OVR_Alg.h

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/************************************************************************************

PublicHeader:   OVR.h
Filename    :   OVR_Alg.h
Content     :   Simple general purpose algorithms: Sort, Binary Search, etc.
Created     :   September 19, 2012
Notes       : 

Copyright   :   Copyright 2014 Oculus VR, Inc. All Rights reserved.

Licensed under the Oculus VR Rift SDK License Version 3.1 (the "License"); 
you may not use the Oculus VR Rift SDK except in compliance with the License, 
which is provided at the time of installation or download, or which 
otherwise accompanies this software in either electronic or hard copy form.

You may obtain a copy of the License at

http://www.oculusvr.com/licenses/LICENSE-3.1 

Unless required by applicable law or agreed to in writing, the Oculus VR SDK 
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

************************************************************************************/

#ifndef OVR_Alg_h
#define OVR_Alg_h

#include "OVR_Types.h"
#include <string.h>

namespace OVR { namespace Alg {


//-----------------------------------------------------------------------------------
// ***** Operator extensions

template <typename T> OVR_FORCE_INLINE void Swap(T &a, T &b) 
{  T temp(a); a = b; b = temp; }


// ***** min/max are not implemented in Visual Studio 6 standard STL

template <typename T> OVR_FORCE_INLINE const T Min(const T a, const T b)
{ return (a < b) ? a : b; }

template <typename T> OVR_FORCE_INLINE const T Max(const T a, const T b)
{ return (b < a) ? a : b; }

template <typename T> OVR_FORCE_INLINE const T Clamp(const T v, const T minVal, const T maxVal)
{ return Max<T>(minVal, Min<T>(v, maxVal)); }

template <typename T> OVR_FORCE_INLINE int     Chop(T f)
{ return (int)f; }

template <typename T> OVR_FORCE_INLINE T       Lerp(T a, T b, T f) 
{ return (b - a) * f + a; }


// These functions stand to fix a stupid VC++ warning (with /Wp64 on):
// "warning C4267: 'argument' : conversion from 'size_t' to 'const unsigned', possible loss of data"
// Use these functions instead of gmin/gmax if the argument has size
// of the pointer to avoid the warning. Though, functionally they are
// absolutelly the same as regular gmin/gmax.
template <typename T>   OVR_FORCE_INLINE const T PMin(const T a, const T b)
{
    OVR_COMPILER_ASSERT(sizeof(T) == sizeof(UPInt));
    return (a < b) ? a : b;
}
template <typename T>   OVR_FORCE_INLINE const T PMax(const T a, const T b)
{
    OVR_COMPILER_ASSERT(sizeof(T) == sizeof(UPInt));
    return (b < a) ? a : b;
}


template <typename T>   OVR_FORCE_INLINE const T Abs(const T v)
{ return (v>=0) ? v : -v; }


//-----------------------------------------------------------------------------------
// ***** OperatorLess
//
template<class T> struct OperatorLess
{
    static bool Compare(const T& a, const T& b)
    {
        return a < b;
    }
};


//-----------------------------------------------------------------------------------
// ***** QuickSortSliced
//
// Sort any part of any array: plain, Array, ArrayPaged, ArrayUnsafe.
// The range is specified with start, end, where "end" is exclusive!
// The comparison predicate must be specified.
template<class Array, class Less> 
void QuickSortSliced(Array& arr, UPInt start, UPInt end, Less less)
{
    enum 
    {
        Threshold = 9
    };

    if(end - start <  2) return;

    SPInt  stack[80];
    SPInt* top   = stack; 
    SPInt  base  = (SPInt)start;
    SPInt  limit = (SPInt)end;

    for(;;)
    {
        SPInt len = limit - base;
        SPInt i, j, pivot;

        if(len > Threshold)
        {
            // we use base + len/2 as the pivot
            pivot = base + len / 2;
            Swap(arr[base], arr[pivot]);

            i = base + 1;
            j = limit - 1;

            // now ensure that *i <= *base <= *j 
            if(less(arr[j],    arr[i])) Swap(arr[j],    arr[i]);
            if(less(arr[base], arr[i])) Swap(arr[base], arr[i]);
            if(less(arr[j], arr[base])) Swap(arr[j], arr[base]);

            for(;;)
            {
                do i++; while( less(arr[i], arr[base]) );
                do j--; while( less(arr[base], arr[j]) );

                if( i > j )
                {
                    break;
                }

                Swap(arr[i], arr[j]);
            }

            Swap(arr[base], arr[j]);

            // now, push the largest sub-array
            if(j - base > limit - i)
            {
                top[0] = base;
                top[1] = j;
                base   = i;
            }
            else
            {
                top[0] = i;
                top[1] = limit;
                limit  = j;
            }
            top += 2;
        }
        else
        {
            // the sub-array is small, perform insertion sort
            j = base;
            i = j + 1;

            for(; i < limit; j = i, i++)
            {
                for(; less(arr[j + 1], arr[j]); j--)
                {
                    Swap(arr[j + 1], arr[j]);
                    if(j == base)
                    {
                        break;
                    }
                }
            }
            if(top > stack)
            {
                top  -= 2;
                base  = top[0];
                limit = top[1];
            }
            else
            {
                break;
            }
        }
    }
}


//-----------------------------------------------------------------------------------
// ***** QuickSortSliced
//
// Sort any part of any array: plain, Array, ArrayPaged, ArrayUnsafe.
// The range is specified with start, end, where "end" is exclusive!
// The data type must have a defined "<" operator.
template<class Array> 
void QuickSortSliced(Array& arr, UPInt start, UPInt end)
{
    typedef typename Array::ValueType ValueType;
    QuickSortSliced(arr, start, end, OperatorLess<ValueType>::Compare);
}

// Same as corresponding G_QuickSortSliced but with checking array limits to avoid
// crash in the case of wrong comparator functor.
template<class Array, class Less> 
bool QuickSortSlicedSafe(Array& arr, UPInt start, UPInt end, Less less)
{
    enum 
    {
        Threshold = 9
    };

    if(end - start <  2) return true;

    SPInt  stack[80];
    SPInt* top   = stack; 
    SPInt  base  = (SPInt)start;
    SPInt  limit = (SPInt)end;

    for(;;)
    {
        SPInt len = limit - base;
        SPInt i, j, pivot;

        if(len > Threshold)
        {
            // we use base + len/2 as the pivot
            pivot = base + len / 2;
            Swap(arr[base], arr[pivot]);

            i = base + 1;
            j = limit - 1;

            // now ensure that *i <= *base <= *j 
            if(less(arr[j],    arr[i])) Swap(arr[j],    arr[i]);
            if(less(arr[base], arr[i])) Swap(arr[base], arr[i]);
            if(less(arr[j], arr[base])) Swap(arr[j], arr[base]);

            for(;;)
            {
                do 
                {   
                    i++; 
                    if (i >= limit)
                        return false;
                } while( less(arr[i], arr[base]) );
                do 
                {
                    j--; 
                    if (j < 0)
                        return false;
                } while( less(arr[base], arr[j]) );

                if( i > j )
                {
                    break;
                }

                Swap(arr[i], arr[j]);
            }

            Swap(arr[base], arr[j]);

            // now, push the largest sub-array
            if(j - base > limit - i)
            {
                top[0] = base;
                top[1] = j;
                base   = i;
            }
            else
            {
                top[0] = i;
                top[1] = limit;
                limit  = j;
            }
            top += 2;
        }
        else
        {
            // the sub-array is small, perform insertion sort
            j = base;
            i = j + 1;

            for(; i < limit; j = i, i++)
            {
                for(; less(arr[j + 1], arr[j]); j--)
                {
                    Swap(arr[j + 1], arr[j]);
                    if(j == base)
                    {
                        break;
                    }
                }
            }
            if(top > stack)
            {
                top  -= 2;
                base  = top[0];
                limit = top[1];
            }
            else
            {
                break;
            }
        }
    }
    return true;
}

template<class Array> 
bool QuickSortSlicedSafe(Array& arr, UPInt start, UPInt end)
{
    typedef typename Array::ValueType ValueType;
    return QuickSortSlicedSafe(arr, start, end, OperatorLess<ValueType>::Compare);
}

//-----------------------------------------------------------------------------------
// ***** QuickSort
//
// Sort an array Array, ArrayPaged, ArrayUnsafe.
// The array must have GetSize() function.
// The comparison predicate must be specified.
template<class Array, class Less> 
void QuickSort(Array& arr, Less less)
{
    QuickSortSliced(arr, 0, arr.GetSize(), less);
}

// checks for boundaries
template<class Array, class Less> 
bool QuickSortSafe(Array& arr, Less less)
{
    return QuickSortSlicedSafe(arr, 0, arr.GetSize(), less);
}


//-----------------------------------------------------------------------------------
// ***** QuickSort
//
// Sort an array Array, ArrayPaged, ArrayUnsafe.
// The array must have GetSize() function.
// The data type must have a defined "<" operator.
template<class Array> 
void QuickSort(Array& arr)
{
    typedef typename Array::ValueType ValueType;
    QuickSortSliced(arr, 0, arr.GetSize(), OperatorLess<ValueType>::Compare);
}

template<class Array> 
bool QuickSortSafe(Array& arr)
{
    typedef typename Array::ValueType ValueType;
    return QuickSortSlicedSafe(arr, 0, arr.GetSize(), OperatorLess<ValueType>::Compare);
}

//-----------------------------------------------------------------------------------
// ***** InsertionSortSliced
//
// Sort any part of any array: plain, Array, ArrayPaged, ArrayUnsafe.
// The range is specified with start, end, where "end" is exclusive!
// The comparison predicate must be specified.
// Unlike Quick Sort, the Insertion Sort works much slower in average, 
// but may be much faster on almost sorted arrays. Besides, it guarantees
// that the elements will not be swapped if not necessary. For example, 
// an array with all equal elements will remain "untouched", while 
// Quick Sort will considerably shuffle the elements in this case.
template<class Array, class Less> 
void InsertionSortSliced(Array& arr, UPInt start, UPInt end, Less less)
{
    UPInt j = start;
    UPInt i = j + 1;
    UPInt limit = end;

    for(; i < limit; j = i, i++)
    {
        for(; less(arr[j + 1], arr[j]); j--)
        {
            Swap(arr[j + 1], arr[j]);
            if(j <= start)
            {
                break;
            }
        }
    }
}


//-----------------------------------------------------------------------------------
// ***** InsertionSortSliced
//
// Sort any part of any array: plain, Array, ArrayPaged, ArrayUnsafe.
// The range is specified with start, end, where "end" is exclusive!
// The data type must have a defined "<" operator.
template<class Array> 
void InsertionSortSliced(Array& arr, UPInt start, UPInt end)
{
    typedef typename Array::ValueType ValueType;
    InsertionSortSliced(arr, start, end, OperatorLess<ValueType>::Compare);
}

//-----------------------------------------------------------------------------------
// ***** InsertionSort
//
// Sort an array Array, ArrayPaged, ArrayUnsafe.
// The array must have GetSize() function.
// The comparison predicate must be specified.

template<class Array, class Less> 
void InsertionSort(Array& arr, Less less)
{
    InsertionSortSliced(arr, 0, arr.GetSize(), less);
}

//-----------------------------------------------------------------------------------
// ***** InsertionSort
//
// Sort an array Array, ArrayPaged, ArrayUnsafe.
// The array must have GetSize() function.
// The data type must have a defined "<" operator.
template<class Array> 
void InsertionSort(Array& arr)
{
    typedef typename Array::ValueType ValueType;
    InsertionSortSliced(arr, 0, arr.GetSize(), OperatorLess<ValueType>::Compare);
}

//-----------------------------------------------------------------------------------
// ***** Median
// Returns a median value of the input array.
// Caveats: partially sorts the array, returns a reference to the array element
// TBD: This needs to be optimized and generalized
//
template<class Array> 
typename Array::ValueType& Median(Array& arr)
{
    UPInt count = arr.GetSize();
    UPInt mid = (count - 1) / 2;
    OVR_ASSERT(count > 0);

    for (UPInt j = 0; j <= mid; j++)
    {
        UPInt min = j;
        for (UPInt k = j + 1; k < count; k++)
            if (arr[k] < arr[min]) 
                min = k;
        Swap(arr[j], arr[min]);
    }
    return arr[mid];
}

//-----------------------------------------------------------------------------------
// ***** LowerBoundSliced
//
template<class Array, class Value, class Less>
UPInt LowerBoundSliced(const Array& arr, UPInt start, UPInt end, const Value& val, Less less)
{
    SPInt first = (SPInt)start;
    SPInt len   = (SPInt)(end - start);
    SPInt half;
    SPInt middle;
    
    while(len > 0) 
    {
        half = len >> 1;
        middle = first + half;
        if(less(arr[middle], val)) 
        {
            first = middle + 1;
            len   = len - half - 1;
        }
        else
        {
            len = half;
        }
    }
    return (UPInt)first;
}


//-----------------------------------------------------------------------------------
// ***** LowerBoundSliced
//
template<class Array, class Value>
UPInt LowerBoundSliced(const Array& arr, UPInt start, UPInt end, const Value& val)
{
    return LowerBoundSliced(arr, start, end, val, OperatorLess<Value>::Compare);
}

//-----------------------------------------------------------------------------------
// ***** LowerBoundSized
//
template<class Array, class Value>
UPInt LowerBoundSized(const Array& arr, UPInt size, const Value& val)
{
    return LowerBoundSliced(arr, 0, size, val, OperatorLess<Value>::Compare);
}

//-----------------------------------------------------------------------------------
// ***** LowerBound
//
template<class Array, class Value, class Less>
UPInt LowerBound(const Array& arr, const Value& val, Less less)
{
    return LowerBoundSliced(arr, 0, arr.GetSize(), val, less);
}


//-----------------------------------------------------------------------------------
// ***** LowerBound
//
template<class Array, class Value>
UPInt LowerBound(const Array& arr, const Value& val)
{
    return LowerBoundSliced(arr, 0, arr.GetSize(), val, OperatorLess<Value>::Compare);
}



//-----------------------------------------------------------------------------------
// ***** UpperBoundSliced
//
template<class Array, class Value, class Less>
UPInt UpperBoundSliced(const Array& arr, UPInt start, UPInt end, const Value& val, Less less)
{
    SPInt first = (SPInt)start;
    SPInt len   = (SPInt)(end - start);
    SPInt half;
    SPInt middle;
    
    while(len > 0) 
    {
        half = len >> 1;
        middle = first + half;
        if(less(val, arr[middle]))
        {
            len = half;
        }
        else 
        {
            first = middle + 1;
            len   = len - half - 1;
        }
    }
    return (UPInt)first;
}


//-----------------------------------------------------------------------------------
// ***** UpperBoundSliced
//
template<class Array, class Value>
UPInt UpperBoundSliced(const Array& arr, UPInt start, UPInt end, const Value& val)
{
    return UpperBoundSliced(arr, start, end, val, OperatorLess<Value>::Compare);
}


//-----------------------------------------------------------------------------------
// ***** UpperBoundSized
//
template<class Array, class Value>
UPInt UpperBoundSized(const Array& arr, UPInt size, const Value& val)
{
    return UpperBoundSliced(arr, 0, size, val, OperatorLess<Value>::Compare);
}


//-----------------------------------------------------------------------------------
// ***** UpperBound
//
template<class Array, class Value, class Less>
UPInt UpperBound(const Array& arr, const Value& val, Less less)
{
    return UpperBoundSliced(arr, 0, arr.GetSize(), val, less);
}


//-----------------------------------------------------------------------------------
// ***** UpperBound
//
template<class Array, class Value>
UPInt UpperBound(const Array& arr, const Value& val)
{
    return UpperBoundSliced(arr, 0, arr.GetSize(), val, OperatorLess<Value>::Compare);
}


//-----------------------------------------------------------------------------------
// ***** ReverseArray
//
template<class Array> void ReverseArray(Array& arr)
{
    SPInt from = 0;
    SPInt to   = arr.GetSize() - 1;
    while(from < to)
    {
        Swap(arr[from], arr[to]);
        ++from;
        --to;
    }
}


// ***** AppendArray
//
template<class CDst, class CSrc> 
void AppendArray(CDst& dst, const CSrc& src)
{
    UPInt i;
    for(i = 0; i < src.GetSize(); i++) 
        dst.PushBack(src[i]);
}

//-----------------------------------------------------------------------------------
// ***** ArrayAdaptor
//
// A simple adapter that provides the GetSize() method and overloads 
// operator []. Used to wrap plain arrays in QuickSort and such.
template<class T> class ArrayAdaptor
{
public:
    typedef T ValueType;
    ArrayAdaptor() : Data(0), Size(0) {}
    ArrayAdaptor(T* ptr, UPInt size) : Data(ptr), Size(size) {}
    UPInt GetSize() const { return Size; }
    const T& operator [] (UPInt i) const { return Data[i]; }
          T& operator [] (UPInt i)       { return Data[i]; }
private:
    T*      Data;
    UPInt   Size;
};


//-----------------------------------------------------------------------------------
// ***** GConstArrayAdaptor
//
// A simple const adapter that provides the GetSize() method and overloads 
// operator []. Used to wrap plain arrays in LowerBound and such.
template<class T> class ConstArrayAdaptor
{
public:
    typedef T ValueType;
    ConstArrayAdaptor() : Data(0), Size(0) {}
    ConstArrayAdaptor(const T* ptr, UPInt size) : Data(ptr), Size(size) {}
    UPInt GetSize() const { return Size; }
    const T& operator [] (UPInt i) const { return Data[i]; }
private:
    const T* Data;
    UPInt    Size;
};



//-----------------------------------------------------------------------------------
extern const UByte UpperBitTable[256];
extern const UByte LowerBitTable[256];



//-----------------------------------------------------------------------------------
inline UByte UpperBit(UPInt val)
{
#ifndef OVR_64BIT_POINTERS

    if (val & 0xFFFF0000)
    {
        return (val & 0xFF000000) ? 
            UpperBitTable[(val >> 24)       ] + 24: 
            UpperBitTable[(val >> 16) & 0xFF] + 16;
    }
    return (val & 0xFF00) ?
        UpperBitTable[(val >> 8) & 0xFF] + 8:
        UpperBitTable[(val     ) & 0xFF];

#else

    if (val & 0xFFFFFFFF00000000)
    {
        if (val & 0xFFFF000000000000)
        {
            return (val & 0xFF00000000000000) ?
                UpperBitTable[(val >> 56)       ] + 56: 
                UpperBitTable[(val >> 48) & 0xFF] + 48;
        }
        return (val & 0xFF0000000000) ?
            UpperBitTable[(val >> 40) & 0xFF] + 40:
            UpperBitTable[(val >> 32) & 0xFF] + 32;
    }
    else
    {
        if (val & 0xFFFF0000)
        {
            return (val & 0xFF000000) ? 
                UpperBitTable[(val >> 24)       ] + 24: 
                UpperBitTable[(val >> 16) & 0xFF] + 16;
        }
        return (val & 0xFF00) ?
            UpperBitTable[(val >> 8) & 0xFF] + 8:
            UpperBitTable[(val     ) & 0xFF];
    }

#endif
}

//-----------------------------------------------------------------------------------
inline UByte LowerBit(UPInt val)
{
#ifndef OVR_64BIT_POINTERS

    if (val & 0xFFFF)
    {
        return (val & 0xFF) ?
            LowerBitTable[ val & 0xFF]:
            LowerBitTable[(val >> 8) & 0xFF] + 8;
    }
    return (val & 0xFF0000) ?
            LowerBitTable[(val >> 16) & 0xFF] + 16:
            LowerBitTable[(val >> 24) & 0xFF] + 24;

#else

    if (val & 0xFFFFFFFF)
    {
        if (val & 0xFFFF)
        {
            return (val & 0xFF) ?
                LowerBitTable[ val & 0xFF]:
                LowerBitTable[(val >> 8) & 0xFF] + 8;
        }
        return (val & 0xFF0000) ?
                LowerBitTable[(val >> 16) & 0xFF] + 16:
                LowerBitTable[(val >> 24) & 0xFF] + 24;
    }
    else
    {
        if (val & 0xFFFF00000000)
        {
             return (val & 0xFF00000000) ?
                LowerBitTable[(val >> 32) & 0xFF] + 32:
                LowerBitTable[(val >> 40) & 0xFF] + 40;
        }
        return (val & 0xFF000000000000) ?
            LowerBitTable[(val >> 48) & 0xFF] + 48:
            LowerBitTable[(val >> 56) & 0xFF] + 56;
    }

#endif
}



// ******* Special (optimized) memory routines
// Note: null (bad) pointer is not tested
class MemUtil
{
public:
                                    
    // Memory compare
    static int      Cmp  (const void* p1, const void* p2, UPInt byteCount)      { return memcmp(p1, p2, byteCount); }
    static int      Cmp16(const void* p1, const void* p2, UPInt int16Count);
    static int      Cmp32(const void* p1, const void* p2, UPInt int32Count);
    static int      Cmp64(const void* p1, const void* p2, UPInt int64Count); 
};

// ** Inline Implementation

inline int MemUtil::Cmp16(const void* p1, const void* p2, UPInt int16Count)
{
    SInt16*  pa  = (SInt16*)p1; 
    SInt16*  pb  = (SInt16*)p2;
    unsigned ic  = 0;
    if (int16Count == 0)
        return 0;
    while (pa[ic] == pb[ic])
        if (++ic==int16Count)
            return 0;
    return pa[ic] > pb[ic] ? 1 : -1;
}
inline int MemUtil::Cmp32(const void* p1, const void* p2, UPInt int32Count)
{
    SInt32*  pa  = (SInt32*)p1;
    SInt32*  pb  = (SInt32*)p2;
    unsigned ic  = 0;
    if (int32Count == 0)
        return 0;
    while (pa[ic] == pb[ic])
        if (++ic==int32Count)
            return 0;
    return pa[ic] > pb[ic] ? 1 : -1;
}
inline int MemUtil::Cmp64(const void* p1, const void* p2, UPInt int64Count)
{
    SInt64*  pa  = (SInt64*)p1;
    SInt64*  pb  = (SInt64*)p2;
    unsigned ic  = 0;
    if (int64Count == 0)
        return 0;
    while (pa[ic] == pb[ic])
        if (++ic==int64Count)
            return 0;
    return pa[ic] > pb[ic] ? 1 : -1;
}

// ** End Inline Implementation


//-----------------------------------------------------------------------------------
// ******* Byte Order Conversions
namespace ByteUtil {

    // *** Swap Byte Order

    // Swap the byte order of a byte array
    inline void     SwapOrder(void* pv, int size)
    {
        UByte*  pb = (UByte*)pv;
        UByte   temp;
        for (int i = 0; i < size>>1; i++)
        { 
            temp            = pb[size-1-i];
            pb[size-1-i]    = pb[i];
            pb[i]           = temp; 
        }
    }

    // Swap the byte order of primitive types
    inline UByte    SwapOrder(UByte v)      { return v; }
    inline SByte    SwapOrder(SByte v)      { return v; }
    inline UInt16   SwapOrder(UInt16 v)     { return UInt16(v>>8)|UInt16(v<<8); }
    inline SInt16   SwapOrder(SInt16 v)     { return SInt16((UInt16(v)>>8)|(v<<8)); }
    inline UInt32   SwapOrder(UInt32 v)     { return (v>>24)|((v&0x00FF0000)>>8)|((v&0x0000FF00)<<8)|(v<<24); }
    inline SInt32   SwapOrder(SInt32 p)     { return (SInt32)SwapOrder(UInt32(p)); }
    inline UInt64   SwapOrder(UInt64 v)
    { 
        return   (v>>56) |
                 ((v&UInt64(0x00FF000000000000ULL))>>40) |
                 ((v&UInt64(0x0000FF0000000000ULL))>>24) |
                 ((v&UInt64(0x000000FF00000000ULL))>>8)  |
                 ((v&UInt64(0x00000000FF000000ULL))<<8)  |
                 ((v&UInt64(0x0000000000FF0000ULL))<<24) |
                 ((v&UInt64(0x000000000000FF00ULL))<<40) |
                 (v<<56); 
    }
    inline SInt64   SwapOrder(SInt64 v)     { return (SInt64)SwapOrder(UInt64(v)); }
    inline float    SwapOrder(float p)      
    { 
        union {
            float p;
            UInt32 v;
        } u;
        u.p = p;
        u.v = SwapOrder(u.v);
        return u.p;
    }

    inline double   SwapOrder(double p)
    { 
        union {
            double p;
            UInt64 v;
        } u;
        u.p = p;
        u.v = SwapOrder(u.v);
        return u.p;
    }
    
    // *** Byte-order conversion

#if (OVR_BYTE_ORDER == OVR_LITTLE_ENDIAN)
    // Little Endian to System (LE)
    inline UByte    LEToSystem(UByte  v)    { return v; }
    inline SByte    LEToSystem(SByte  v)    { return v; }
    inline UInt16   LEToSystem(UInt16 v)    { return v; }
    inline SInt16   LEToSystem(SInt16 v)    { return v; }
    inline UInt32   LEToSystem(UInt32 v)    { return v; }
    inline SInt32   LEToSystem(SInt32 v)    { return v; }
    inline UInt64   LEToSystem(UInt64 v)    { return v; }
    inline SInt64   LEToSystem(SInt64 v)    { return v; }
    inline float    LEToSystem(float  v)    { return v; }
    inline double   LEToSystem(double v)    { return v; }

    // Big Endian to System (LE)
    inline UByte    BEToSystem(UByte  v)    { return SwapOrder(v); }
    inline SByte    BEToSystem(SByte  v)    { return SwapOrder(v); }
    inline UInt16   BEToSystem(UInt16 v)    { return SwapOrder(v); }
    inline SInt16   BEToSystem(SInt16 v)    { return SwapOrder(v); }
    inline UInt32   BEToSystem(UInt32 v)    { return SwapOrder(v); }
    inline SInt32   BEToSystem(SInt32 v)    { return SwapOrder(v); }
    inline UInt64   BEToSystem(UInt64 v)    { return SwapOrder(v); }
    inline SInt64   BEToSystem(SInt64 v)    { return SwapOrder(v); }
    inline float    BEToSystem(float  v)    { return SwapOrder(v); }
    inline double   BEToSystem(double v)    { return SwapOrder(v); }

    // System (LE) to Little Endian
    inline UByte    SystemToLE(UByte  v)    { return v; }
    inline SByte    SystemToLE(SByte  v)    { return v; }
    inline UInt16   SystemToLE(UInt16 v)    { return v; }
    inline SInt16   SystemToLE(SInt16 v)    { return v; }
    inline UInt32   SystemToLE(UInt32 v)    { return v; }
    inline SInt32   SystemToLE(SInt32 v)    { return v; }
    inline UInt64   SystemToLE(UInt64 v)    { return v; }
    inline SInt64   SystemToLE(SInt64 v)    { return v; }
    inline float    SystemToLE(float  v)    { return v; }
    inline double   SystemToLE(double v)    { return v; }   

    // System (LE) to Big Endian
    inline UByte    SystemToBE(UByte  v)    { return SwapOrder(v); }
    inline SByte    SystemToBE(SByte  v)    { return SwapOrder(v); }
    inline UInt16   SystemToBE(UInt16 v)    { return SwapOrder(v); }
    inline SInt16   SystemToBE(SInt16 v)    { return SwapOrder(v); }
    inline UInt32   SystemToBE(UInt32 v)    { return SwapOrder(v); }
    inline SInt32   SystemToBE(SInt32 v)    { return SwapOrder(v); }
    inline UInt64   SystemToBE(UInt64 v)    { return SwapOrder(v); }
    inline SInt64   SystemToBE(SInt64 v)    { return SwapOrder(v); }
    inline float    SystemToBE(float  v)    { return SwapOrder(v); }
    inline double   SystemToBE(double v)    { return SwapOrder(v); }

#elif (OVR_BYTE_ORDER == OVR_BIG_ENDIAN)
    // Little Endian to System (BE)
    inline UByte    LEToSystem(UByte  v)    { return SwapOrder(v); }
    inline SByte    LEToSystem(SByte  v)    { return SwapOrder(v); }
    inline UInt16   LEToSystem(UInt16 v)    { return SwapOrder(v); }
    inline SInt16   LEToSystem(SInt16 v)    { return SwapOrder(v); }
    inline UInt32   LEToSystem(UInt32 v)    { return SwapOrder(v); }
    inline SInt32   LEToSystem(SInt32 v)    { return SwapOrder(v); }
    inline UInt64   LEToSystem(UInt64 v)    { return SwapOrder(v); }
    inline SInt64   LEToSystem(SInt64 v)    { return SwapOrder(v); }
    inline float    LEToSystem(float  v)    { return SwapOrder(v); }
    inline double   LEToSystem(double v)    { return SwapOrder(v); }

    // Big Endian to System (BE)
    inline UByte    BEToSystem(UByte  v)    { return v; }
    inline SByte    BEToSystem(SByte  v)    { return v; }
    inline UInt16   BEToSystem(UInt16 v)    { return v; }
    inline SInt16   BEToSystem(SInt16 v)    { return v; }
    inline UInt32   BEToSystem(UInt32 v)    { return v; }
    inline SInt32   BEToSystem(SInt32 v)    { return v; }
    inline UInt64   BEToSystem(UInt64 v)    { return v; }
    inline SInt64   BEToSystem(SInt64 v)    { return v; }
    inline float    BEToSystem(float  v)    { return v; }
    inline double   BEToSystem(double v)    { return v; }

    // System (BE) to Little Endian
    inline UByte    SystemToLE(UByte  v)    { return SwapOrder(v); }
    inline SByte    SystemToLE(SByte  v)    { return SwapOrder(v); }
    inline UInt16   SystemToLE(UInt16 v)    { return SwapOrder(v); }
    inline SInt16   SystemToLE(SInt16 v)    { return SwapOrder(v); }
    inline UInt32   SystemToLE(UInt32 v)    { return SwapOrder(v); }
    inline SInt32   SystemToLE(SInt32 v)    { return SwapOrder(v); }
    inline UInt64   SystemToLE(UInt64 v)    { return SwapOrder(v); }
    inline SInt64   SystemToLE(SInt64 v)    { return SwapOrder(v); }
    inline float    SystemToLE(float  v)    { return SwapOrder(v); }
    inline double   SystemToLE(double v)    { return SwapOrder(v); }

    // System (BE) to Big Endian
    inline UByte    SystemToBE(UByte  v)    { return v; }
    inline SByte    SystemToBE(SByte  v)    { return v; }
    inline UInt16   SystemToBE(UInt16 v)    { return v; }
    inline SInt16   SystemToBE(SInt16 v)    { return v; }
    inline UInt32   SystemToBE(UInt32 v)    { return v; }
    inline SInt32   SystemToBE(SInt32 v)    { return v; }
    inline UInt64   SystemToBE(UInt64 v)    { return v; }
    inline SInt64   SystemToBE(SInt64 v)    { return v; }
    inline float    SystemToBE(float  v)    { return v; }
    inline double   SystemToBE(double v)    { return v; }

#else
    #error "OVR_BYTE_ORDER must be defined to OVR_LITTLE_ENDIAN or OVR_BIG_ENDIAN"
#endif

} // namespace ByteUtil



// Used primarily for hardware interfacing such as sensor reports, firmware, etc.
// Reported data is all little-endian.
inline UInt16 DecodeUInt16(const UByte* buffer)
{
    return ByteUtil::LEToSystem ( *(const UInt16*)buffer );
}

inline SInt16 DecodeSInt16(const UByte* buffer)
{
    return ByteUtil::LEToSystem ( *(const SInt16*)buffer );
}

inline UInt32 DecodeUInt32(const UByte* buffer)
{    
    return ByteUtil::LEToSystem ( *(const UInt32*)buffer );
}

inline SInt32 DecodeSInt32(const UByte* buffer)
{    
    return ByteUtil::LEToSystem ( *(const SInt32*)buffer );
}

inline float DecodeFloat(const UByte* buffer)
{
    union {
        UInt32 U;
        float  F;
    };

    U = DecodeUInt32(buffer);
    return F;
}

inline void EncodeUInt16(UByte* buffer, UInt16 val)
{
    *(UInt16*)buffer = ByteUtil::SystemToLE ( val );
}

inline void EncodeSInt16(UByte* buffer, SInt16 val)
{
    *(SInt16*)buffer = ByteUtil::SystemToLE ( val );
}

inline void EncodeUInt32(UByte* buffer, UInt32 val)
{
    *(UInt32*)buffer = ByteUtil::SystemToLE ( val );
}

inline void EncodeSInt32(UByte* buffer, SInt32 val)
{
    *(SInt32*)buffer = ByteUtil::SystemToLE ( val );
}

inline void EncodeFloat(UByte* buffer, float val)
{
    union {
        UInt32 U;
        float  F;
    };

    F = val;
    EncodeUInt32(buffer, U);
}

// Converts an 8-bit binary-coded decimal
inline SByte DecodeBCD(UByte byte)
{
    UByte digit1 = (byte >> 4) & 0x0f;
    UByte digit2 = byte & 0x0f;
    int decimal = digit1 * 10 + digit2;   // maximum value = 99
    return (SByte)decimal;
}


}} // OVR::Alg

#endif