first-fit-top.h

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/*
 * This file is part of the µOS++ distribution.
 *   (https://github.com/micro-os-plus)
 * Copyright (c) 2016-2023 Liviu Ionescu. All rights reserved.
 *
 * Permission to use, copy, modify, and/or distribute this software
 * for any purpose is hereby granted, under the terms of the MIT license.
 *
 * If a copy of the license was not distributed with this file, it can
 * be obtained from https://opensource.org/licenses/mit/.
 */
 
#ifndef CMSIS_PLUS_MEMORY_FIRST_FIT_TOP_H_
#define CMSIS_PLUS_MEMORY_FIRST_FIT_TOP_H_
 
// ----------------------------------------------------------------------------
 
#if defined(__cplusplus)
 
// ----------------------------------------------------------------------------
 
#include <cmsis-plus/rtos/os.h>
 
// ----------------------------------------------------------------------------
 
#pragma GCC diagnostic push
#if defined(__clang__)
#pragma clang diagnostic ignored "-Wc++98-compat"
#pragma clang diagnostic ignored "-Wdocumentation-unknown-command"
#endif
 
// ----------------------------------------------------------------------------
 
namespace os
{
  namespace memory
  {
 
    // ========================================================================
 
    class first_fit_top : public rtos::memory::memory_resource
    {
    public:
 
      first_fit_top (void* addr, std::size_t bytes);
 
      first_fit_top (const char* name, void* addr, std::size_t bytes);
 
    protected:
 
      first_fit_top () = default;
 
      first_fit_top (const char* name);
 
    public:
 
      // The rule of five.
      first_fit_top (const first_fit_top&) = delete;
      first_fit_top (first_fit_top&&) = delete;
      first_fit_top&
      operator= (const first_fit_top&) = delete;
      first_fit_top&
      operator= (first_fit_top&&) = delete;
 
      virtual
      ~first_fit_top () override;
 
    protected:
 
#pragma GCC diagnostic push
#if defined(__clang__)
#pragma clang diagnostic ignored "-Wpadded"
#elif defined(__GNUC__)
#pragma GCC diagnostic ignored "-Wpadded"
#endif
 
      // A 'chunk' is where the user block resides; it keeps track of size,
      // it accommodates alignment and helps maintain the free list.
      typedef struct chunk_s
      {
        // The actual chunk size, in bytes;
        // the next chunk starts exactly after this number of bytes.
        // This is the only overhead that applies to all allocated blocks.
        std::size_t size;
 
        // For allocated chunks, here, or at the next address that
        // satisfies the required alignment, starts the payload.
 
        // When the chunk is in the free list, instead of the
        // payload, here is a pointer to the next chunk.
        /* struct */ chunk_s* next;
      } chunk_t;
 
#pragma GCC diagnostic pop
 
      void
      internal_construct_ (void* addr, std::size_t bytes);
 
      void
      internal_reset_ (void) noexcept;
 
      void*
      internal_align_ (chunk_t* chunk, std::size_t bytes, std::size_t alignment);
 
      virtual void*
      do_allocate (std::size_t bytes, std::size_t alignment) override;
 
      virtual void
      do_deallocate (void* addr, std::size_t bytes, std::size_t alignment)
          noexcept override;
 
      virtual std::size_t
      do_max_size (void) const noexcept override;
 
      virtual void
      do_reset (void) noexcept override;
 
    protected:
 
      // Offset of payload inside the chunk.
      static constexpr std::size_t chunk_offset = offsetof(chunk_t, next);
      static constexpr std::size_t chunk_align = sizeof(void*);
      static constexpr std::size_t chunk_minsize = sizeof(chunk_t);
 
      static constexpr std::size_t block_minsize = sizeof(void *);
 
      // Extra padding from chunk to block.
      static constexpr std::size_t
      calc_block_padding (std::size_t block_align)
      {
        return os::rtos::memory::max (block_align, chunk_align) - chunk_align;
      }
 
      // The minimum chunk to it the block.
      static constexpr std::size_t
      calc_block_minchunk (std::size_t block_padding)
      {
        return chunk_offset + block_minsize + block_padding;
      }
 
      void* arena_addr_ = nullptr;
      // No need for arena_size_bytes_, use total_bytes_.
 
      chunk_t* free_list_ = nullptr;
 
    };
 
    // ========================================================================
 
    template<std::size_t N>
      class first_fit_top_inclusive : public first_fit_top
      {
      public:
 
        static const std::size_t bytes = N;
 
        first_fit_top_inclusive (void);
 
        first_fit_top_inclusive (const char* name);
 
      public:
 
        // The rule of five.
        first_fit_top_inclusive (const first_fit_top_inclusive&) = delete;
        first_fit_top_inclusive (first_fit_top_inclusive&&) = delete;
        first_fit_top_inclusive&
        operator= (const first_fit_top_inclusive&) = delete;
        first_fit_top_inclusive&
        operator= (first_fit_top_inclusive&&) = delete;
 
        virtual
        ~first_fit_top_inclusive ();
 
      protected:
 
        char arena_[bytes];
 
      };
 
    // ========================================================================
 
    template<typename A = os::rtos::memory::allocator<char>>
      class first_fit_top_allocated : public first_fit_top
      {
      public:
 
        using value_type = char;
 
        using allocator_type = A;
 
        using allocator_traits = std::allocator_traits<A>;
 
        // It is recommended to have the same type, but at least the types
        // should have the same size.
        static_assert(sizeof(value_type) == sizeof(typename allocator_traits::value_type),
            "The allocator must be parametrised with a type of same size.");
 
        first_fit_top_allocated (std::size_t bytes,
                                 const allocator_type& allocator =
                                     allocator_type ());
 
        first_fit_top_allocated (const char* name, std::size_t bytes,
                                 const allocator_type& allocator =
                                     allocator_type ());
 
      public:
 
        // The rule of five.
        first_fit_top_allocated (const first_fit_top_allocated&) = delete;
        first_fit_top_allocated (first_fit_top_allocated&&) = delete;
        first_fit_top_allocated&
        operator= (const first_fit_top_allocated&) = delete;
        first_fit_top_allocated&
        operator= (first_fit_top_allocated&&) = delete;
 
        virtual
        ~first_fit_top_allocated ();
 
      protected:
 
        allocator_type* allocator_ = nullptr;
 
      };
 
  // --------------------------------------------------------------------------
  } /* namespace memory */
} /* namespace os */
 
// ===== Inline & template implementations ====================================
 
namespace os
{
  namespace memory
  {
 
    // ========================================================================
 
    inline
    first_fit_top::first_fit_top (const char* name) :
        rtos::memory::memory_resource
          { name }
    {
    }
 
    inline
    first_fit_top::first_fit_top (void* addr, std::size_t bytes) :
        first_fit_top
          { nullptr, addr, bytes }
    {
    }
 
    inline
    first_fit_top::first_fit_top (const char* name, void* addr,
                                  std::size_t bytes) :
        rtos::memory::memory_resource
          { name }
    {
      trace::printf ("%s(%p,%u) @%p %s\n", __func__, addr, bytes, this,
                     this->name ());
 
      internal_construct_ (addr, bytes);
    }
 
    // ========================================================================
 
    template<std::size_t N>
      inline
      first_fit_top_inclusive<N>::first_fit_top_inclusive () :
          first_fit_top_inclusive (nullptr)
      {
      }
 
    template<std::size_t N>
      inline
      first_fit_top_inclusive<N>::first_fit_top_inclusive (const char* name) :
          first_fit_top
            { name }
      {
        trace::printf ("%s() @%p %s\n", __func__, this, this->name ());
 
        internal_construct_ (&arena_[0], bytes);
      }
 
    template<std::size_t N>
      first_fit_top_inclusive<N>::~first_fit_top_inclusive ()
      {
        trace::printf ("%s() @%p %s\n", __func__, this, this->name ());
      }
 
    // ========================================================================
 
    template<typename A>
      inline
      first_fit_top_allocated<A>::first_fit_top_allocated (
          std::size_t bytes, const allocator_type& allocator) :
          first_fit_top_allocated (nullptr, bytes, allocator)
      {
      }
 
    template<typename A>
      first_fit_top_allocated<A>::first_fit_top_allocated (
          const char* name, std::size_t bytes, const allocator_type& allocator) :
          first_fit_top
            { name }
      {
        trace::printf ("%s(%u) @%p %s\n", __func__, bytes, this, this->name ());
 
        // Remember the allocator, it'll be used by the destructor.
        allocator_ =
            static_cast<allocator_type*> (&const_cast<allocator_type&> (allocator));
 
        void* addr = allocator_->allocate (bytes);
        if (addr == nullptr)
          {
            estd::__throw_bad_alloc ();
          }
 
        internal_construct_ (addr, bytes);
      }
 
    template<typename A>
      first_fit_top_allocated<A>::~first_fit_top_allocated ()
      {
        trace::printf ("%s() @%p %s\n", __func__, this, this->name ());
 
        // Skip in case a derived class did the deallocation.
        if (allocator_ != nullptr)
          {
            allocator_->deallocate (
                static_cast<typename allocator_traits::pointer> (arena_addr_),
                total_bytes_);
 
            // Prevent another deallocation.
            allocator_ = nullptr;
          }
      }
 
  // --------------------------------------------------------------------------
 
  } /* namespace memory */
} /* namespace os */
 
#pragma GCC diagnostic pop
 
// ----------------------------------------------------------------------------
 
#endif /* __cplusplus */
 
// ----------------------------------------------------------------------------
 
#endif /* CMSIS_PLUS_MEMORY_FIRST_FIT_TOP_H_ */