74 lines
2.2 KiB
C++
74 lines
2.2 KiB
C++
/*
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* Copyright (C) 2020 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <stddef.h>
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#include <sys/uio.h>
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#include <cstdint>
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#include <optional>
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#include <log/log.h>
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#include <utils/Errors.h>
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#define TEST_AND_RETURN(value, expr) \
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do { \
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if (!(expr)) { \
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ALOGE("Failed to call: %s", #expr); \
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return value; \
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} \
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} while (0)
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namespace android {
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// avoid optimizations
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void zeroMemory(uint8_t* data, size_t size);
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// View of contiguous sequence. Similar to std::span.
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template <typename T>
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struct Span {
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T* data = nullptr;
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size_t size = 0;
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size_t byteSize() { return size * sizeof(T); }
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iovec toIovec() { return {const_cast<std::remove_const_t<T>*>(data), byteSize()}; }
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// Truncates `this` to a length of `offset` and returns a span with the
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// remainder.
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//
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// `std::nullopt` iff offset > size.
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std::optional<Span<T>> splitOff(size_t offset) {
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if (offset > size) {
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return std::nullopt;
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}
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Span<T> rest = {data + offset, size - offset};
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size = offset;
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return rest;
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}
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// Returns nullopt if the byte size of `this` isn't evenly divisible by sizeof(U).
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template <typename U>
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std::optional<Span<U>> reinterpret() const {
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// Only allow casting from bytes for simplicity.
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static_assert(std::is_same_v<std::remove_const_t<T>, uint8_t>);
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if (size % sizeof(U) != 0) {
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return std::nullopt;
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}
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return Span<U>{reinterpret_cast<U*>(data), size / sizeof(U)};
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}
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};
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} // namespace android
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