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// Copyright 2022 Google LLC
// SPDX-License-Identifier: Apache-2.0
//
// 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.
// Per-target include guard
#if defined(HIGHWAY_HWY_CONTRIB_ALGO_COPY_INL_H_) == \
defined(HWY_TARGET_TOGGLE)
#ifdef HIGHWAY_HWY_CONTRIB_ALGO_COPY_INL_H_
#undef HIGHWAY_HWY_CONTRIB_ALGO_COPY_INL_H_
#else
#define HIGHWAY_HWY_CONTRIB_ALGO_COPY_INL_H_
#endif
#include "hwy/highway.h"
HWY_BEFORE_NAMESPACE();
namespace hwy {
namespace HWY_NAMESPACE {
// These functions avoid having to write a loop plus remainder handling in the
// (unfortunately still common) case where arrays are not aligned/padded. If the
// inputs are known to be aligned/padded, it is more efficient to write a single
// loop using Load(). We do not provide a CopyAlignedPadded because it
// would be more verbose than such a loop.
// Fills `to`[0, `count`) with `value`.
template <class D, typename T = TFromD<D>>
void Fill(D d, T value, size_t count, T* HWY_RESTRICT to) {
const size_t N = Lanes(d);
const Vec<D> v = Set(d, value);
size_t idx = 0;
for (; idx + N <= count; idx += N) {
StoreU(v, d, to + idx);
}
// `count` was a multiple of the vector length `N`: already done.
if (HWY_UNLIKELY(idx == count)) return;
const size_t remaining = count - idx;
HWY_DASSERT(0 != remaining && remaining < N);
SafeFillN(remaining, value, d, to + idx);
}
// Copies `from`[0, `count`) to `to`, which must not overlap `from`.
template <class D, typename T = TFromD<D>>
void Copy(D d, const T* HWY_RESTRICT from, size_t count, T* HWY_RESTRICT to) {
const size_t N = Lanes(d);
size_t idx = 0;
for (; idx + N <= count; idx += N) {
const Vec<D> v = LoadU(d, from + idx);
StoreU(v, d, to + idx);
}
// `count` was a multiple of the vector length `N`: already done.
if (HWY_UNLIKELY(idx == count)) return;
const size_t remaining = count - idx;
HWY_DASSERT(0 != remaining && remaining < N);
SafeCopyN(remaining, d, from + idx, to + idx);
}
// For idx in [0, count) in ascending order, appends `from[idx]` to `to` if the
// corresponding mask element of `func(d, v)` is true. Returns the STL-style end
// of the newly written elements in `to`.
//
// `func` is either a functor with a templated operator()(d, v) returning a
// mask, or a generic lambda if using C++14. Due to apparent limitations of
// Clang on Windows, it is currently necessary to add HWY_ATTR before the
// opening { of the lambda to avoid errors about "function .. requires target".
//
// NOTE: this is only supported for 16-, 32- or 64-bit types.
// NOTE: Func may be called a second time for elements it has already seen, but
// these elements will not be written to `to` again.
template <class D, class Func, typename T = TFromD<D>>
T* CopyIf(D d, const T* HWY_RESTRICT from, size_t count, T* HWY_RESTRICT to,
const Func& func) {
const size_t N = Lanes(d);
size_t idx = 0;
for (; idx + N <= count; idx += N) {
const Vec<D> v = LoadU(d, from + idx);
to += CompressBlendedStore(v, func(d, v), d, to);
}
// `count` was a multiple of the vector length `N`: already done.
if (HWY_UNLIKELY(idx == count)) return to;
#if HWY_MEM_OPS_MIGHT_FAULT
// Proceed one by one.
const CappedTag<T, 1> d1;
for (; idx < count; ++idx) {
using V1 = Vec<decltype(d1)>;
// Workaround for -Waggressive-loop-optimizations on GCC 8
// (iteration 2305843009213693951 invokes undefined behavior for T=i64)
const uintptr_t addr = reinterpret_cast<uintptr_t>(from);
const T* HWY_RESTRICT from_idx =
reinterpret_cast<const T * HWY_RESTRICT>(addr + (idx * sizeof(T)));
const V1 v = LoadU(d1, from_idx);
// Avoid storing to `to` unless we know it should be kept - otherwise, we
// might overrun the end if it was allocated for the exact count.
if (CountTrue(d1, func(d1, v)) == 0) continue;
StoreU(v, d1, to);
to += 1;
}
#else
// Start index of the last unaligned whole vector, ending at the array end.
const size_t last = count - N;
// Number of elements before `from` or already written.
const size_t invalid = idx - last;
HWY_DASSERT(0 != invalid && invalid < N);
const Mask<D> mask = Not(FirstN(d, invalid));
const Vec<D> v = MaskedLoad(mask, d, from + last);
to += CompressBlendedStore(v, And(mask, func(d, v)), d, to);
#endif
return to;
}
// NOLINTNEXTLINE(google-readability-namespace-comments)
} // namespace HWY_NAMESPACE
} // namespace hwy
HWY_AFTER_NAMESPACE();
#endif // HIGHWAY_HWY_CONTRIB_ALGO_COPY_INL_H_
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