pod_vector.hpp

#pragma once
#include <boost/container/vector.hpp>
#include <boost/predef.h>
 
#include <cinttypes>
#include <cstddef>
#include <cstdlib>
#include <type_traits>
#include <vector>
 
namespace ossia
{
#if defined(_MSC_VER) && defined(_DEBUG)
template <class T>
struct pod_allocator
{
  using value_type = T;
 
  template <typename... Args>
  explicit pod_allocator(Args&&...) noexcept
  {
  }
 
  pod_allocator() noexcept = default;
  pod_allocator(const pod_allocator&) noexcept = default;
  pod_allocator(pod_allocator&&) noexcept = default;
  pod_allocator& operator=(const pod_allocator&) noexcept = default;
  pod_allocator& operator=(pod_allocator&&) noexcept = default;
 
  static inline T* allocate(std::size_t num) noexcept { return new T[num]; }
 
  static inline void deallocate(T* p, std::size_t) noexcept { delete[] p; }
 
  friend inline bool
  operator==(const pod_allocator& lhs, const pod_allocator& rhs) noexcept
  {
    return true;
  }
  friend inline bool
  operator!=(const pod_allocator& lhs, const pod_allocator& rhs) noexcept
  {
    return false;
  }
};
 
template <class T, std::size_t Align>
using aligned_pod_allocator = pod_allocator<T>;
 
#else
template <class T>
struct pod_allocator
{
  using value_type = T;
 
  pod_allocator() noexcept = default;
  pod_allocator(const pod_allocator&) noexcept = default;
  pod_allocator(pod_allocator&&) noexcept = default;
  pod_allocator& operator=(const pod_allocator&) noexcept = default;
  pod_allocator& operator=(pod_allocator&&) noexcept = default;
 
  static inline T* allocate(std::size_t num) noexcept
  {
    static_assert(
        std::is_standard_layout_v<T> && std::is_trivial_v<T>,
        "can only be used with POD types");
    static_assert(
        alignof(T) <= alignof(std::max_align_t),
        "type must not have specific alignment requirements");
 
    return (T*)std::malloc(sizeof(T) * num);
  }
 
  static inline void deallocate(T* p, std::size_t) noexcept { std::free(p); }
 
  friend inline bool operator==(pod_allocator lhs, pod_allocator rhs) noexcept
  {
    return true;
  }
  friend inline bool operator!=(pod_allocator lhs, pod_allocator rhs) noexcept
  {
    return false;
  }
};
 
template <class T, std::size_t Align>
struct aligned_pod_allocator
{
  template <class U>
  struct rebind
  {
    using other = aligned_pod_allocator<U, Align>;
  };
 
  using value_type = T;
 
  aligned_pod_allocator() noexcept = default;
  aligned_pod_allocator(const aligned_pod_allocator&) noexcept = default;
  aligned_pod_allocator(aligned_pod_allocator&&) noexcept = default;
  aligned_pod_allocator& operator=(const aligned_pod_allocator&) noexcept = default;
  aligned_pod_allocator& operator=(aligned_pod_allocator&&) noexcept = default;
 
#if defined(__linux__) || defined(__unix__) || defined(__unix) || defined(__APPLE__) \
    || defined(__EMSCRIPTEN__)
#define OSSIA_HAS_POSIX_MEMALIGN 1
#endif
 
  template <typename U>
  static constexpr bool has_posix_memalign() noexcept
  {
#if defined(__linux__) || defined(__unix__) || defined(__unix) || defined(__APPLE__) \
    || defined(__EMSCRIPTEN__)
    return true;
#else
    return false;
#endif
  }
 
  static inline T* allocate(std::size_t num) noexcept
  {
    static_assert(
        std::is_standard_layout_v<T> && std::is_trivial_v<T>,
        "can only be used with POD types");
    static_assert(
        alignof(T) <= alignof(std::max_align_t),
        "type must not have specific alignment requirements");
 
    if constexpr(Align != __STDCPP_DEFAULT_NEW_ALIGNMENT__)
    {
#if defined(_WIN32)
      return static_cast<T*>(::_aligned_malloc(sizeof(T) * num, Align));
#else
      void* p{};
#if OSSIA_HAS_POSIX_MEMALIGN
      {
        posix_memalign(&p, Align, sizeof(T) * num);
      }
#else
      {
        static_assert(Align < 128);
        p = std::malloc(sizeof(T) * num + Align + 1);
        const auto pb = uintptr_t(p);
        auto pptr = uintptr_t(p);
 
        while((pptr % Align) != 0)
        {
          pptr++;
        }
        if(pb == pptr)
        {
          pptr += Align;
        }
        *(unsigned char*)(pptr - 1) = (pptr - pb);
        p = (void*)pptr;
      }
#endif
      return static_cast<T*>(p);
#endif
    }
    else
    {
      return (T*)std::malloc(sizeof(T) * num);
    }
  }
 
  static inline void deallocate(T* p, std::size_t) noexcept
  {
#if defined(_WIN32)
    if constexpr(Align != __STDCPP_DEFAULT_NEW_ALIGNMENT__)
    {
      ::_aligned_free(p);
    }
    else
    {
      std::free(p);
    }
#else
#if OSSIA_HAS_POSIX_MEMALIGN
    {
      std::free(p);
    }
#else
    {
      auto count = *(((unsigned char*)p) - 1);
      auto root = ((unsigned char*)p - count);
      std::free(root);
    }
#endif
#endif
  }
 
  friend inline bool
  operator==(aligned_pod_allocator lhs, aligned_pod_allocator rhs) noexcept
  {
    return true;
  }
  friend inline bool
  operator!=(aligned_pod_allocator lhs, aligned_pod_allocator rhs) noexcept
  {
    return false;
  }
};
#endif
 
template <typename T>
struct pod_allocator_avx2 : aligned_pod_allocator<T, 32>
{
  template <class U>
  struct rebind
  {
    using other = pod_allocator_avx2<U>;
  };
  using aligned_pod_allocator<T, 32>::aligned_pod_allocator;
};
 
template <typename T>
using pod_vector = boost::container::vector<T, pod_allocator_avx2<T>>;
 
using int_vector = pod_vector<int>;
using float_vector = pod_vector<float>;
using double_vector = pod_vector<double>;
}