AAX_Alignment.h

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/*================================================================================================*/
/*
 *  Copyright 2009-2015, 2023 Avid Technology, Inc.
 *  All rights reserved.
 *  
 *  CONFIDENTIAL: this document contains confidential information of Avid. Do
 *  not disclose to any third party. Use of the information contained in this
 *  document is subject to an Avid SDK license.
 */
 
/*================================================================================================*/
 
#ifndef AAX_ALIGNMENT_H
#define AAX_ALIGNMENT_H
 
#include <stddef.h>
 
namespace AAX
{
 
    inline void alignFree(void *p)
    {   
        char** aTempPtr=reinterpret_cast<char**>(p);
        aTempPtr--;                         //backup 4 bytes past the beginning of the buffer
        char* aRealPtr = aTempPtr[0];       //Get the real address
 
        if(aRealPtr)
            ::delete[] aRealPtr;
    }
 
    template <class T> 
    T* alignMalloc(int iArraySize, int iAlignment)
    {
        // We can seriously mess ourselves up if alignment is not a power of 2
        if ((iAlignment != 2) && (iAlignment != 4) && (iAlignment != 8) && (iAlignment != 16) && (iAlignment != 32)) {
            return 0;
        }
        // We can't allocate a negative-size array
        if (iArraySize <= 0) {
            return 0;
        }
 
        const unsigned int cSizeOfPointer = sizeof(char*);
        // Over-allocate memory by the maximum offset we could be from our requested alignment
        char* aRealPtr = ::new char[iArraySize*sizeof(T) + iAlignment + cSizeOfPointer];
        if (!aRealPtr) {
            return 0;
        }
        char* p=aRealPtr;
        p+=cSizeOfPointer;  //Skip four bytes (we store the real base address here)
        size_t mod = size_t(p) & (iAlignment-1);
        if (mod)
            p += (iAlignment - mod);
        *reinterpret_cast<char**>(p-cSizeOfPointer)=aRealPtr;   //Save the real address.  We'll need it for delete.
        return (T*) p;
    }
} // namespace AAX
 
#endif //AAX_ALIGNMENT_H