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Diffstat (limited to 'thirdparty/astcenc/astcenc_weight_align.cpp')
| -rw-r--r-- | thirdparty/astcenc/astcenc_weight_align.cpp | 479 |
1 files changed, 479 insertions, 0 deletions
diff --git a/thirdparty/astcenc/astcenc_weight_align.cpp b/thirdparty/astcenc/astcenc_weight_align.cpp new file mode 100644 index 0000000000..e40a318cf5 --- /dev/null +++ b/thirdparty/astcenc/astcenc_weight_align.cpp @@ -0,0 +1,479 @@ +// SPDX-License-Identifier: Apache-2.0 +// ---------------------------------------------------------------------------- +// Copyright 2011-2022 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. +// ---------------------------------------------------------------------------- + +#if !defined(ASTCENC_DECOMPRESS_ONLY) + +/** + * @brief Functions for angular-sum algorithm for weight alignment. + * + * This algorithm works as follows: + * - we compute a complex number P as (cos s*i, sin s*i) for each weight, + * where i is the input value and s is a scaling factor based on the spacing between the weights. + * - we then add together complex numbers for all the weights. + * - we then compute the length and angle of the resulting sum. + * + * This should produce the following results: + * - perfect alignment results in a vector whose length is equal to the sum of lengths of all inputs + * - even distribution results in a vector of length 0. + * - all samples identical results in perfect alignment for every scaling. + * + * For each scaling factor within a given set, we compute an alignment factor from 0 to 1. This + * should then result in some scalings standing out as having particularly good alignment factors; + * we can use this to produce a set of candidate scale/shift values for various quantization levels; + * we should then actually try them and see what happens. + */ + +#include "astcenc_internal.h" +#include "astcenc_vecmathlib.h" + +#include <stdio.h> +#include <cassert> +#include <cstring> + +static constexpr unsigned int ANGULAR_STEPS { 32 }; + +static_assert((ANGULAR_STEPS % ASTCENC_SIMD_WIDTH) == 0, + "ANGULAR_STEPS must be multiple of ASTCENC_SIMD_WIDTH"); + +static_assert(ANGULAR_STEPS >= 32, + "ANGULAR_STEPS must be at least max(steps_for_quant_level)"); + +// Store a reduced sin/cos table for 64 possible weight values; this causes +// slight quality loss compared to using sin() and cos() directly. Must be 2^N. +static constexpr unsigned int SINCOS_STEPS { 64 }; + +static const uint8_t steps_for_quant_level[12] { + 2, 3, 4, 5, 6, 8, 10, 12, 16, 20, 24, 32 +}; + +alignas(ASTCENC_VECALIGN) static float sin_table[SINCOS_STEPS][ANGULAR_STEPS]; +alignas(ASTCENC_VECALIGN) static float cos_table[SINCOS_STEPS][ANGULAR_STEPS]; + +#if defined(ASTCENC_DIAGNOSTICS) + static bool print_once { true }; +#endif + +/* See header for documentation. */ +void prepare_angular_tables() +{ + for (unsigned int i = 0; i < ANGULAR_STEPS; i++) + { + float angle_step = static_cast<float>(i + 1); + + for (unsigned int j = 0; j < SINCOS_STEPS; j++) + { + sin_table[j][i] = static_cast<float>(sinf((2.0f * astc::PI / (SINCOS_STEPS - 1.0f)) * angle_step * static_cast<float>(j))); + cos_table[j][i] = static_cast<float>(cosf((2.0f * astc::PI / (SINCOS_STEPS - 1.0f)) * angle_step * static_cast<float>(j))); + } + } +} + +/** + * @brief Compute the angular alignment factors and offsets. + * + * @param weight_count The number of (decimated) weights. + * @param dec_weight_ideal_value The ideal decimated unquantized weight values. + * @param max_angular_steps The maximum number of steps to be tested. + * @param[out] offsets The output angular offsets array. + */ +static void compute_angular_offsets( + unsigned int weight_count, + const float* dec_weight_ideal_value, + unsigned int max_angular_steps, + float* offsets +) { + promise(weight_count > 0); + promise(max_angular_steps > 0); + + alignas(ASTCENC_VECALIGN) int isamplev[BLOCK_MAX_WEIGHTS]; + + // Precompute isample; arrays are always allocated 64 elements long + for (unsigned int i = 0; i < weight_count; i += ASTCENC_SIMD_WIDTH) + { + // Add 2^23 and interpreting bits extracts round-to-nearest int + vfloat sample = loada(dec_weight_ideal_value + i) * (SINCOS_STEPS - 1.0f) + vfloat(12582912.0f); + vint isample = float_as_int(sample) & vint((SINCOS_STEPS - 1)); + storea(isample, isamplev + i); + } + + // Arrays are multiple of SIMD width (ANGULAR_STEPS), safe to overshoot max + vfloat mult = vfloat(1.0f / (2.0f * astc::PI)); + + for (unsigned int i = 0; i < max_angular_steps; i += ASTCENC_SIMD_WIDTH) + { + vfloat anglesum_x = vfloat::zero(); + vfloat anglesum_y = vfloat::zero(); + + for (unsigned int j = 0; j < weight_count; j++) + { + int isample = isamplev[j]; + anglesum_x += loada(cos_table[isample] + i); + anglesum_y += loada(sin_table[isample] + i); + } + + vfloat angle = atan2(anglesum_y, anglesum_x); + vfloat ofs = angle * mult; + storea(ofs, offsets + i); + } +} + +/** + * @brief For a given step size compute the lowest and highest weight. + * + * Compute the lowest and highest weight that results from quantizing using the given stepsize and + * offset, and then compute the resulting error. The cut errors indicate the error that results from + * forcing samples that should have had one weight value one step up or down. + * + * @param weight_count The number of (decimated) weights. + * @param dec_weight_ideal_value The ideal decimated unquantized weight values. + * @param max_angular_steps The maximum number of steps to be tested. + * @param max_quant_steps The maximum quantization level to be tested. + * @param offsets The angular offsets array. + * @param[out] lowest_weight Per angular step, the lowest weight. + * @param[out] weight_span Per angular step, the span between lowest and highest weight. + * @param[out] error Per angular step, the error. + * @param[out] cut_low_weight_error Per angular step, the low weight cut error. + * @param[out] cut_high_weight_error Per angular step, the high weight cut error. + */ +static void compute_lowest_and_highest_weight( + unsigned int weight_count, + const float* dec_weight_ideal_value, + unsigned int max_angular_steps, + unsigned int max_quant_steps, + const float* offsets, + float* lowest_weight, + int* weight_span, + float* error, + float* cut_low_weight_error, + float* cut_high_weight_error +) { + promise(weight_count > 0); + promise(max_angular_steps > 0); + + vfloat rcp_stepsize = vfloat::lane_id() + vfloat(1.0f); + + // Arrays are ANGULAR_STEPS long, so always safe to run full vectors + for (unsigned int sp = 0; sp < max_angular_steps; sp += ASTCENC_SIMD_WIDTH) + { + vfloat minidx(128.0f); + vfloat maxidx(-128.0f); + vfloat errval = vfloat::zero(); + vfloat cut_low_weight_err = vfloat::zero(); + vfloat cut_high_weight_err = vfloat::zero(); + vfloat offset = loada(offsets + sp); + + for (unsigned int j = 0; j < weight_count; j++) + { + vfloat sval = load1(dec_weight_ideal_value + j) * rcp_stepsize - offset; + vfloat svalrte = round(sval); + vfloat diff = sval - svalrte; + errval += diff * diff; + + // Reset tracker on min hit + vmask mask = svalrte < minidx; + minidx = select(minidx, svalrte, mask); + cut_low_weight_err = select(cut_low_weight_err, vfloat::zero(), mask); + + // Accumulate on min hit + mask = svalrte == minidx; + vfloat accum = cut_low_weight_err + vfloat(1.0f) - vfloat(2.0f) * diff; + cut_low_weight_err = select(cut_low_weight_err, accum, mask); + + // Reset tracker on max hit + mask = svalrte > maxidx; + maxidx = select(maxidx, svalrte, mask); + cut_high_weight_err = select(cut_high_weight_err, vfloat::zero(), mask); + + // Accumulate on max hit + mask = svalrte == maxidx; + accum = cut_high_weight_err + vfloat(1.0f) + vfloat(2.0f) * diff; + cut_high_weight_err = select(cut_high_weight_err, accum, mask); + } + + // Write out min weight and weight span; clamp span to a usable range + vint span = float_to_int(maxidx - minidx + vfloat(1)); + span = min(span, vint(max_quant_steps + 3)); + span = max(span, vint(2)); + storea(minidx, lowest_weight + sp); + storea(span, weight_span + sp); + + // The cut_(lowest/highest)_weight_error indicate the error that results from forcing + // samples that should have had the weight value one step (up/down). + vfloat ssize = 1.0f / rcp_stepsize; + vfloat errscale = ssize * ssize; + storea(errval * errscale, error + sp); + storea(cut_low_weight_err * errscale, cut_low_weight_error + sp); + storea(cut_high_weight_err * errscale, cut_high_weight_error + sp); + + rcp_stepsize = rcp_stepsize + vfloat(ASTCENC_SIMD_WIDTH); + } +} + +/** + * @brief The main function for the angular algorithm. + * + * @param weight_count The number of (decimated) weights. + * @param dec_weight_ideal_value The ideal decimated unquantized weight values. + * @param max_quant_level The maximum quantization level to be tested. + * @param[out] low_value Per angular step, the lowest weight value. + * @param[out] high_value Per angular step, the highest weight value. + */ +static void compute_angular_endpoints_for_quant_levels( + unsigned int weight_count, + const float* dec_weight_ideal_value, + unsigned int max_quant_level, + float low_value[TUNE_MAX_ANGULAR_QUANT + 1], + float high_value[TUNE_MAX_ANGULAR_QUANT + 1] +) { + unsigned int max_quant_steps = steps_for_quant_level[max_quant_level]; + unsigned int max_angular_steps = steps_for_quant_level[max_quant_level]; + + alignas(ASTCENC_VECALIGN) float angular_offsets[ANGULAR_STEPS]; + + compute_angular_offsets(weight_count, dec_weight_ideal_value, + max_angular_steps, angular_offsets); + + alignas(ASTCENC_VECALIGN) float lowest_weight[ANGULAR_STEPS]; + alignas(ASTCENC_VECALIGN) int32_t weight_span[ANGULAR_STEPS]; + alignas(ASTCENC_VECALIGN) float error[ANGULAR_STEPS]; + alignas(ASTCENC_VECALIGN) float cut_low_weight_error[ANGULAR_STEPS]; + alignas(ASTCENC_VECALIGN) float cut_high_weight_error[ANGULAR_STEPS]; + + compute_lowest_and_highest_weight(weight_count, dec_weight_ideal_value, + max_angular_steps, max_quant_steps, + angular_offsets, lowest_weight, weight_span, error, + cut_low_weight_error, cut_high_weight_error); + + // For each quantization level, find the best error terms. Use packed vectors so data-dependent + // branches can become selects. This involves some integer to float casts, but the values are + // small enough so they never round the wrong way. + vfloat4 best_results[36]; + + // Initialize the array to some safe defaults + promise(max_quant_steps > 0); + for (unsigned int i = 0; i < (max_quant_steps + 4); i++) + { + // Lane<0> = Best error + // Lane<1> = Best scale; -1 indicates no solution found + // Lane<2> = Cut low weight + best_results[i] = vfloat4(ERROR_CALC_DEFAULT, -1.0f, 0.0f, 0.0f); + } + + promise(max_angular_steps > 0); + for (unsigned int i = 0; i < max_angular_steps; i++) + { + float i_flt = static_cast<float>(i); + + int idx_span = weight_span[i]; + + float error_cut_low = error[i] + cut_low_weight_error[i]; + float error_cut_high = error[i] + cut_high_weight_error[i]; + float error_cut_low_high = error[i] + cut_low_weight_error[i] + cut_high_weight_error[i]; + + // Check best error against record N + vfloat4 best_result = best_results[idx_span]; + vfloat4 new_result = vfloat4(error[i], i_flt, 0.0f, 0.0f); + vmask4 mask = vfloat4(best_result.lane<0>()) > vfloat4(error[i]); + best_results[idx_span] = select(best_result, new_result, mask); + + // Check best error against record N-1 with either cut low or cut high + best_result = best_results[idx_span - 1]; + + new_result = vfloat4(error_cut_low, i_flt, 1.0f, 0.0f); + mask = vfloat4(best_result.lane<0>()) > vfloat4(error_cut_low); + best_result = select(best_result, new_result, mask); + + new_result = vfloat4(error_cut_high, i_flt, 0.0f, 0.0f); + mask = vfloat4(best_result.lane<0>()) > vfloat4(error_cut_high); + best_results[idx_span - 1] = select(best_result, new_result, mask); + + // Check best error against record N-2 with both cut low and high + best_result = best_results[idx_span - 2]; + new_result = vfloat4(error_cut_low_high, i_flt, 1.0f, 0.0f); + mask = vfloat4(best_result.lane<0>()) > vfloat4(error_cut_low_high); + best_results[idx_span - 2] = select(best_result, new_result, mask); + } + + for (unsigned int i = 0; i <= max_quant_level; i++) + { + unsigned int q = steps_for_quant_level[i]; + int bsi = static_cast<int>(best_results[q].lane<1>()); + + // Did we find anything? +#if defined(ASTCENC_DIAGNOSTICS) + if ((bsi < 0) && print_once) + { + print_once = false; + printf("INFO: Unable to find full encoding within search error limit.\n\n"); + } +#endif + + bsi = astc::max(0, bsi); + + float lwi = lowest_weight[bsi] + best_results[q].lane<2>(); + float hwi = lwi + static_cast<float>(q) - 1.0f; + + float stepsize = 1.0f / (1.0f + static_cast<float>(bsi)); + low_value[i] = (angular_offsets[bsi] + lwi) * stepsize; + high_value[i] = (angular_offsets[bsi] + hwi) * stepsize; + } +} + +/* See header for documentation. */ +void compute_angular_endpoints_1plane( + bool only_always, + const block_size_descriptor& bsd, + const float* dec_weight_ideal_value, + unsigned int max_weight_quant, + compression_working_buffers& tmpbuf +) { + float (&low_value)[WEIGHTS_MAX_BLOCK_MODES] = tmpbuf.weight_low_value1; + float (&high_value)[WEIGHTS_MAX_BLOCK_MODES] = tmpbuf.weight_high_value1; + + float (&low_values)[WEIGHTS_MAX_DECIMATION_MODES][TUNE_MAX_ANGULAR_QUANT + 1] = tmpbuf.weight_low_values1; + float (&high_values)[WEIGHTS_MAX_DECIMATION_MODES][TUNE_MAX_ANGULAR_QUANT + 1] = tmpbuf.weight_high_values1; + + unsigned int max_decimation_modes = only_always ? bsd.decimation_mode_count_always + : bsd.decimation_mode_count_selected; + promise(max_decimation_modes > 0); + for (unsigned int i = 0; i < max_decimation_modes; i++) + { + const decimation_mode& dm = bsd.decimation_modes[i]; + if (!dm.is_ref_1_plane(static_cast<quant_method>(max_weight_quant))) + { + continue; + } + + unsigned int weight_count = bsd.get_decimation_info(i).weight_count; + + unsigned int max_precision = dm.maxprec_1plane; + if (max_precision > TUNE_MAX_ANGULAR_QUANT) + { + max_precision = TUNE_MAX_ANGULAR_QUANT; + } + + if (max_precision > max_weight_quant) + { + max_precision = max_weight_quant; + } + + compute_angular_endpoints_for_quant_levels( + weight_count, + dec_weight_ideal_value + i * BLOCK_MAX_WEIGHTS, + max_precision, low_values[i], high_values[i]); + } + + unsigned int max_block_modes = only_always ? bsd.block_mode_count_1plane_always + : bsd.block_mode_count_1plane_selected; + promise(max_block_modes > 0); + for (unsigned int i = 0; i < max_block_modes; i++) + { + const block_mode& bm = bsd.block_modes[i]; + assert(!bm.is_dual_plane); + + unsigned int quant_mode = bm.quant_mode; + unsigned int decim_mode = bm.decimation_mode; + + if (quant_mode <= TUNE_MAX_ANGULAR_QUANT) + { + low_value[i] = low_values[decim_mode][quant_mode]; + high_value[i] = high_values[decim_mode][quant_mode]; + } + else + { + low_value[i] = 0.0f; + high_value[i] = 1.0f; + } + } +} + +/* See header for documentation. */ +void compute_angular_endpoints_2planes( + const block_size_descriptor& bsd, + const float* dec_weight_ideal_value, + unsigned int max_weight_quant, + compression_working_buffers& tmpbuf +) { + float (&low_value1)[WEIGHTS_MAX_BLOCK_MODES] = tmpbuf.weight_low_value1; + float (&high_value1)[WEIGHTS_MAX_BLOCK_MODES] = tmpbuf.weight_high_value1; + float (&low_value2)[WEIGHTS_MAX_BLOCK_MODES] = tmpbuf.weight_low_value2; + float (&high_value2)[WEIGHTS_MAX_BLOCK_MODES] = tmpbuf.weight_high_value2; + + float (&low_values1)[WEIGHTS_MAX_DECIMATION_MODES][TUNE_MAX_ANGULAR_QUANT + 1] = tmpbuf.weight_low_values1; + float (&high_values1)[WEIGHTS_MAX_DECIMATION_MODES][TUNE_MAX_ANGULAR_QUANT + 1] = tmpbuf.weight_high_values1; + float (&low_values2)[WEIGHTS_MAX_DECIMATION_MODES][TUNE_MAX_ANGULAR_QUANT + 1] = tmpbuf.weight_low_values2; + float (&high_values2)[WEIGHTS_MAX_DECIMATION_MODES][TUNE_MAX_ANGULAR_QUANT + 1] = tmpbuf.weight_high_values2; + + promise(bsd.decimation_mode_count_selected > 0); + for (unsigned int i = 0; i < bsd.decimation_mode_count_selected; i++) + { + const decimation_mode& dm = bsd.decimation_modes[i]; + if (!dm.is_ref_2_plane(static_cast<quant_method>(max_weight_quant))) + { + continue; + } + + unsigned int weight_count = bsd.get_decimation_info(i).weight_count; + + unsigned int max_precision = dm.maxprec_2planes; + if (max_precision > TUNE_MAX_ANGULAR_QUANT) + { + max_precision = TUNE_MAX_ANGULAR_QUANT; + } + + if (max_precision > max_weight_quant) + { + max_precision = max_weight_quant; + } + + compute_angular_endpoints_for_quant_levels( + weight_count, + dec_weight_ideal_value + i * BLOCK_MAX_WEIGHTS, + max_precision, low_values1[i], high_values1[i]); + + compute_angular_endpoints_for_quant_levels( + weight_count, + dec_weight_ideal_value + i * BLOCK_MAX_WEIGHTS + WEIGHTS_PLANE2_OFFSET, + max_precision, low_values2[i], high_values2[i]); + } + + unsigned int start = bsd.block_mode_count_1plane_selected; + unsigned int end = bsd.block_mode_count_1plane_2plane_selected; + for (unsigned int i = start; i < end; i++) + { + const block_mode& bm = bsd.block_modes[i]; + unsigned int quant_mode = bm.quant_mode; + unsigned int decim_mode = bm.decimation_mode; + + if (quant_mode <= TUNE_MAX_ANGULAR_QUANT) + { + low_value1[i] = low_values1[decim_mode][quant_mode]; + high_value1[i] = high_values1[decim_mode][quant_mode]; + low_value2[i] = low_values2[decim_mode][quant_mode]; + high_value2[i] = high_values2[decim_mode][quant_mode]; + } + else + { + low_value1[i] = 0.0f; + high_value1[i] = 1.0f; + low_value2[i] = 0.0f; + high_value2[i] = 1.0f; + } + } +} + +#endif |