block-pool.cpp

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/*
 * This file is part of the µOS++ project (https://micro-os-plus.github.io/).
 * Copyright (c) 2016-2025 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.
 */
 
#if defined(OS_USE_OS_APP_CONFIG_H)
#include <cmsis-plus/os-app-config.h>
#endif
 
#include <cmsis-plus/memory/block-pool.h>
#include <cmsis-plus/rtos/os.h>
 
// ----------------------------------------------------------------------------
 
#if defined(__clang__)
#pragma clang diagnostic ignored "-Wc++98-compat"
#endif
 
// ----------------------------------------------------------------------------
 
namespace os
{
  namespace memory
  {
 
    // ========================================================================
 
    block_pool::~block_pool ()
    {
      trace::printf ("%s() @%p %s\n", __func__, this, this->name ());
    }
 
#pragma GCC diagnostic push
#if defined(__clang__)
#pragma clang diagnostic ignored "-Wunused-parameter"
#elif defined(__GNUC__)
#pragma GCC diagnostic ignored "-Wunused-parameter"
#endif
 
    void*
    block_pool::do_allocate (std::size_t bytes, std::size_t alignment)
    {
      assert (bytes <= block_size_bytes_);
 
      if (first_ == nullptr)
        {
          return nullptr;
        }
 
      void* p = static_cast<void*> (first_);
      first_ = *(static_cast<void**> (first_));
 
#pragma GCC diagnostic push
#if defined(__clang__)
#pragma clang diagnostic ignored "-Wdeprecated-volatile"
#elif defined(__GNUC__)
#pragma GCC diagnostic ignored "-Wvolatile"
#endif
      ++count_;
#pragma GCC diagnostic pop
 
      // Update statistics.
      // What is subtracted from free is added to allocated.
      internal_increase_allocated_statistics (block_size_bytes_);
 
#if defined(OS_TRACE_LIBCPP_MEMORY_RESOURCE)
      trace::printf ("%s(%u,%u)=%p,%u @%p %s\n", __func__, bytes, alignment, p,
                     block_size_bytes_, this, name ());
#endif
 
      return p;
    }
 
    void
    block_pool::do_deallocate (void* addr, std::size_t bytes,
                               std::size_t alignment) noexcept
    {
#if defined(OS_TRACE_LIBCPP_MEMORY_RESOURCE)
      trace::printf ("%s(%p,%u,%u) @%p %s\n", __func__, addr, bytes, alignment,
                     this, name ());
#endif
 
#pragma GCC diagnostic push
#if defined(__clang__)
#pragma clang diagnostic ignored "-Wunsafe-buffer-usage"
#endif
      if ((addr < pool_addr_)
          || (addr >= (static_cast<char*> (pool_addr_)
                       + blocks_ * block_size_bytes_)))
        {
          assert (false);
          return;
        }
#pragma GCC diagnostic pop
 
      // Perform a push_front() on the single linked LIFO list,
      // i.e. add the block to the beginning of the list.
 
      // Link previous list to this block; may be null, but it does
      // not matter.
      *(static_cast<void**> (addr)) = first_;
 
      // Now this block is the first in the free list..
      first_ = addr;
 
#pragma GCC diagnostic push
#if defined(__clang__)
#pragma clang diagnostic ignored "-Wdeprecated-volatile"
#elif defined(__GNUC__)
#pragma GCC diagnostic ignored "-Wvolatile"
#endif
      --count_;
#pragma GCC diagnostic pop
 
      // Update statistics.
      // What is subtracted from allocated is added to free.
      internal_decrease_allocated_statistics (block_size_bytes_);
    }
 
#pragma GCC diagnostic push
 
    std::size_t
    block_pool::do_max_size (void) const noexcept
    {
      return block_size_bytes_ * blocks_;
    }
 
    void
    block_pool::do_reset (void) noexcept
    {
#if defined(OS_TRACE_LIBCPP_MEMORY_RESOURCE)
      trace::printf ("%s() @%p %s\n", __func__, this, name ());
#endif
      internal_reset_ ();
    }
 
    void
    block_pool::internal_construct_ (std::size_t blocks,
                                     std::size_t block_size_bytes, void* addr,
                                     std::size_t bytes) noexcept
    {
      blocks_ = blocks;
 
      block_size_bytes_
          = rtos::memory::align_size (block_size_bytes, alignof (void*));
      assert (block_size_bytes_ >= sizeof (void*));
 
      assert (addr != nullptr);
      pool_addr_ = addr;
 
      std::size_t align_sz = bytes;
 
      void* res;
      // Possibly adjust the last two parameters.
      res = std::align (alignof (void*), blocks * block_size_bytes_,
                        pool_addr_, align_sz);
 
      // std::align() will fail if it cannot fit the adjusted block size.
      if (res != nullptr)
        {
          assert (res != nullptr);
        }
 
      // The extra assert is made redundant by std::align().
      // assert(blocks * block_size_bytes_ <= align_sz);
 
      total_bytes_ = blocks_ * block_size_bytes_;
 
      internal_reset_ ();
    }
 
    void
    block_pool::internal_reset_ (void) noexcept
    {
      // Construct a linked list of blocks. Store the pointer at
      // the beginning of each block. Each block
      // will hold the address of the next free block, or nullptr at the end.
#pragma GCC diagnostic push
#if defined(__clang__)
#pragma clang diagnostic ignored "-Wunsafe-buffer-usage"
#endif
      char* p = static_cast<char*> (pool_addr_);
      for (std::size_t i = 1; i < blocks_; ++i)
        {
          // Compute the address of the next block;
          char* pn = p + block_size_bytes_;
 
          // Make this block point to the next one.
          *(static_cast<void**> (static_cast<void*> (p))) = pn;
          // Advance pointer
          p = pn;
        }
#pragma GCC diagnostic pop
 
      // Mark end of list.
      *(static_cast<void**> (static_cast<void*> (p))) = nullptr;
 
      first_ = pool_addr_; // Pointer to first block.
 
      count_ = 0; // No allocated blocks.
 
      allocated_bytes_ = 0;
      max_allocated_bytes_ = 0;
      free_bytes_ = total_bytes_;
      allocated_chunks_ = 0;
      free_chunks_ = blocks_;
    }
 
    // ------------------------------------------------------------------------
  } /* namespace memory */
} /* namespace os */
 
// ----------------------------------------------------------------------------