143 lines
3.3 KiB
C++
143 lines
3.3 KiB
C++
/* Copyright 2019-2020 Canaan Inc.
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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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#pragma once
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#include "compiler_defs.h"
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#include <cstring>
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#include <gsl/gsl-lite.hpp>
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BEGIN_NS_NNCASE_RUNTIME
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class span_reader
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{
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public:
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span_reader(gsl::span<const gsl::byte> span)
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: span_(span)
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{
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}
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bool empty() const noexcept { return span_.empty(); }
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size_t avail() const noexcept { return span_.size_bytes(); }
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template <class T>
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T read()
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{
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auto value = *reinterpret_cast<const T *>(span_.data());
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advance(sizeof(T));
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return value;
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}
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template <class T>
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T read_unaligned()
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{
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alignas(T) uint8_t storage[sizeof(T)];
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std::memcpy(storage, span_.data(), sizeof(T));
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advance(sizeof(T));
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return *reinterpret_cast<const T *>(storage);
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}
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template <class T>
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void read(T &value)
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{
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value = *reinterpret_cast<const T *>(span_.data());
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advance(sizeof(T));
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}
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template <class T>
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void read_span(gsl::span<const T> &span, size_t size)
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{
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span = { reinterpret_cast<const T *>(span_.data()), size };
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advance(sizeof(T) * size);
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}
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template <class T = gsl::byte>
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gsl::span<const T> read_span(size_t size)
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{
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gsl::span<const T> span(reinterpret_cast<const T *>(span_.data()), size);
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advance(sizeof(T) * size);
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return span;
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}
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void read_avail(gsl::span<const gsl::byte> &span)
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{
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span = span_;
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span_ = {};
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}
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gsl::span<const gsl::byte> read_avail()
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{
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auto span = span_;
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span_ = {};
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return span;
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}
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gsl::span<const gsl::byte> peek_avail()
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{
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return span_;
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}
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template <class T>
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T peek()
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{
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auto value = *reinterpret_cast<const T *>(span_.data());
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return value;
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}
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template <class T>
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T peek_unaligned()
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{
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T value;
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std::memcpy(&value, span_.data(), sizeof(T));
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return value;
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}
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template <class T>
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T peek_unaligned_with_offset(size_t offset)
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{
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T value;
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std::memcpy(&value, span_.data() + offset, sizeof(T));
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return value;
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}
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template <class T>
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const T *get_ref()
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{
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auto ptr = reinterpret_cast<const T *>(span_.data());
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advance(sizeof(T));
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return ptr;
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}
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template <class T>
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void get_ref(const T *&ptr)
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{
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ptr = get_ref<T>();
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}
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void skip(size_t count)
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{
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advance(count);
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}
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private:
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void advance(size_t count)
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{
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span_ = span_.subspan(count);
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}
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private:
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gsl::span<const gsl::byte> span_;
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};
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END_NS_NNCASE_RUNTIME
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