1u, TUNE_MAX_TRIAL_CANDIDATES);
  config.tune_2partitioning_candidate_limit = astc::clamp(config.tune_2partitioning_candidate_limit, 1u, TUNE_MAX_PARTITIONING_CANDIDATES);
  config.tune_3partitioning_candidate_limit = astc::clamp(config.tune_3partitioning_candidate_limit, 1u, TUNE_MAX_PARTITIONING_CANDIDATES);
  config.tune_4partitioning_candidate_limit = astc::clamp(config.tune_4partitioning_candidate_limit, 1u, TUNE_MAX_PARTITIONING_CANDIDATES);
  config.tune_db_limit = astc::max(config.tune_db_limit, 0.0f);
  config.tune_mse_overshoot = astc::max(config.tune_mse_overshoot, 1.0f);
  config.tune_2partition_early_out_limit_factor = astc::max(config.tune_2partition_early_out_limit_factor, 0.0f);
  config.tune_3partition_early_out_limit_factor = astc::max(config.tune_3partition_early_out_limit_factor, 0.0f);
  config.tune_2plane_early_out_limit_correlation = astc::max(config.tune_2plane_early_out_limit_correlation, 0.0f);

  // Specifying a zero weight color component is not allowed; force to small value
  float max_weight = astc::max(astc::max(config.cw_r_weight, config.cw_g_weight),
                               astc::max(config.cw_b_weight, config.cw_a_weight));
  if (max_weight > 0.0f)
  {
    max_weight /= 1000.0f;
    config.cw_r_weight = astc::max(config.cw_r_weight, max_weight);
    config.cw_g_weight = astc::max(config.cw_g_weight, max_weight);
    config.cw_b_weight = astc::max(config.cw_b_weight, max_weight);
    config.cw_a_weight = astc::max(config.cw_a_weight, max_weight);
  }
  // If all color components error weights are zero then return an error
  else
  {
    return ASTCENC_ERR_BAD_PARAM;
  }

  return ASTCENC_SUCCESS;
}

/* See header for documentation. */
astcenc_error astcenc_config_init(
  astcenc_profile profile,
  unsigned int block_x,
  unsigned int block_y,
  unsigned int block_z,
  float quality,
  unsigned int flags,
  astcenc_config* configp
) {
  astcenc_error status;

  status = validate_cpu_float();
  if (status != ASTCENC_SUCCESS)
  {
    return status;
  }

  // Zero init all config fields; although most of will be over written
  astcenc_config& config = *configp;
  std::memset(&config, 0, sizeof(config));

  // Process the block size
  // For 2D blocks Z==0 is accepted, but convert to 1
  block_z = astc::max(block_z, 1u);
  status = validate_block_size(block_x, block_y, block_z);
  if (status != ASTCENC_SUCCESS)
  {
    return status;
  }

  config.block_x = block_x;
  config.block_y = block_y;
  config.block_z = block_z;

  float texels = static_cast<float>(block_x * block_y * block_z);
  float ltexels = logf(texels) / logf(10.0f);

  // Process the performance quality level or preset; note that this must be done before we
  // process any additional settings, such as color profile and flags, which may replace some of
  // these settings with more use case tuned values
  if (quality < ASTCENC_PRE_FASTEST ||
      quality > ASTCENC_PRE_EXHAUSTIVE)
  {
    return ASTCENC_ERR_BAD_QUALITY;
  }

  static const std::array<astcenc_preset_config, 6>* preset_configs;
  size_t texels_int = block_x * block_y * block_z;
  if (texels_int < 25)
  {
    preset_configs = &preset_configs_high;
  }
  else if (texels_int < 64)
  {
    preset_configs = &preset_configs_mid;
  }
  else
  {
    preset_configs = &preset_configs_low;
  }

  // Determine which preset to use, or which pair to interpolate
  size_t start;
  size_t end;
  for (end = 0; end < preset_configs->size(); end++)
  {
    if ((*preset_configs)[end].quality >= quality)
    {
      break;
    }
  }

  start = end == 0 ? 0 : end - 1;

  // Start and end node are the same - so just transfer the values.
  if (start == end)
  {
    config.tune_partition_count_limit = (*preset_configs)[start].tune_partition_count_limit;
    config.tune_2partition_index_limit = (*preset_configs)[start].tune_2partition_index_limit;
    config.tune_3partition_index_limit = (*preset_configs)[start].tune_3partition_index_limit;
    config.tune_4partition_index_limit = (*preset_configs)[start].tune_4partition_index_limit;
    config.tune_block_mode_limit = (*preset_configs)[start].tune_block_mode_limit;
    config.tune_refinement_limit = (*preset_configs)[start].tune_refinement_limit;
    config.tune_candidate_limit = (*preset_configs)[start].tune_candidate_limit;
    config.tune_2partitioning_candidate_limit = (*preset_configs)[start].tune_2partitioning_candidate_limit;
    config.tune_3partitioning_candidate_limit = (*preset_configs)[start].tune_3partitioning_candidate_limit;
    config.tune_4partitioning_candidate_limit = (*preset_configs)[start].tune_4partitioning_candidate_limit;
    config.tune_db_limit = astc::max((*preset_configs)[start].tune_db_limit_a_base - 35 * ltexels,
                                     (*preset_configs)[start].tune_db_limit_b_base - 19 * ltexels);

    config.tune_mse_overshoot = (*preset_configs)[start].tune_mse_overshoot;

    config.tune_2partition_early_out_limit_factor = (*preset_configs)[start].tune_2partition_early_out_limit_factor;
    config.tune_3partition_early_out_limit_factor = (*preset_configs)[start].tune_3partition_early_out_limit_factor;
    config.tune_2plane_early_out_limit_correlation = (*preset_configs)[start].tune_2plane_early_out_limit_correlation;
    config.tune_search_mode0_enable = (*preset_configs)[start].tune_search_mode0_enable;
  }
  // Start and end node are not the same - so interpolate between them
  else
  {
    auto& node_a = (*preset_configs)[start];
    auto& node_b = (*preset_configs)[end];

    float wt_range = node_b.quality - node_a.quality;
    assert(wt_range > 0);

    // Compute interpolation factors
    float wt_node_a = (node_b.quality - quality) / wt_range;
    float wt_node_b = (quality - node_a.quality) / wt_range;

    #define LERP(param) ((node_a.param * wt_node_a) + (node_b.param * wt_node_b))
    #define LERPI(param) astc::flt2int_rtn(\
                             (static_cast<float>(node_a.param) * wt_node_a) + \
                             (static_cast<float>(node_b.param) * wt_node_b))
    #define LERPUI(param) static_cast<unsigned int>(LERPI(param))

    config.tune_partition_count_limit = LERPI(tune_partition_count_limit);
    config.tune_2partition_index_limit = LERPI(tune_2partition_index_limit);
    config.tune_3partition_index_limit = LERPI(tune_3partition_index_limit);
    config.tune_4partition_index_limit = LERPI(tune_4partition_index_limit);
    config.tune_block_mode_limit = LERPI(tune_block_mode_limit);
    config.tune_refinement_limit = LERPI(tune_refinement_limit);
    config.tune_candidate_limit = LERPUI(tune_candidate_limit);
    config.tune_2partitioning_candidate_limit = LERPUI(tune_2partitioning_candidate_limit);
    config.tune_3partitioning_candidate_limit = LERPUI(tune_3partitioning_candidate_limit);
    config.tune_4partitioning_candidate_limit = LERPUI(tune_4partitioning_candidate_limit);
    config.tune_db_limit = astc::max(LERP(tune_db_limit_a_base) - 35 * ltexels,
                                     LERP(tune_db_limit_b_base) - 19 * ltexels);

    config.tune_mse_overshoot = LERP(tune_mse_overshoot);

    config.tune_2partition_early_out_limit_factor = LERP(tune_2partition_early_out_limit_factor);
    config.tune_3partition_early_out_limit_factor = LERP(tune_3partition_early_out_limit_factor);
    config.tune_2plane_early_out_limit_correlation = LERP(tune_2plane_early_out_limit_correlation);
    config.tune_search_mode0_enable = LERP(tune_search_mode0_enable);
    #undef LERP
    #undef LERPI
    #undef LERPUI
  }

  // Set heuristics to the defaults for each color profile
  config.cw_r_weight = 1.0f;
  config.cw_g_weight = 1.0f;
  config.cw_b_weight = 1.0f;
  config.cw_a_weight = 1.0f;

  config.a_scale_radius = 0;

  config.rgbm_m_scale = 0.0f;

  config.profile = profile;

  // Values in this enum are from an external user, so not guaranteed to be
  // bounded to the enum values
  switch (static_cast<int>(profile))
  {
  case ASTCENC_PRF_LDR:
  case ASTCENC_PRF_LDR_SRGB:
    break;
  case ASTCENC_PRF_HDR_RGB_LDR_A:
  case ASTCENC_PRF_HDR:
    config.tune_db_limit = 999.0f;
    config.tune_search_mode0_enable = 0.0f;
    break;
  default:
    return ASTCENC_ERR_BAD_PROFILE;
  }

  // Flags field must not contain any unknown flag bits
  status = validate_flags(profile, flags);
  if (status != ASTCENC_SUCCESS)
  {
    return status;
  }

  if (flags & ASTCENC_FLG_MAP_NORMAL)
  {
    // Normal map encoding uses L+A blocks, so allow one more partitioning
    // than normal. We need need fewer bits for endpoints, so more likely
    // to be able to use more partitions than an RGB/RGBA block
    config.tune_partition_count_limit = astc::min(config.tune_partition_count_limit + 1u, 4u);

    config.cw_g_weight = 0.0f;
    config.cw_b_weight = 0.0f;
    config.tune_2partition_early_out_limit_factor *= 1.5f;
    config.tune_3partition_early_out_limit_factor *= 1.5f;
    config.tune_2plane_early_out_limit_correlation = 0.99f;

    // Normals are prone to blocking artifacts on smooth curves
    // so force compressor to try harder here ...
    config.tune_db_limit *= 1.03f;
  }
  else if (flags & ASTCENC_FLG_MAP_RGBM)
  {
    config.rgbm_m_scale = 5.0f;
    config.cw_a_weight = 2.0f * config.rgbm_m_scale;
  }
  else // (This is color data)
  {
    // This is a very basic perceptual metric for RGB color data, which weights error
    // significance by the perceptual luminance contribution of each color channel. For
    // luminance the usual weights to compute luminance from a linear RGB value are as
    // follows:
    //
    //     l = r * 0.3 + g * 0.59 + b * 0.11
    //
    // ... but we scale these up to keep a better balance between color and alpha. Note
    // that if the content is using alpha we'd recommend using the -a option to weight
    // the color contribution by the alpha transparency.
    if (flags & ASTCENC_FLG_USE_PERCEPTUAL)
    {
      config.cw_r_weight = 0.30f * 2.25f;
      config.cw_g_weight = 0.59f * 2.25f;
      config.cw_b_weight = 0.11f * 2.25f;
    }
  }
  config.flags = flags;

  return ASTCENC_SUCCESS;
}

/* See header for documentation. */
astcenc_error astcenc_context_alloc(
  const astcenc_config* configp,
  unsigned int thread_count,
  astcenc_context** context,
  const astcenc_context* parent_context
) {
  astcenc_error status;

  status = validate_cpu_float();
  if (status != ASTCENC_SUCCESS)
  {
    return status;
  }

  if (thread_count == 0)
  {
    return ASTCENC_ERR_BAD_PARAM;
  }

#if defined(ASTCENC_DIAGNOSTICS)
  // Force single threaded compressor use in diagnostic mode
  if (thread_count != 1)
  {
    return ASTCENC_ERR_BAD_PARAM;
  }
#endif

  // Exactly one of config or parent_context must be set
  bool has_config = configp != nullptr;
  bool has_parent = parent_context != nullptr;
  if (!(has_config ^ has_parent))
  {
    return ASTCENC_ERR_BAD_PARAM;
  }

  if (has_parent)
  {
    configp = &parent_context->context.config;
  }

  const astcenc_config& config = *configp;
  astcenc_context* ctxo = new astcenc_context;
  astcenc_contexti* ctx = &ctxo->context;
  ctx->thread_count = thread_count;
  ctx->config = *configp;
  ctx->working_buffers = nullptr;

  // These are allocated per-compress, as they depend on image size
  ctx->input_alpha_averages = nullptr;

  // Copy the config first and validate the copy (we may modify it)
  status = validate_config(ctx->config);
  if (status != ASTCENC_SUCCESS)
  {
    delete ctxo;
    return status;
  }

  if (!parent_context)
  {
    block_size_descriptor* bsd = aligned_malloc<block_size_descriptor>(sizeof(block_size_descriptor), ASTCENC_VECALIGN);
    if (!bsd)
    {
      delete ctxo;
      return ASTCENC_ERR_OUT_OF_MEM;
    }

    bool can_omit_modes = static_cast<bool>(config.flags & ASTCENC_FLG_SELF_DECOMPRESS_ONLY);
    init_block_size_descriptor(config.block_x, config.block_y, config.block_z,
                               can_omit_modes,
                               config.tune_partition_count_limit,
                               static_cast<float>(config.tune_block_mode_limit) / 100.0f,
                               *bsd);

    ctx->owns_bsd = true;
    ctx->bsd = bsd;
  }
  else
  {
    ctx->owns_bsd = false;
    ctx->bsd = parent_context->context.bsd;
  }

#if !defined(ASTCENC_DECOMPRESS_ONLY)
  // Do setup only needed by compression
  if (!(ctx->config.flags & ASTCENC_FLG_DECOMPRESS_ONLY))
  {
    // Turn a dB limit into a per-texel error for faster use later
    if ((ctx->config.profile == ASTCENC_PRF_LDR) || (ctx->config.profile == ASTCENC_PRF_LDR_SRGB))
    {
      ctx->config.tune_db_limit = astc::pow(0.1f, ctx->config.tune_db_limit * 0.1f) * 65535.0f * 65535.0f;
    }
    else
    {
      ctx->config.tune_db_limit = 0.0f;
    }

    size_t worksize = sizeof(compression_working_buffers) * thread_count;
    ctx->working_buffers = aligned_malloc<compression_working_buffers>(worksize, ASTCENC_VECALIGN);
    static_assert((ASTCENC_VECALIGN == 0) || ((sizeof(compression_working_buffers) % ASTCENC_VECALIGN) == 0),
                  "compression_working_buffers size must be multiple of vector alignment");
    if (!ctx->working_buffers)
    {
      if (ctx->owns_bsd)
      {
        aligned_free<const block_size_descriptor>(ctx->bsd);
      }
      delete ctxo;
      *context = nullptr;
      return ASTCENC_ERR_OUT_OF_MEM;
    }
  }
#endif

#if defined(ASTCENC_DIAGNOSTICS)
  ctx->trace_log = new TraceLog(ctx->config.trace_file_path);
  if (!ctx->trace_log->m_file)
  {
    return ASTCENC_ERR_DTRACE_FAILURE;
  }

  trace_add_data("block_x", config.block_x);
  trace_add_data("block_y", config.block_y);
  trace_add_data("block_z", config.block_z);
#endif

  *context = ctxo;

#if !defined(ASTCENC_DECOMPRESS_ONLY)
  prepare_angular_tables();
#endif

  return ASTCENC_SUCCESS;
}

/* See header for documentation. */
void astcenc_context_free(
  astcenc_context* ctxo
) {
  if (ctxo)
  {
    astcenc_contexti* ctx = &ctxo->context;
    aligned_free<compression_working_buffers>(ctx->working_buffers);
    if (ctx->owns_bsd)
    {
      aligned_free<const block_size_descriptor>(ctx->bsd);
    }
#if defined(ASTCENC_DIAGNOSTICS)
    delete ctx->trace_log;
#endif
    delete ctxo;
  }
}

#if !defined(ASTCENC_DECOMPRESS_ONLY)

/**
 * @brief Compress an image, after any preflight has completed.
 *
 * @param[out] ctxo           The compressor context.
 * @param      thread_index   The thread index.
 * @param      image          The input image.
 * @param      swizzle        The input swizzle.
 * @param[out] buffer         The output array for the compressed data.
 */
static void compress_image(
  astcenc_context& ctxo,
  unsigned int thread_index,
  const astcenc_image& image,
  const astcenc_swizzle& swizzle,
  uint8_t* buffer
) {
  astcenc_contexti& ctx = ctxo.context;
  const block_size_descriptor& bsd = *ctx.bsd;
  astcenc_profile decode_mode = ctx.config.profile;

  image_block blk;

  size_t block_x = bsd.dim_x;
  size_t block_y = bsd.dim_y;
  size_t block_z = bsd.dim_z;
  blk.texel_count = static_cast<uint8_t>(block_x * block_y * block_z);

  size_t dim_x = image.dim_x;
  size_t dim_y = image.dim_y;
  size_t dim_z = image.dim_z;

  size_t blocks_x = astc::get_block_count_safe(dim_x, block_x);
  size_t blocks_y = astc::get_block_count_safe(dim_y, block_y);
  size_t blocks_z = astc::get_block_count_safe(dim_z, block_z);

  size_t block_count = get_blocks_count(blocks_x, blocks_y, blocks_z);
  // Should never fail here - tested in caller before calling here
  assert(block_count > 0);


  size_t row_blocks = blocks_x;
  size_t plane_blocks = blocks_x * blocks_y;

  blk.decode_unorm8 = ctxo.context.config.flags & ASTCENC_FLG_USE_DECODE_UNORM8;

  // Populate the block channel weights
  blk.channel_weight = vfloat4(ctx.config.cw_r_weight,
                               ctx.config.cw_g_weight,
                               ctx.config.cw_b_weight,
                               ctx.config.cw_a_weight);

  // Use preallocated scratch buffer
  auto& temp_buffers = ctx.working_buffers[thread_index];

  // Only the first thread actually runs the initializer
  ctxo.manage_compress.init(block_count, ctx.config.progress_callback);

  // Determine if we can use an optimized load function
  bool needs_swz = (swizzle.r != ASTCENC_SWZ_R) || (swizzle.g != ASTCENC_SWZ_G) ||
                   (swizzle.b != ASTCENC_SWZ_B) || (swizzle.a != ASTCENC_SWZ_A);

  bool needs_hdr = (decode_mode == ASTCENC_PRF_HDR) ||
                   (decode_mode == ASTCENC_PRF_HDR_RGB_LDR_A);

  bool use_fast_load = !needs_swz && !needs_hdr &&
                       block_z == 1 && image.data_type == ASTCENC_TYPE_U8;

  auto load_func = load_image_block;
  if (use_fast_load)
  {
    load_func = load_image_block_fast_ldr;
  }

  // All threads run this processing loop until there is no work remaining
  while (true)
  {
    size_t count;
    size_t base = ctxo.manage_compress.get_task_assignment(16, count);
    if (!count)
    {
      break;
    }

    for (size_t i = base; i < base + count; i++)
    {
      // Decode i into x, y, z block indices
      size_t z = i / plane_blocks;
      size_t rem = i - (z * plane_blocks);
      size_t y = rem / row_blocks;
      size_t x = rem - (y * row_blocks);

      // Test if we can apply some basic alpha-scale RDO
      bool use_full_block = true;
      if (ctx.config.a_scale_radius != 0 && block_z == 1)
      {
        size_t start_x = x * block_x;
        size_t end_x = astc::min(dim_x, start_x + block_x);

        size_t start_y = y * block_y;
        size_t end_y = astc::min(dim_y, start_y + block_y);

        // SATs accumulate error, so don't test exactly zero. Test for
        // less than 1 alpha in the expanded block footprint that
        // includes the alpha radius.
        size_t x_footprint = block_x + 2 * (ctx.config.a_scale_radius - 1);
        size_t y_footprint = block_y + 2 * (ctx.config.a_scale_radius - 1);

        float footprint = static_cast<float>(x_footprint * y_footprint);
        float threshold = 0.9f / (255.0f * footprint);

        // Do we have any alpha values?
        use_full_block = false;
        for (size_t ay = start_y; ay < end_y; ay++)
        {
          for (size_t ax = start_x; ax < end_x; ax++)
          {
            float a_avg = ctx.input_alpha_averages[ay * dim_x + ax];
            if (a_avg > threshold)
            {
              use_full_block = true;
              ax = end_x;
              ay = end_y;
            }
          }
        }
      }

      // Fetch the full block for compression
      if (use_full_block)
      {
        load_func(decode_mode, image, blk, bsd, x * block_x, y * block_y, z * block_z, swizzle);

        // Scale RGB error contribution by the maximum alpha in the block
        // This encourages preserving alpha accuracy in regions with high
        // transparency, and can buy up to 0.5 dB PSNR.
        if (ctx.config.flags & ASTCENC_FLG_USE_ALPHA_WEIGHT)
        {
          float alpha_scale = blk.data_max.lane<3>() * (1.0f / 65535.0f);
          blk.channel_weight = vfloat4(ctx.config.cw_r_weight * alpha_scale,
                                       ctx.config.cw_g_weight * alpha_scale,
                                       ctx.config.cw_b_weight * alpha_scale,
                                       ctx.config.cw_a_weight);
        }
      }
      // Apply alpha scale RDO - substitute constant color block
      else
      {
        blk.origin_texel = vfloat4::zero();
        blk.data_min = vfloat4::zero();
        blk.data_mean = vfloat4::zero();
        blk.data_max = vfloat4::zero();
        blk.grayscale = true;
      }

      size_t offset = ((z * blocks_y + y) * blocks_x + x) * 16;
      uint8_t *bp = buffer + offset;
      compress_block(ctx, blk, bp, temp_buffers);
    }

    ctxo.manage_compress.complete_task_assignment(count);
  }
}

/**
 * @brief Compute regional averages in an image.
 *
 * This function can be called by multiple threads, but only after a single
 * thread calls the setup function @c init_compute_averages().
 *
 * Results are written back into @c img->input_alpha_averages.
 *
 * @param[out] ctx   The context.
 * @param      ag    The average and variance arguments created during setup.
 */
static void compute_averages(
  astcenc_context& ctx,
  const avg_args &ag
) {
  pixel_region_args arg = ag.arg;
  arg.work_memory = new vfloat4[ag.work_memory_size];

  size_t size_x = ag.img_size_x;
  size_t size_y = ag.img_size_y;
  size_t size_z = ag.img_size_z;

  size_t step_xy = ag.blk_size_xy;
  size_t step_z = ag.blk_size_z;

  size_t tasks_y = (size_y + step_xy - 1) / step_xy;

  // All threads run this processing loop until there is no work remaining
  while (true)
  {
    size_t count;
    size_t base = ctx.manage_avg.get_task_assignment(16, count);
    if (!count)
    {
      break;
    }

    for (size_t i = base; i < base + count; i++)
    {
      size_t z_task = i / tasks_y;
      size_t y_task = i - (z_task * tasks_y);

      size_t z = z_task * step_z;
      size_t y = y_task * step_xy;

      arg.size_z = astc::min(step_z, size_z - z);
      arg.offset_z = z;

      arg.size_y = astc::min(step_xy, size_y - y);
      arg.offset_y = y;

      for (size_t x = 0; x < size_x; x += step_xy)
      {
        arg.size_x = astc::min(step_xy, size_x - x);
        arg.offset_x = x;
        compute_pixel_region_variance(ctx.context, arg);
      }
    }

    ctx.manage_avg.complete_task_assignment(count);
  }

  delete[] arg.work_memory;
}

#endif

/* See header for documentation. */
astcenc_error astcenc_compress_image(
  astcenc_context* ctxo,
  astcenc_image* imagep,
  const astcenc_swizzle* swizzle,
  uint8_t* data_out,
  size_t data_len,
  unsigned int thread_index
) {
#if defined(ASTCENC_DECOMPRESS_ONLY)
  (void)ctxo;
  (void)imagep;
  (void)swizzle;
  (void)data_out;
  (void)data_len;
  (void)thread_index;
  return ASTCENC_ERR_BAD_CONTEXT;
#else
  astcenc_contexti* ctx = &ctxo->context;
  astcenc_error status;
  astcenc_image& image = *imagep;

  if (ctx->config.flags & ASTCENC_FLG_DECOMPRESS_ONLY)
  {
    return ASTCENC_ERR_BAD_CONTEXT;
  }

  status = validate_compression_swizzle(*swizzle);
  if (status != ASTCENC_SUCCESS)
  {
    return status;
  }

  if (thread_index >= ctx->thread_count)
  {
    return ASTCENC_ERR_BAD_PARAM;
  }

  size_t dim_x = image.dim_x;
  size_t dim_y = image.dim_y;
  size_t dim_z = image.dim_z;

  size_t texel_count = get_texels_count(dim_x, dim_y, dim_z);
  // Cumulative texel sizes would overflow a size_t
  if (texel_count == 0)
  {
    return ASTCENC_ERR_BAD_PARAM;
  }

  size_t block_x = ctx->config.block_x;
  size_t block_y = ctx->config.block_y;
  size_t block_z = ctx->config.block_z;

  size_t blocks_x = astc::get_block_count_safe(dim_x, block_x);
  size_t blocks_y = astc::get_block_count_safe(dim_y, block_y);
  size_t blocks_z = astc::get_block_count_safe(dim_z, block_z);

  size_t block_count = get_blocks_count(blocks_x, blocks_y, blocks_z);
  // Cumulative block sizes would overflow a size_t
  if (block_count == 0)
  {
    return ASTCENC_ERR_BAD_PARAM;
  }

  // Check we have enough output space, size_needed calc cannot overflow as
  // get_blocks_count() already validated that a byte count would fit
  size_t size_needed = block_count * 16;
  if (data_len < size_needed)
  {
    return ASTCENC_ERR_OUT_OF_MEM;
  }

  // If context thread count is one then implicitly reset
  if (ctx->thread_count == 1)
  {
    astcenc_compress_reset(ctxo);
  }

  if (ctx->config.a_scale_radius != 0)
  {
    // First thread to enter will do setup, other threads will subsequently
    // enter the critical section but simply skip over the initialization
    auto init_avg = [ctx, &image, swizzle, texel_count]() {
      // Perform memory allocations for the destination buffers
      ctx->input_alpha_averages = new float[texel_count];

      return init_compute_averages(
        image, ctx->config.a_scale_radius, *swizzle,
        ctx->avg_preprocess_args);
    };

    // Only the first thread actually runs the initializer
    ctxo->manage_avg.init(init_avg);

    // All threads will enter this function and dynamically grab work
    compute_averages(*ctxo, ctx->avg_preprocess_args);
  }

  // Wait for compute_averages to complete before compressing
  ctxo->manage_avg.wait();

  compress_image(*ctxo, thread_index, image, *swizzle, data_out);

  // Wait for compress to complete before freeing memory
  ctxo->manage_compress.wait();

  auto term_compress = [ctx]() {
    delete[] ctx->input_alpha_averages;
    ctx->input_alpha_averages = nullptr;
  };

  // Only the first thread to arrive actually runs the term
  ctxo->manage_compress.term(term_compress);

  return ASTCENC_SUCCESS;
#endif
}

/* See header for documentation. */
astcenc_error astcenc_compress_reset(
  astcenc_context* ctxo
) {
#if defined(ASTCENC_DECOMPRESS_ONLY)
  (void)ctxo;
  return ASTCENC_ERR_BAD_CONTEXT;
#else
  astcenc_contexti* ctx = &ctxo->context;
  if (ctx->config.flags & ASTCENC_FLG_DECOMPRESS_ONLY)
  {
    return ASTCENC_ERR_BAD_CONTEXT;
  }

  ctxo->manage_avg.reset();
  ctxo->manage_compress.reset();
  return ASTCENC_SUCCESS;
#endif
}

/* See header for documentation. */
astcenc_error astcenc_compress_cancel(
  astcenc_context* ctxo
) {
#if defined(ASTCENC_DECOMPRESS_ONLY)
  (void)ctxo;
  return ASTCENC_ERR_BAD_CONTEXT;
#else
  astcenc_contexti* ctx = &ctxo->context;
  if (ctx->config.flags & ASTCENC_FLG_DECOMPRESS_ONLY)
  {
    return ASTCENC_ERR_BAD_CONTEXT;
  }

  // Cancel compression before cancelling avg. This avoids the race condition
  // where cancelling them in the other order could see a compression worker
  // starting to process even though some of the avg data is undefined.
  ctxo->manage_compress.cancel();
  ctxo->manage_avg.cancel();
  return ASTCENC_SUCCESS;
#endif
}

/* See header for documentation. */
astcenc_error astcenc_decompress_image(
  astcenc_context* ctxo,
  const uint8_t* data,
  size_t data_len,
  astcenc_image* image_outp,
  const astcenc_swizzle* swizzle,
  unsigned int thread_index
) {
  astcenc_error status;
  astcenc_image& image_out = *image_outp;
  astcenc_contexti* ctx = &ctxo->context;

  // Today this doesn't matter (working set on stack) but might in future ...
  if (thread_index >= ctx->thread_count)
  {
    return ASTCENC_ERR_BAD_PARAM;
  }

  status = validate_decompression_swizzle(*swizzle);
  if (status != ASTCENC_SUCCESS)
  {
    return status;
  }

  size_t dim_x = image_out.dim_x;
  size_t dim_y = image_out.dim_y;
  size_t dim_z = image_out.dim_z;

  size_t texel_count = get_texels_count(dim_x, dim_y, dim_z);
  // Cumulative texel sizes would overflow a size_t
  if (texel_count == 0)
  {
    return ASTCENC_ERR_BAD_PARAM;
  }

  size_t block_x = ctx->config.block_x;
  size_t block_y = ctx->config.block_y;
  size_t block_z = ctx->config.block_z;

  size_t blocks_x = astc::get_block_count_safe(dim_x, block_x);
  size_t blocks_y = astc::get_block_count_safe(dim_y, block_y);
  size_t blocks_z = astc::get_block_count_safe(dim_z, block_z);

  size_t block_count = get_blocks_count(blocks_x, blocks_y, blocks_z);
  // Cumulative block sizes would overflow a size_t
  if (block_count == 0)
  {
    return ASTCENC_ERR_BAD_PARAM;
  }

  // Check we have enough output space, size_needed calc cannot overflow as
  // get_blocks_count() already validated that a byte count would fit
  size_t size_needed = block_count * 16;
  if (data_len < size_needed)
  {
    return ASTCENC_ERR_OUT_OF_MEM;
  }

  size_t row_blocks = blocks_x;
  size_t plane_blocks = blocks_x * blocks_y;

  image_block blk {};
  blk.texel_count = static_cast<uint8_t>(block_x * block_y * block_z);

  // Decode mode inferred from the output data type
  blk.decode_unorm8 = image_out.data_type == ASTCENC_TYPE_U8;

  // If context thread count is one then implicitly reset
  if (ctx->thread_count == 1)
  {
    astcenc_decompress_reset(ctxo);
  }

  // Only the first thread actually runs the initializer
  ctxo->manage_decompress.init(block_count, nullptr);

  // All threads run this processing loop until there is no work remaining
  while (true)
  {
    size_t count;
    size_t base = ctxo->manage_decompress.get_task_assignment(128, count);
    if (!count)
    {
      break;
    }

    for (size_t i = base; i < base + count; i++)
    {
      // Decode i into x, y, z block indices
      size_t z = i / plane_blocks;
      size_t rem = i - (z * plane_blocks);
      size_t y = rem / row_blocks;
      size_t x = rem - (y * row_blocks);

      size_t offset = (((z * blocks_y + y) * blocks_x) + x) * 16;
      const uint8_t* bp = data + offset;

      symbolic_compressed_block scb;

      physical_to_symbolic(*ctx->bsd, bp, scb);

      decompress_symbolic_block(ctx->config.profile, *ctx->bsd,
                                x * block_x,
                                y * block_y,
                                z * block_z,
                                scb, blk);

      store_image_block(image_out, blk, *ctx->bsd,
                        x * block_x, y * block_y, z * block_z,
                        *swizzle);
    }

    ctxo->manage_decompress.complete_task_assignment(count);
  }

  return ASTCENC_SUCCESS;
}

/* See header for documentation. */
astcenc_error astcenc_decompress_reset(
  astcenc_context* ctxo
) {
  ctxo->manage_decompress.reset();
  return ASTCENC_SUCCESS;
}

/* See header for documentation. */
astcenc_error astcenc_get_block_info(
  astcenc_context* ctxo,
  const uint8_t data[16],
  astcenc_block_info* info
) {
#if defined(ASTCENC_DECOMPRESS_ONLY)
  (void)ctxo;
  (void)data;
  (void)info;
  return ASTCENC_ERR_BAD_CONTEXT;
#else
  astcenc_contexti* ctx = &ctxo->context;

  // Decode the compressed data into a symbolic form
  symbolic_compressed_block scb;
  physical_to_symbolic(*ctx->bsd, data, scb);

  // Fetch the appropriate partition and decimation tables
  const block_size_descriptor& bsd = *ctx->bsd;

  // Start from a clean slate
  memset(info, 0, sizeof(*info));

  // Basic info we can always populate
  info->profile = ctx->config.profile;

  info->block_x = ctx->config.block_x;
  info->block_y = ctx->config.block_y;
  info->block_z = ctx->config.block_z;
  info->texel_count = bsd.texel_count;

  // Check for error blocks first
  info->is_error_block = scb.block_type == SYM_BTYPE_ERROR;
  if (info->is_error_block)
  {
    return ASTCENC_SUCCESS;
  }

  // Check for constant color blocks second
  info->is_constant_block = scb.block_type == SYM_BTYPE_CONST_F16 ||
                            scb.block_type == SYM_BTYPE_CONST_U16;
  if (info->is_constant_block)
  {
    return ASTCENC_SUCCESS;
  }

  // Otherwise handle a full block ; known to be valid after conditions above have been checked
  unsigned int partition_count = scb.partition_count;
  const auto& pi = bsd.get_partition_info(partition_count, scb.partition_index);

  const block_mode& bm = bsd.get_block_mode(scb.block_mode);
  const decimation_info& di = bsd.get_decimation_info(bm.decimation_mode);

  info->weight_x = di.weight_x;
  info->weight_y = di.weight_y;
  info->weight_z = di.weight_z;

  info->is_dual_plane_block = bm.is_dual_plane != 0;

  info->partition_count = scb.partition_count;
  info->partition_index = scb.partition_index;
  info->dual_plane_component = scb.plane2_component;

  info->color_level_count = get_quant_level(scb.get_color_quant_mode());
  info->weight_level_count = get_quant_level(bm.get_weight_quant_mode());

  // Unpack color endpoints for each active partition
  for (size_t i = 0; i < scb.partition_count; i++)
  {
    bool rgb_hdr;
    bool a_hdr;
    vint4 endpnt[2];

    unpack_color_endpoints(ctx->config.profile,
                           scb.color_formats[i],
                           scb.color_values[i],
                           rgb_hdr, a_hdr,
                           endpnt[0], endpnt[1]);

    // Store the color endpoint mode info
    info->color_endpoint_modes[i] = scb.color_formats[i];
    info->is_hdr_block = info->is_hdr_block || rgb_hdr || a_hdr;

    // Store the unpacked and decoded color endpoint
    vmask4 hdr_mask(rgb_hdr, rgb_hdr, rgb_hdr, a_hdr);
    for (size_t j = 0; j < 2; j++)
    {
      vint4 color_lns = lns_to_sf16(endpnt[j]);
      vint4 color_unorm = unorm16_to_sf16(endpnt[j]);
      vint4 datai = select(color_unorm, color_lns, hdr_mask);
      store(float16_to_float(datai), info->color_endpoints[i][j]);
    }
  }

  // Unpack weights for each texel
  int weight_plane1[BLOCK_MAX_TEXELS];
  int weight_plane2[BLOCK_MAX_TEXELS];

  unpack_weights(bsd, scb, di, bm.is_dual_plane, weight_plane1, weight_plane2);
  for (size_t i = 0; i < bsd.texel_count; i++)
  {
    info->weight_values_plane1[i] = static_cast<float>(weight_plane1[i]) * (1.0f / WEIGHTS_TEXEL_SUM);
    if (info->is_dual_plane_block)
    {
      info->weight_values_plane2[i] = static_cast<float>(weight_plane2[i]) * (1.0f / WEIGHTS_TEXEL_SUM);
    }
  }

  // Unpack partition assignments for each texel
  for (size_t i = 0; i < bsd.texel_count; i++)
  {
    info->partition_assignment[i] = pi.partition_of_texel[i];
  }

  return ASTCENC_SUCCESS;
#endif
}

/* See header for documentation. */
const char* astcenc_get_error_string(
  astcenc_error status
) {
  // Values in this enum are from an external user, so not guaranteed to be
  // bounded to the enum values
  switch (static_cast<int>(status))
  {
  case ASTCENC_SUCCESS:
    return "ASTCENC_SUCCESS";
  case ASTCENC_ERR_OUT_OF_MEM:
    return "ASTCENC_ERR_OUT_OF_MEM";
  case ASTCENC_ERR_BAD_CPU_FLOAT:
    return "ASTCENC_ERR_BAD_CPU_FLOAT";
  case ASTCENC_ERR_BAD_PARAM:
    return "ASTCENC_ERR_BAD_PARAM";
  case ASTCENC_ERR_BAD_BLOCK_SIZE:
    return "ASTCENC_ERR_BAD_BLOCK_SIZE";
  case ASTCENC_ERR_BAD_PROFILE:
    return "ASTCENC_ERR_BAD_PROFILE";
  case ASTCENC_ERR_BAD_QUALITY:
    return "ASTCENC_ERR_BAD_QUALITY";
  case ASTCENC_ERR_BAD_FLAGS:
    return "ASTCENC_ERR_BAD_FLAGS";
  case ASTCENC_ERR_BAD_SWIZZLE:
    return "ASTCENC_ERR_BAD_SWIZZLE";
  case ASTCENC_ERR_BAD_CONTEXT:
    return "ASTCENC_ERR_BAD_CONTEXT";
  case ASTCENC_ERR_NOT_IMPLEMENTED:
    return "ASTCENC_ERR_NOT_IMPLEMENTED";
  case ASTCENC_ERR_BAD_DECODE_MODE:
    return "ASTCENC_ERR_BAD_DECODE_MODE";
#if defined(ASTCENC_DIAGNOSTICS)
  case ASTCENC_ERR_DTRACE_FAILURE:
    return "ASTCENC_ERR_DTRACE_FAILURE";
#endif
  default:
    return nullptr;
  }
}

Coverage Report

Created: 2026-06-04 06:52