godot/thirdparty/astcenc/astcenc_partition_tables.cpp
K. S. Ernest (iFire) Lee 696346f4cc
Add ASTC compression and decompression with Arm astcenc.
Co-authored-by: Gordon A Macpherson <gordon.a.macpherson@gmail.com>
Co-authored-by: Rémi Verschelde <rverschelde@gmail.com>
2023-01-19 16:27:59 +01:00

482 lines
13 KiB
C++

// SPDX-License-Identifier: Apache-2.0
// ----------------------------------------------------------------------------
// Copyright 2011-2023 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 generating partition tables on demand.
*/
#include "astcenc_internal.h"
/** @brief The number of 64-bit words needed to represent a canonical partition bit pattern. */
#define BIT_PATTERN_WORDS (((ASTCENC_BLOCK_MAX_TEXELS * 2) + 63) / 64)
/**
* @brief Generate a canonical representation of a partition pattern.
*
* The returned value stores two bits per texel, for up to 6x6x6 texels, where the two bits store
* the remapped texel index. Remapping ensures that we only match on the partition pattern,
* independent of the partition order generated by the hash.
*
* @param texel_count The number of texels in the block.
* @param partition_of_texel The partition assignments, in hash order.
* @param[out] bit_pattern The output bit pattern representation.
*/
static void generate_canonical_partitioning(
unsigned int texel_count,
const uint8_t* partition_of_texel,
uint64_t bit_pattern[BIT_PATTERN_WORDS]
) {
// Clear the pattern
for (unsigned int i = 0; i < BIT_PATTERN_WORDS; i++)
{
bit_pattern[i] = 0;
}
// Store a mapping to reorder the raw partitions so that the partitions are ordered such
// that the lowest texel index in partition N is smaller than the lowest texel index in
// partition N + 1.
int mapped_index[BLOCK_MAX_PARTITIONS];
int map_weight_count = 0;
for (unsigned int i = 0; i < BLOCK_MAX_PARTITIONS; i++)
{
mapped_index[i] = -1;
}
for (unsigned int i = 0; i < texel_count; i++)
{
int index = partition_of_texel[i];
if (mapped_index[index] < 0)
{
mapped_index[index] = map_weight_count++;
}
uint64_t xlat_index = mapped_index[index];
bit_pattern[i >> 5] |= xlat_index << (2 * (i & 0x1F));
}
}
/**
* @brief Compare two canonical patterns to see if they are the same.
*
* @param part1 The first canonical bit pattern to check.
* @param part2 The second canonical bit pattern to check.
*
* @return @c true if the patterns are the same, @c false otherwise.
*/
static bool compare_canonical_partitionings(
const uint64_t part1[BIT_PATTERN_WORDS],
const uint64_t part2[BIT_PATTERN_WORDS]
) {
return (part1[0] == part2[0])
#if BIT_PATTERN_WORDS > 1
&& (part1[1] == part2[1])
#endif
#if BIT_PATTERN_WORDS > 2
&& (part1[2] == part2[2])
#endif
#if BIT_PATTERN_WORDS > 3
&& (part1[3] == part2[3])
#endif
#if BIT_PATTERN_WORDS > 4
&& (part1[4] == part2[4])
#endif
#if BIT_PATTERN_WORDS > 5
&& (part1[5] == part2[5])
#endif
#if BIT_PATTERN_WORDS > 6
&& (part1[6] == part2[6])
#endif
;
}
/**
* @brief Hash function used for procedural partition assignment.
*
* @param inp The hash seed.
*
* @return The hashed value.
*/
static uint32_t hash52(
uint32_t inp
) {
inp ^= inp >> 15;
// (2^4 + 1) * (2^7 + 1) * (2^17 - 1)
inp *= 0xEEDE0891;
inp ^= inp >> 5;
inp += inp << 16;
inp ^= inp >> 7;
inp ^= inp >> 3;
inp ^= inp << 6;
inp ^= inp >> 17;
return inp;
}
/**
* @brief Select texel assignment for a single coordinate.
*
* @param seed The seed - the partition index from the block.
* @param x The texel X coordinate in the block.
* @param y The texel Y coordinate in the block.
* @param z The texel Z coordinate in the block.
* @param partition_count The total partition count of this encoding.
* @param small_block @c true if the block has fewer than 32 texels.
*
* @return The assigned partition index for this texel.
*/
static uint8_t select_partition(
int seed,
int x,
int y,
int z,
int partition_count,
bool small_block
) {
// For small blocks bias the coordinates to get better distribution
if (small_block)
{
x <<= 1;
y <<= 1;
z <<= 1;
}
seed += (partition_count - 1) * 1024;
uint32_t rnum = hash52(seed);
uint8_t seed1 = rnum & 0xF;
uint8_t seed2 = (rnum >> 4) & 0xF;
uint8_t seed3 = (rnum >> 8) & 0xF;
uint8_t seed4 = (rnum >> 12) & 0xF;
uint8_t seed5 = (rnum >> 16) & 0xF;
uint8_t seed6 = (rnum >> 20) & 0xF;
uint8_t seed7 = (rnum >> 24) & 0xF;
uint8_t seed8 = (rnum >> 28) & 0xF;
uint8_t seed9 = (rnum >> 18) & 0xF;
uint8_t seed10 = (rnum >> 22) & 0xF;
uint8_t seed11 = (rnum >> 26) & 0xF;
uint8_t seed12 = ((rnum >> 30) | (rnum << 2)) & 0xF;
// Squaring all the seeds in order to bias their distribution towards lower values.
seed1 *= seed1;
seed2 *= seed2;
seed3 *= seed3;
seed4 *= seed4;
seed5 *= seed5;
seed6 *= seed6;
seed7 *= seed7;
seed8 *= seed8;
seed9 *= seed9;
seed10 *= seed10;
seed11 *= seed11;
seed12 *= seed12;
int sh1, sh2;
if (seed & 1)
{
sh1 = (seed & 2 ? 4 : 5);
sh2 = (partition_count == 3 ? 6 : 5);
}
else
{
sh1 = (partition_count == 3 ? 6 : 5);
sh2 = (seed & 2 ? 4 : 5);
}
int sh3 = (seed & 0x10) ? sh1 : sh2;
seed1 >>= sh1;
seed2 >>= sh2;
seed3 >>= sh1;
seed4 >>= sh2;
seed5 >>= sh1;
seed6 >>= sh2;
seed7 >>= sh1;
seed8 >>= sh2;
seed9 >>= sh3;
seed10 >>= sh3;
seed11 >>= sh3;
seed12 >>= sh3;
int a = seed1 * x + seed2 * y + seed11 * z + (rnum >> 14);
int b = seed3 * x + seed4 * y + seed12 * z + (rnum >> 10);
int c = seed5 * x + seed6 * y + seed9 * z + (rnum >> 6);
int d = seed7 * x + seed8 * y + seed10 * z + (rnum >> 2);
// Apply the saw
a &= 0x3F;
b &= 0x3F;
c &= 0x3F;
d &= 0x3F;
// Remove some of the components if we are to output < 4 partitions.
if (partition_count <= 3)
{
d = 0;
}
if (partition_count <= 2)
{
c = 0;
}
if (partition_count <= 1)
{
b = 0;
}
uint8_t partition;
if (a >= b && a >= c && a >= d)
{
partition = 0;
}
else if (b >= c && b >= d)
{
partition = 1;
}
else if (c >= d)
{
partition = 2;
}
else
{
partition = 3;
}
return partition;
}
/**
* @brief Generate a single partition info structure.
*
* @param[out] bsd The block size information.
* @param partition_count The partition count of this partitioning.
* @param partition_index The partition index / seed of this partitioning.
* @param partition_remap_index The remapped partition index of this partitioning.
* @param[out] pi The partition info structure to populate.
*
* @return True if this is a useful partition index, False if we can skip it.
*/
static bool generate_one_partition_info_entry(
block_size_descriptor& bsd,
unsigned int partition_count,
unsigned int partition_index,
unsigned int partition_remap_index,
partition_info& pi
) {
int texels_per_block = bsd.texel_count;
bool small_block = texels_per_block < 32;
uint8_t *partition_of_texel = pi.partition_of_texel;
// Assign texels to partitions
int texel_idx = 0;
int counts[BLOCK_MAX_PARTITIONS] { 0 };
for (unsigned int z = 0; z < bsd.zdim; z++)
{
for (unsigned int y = 0; y < bsd.ydim; y++)
{
for (unsigned int x = 0; x < bsd.xdim; x++)
{
uint8_t part = select_partition(partition_index, x, y, z, partition_count, small_block);
pi.texels_of_partition[part][counts[part]++] = static_cast<uint8_t>(texel_idx++);
*partition_of_texel++ = part;
}
}
}
// Fill loop tail so we can overfetch later
for (unsigned int i = 0; i < partition_count; i++)
{
int ptex_count = counts[i];
int ptex_count_simd = round_up_to_simd_multiple_vla(ptex_count);
for (int j = ptex_count; j < ptex_count_simd; j++)
{
pi.texels_of_partition[i][j] = pi.texels_of_partition[i][ptex_count - 1];
}
}
// Populate the actual procedural partition count
if (counts[0] == 0)
{
pi.partition_count = 0;
}
else if (counts[1] == 0)
{
pi.partition_count = 1;
}
else if (counts[2] == 0)
{
pi.partition_count = 2;
}
else if (counts[3] == 0)
{
pi.partition_count = 3;
}
else
{
pi.partition_count = 4;
}
// Populate the partition index
pi.partition_index = static_cast<uint16_t>(partition_index);
// Populate the coverage bitmaps for 2/3/4 partitions
uint64_t* bitmaps { nullptr };
if (partition_count == 2)
{
bitmaps = bsd.coverage_bitmaps_2[partition_remap_index];
}
else if (partition_count == 3)
{
bitmaps = bsd.coverage_bitmaps_3[partition_remap_index];
}
else if (partition_count == 4)
{
bitmaps = bsd.coverage_bitmaps_4[partition_remap_index];
}
for (unsigned int i = 0; i < BLOCK_MAX_PARTITIONS; i++)
{
pi.partition_texel_count[i] = static_cast<uint8_t>(counts[i]);
}
// Valid partitionings have texels in all of the requested partitions
bool valid = pi.partition_count == partition_count;
if (bitmaps)
{
// Populate the partition coverage bitmap
for (unsigned int i = 0; i < partition_count; i++)
{
bitmaps[i] = 0ULL;
}
unsigned int texels_to_process = astc::min(bsd.texel_count, BLOCK_MAX_KMEANS_TEXELS);
for (unsigned int i = 0; i < texels_to_process; i++)
{
unsigned int idx = bsd.kmeans_texels[i];
bitmaps[pi.partition_of_texel[idx]] |= 1ULL << i;
}
}
return valid;
}
static void build_partition_table_for_one_partition_count(
block_size_descriptor& bsd,
bool can_omit_partitionings,
unsigned int partition_count_cutoff,
unsigned int partition_count,
partition_info* ptab,
uint64_t* canonical_patterns
) {
unsigned int next_index = 0;
bsd.partitioning_count_selected[partition_count - 1] = 0;
bsd.partitioning_count_all[partition_count - 1] = 0;
// Skip tables larger than config max partition count if we can omit modes
if (can_omit_partitionings && (partition_count > partition_count_cutoff))
{
return;
}
// Iterate through twice
// - Pass 0: Keep selected partitionings
// - Pass 1: Keep non-selected partitionings (skip if in omit mode)
unsigned int max_iter = can_omit_partitionings ? 1 : 2;
// Tracker for things we built in the first iteration
uint8_t build[BLOCK_MAX_PARTITIONINGS] { 0 };
for (unsigned int x = 0; x < max_iter; x++)
{
for (unsigned int i = 0; i < BLOCK_MAX_PARTITIONINGS; i++)
{
// Don't include things we built in the first pass
if ((x == 1) && build[i])
{
continue;
}
bool keep_useful = generate_one_partition_info_entry(bsd, partition_count, i, next_index, ptab[next_index]);
if ((x == 0) && !keep_useful)
{
continue;
}
generate_canonical_partitioning(bsd.texel_count, ptab[next_index].partition_of_texel, canonical_patterns + next_index * BIT_PATTERN_WORDS);
bool keep_canonical = true;
for (unsigned int j = 0; j < next_index; j++)
{
bool match = compare_canonical_partitionings(canonical_patterns + next_index * BIT_PATTERN_WORDS, canonical_patterns + j * BIT_PATTERN_WORDS);
if (match)
{
keep_canonical = false;
break;
}
}
if (keep_useful && keep_canonical)
{
if (x == 0)
{
bsd.partitioning_packed_index[partition_count - 2][i] = static_cast<uint16_t>(next_index);
bsd.partitioning_count_selected[partition_count - 1]++;
bsd.partitioning_count_all[partition_count - 1]++;
build[i] = 1;
next_index++;
}
}
else
{
if (x == 1)
{
bsd.partitioning_packed_index[partition_count - 2][i] = static_cast<uint16_t>(next_index);
bsd.partitioning_count_all[partition_count - 1]++;
next_index++;
}
}
}
}
}
/* See header for documentation. */
void init_partition_tables(
block_size_descriptor& bsd,
bool can_omit_partitionings,
unsigned int partition_count_cutoff
) {
partition_info* par_tab2 = bsd.partitionings;
partition_info* par_tab3 = par_tab2 + BLOCK_MAX_PARTITIONINGS;
partition_info* par_tab4 = par_tab3 + BLOCK_MAX_PARTITIONINGS;
partition_info* par_tab1 = par_tab4 + BLOCK_MAX_PARTITIONINGS;
generate_one_partition_info_entry(bsd, 1, 0, 0, *par_tab1);
bsd.partitioning_count_selected[0] = 1;
bsd.partitioning_count_all[0] = 1;
uint64_t* canonical_patterns = new uint64_t[BLOCK_MAX_PARTITIONINGS * BIT_PATTERN_WORDS];
build_partition_table_for_one_partition_count(bsd, can_omit_partitionings, partition_count_cutoff, 2, par_tab2, canonical_patterns);
build_partition_table_for_one_partition_count(bsd, can_omit_partitionings, partition_count_cutoff, 3, par_tab3, canonical_patterns);
build_partition_table_for_one_partition_count(bsd, can_omit_partitionings, partition_count_cutoff, 4, par_tab4, canonical_patterns);
delete[] canonical_patterns;
}