context.h

// Copyright 2024 The Pigweed Authors
//
// 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
//
//     https://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.
#pragma once
 
#include <cstddef>
#include <limits>
 
#include "pw_thread/attrs.h"
#include "pw_thread/stack.h"
#include "pw_thread_backend/context.h"
 
namespace pw {
 
inline constexpr size_t kExternallyAllocatedThreadStack =
    std::numeric_limits<size_t>::max();
 
template <size_t kStackSizeBytes = kExternallyAllocatedThreadStack>
class ThreadContext {
 public:
  constexpr ThreadContext() = default;
 
  ThreadContext(const ThreadContext&) = delete;
  ThreadContext& operator=(const ThreadContext&) = delete;
 
  constexpr thread::backend::NativeContextWithStack<kStackSizeBytes>& native() {
    return native_context_;
  }
 
 private:
  thread::backend::NativeContextWithStack<kStackSizeBytes> native_context_;
};
 
// ThreadContext with externally allocated stack.
template <>
class ThreadContext<kExternallyAllocatedThreadStack> {
 public:
  constexpr ThreadContext() = default;
 
  ThreadContext(const ThreadContext&) = delete;
  ThreadContext& operator=(const ThreadContext&) = delete;
 
  constexpr thread::backend::NativeContext& native() { return native_context_; }
 
 private:
  thread::backend::NativeContext native_context_;
};
 
template <const ThreadAttrs& kAttributes>
class ThreadContextFor {
 public:
  constexpr ThreadContextFor() = default;
 
  ThreadContextFor(const ThreadContextFor&) = delete;
  ThreadContextFor& operator=(const ThreadContextFor&) = delete;
 
  constexpr auto& native() { return context_.native(); }
 
 private:
  ThreadContext<kAttributes.has_external_stack()
                    ? kExternallyAllocatedThreadStack
                    : kAttributes.stack_size_bytes()>
      context_;
};
 
using DefaultThreadContext =
    ThreadContext<thread::backend::kDefaultStackSizeBytes>;
 
}  // namespace pw