MemoryX.h

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#ifndef __AUDACITY_MEMORY_X_H__
#define __AUDACITY_MEMORY_X_H__
 
// C++ standard header <memory> with a few extensions
#include <memory>
#include <new> // align_val_t and hardware_destructive_interference_size
#include <cstdlib> // Needed for free.
#include <cmath>
#ifndef safenew
#define safenew new
#endif
 
#include <functional>
#include <limits>
 
#include <cstdint>
 
/*
 * ArrayOf<X>
 * Not to be confused with std::array (which takes a fixed size) or std::vector
 * This maintains a pointer allocated by NEW X[].  It's cheap: only one pointer,
 * with no size and capacity information for resizing as for vector, and if X is
 * a built-in numeric or pointer type, by default there is no zero filling at
 * allocation time.
 */
 
template<typename X>
class ArrayOf : public std::unique_ptr<X[]>
{
public:
   ArrayOf() {}
 
   template<typename Integral>
   explicit ArrayOf(Integral count, bool initialize = false)
   {
      static_assert(std::is_unsigned<Integral>::value, "Unsigned arguments only");
      reinit(count, initialize);
   }
 
   //ArrayOf(const ArrayOf&) = delete;
   ArrayOf(const ArrayOf&) = delete;
   ArrayOf(ArrayOf&& that)
      : std::unique_ptr < X[] >
         (std::move((std::unique_ptr < X[] >&)(that)))
   {
   }
   ArrayOf& operator= (ArrayOf &&that)
   {
      std::unique_ptr<X[]>::operator=(std::move(that));
      return *this;
   }
   ArrayOf& operator= (std::unique_ptr<X[]> &&that)
   {
      std::unique_ptr<X[]>::operator=(std::move(that));
      return *this;
   }
 
   template< typename Integral >
   void reinit(Integral count,
               bool initialize = false)
   {
      static_assert(std::is_unsigned<Integral>::value, "Unsigned arguments only");
      if (initialize)
         // Initialize elements (usually, to zero for a numerical type)
         std::unique_ptr<X[]>::reset(safenew X[count]{});
      else
         // Avoid the slight initialization overhead
         std::unique_ptr<X[]>::reset(safenew X[count]);
   }
};
 
template<typename X>
class ArraysOf : public ArrayOf<ArrayOf<X>>
{
public:
   ArraysOf() {}
 
   template<typename Integral>
   explicit ArraysOf(Integral N)
      : ArrayOf<ArrayOf<X>>( N )
   {}
 
   template<typename Integral1, typename Integral2 >
   ArraysOf(Integral1 N, Integral2 M, bool initialize = false)
   : ArrayOf<ArrayOf<X>>( N )
   {
      static_assert(std::is_unsigned<Integral1>::value, "Unsigned arguments only");
      static_assert(std::is_unsigned<Integral2>::value, "Unsigned arguments only");
      for (size_t ii = 0; ii < N; ++ii)
         (*this)[ii] = ArrayOf<X>{ M, initialize };
   }
 
   //ArraysOf(const ArraysOf&) = delete;
   ArraysOf(const ArraysOf&) =delete;
   ArraysOf& operator= (ArraysOf&& that)
   {
      ArrayOf<ArrayOf<X>>::operator=(std::move(that));
      return *this;
   }
 
   template< typename Integral >
   void reinit(Integral count)
   {
      ArrayOf<ArrayOf<X>>::reinit( count );
   }
 
   template< typename Integral >
   void reinit(Integral count, bool initialize)
   {
      ArrayOf<ArrayOf<X>>::reinit( count, initialize );
   }
 
   template<typename Integral1, typename Integral2 >
   void reinit(Integral1 countN, Integral2 countM, bool initialize = false)
   {
      static_assert(std::is_unsigned<Integral1>::value, "Unsigned arguments only");
      static_assert(std::is_unsigned<Integral2>::value, "Unsigned arguments only");
      reinit(countN, false);
      for (size_t ii = 0; ii < countN; ++ii)
         (*this)[ii].reinit(countM, initialize);
   }
};
 
struct freer { void operator() (void *p) const { free(p); } };
 
template< typename T >
using MallocPtr = std::unique_ptr< T, freer >;
 
template <typename Character = char>
using MallocString = std::unique_ptr< Character[], freer >;
 
template <typename T>
struct Destroyer {
   void operator () (T *p) const { if (p) p->Destroy(); }
};
 
template <typename T>
using Destroy_ptr = std::unique_ptr<T, Destroyer<T>>;
 
// Construct this from any copyable function object, such as a lambda
template <typename F>
struct Finally {
   Finally(F f) : clean( f ) {}
   ~Finally() { clean(); }
   F clean;
};
 
template <typename F>
[[nodiscard]] Finally<F> finally (F f)
{
   return Finally<F>(f);
}
 
 
template<typename F> Finally(F) -> Finally<F>;
 
#include <algorithm>
 
template< typename T >
struct RestoreValue {
   T oldValue;
   void operator () ( T *p ) const { if (p) *p = oldValue; }
};
 
 
template< typename T >
class ValueRestorer : public std::unique_ptr< T, RestoreValue<T> >
{
   using std::unique_ptr< T, RestoreValue<T> >::reset; // make private
   // But release() remains public and can be useful to commit a changed value
public:
   explicit ValueRestorer( T &var )
      : std::unique_ptr< T, RestoreValue<T> >( &var, { var } )
   {}
   explicit ValueRestorer( T &var, const T& newValue )
      : std::unique_ptr< T, RestoreValue<T> >( &var, { var } )
   { var = newValue; }
   ValueRestorer(ValueRestorer &&that)
      : std::unique_ptr < T, RestoreValue<T> > ( std::move(that) ) {};
   ValueRestorer & operator= (ValueRestorer &&that)
   {
      if (this != &that)
         std::unique_ptr < T, RestoreValue<T> >::operator=(std::move(that));
      return *this;
   }
};
 
template< typename T >
struct CopyableValueRestorer {
   explicit CopyableValueRestorer(T& var)
      : pointer{ &var, RestoreValue<T>{ var } }
   {}
   CopyableValueRestorer(T& var, const T& newValue)
      : pointer{ &var, RestoreValue<T>{ var } }
   {
      var = newValue;
   }
 
   std::shared_ptr<T> pointer;
};
 
template< typename T >
ValueRestorer< T > valueRestorer( T& var )
{ return ValueRestorer< T >{ var }; }
 
template< typename T >
ValueRestorer< T > valueRestorer( T& var, const T& newValue )
{ return ValueRestorer< T >{ var, newValue }; }
 
 
struct UTILITY_API alignas(
#if defined(_WIN32) && defined(_MSC_VER)
   // MSVC supports this symbol in std, but MinGW uses libstdc++, which it does not.
   std::hardware_destructive_interference_size
#else
   // That constant isn't defined for the other builds yet
   64 /* ? */
#endif
)
 
NonInterferingBase {
   static void *operator new(std::size_t count, std::align_val_t al);
   static void operator delete(void *ptr, std::align_val_t al);
 
#if defined (_MSC_VER) && defined(_DEBUG)
   // Versions that work in the presence of the DEBUG_NEW macro.
   // Ignore the arguments supplied by the macro and forward to the
   // other overloads.
   static void *operator new(
      std::size_t count, std::align_val_t al, int, const char *, int)
   { return operator new(count, al); }
   static void operator delete(
      void *ptr, std::align_val_t al, int, const char *, int)
   { return operator delete(ptr, al); }
#endif
};
 
 
template<typename T> // CRTP
struct SharedNonInterfering : NonInterferingBase
{
   template<typename... Args>
   static std::shared_ptr<T> make_shared(Args &&...args)
   {
      return std::
#ifdef __APPLE__
         // shared_ptr must be constructed from unique_ptr on Mac
         make_unique
#else
         make_shared
#endif
                    <T>(std::forward<Args>(args)...);
   }
};
 
template< typename T > struct NonInterfering
   : NonInterferingBase // Inherit operators; use empty base class optimization
   , T
{
   using T::T;
 
   void Set(const T &other)
   {
      T::operator =(other);
   }
 
   void Set(T &&other)
   {
      T::operator =(std::move(other));
   }
};
 
// These macros are used widely, so declared here.
#define QUANTIZED_TIME(time, rate) (floor(((double)(time) * (rate)) + 0.5) / (rate))
// dB - linear amplitude conversions
#define DB_TO_LINEAR(x) (pow(10.0, (x) / 20.0))
#define LINEAR_TO_DB(x) (20.0 * log10(x))
 
#define MAX_AUDIO (1. - 1./(1<<15))
 
template<typename T>
struct AtomicUniquePointer : public std::atomic<T*> {
   static_assert(AtomicUniquePointer::is_always_lock_free);
   using std::atomic<T*>::atomic;
 
   void reset(T *p = nullptr) {
      delete this->exchange(p, std::memory_order_release);
   }
   template<typename... Args> void emplace(Args &&... args) {
      reset(safenew T(std::forward<Args>(args)...));
   }
   ~AtomicUniquePointer() { reset(); }
private:
   using std::atomic<T*>::fetch_add;
   using std::atomic<T*>::fetch_sub;
};
 
inline bool IsLittleEndian() noexcept
{
   const std::uint32_t x = 1u;
   return static_cast<const unsigned char*>(static_cast<const void*>(&x))[0];
   // We will assume the same for other widths!
}
 
template <typename IntType>
constexpr IntType SwapIntBytes(IntType value) noexcept
{
   static_assert(std::is_integral<IntType>::value, "Integral type required");
 
   constexpr auto size = sizeof(IntType);
 
   static_assert(
      size == 1 || size == 2 || size == 4 || size == 8, "Unsupported size");
 
   if constexpr (size == 1)
      return value;
   else if constexpr (size == 2)
      return (value >> 8) | (value << 8);
   else if constexpr (size == 4) // On x86, this (and 64 bit version) is a single instruction! (At least, clang is smart enough to do that)
      return ((value >> 24) & 0xFF) | ((value >> 8) & 0xFF00) |
             ((value << 8) & 0xFF0000) | ((value << 24) & 0xFF000000);
   else if constexpr (size == 8)
      return ((value >> 56) & 0xFF) | ((value >> 40) & 0xFF00) |
             ((value >> 24) & 0xFF0000) | ((value >> 8) & 0xFF000000) |
             ((value << 8) & 0xFF00000000) | ((value << 24) & 0xFF0000000000) |
             ((value << 40) & 0xFF000000000000) |
             ((value << 56) & 0xFF00000000000000);
 
   // Unreachable
   return value;
}
 
#endif // __AUDACITY_MEMORY_X_H__