e2e1984e60
A few headers like BLI_math_constants.h and BLI_utildefines.h keep working for C code, for remaining makesdna and userdef defaults code in C. Pull Request: https://projects.blender.org/blender/blender/pulls/134406
69 lines
2.3 KiB
C++
69 lines
2.3 KiB
C++
/* SPDX-FileCopyrightText: 2024 Blender Authors
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*
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* SPDX-License-Identifier: GPL-2.0-or-later */
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#include "BLI_bit_bool_conversion.hh"
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#include "BLI_simd.hh"
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namespace blender::bits {
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bool or_bools_into_bits(const Span<bool> bools,
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MutableBitSpan r_bits,
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const int64_t allowed_overshoot)
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{
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BLI_assert(r_bits.size() >= bools.size());
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if (bools.is_empty()) {
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return false;
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}
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int64_t bool_i = 0;
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const bool *bools_ = bools.data();
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bool any_true = false;
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/* Conversion from bools to bits can be way faster with intrinsics. That's because instead of
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* processing one element at a time, we can process 16 at once. */
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#if BLI_HAVE_SSE2
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/* Initialize zeros, so that we can compare against it. */
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const __m128i zero_bytes = _mm_set1_epi8(0);
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int64_t iteration_end = bools.size();
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if (iteration_end % 16 > 0) {
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if (allowed_overshoot >= 16) {
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iteration_end = (iteration_end + 16) & ~15;
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}
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}
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/* Iterate over chunks of booleans. */
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for (; bool_i + 16 <= iteration_end; bool_i += 16) {
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/* Load 16 bools at once. */
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const __m128i group = _mm_loadu_si128(reinterpret_cast<const __m128i *>(bools_ + bool_i));
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/* Compare them all against zero. The result is a mask of the form [0x00, 0xff, 0xff, ...]. */
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const __m128i is_false_byte_mask = _mm_cmpeq_epi8(group, zero_bytes);
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/* Compress the byte-mask into a bit mask. This takes one bit from each byte. */
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const uint16_t is_false_mask = _mm_movemask_epi8(is_false_byte_mask);
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/* Now we have a bit mask where each bit corresponds to an input boolean. */
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const uint16_t is_true_mask = ~is_false_mask;
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any_true |= is_true_mask != 0;
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const int start_bit_in_int = (r_bits.bit_range().start() + bool_i) & BitIndexMask;
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BitInt *start_bit_int = int_containing_bit(r_bits.data(), r_bits.bit_range().start() + bool_i);
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*start_bit_int |= BitInt(is_true_mask) << start_bit_in_int;
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if (start_bit_in_int > BitsPerInt - 16) {
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/* It's possible that the bits need inserted in two consecutive integers. */
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start_bit_int[1] |= BitInt(is_true_mask) >> (64 - start_bit_in_int);
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}
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}
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#endif
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/* Process remaining bools. */
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for (; bool_i < bools.size(); bool_i++) {
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if (bools_[bool_i]) {
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r_bits[bool_i].set();
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any_true = true;
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}
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}
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return any_true;
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}
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} // namespace blender::bits
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