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/*
* Copyright (C) 2020 The Android Open Source Project
*
* 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.
*/
#include <stddef.h>
#include <sys/uio.h>
#include <cstdint>
#include <optional>
#include <log/log.h>
#include <utils/Errors.h>
#define TEST_AND_RETURN(value, expr) \
do { \
if (!(expr)) { \
ALOGE("Failed to call: %s", #expr); \
return value; \
} \
} while (0)
namespace android {
// avoid optimizations
void zeroMemory(uint8_t* data, size_t size);
// View of contiguous sequence. Similar to std::span.
template <typename T>
struct Span {
T* data = nullptr;
size_t size = 0;
size_t byteSize() { return size * sizeof(T); }
iovec toIovec() { return {const_cast<std::remove_const_t<T>*>(data), byteSize()}; }
// Truncates `this` to a length of `offset` and returns a span with the
// remainder.
//
// `std::nullopt` iff offset > size.
std::optional<Span<T>> splitOff(size_t offset) {
if (offset > size) {
return std::nullopt;
}
Span<T> rest = {data + offset, size - offset};
size = offset;
return rest;
}
// Returns nullopt if the byte size of `this` isn't evenly divisible by sizeof(U).
template <typename U>
std::optional<Span<U>> reinterpret() const {
// Only allow casting from bytes for simplicity.
static_assert(std::is_same_v<std::remove_const_t<T>, uint8_t>);
if (size % sizeof(U) != 0) {
return std::nullopt;
}
return Span<U>{reinterpret_cast<U*>(data), size / sizeof(U)};
}
};
} // namespace android
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