D3dcache.cpp

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/****************************************************************************************/
/*  D3DCache.cpp                                                                        */
/*                                                                                      */
/*  Author: John Pollard                                                                */
/*  Description: D3D cache manager                                                      */
/*                                                                                      */
/*  02/25/2001 Wendell Buckner
/*   This texture pointer is no longer valid under directx 7.  Set it to TRUE so there is
/*   something there when  the code does assert checks.
/*  07/16/2000 Wendell Buckner
/*   Convert to Directx7...    
/*                                                                                      */
/*  The contents of this file are subject to the Genesis3D Public License               */
/*  Version 1.01 (the "License"); you may not use this file except in                   */
/*  compliance with the License. You may obtain a copy of the License at                */
/*  http://www.genesis3d.com                                                            */
/*                                                                                      */
/*  Software distributed under the License is distributed on an "AS IS"                 */
/*  basis, WITHOUT WARRANTY OF ANY KIND, either express or implied.  See                */
/*  the License for the specific language governing rights and limitations              */
/*  under the License.                                                                  */
/*                                                                                      */
/*  The Original Code is Genesis3D, released March 25, 1999.                            */
/*Genesis3D Version 1.1 released November 15, 1999                            */
/*  Copyright (C) 1999 WildTangent, Inc. All Rights Reserved           */
/*                                                                                      */
/****************************************************************************************/
#include <Windows.h>
#include <Stdio.h>
#include <Assert.h>
#include <DDraw.h>
#include <D3D.h>

#include "D3DCache.h"

// Cache types are just the different types of textures
// Texutres may vary from width/height/num miplevels/etc...
// Cache types is just a way to combine them to similar types...
#define D3DCACHE_MAX_CACHE_TYPES                128             

//========================================================================================================
//========================================================================================================
typedef struct D3DCache_Type
{
        int32                                   Log;
        int32                                   Width;                                          // Width/Height
        int32                                   Height;
        int32                                   NumMipLevels;
        int32                                   Stage;
        int32                                   RefCount;                                       // How many references to this cache_type

        DDSURFACEDESC2                  ddsd;                                           // DD surface description

        D3DCache_Slot                   *Slots;                                         // Cache slots for this Cache type
        int32                                   NumUsedSlots;                           // Number of slots being used

        D3DCache_Type                   *SelfCheck;
        D3DCache                                *Cache;
} D3DCache_Type;

typedef struct D3DCache
{
        struct D3DCache                 *SelfCheck;

        char                                    Name[D3DCACHE_MAX_NAME];

/* 07/16/2000 Wendell Buckner
    Convert to Directx7...    
        LPDIRECTDRAW4                   lpDD;                                           // DD object for the cache manager */
        LPDIRECTDRAW7                   lpDD;                                           // DD object for the cache manager
        

        DDMemMgr_Partition              *Partition;

        geBoolean                               UseStages;

        D3DCache_Type                   CacheTypes[D3DCACHE_MAX_CACHE_TYPES];   // CacheTypes
} D3DCache;

typedef struct D3DCache_Slot
{
        struct D3DCache_Slot    *SelfCheck;

        D3DCache_Type                   *CacheType;

/* 07/16/2000 Wendell Buckner
    Convert to Directx7...    
        LPDIRECTDRAWSURFACE4    Surface;                                                // The DD surface for this slot
        LPDIRECT3DTEXTURE2              Texture;                                                // The texture interface to the surface */
        LPDIRECTDRAWSURFACE7    Surface;                                                // The DD surface for this slot
        LPDIRECTDRAWSURFACE7    Texture;                                                // The texture interface to the surface

        uint32                                  LRU;                                                    // Current LRU for cache slot
                                                
        void                                    *UserData;

} D3DCache_Slot;

//========================================================================================================
//========================================================================================================

//========================================================================================================
//      D3DCache_Create
//========================================================================================================

/* 07/16/2000 Wendell Buckner
    Convert to Directx7...    
D3DCache *D3DCache_Create(const char *Name, LPDIRECTDRAW4 lpDD, DDMemMgr_Partition *Partition, geBoolean UseStages) */
D3DCache *D3DCache_Create(const char *Name, LPDIRECTDRAW7 lpDD, DDMemMgr_Partition *Partition, geBoolean UseStages)
{
        D3DCache                *Cache;

        assert(strlen(Name) < D3DCACHE_MAX_NAME);

        Cache = (D3DCache*)malloc(sizeof(D3DCache));

        if (!Cache)
                return NULL;

        memset(Cache, 0, sizeof(D3DCache));

        Cache->lpDD = lpDD;

        Cache->Partition = Partition;

        Cache->UseStages = UseStages;

        Cache->SelfCheck = Cache;

        strcpy(Cache->Name, Name);

        return Cache;
}

//========================================================================================================
//      D3DCache_Destroy
//========================================================================================================
void D3DCache_Destroy(D3DCache *Cache)
{
        assert(Cache);

        D3DCache_FreeAllSlots(Cache);

        free(Cache);
}

//========================================================================================================
//      D3DCache_IsValid
//========================================================================================================
geBoolean D3DCache_IsValid(D3DCache *Cache)
{
        if (!Cache)
                return GE_FALSE;

        if (Cache->SelfCheck != Cache)
                return GE_FALSE;

        return GE_TRUE;
}

//========================================================================================================
//========================================================================================================
geBoolean D3DCache_EvictAllSurfaces(D3DCache *Cache)
{
        int32                   i;
        D3DCache_Type   *pCacheType;

        assert(D3DCache_IsValid(Cache));

        for (pCacheType = Cache->CacheTypes, i=0; i< D3DCACHE_MAX_CACHE_TYPES; i++, pCacheType++)
        {
                D3DCache_Slot           *pSlot;
                int32                           s;

                if (!pCacheType->RefCount)
                        continue;

                assert(D3DCache_TypeIsValid(pCacheType));

                for (pSlot = pCacheType->Slots, s=0; s<pCacheType->NumUsedSlots; s++, pSlot++)
                {
                        D3DCache_SlotSetUserData(pSlot, NULL);
                }
        }
        
        return GE_TRUE;
}

//========================================================================================================
//========================================================================================================
D3DCache_Type *D3DCache_FindCacheType(D3DCache *Cache, int32 Width, int32 Height, int32 NumMipLevels, int32 Stage, const DDSURFACEDESC2 *ddsd)
{
        int32                   i;
        D3DCache_Type   *pCacheType;

        assert(D3DCache_IsValid(Cache));

        pCacheType = Cache->CacheTypes;

        for (i=0; i<D3DCACHE_MAX_CACHE_TYPES; i++, pCacheType++)
        {
                if (pCacheType->RefCount == 0)                  // Nobody is using this slot yet
                        continue;

                assert(D3DCache_TypeIsValid(pCacheType));

                if (pCacheType->Width != Width)
                        continue;
                if (pCacheType->Height != Height)
                        continue;

                if (pCacheType->NumMipLevels != NumMipLevels)
                        continue;

                if (pCacheType->Stage != Stage)
                        continue;

                if (memcmp(&pCacheType->ddsd, ddsd, sizeof(DDSURFACEDESC2)))
                        continue;
                
                return pCacheType;                                              // Found a match
        }

        return NULL;                                                            // Cache Type not found!!!
}

//========================================================================================================
//========================================================================================================
D3DCache_Type *D3DCache_InsertCacheType(D3DCache *Cache, int32 Width, int32 Height, int32 NumMipLevels, int32 Stage, const DDSURFACEDESC2 *ddsd)
{
        int32                   i;
        D3DCache_Type   *pCacheType;

        assert(D3DCache_IsValid(Cache));

        pCacheType = Cache->CacheTypes;

        for (i=0; i<D3DCACHE_MAX_CACHE_TYPES; i++, pCacheType++)
        {
                if (pCacheType->RefCount == 0)                  // Nobody is using this slot yet
                        break;
        }

        if (i == D3DCACHE_MAX_CACHE_TYPES)                      // No types left
                return NULL;

        assert(pCacheType->Slots == NULL);
        assert(pCacheType->NumUsedSlots == 0);

        pCacheType->Width = Width;
        pCacheType->Height = Height;
        pCacheType->NumMipLevels = NumMipLevels;
        pCacheType->Stage = Stage;
        pCacheType->ddsd = *ddsd;

        pCacheType->SelfCheck = pCacheType;
        pCacheType->Cache = Cache;

        pCacheType->Log = GetLog(Width, Height);

        // Found one
        pCacheType->RefCount++;

        return pCacheType;
}

//========================================================================================================
//========================================================================================================
D3DCache_Type *D3DCache_TypeCreate(D3DCache *Cache, int32 Width, int32 Height, int32 NumMipLevels, int32 Stage, const DDSURFACEDESC2 *ddsd)
{
        D3DCache_Type           *CacheType;

        assert(D3DCache_IsValid(Cache));

        CacheType = D3DCache_FindCacheType(Cache, Width, Height, NumMipLevels, Stage, ddsd);

        if (CacheType)
        {
                CacheType->RefCount++;
                return CacheType;
        }

        // Could not find one allready in the list, so add a new one...
        return D3DCache_InsertCacheType(Cache, Width, Height, NumMipLevels, Stage, ddsd);
}

//========================================================================================================
//      D3DCache_TypeDestroy
//========================================================================================================
void D3DCache_TypeDestroy(D3DCache_Type *CacheType)
{
        assert(CacheType->RefCount > 0);
        assert(D3DCache_TypeIsValid(CacheType));

        CacheType->RefCount--;

        if (CacheType->RefCount == 0)
        {
                if (CacheType->Slots)
                {
                        D3DCache_Slot   *pSlot;
                        int32                   k;

                        // Go through each slot, and free all the surfaces on them
                        for (pSlot = CacheType->Slots, k=0; k< CacheType->NumUsedSlots; k++, pSlot++)
                        {
                                assert(D3DCache_SlotIsValid(pSlot));
                                assert(pSlot->Surface);
                                assert(pSlot->Texture);

/*   02/25/2001 Wendell Buckner
/*    This texture pointer is no longer valid under directx 7.  Set it to TRUE so there is
/*    something there when  the code does assert checks.
                                if (pSlot->Texture)
                                        pSlot->Texture->Release();*/
                                if (pSlot->Surface)
                                        pSlot->Surface->Release();
                        }

                        free(CacheType->Slots);
                        CacheType->Slots = NULL;
                        CacheType->NumUsedSlots = 0;
                }
        }
}

//========================================================================================================
//      D3DCache_TypeIsValid
//========================================================================================================
geBoolean D3DCache_TypeIsValid(D3DCache_Type *Type)
{
        if (!Type)
                return GE_FALSE;

        if (Type->SelfCheck != Type)
                return GE_FALSE;

        if (!D3DCache_IsValid(Type->Cache))
                return GE_FALSE;

        return GE_TRUE;
}

//========================================================================================================
//      D3DCache_FreeAllSlots
//========================================================================================================
geBoolean D3DCache_FreeAllSlots(D3DCache *Cache)
{
        int32                   i;
        D3DCache_Type   *pCacheType;

        assert(D3DCache_IsValid(Cache));

        pCacheType = Cache->CacheTypes;

        for (i=0; i< D3DCACHE_MAX_CACHE_TYPES; i++, pCacheType++)
        {
                D3DCache_Slot   *pSlot;
                int32                   k;

                assert(pCacheType->RefCount >= 0);

                if (pCacheType->RefCount == 0)
                {
                        assert(pCacheType->Slots == NULL);
                        continue;
                }

                assert(D3DCache_TypeIsValid(pCacheType));

                // Go through each slot, and free all the surfaces on them
                for (pSlot = pCacheType->Slots, k=0; k< pCacheType->NumUsedSlots; k++, pSlot++)
                {
                        assert(D3DCache_SlotIsValid(pSlot));
                        assert(pSlot->Surface);
                        assert(pSlot->Texture);

/*   02/25/2001 Wendell Buckner
/*    This texture pointer is no longer valid under directx 7.  Set it to TRUE so there is
/*    something there when  the code does assert checks.
                        if (pSlot->Texture)
                                pSlot->Texture->Release();*/
                        if (pSlot->Surface)
                                pSlot->Surface->Release();
                }

                if (pCacheType->Slots)
                        free(pCacheType->Slots);

                pCacheType->Slots = NULL;
                pCacheType->NumUsedSlots = 0;
        }

        DDMemMgr_PartitionReset(Cache->Partition);                      // Reset the caches memory manager

        return GE_TRUE;
}

//========================================================================================================
//      D3DCache_WriteToFile
//========================================================================================================
geBoolean D3DCache_WriteToFile(D3DCache *Cache, const char *FileName, geBoolean Append)
{
        int32                   i;
        D3DCache_Type   *pCacheType;
        int32                   TotalRef, TotalUsed;
        SYSTEMTIME              Time;
        FILE                    *f;

        if (Append)
                f = fopen(FileName, "a+t");
        else
                f = fopen(FileName, "w");

        if (!f)
                return GE_FALSE;

        GetSystemTime(&Time);

        fprintf(f, "=======================================================\n");
        fprintf(f, "Date: %i/%i/%i, Time: %i:%i\n", Time.wMonth, Time.wDay, Time.wYear, Time.wHour, Time.wMinute);
        fprintf(f, "Cache Name: %s\n", Cache->Name);
        fprintf(f, "Total Mem: %5i\n", DDMemMgr_PartitionGetTotalMem(Cache->Partition));
        fprintf(f, "Free Mem: %5i\n", DDMemMgr_PartitionGetFreeMem(Cache->Partition));
        fprintf(f, " --- Slots ---\n");

        TotalRef = TotalUsed = 0;

        pCacheType = Cache->CacheTypes;

        for (i=0; i< D3DCACHE_MAX_CACHE_TYPES; i++, pCacheType++)
        {
                if (!pCacheType->RefCount)
                        continue;

                fprintf(f, "Width: %3i, Height %3i, Mips: %2i, Stage: %2i, Ref: %4i, Used: %4i\n",
                        pCacheType->Width, pCacheType->Height, pCacheType->NumMipLevels, pCacheType->Stage, pCacheType->RefCount, pCacheType->NumUsedSlots);

                TotalRef += pCacheType->RefCount;
                TotalUsed += pCacheType->NumUsedSlots;
        }

        fprintf(f, "Total Ref: %4i, Total Used: %4i\n", TotalRef, TotalUsed);

        fclose(f);

        return GE_TRUE;
}

static geBoolean                AppendHack = GE_FALSE;

// HACK!!!!
void                            D3DMain_Log(LPSTR Str, ... );
//========================================================================================================
//      D3DCache_AdjustSlots
//========================================================================================================
geBoolean D3DCache_AdjustSlots(D3DCache *Cache, const int32 *MaxTable, geBoolean UsePartition)
{
        D3DCache_Type   *pCacheType;
        int32                   i, Total, NumPasses;

        assert(D3DCache_IsValid(Cache));

        D3DCache_FreeAllSlots(Cache);                                                   // Just get rid of everything for now...
        DDMemMgr_PartitionReset(Cache->Partition);                              // Reset the caches memory manager

        Total = 0;
        NumPasses = 0;

        while(1)
        {
                D3DCache_Slot           *LastSlot;

                LastSlot = NULL;

                pCacheType = Cache->CacheTypes;

                for (i=0; i< D3DCACHE_MAX_CACHE_TYPES; i++, pCacheType++)
                {
                        D3DCache_Slot   *pSlot;
                        uint32                  Size, Width, Height, Result;

                        if (pCacheType->RefCount <= 0)
                        {
                                assert(pCacheType->Slots == NULL);
                                continue;
                        }

                        if (pCacheType->NumUsedSlots >= pCacheType->RefCount)
                                continue;                                       // This is all we need for this slot...

                        if (pCacheType->NumUsedSlots >= MaxTable[pCacheType->Log])
                                continue;

                        if (!pCacheType->Slots)                 // If no slots have been allocated, allocate them now...
                        {
                                pCacheType->Slots = (D3DCache_Slot*)malloc(sizeof(D3DCache_Type)*pCacheType->RefCount);
                                memset(pCacheType->Slots, 0, sizeof(D3DCache_Type)*pCacheType->RefCount);
                        }

                        Width = pCacheType->Width;
                        Height = pCacheType->Height;

                        Size = Width*Height*(pCacheType->ddsd.ddpfPixelFormat.dwRGBBitCount>>3);  // (BitCount/8)
                
                        if (UsePartition)
                        {
                                if (!DDMemMgr_PartitionAllocMem(Cache->Partition, Size))
                                {
                                        LastSlot = NULL;        // Make a complete stop
                                        break;                          // No more memory in the partition, stop now...
                                }
                        }

                        pSlot = &pCacheType->Slots[pCacheType->NumUsedSlots];
                        pSlot->SelfCheck = pSlot;

                        pSlot->CacheType = pCacheType;

                        // Allocate surfaces now
                        Result = D3DCache_SetupSlot(Cache, pSlot, Width, Height, &pCacheType->ddsd, Cache->UseStages, pCacheType->Stage);

                        if (!Result)
                        {
                                memset(pSlot, 0, sizeof(D3DCache_Slot));
                                break;
                        }
                        else if (Result == -1)
                        {
                                D3DMain_Log("D3DCache_AdjustSlots:  D3DCache_SetupSlot failed.\n");
                                return GE_FALSE;
                        }

                        pCacheType->NumUsedSlots++;
                        Total++;

                        LastSlot = pSlot;
                }

                NumPasses++;

                if (!LastSlot)          // Nothing was allocated on that pass, so assume we are out of memory
                        break;
        }

        pCacheType = Cache->CacheTypes;
        
        // Go through one last time, and make sure all got allocated
        for (i=0; i< D3DCACHE_MAX_CACHE_TYPES; i++, pCacheType++)
        {
                if (pCacheType->RefCount <= 0)
                {
                        assert(pCacheType->Slots == NULL);
                        continue;
                }

                if (pCacheType->NumUsedSlots <= 0)              
                {
                        D3DMain_Log("D3DCache_AdjustSlots:  Out of ram creating surfaces for cache.\n");
                        D3DMain_Log("D3DCache_AdjustSlots:  Pick a display mode with a smaller resolution.\n");
                        return GE_FALSE;                        // Not all slots with refs got a texture
                }

                assert(pCacheType->Slots != NULL);
        }

        D3DCache_WriteToFile(Cache, "D3DCache.Log", AppendHack);
        AppendHack = GE_TRUE;

        return GE_TRUE;
}

//========================================================================================================
//      D3DCache_SlotIsValid
//========================================================================================================
geBoolean D3DCache_SlotIsValid(D3DCache_Slot *Slot)
{
        if (!Slot)
                return GE_FALSE;

        if (Slot->SelfCheck != Slot)
                return GE_FALSE;

        return GE_TRUE;
}

//=====================================================================================
//      D3DCache_SetupSlot
//
//      Returns -1 on failure
//      Returns 0 on out of memory
//      Returns 1 on success
//=====================================================================================
int32 D3DCache_SetupSlot(D3DCache *Cache, D3DCache_Slot *Slot, int32 Width, int32 Height, const DDSURFACEDESC2 *SurfDesc, geBoolean UseStage, int32 Stage)
{
/* 07/16/2000 Wendell Buckner
    Convert to Directx7...    
        LPDIRECTDRAWSURFACE4 Surface; */
        LPDIRECTDRAWSURFACE7 Surface;
        
        DDSURFACEDESC2          ddsd;
        HRESULT                         Hr;
                        
        assert(D3DCache_IsValid(Cache));
        assert(D3DCache_SlotIsValid(Slot));

        memcpy(&ddsd, SurfDesc, sizeof(DDSURFACEDESC2));

        ddsd.dwSize = sizeof(DDSURFACEDESC2);
        ddsd.dwFlags = DDSD_CAPS | DDSD_HEIGHT | DDSD_WIDTH | DDSD_PIXELFORMAT;

        if (UseStage)
                ddsd.dwFlags |= DDSD_TEXTURESTAGE;

        ddsd.ddsCaps.dwCaps = DDSCAPS_TEXTURE | DDSCAPS_VIDEOMEMORY | DDSCAPS_LOCALVIDMEM;
        ddsd.ddsCaps.dwCaps2 = DDSCAPS2_HINTDYNAMIC;
        ddsd.ddsCaps.dwCaps3 = 0;
        ddsd.ddsCaps.dwCaps4 = 0;
        ddsd.dwHeight = Width;
        ddsd.dwWidth = Height;
        
        ddsd.dwTextureStage = Stage;
        
        Hr = Cache->lpDD->CreateSurface(&ddsd, &Surface, NULL);

        if(Hr != DD_OK) 
        { 
                if (Hr == DDERR_OUTOFVIDEOMEMORY)
                {
                        return 0;
                }

                return -1;
        }

        Slot->Surface = Surface;

        // Set the color key
#if 0
        {
                DDCOLORKEY                      CKey;
                
                // Create the color key for this surface
                CKey.dwColorSpaceLowValue = 1;
                CKey.dwColorSpaceHighValue = 1;
                
                if (Slot->Surface->SetColorKey(DDCKEY_SRCBLT , &CKey) != DD_OK)
                {
                        Slot->Surface->Release();
                        Slot->Surface = NULL;
                        return -1;
                }
        }
 #endif

/* 02/25/2001 Wendell Buckner
   This texture pointer is no longer valid under directx 7.  Set it to TRUE so there is
   something there when  the code does assert checks.
        Hr = Surface->QueryInterface(IID_IDirect3DTexture2, (void**)&Slot->Texture);  

        if(Hr != DD_OK) 
        { 
                Surface->Release();
                return -1;
        }*/
    Slot->Texture = Surface;

        return 1;               // All good dude
}


//========================================================================================================
//      D3DCache_TypeFindSlot
//========================================================================================================
D3DCache_Slot *D3DCache_TypeFindSlot(D3DCache_Type *CacheType)
{
        D3DCache_Slot   *pBestSlot, *pSlot;
        uint32                  BestLRU;
        int32                   i;

        assert(D3DCache_TypeIsValid(CacheType));

        assert(CacheType->Slots);

        pSlot = CacheType->Slots;
        pBestSlot = pSlot;
        BestLRU = pBestSlot->LRU;

        for (i=0; i< CacheType->NumUsedSlots; i++, pSlot++)
        {
                assert(D3DCache_SlotIsValid(pSlot));

                if (pSlot->LRU < BestLRU)
                {
                        pBestSlot = pSlot;
                        BestLRU = pSlot->LRU;
                }
        }

        pBestSlot->LRU = 0;
        pBestSlot->UserData = NULL;

        return pBestSlot;
}

//========================================================================================================
//      D3DCache_SlotSetUserData
//========================================================================================================
void D3DCache_SlotSetUserData(D3DCache_Slot *Slot, void *UserData)
{
        assert(D3DCache_SlotIsValid(Slot));

        Slot->UserData = UserData;
}

//========================================================================================================
//      D3DCache_SlotGetUserData
//========================================================================================================
void *D3DCache_SlotGetUserData(D3DCache_Slot *Slot)
{
        assert(D3DCache_SlotIsValid(Slot));

        return Slot->UserData;
}

//========================================================================================================
//      D3DCache_SlotSetLRU
//========================================================================================================
void D3DCache_SlotSetLRU(D3DCache_Slot *Slot, uint32 LRU)
{
        assert(D3DCache_SlotIsValid(Slot));

        Slot->LRU = LRU;
}

//========================================================================================================
//      D3DCache_SlotGetLRU
//========================================================================================================
uint32 D3DCache_SlotGetLRU(D3DCache_Slot *Slot)
{
        assert(D3DCache_SlotIsValid(Slot));

        return Slot->LRU;
}

/* 07/16/2000 Wendell Buckner
    Convert to Directx7...    
LPDIRECT3DTEXTURE2 D3DCache_SlotGetTexture(D3DCache_Slot *Slot)    */
LPDIRECTDRAWSURFACE7  D3DCache_SlotGetTexture(D3DCache_Slot *Slot)
{
        assert(D3DCache_SlotIsValid(Slot));

        return Slot->Texture;
}

/* 07/16/2000 Wendell Buckner
    Convert to Directx7...    
LPDIRECTDRAWSURFACE4 D3DCache_SlotGetSurface(D3DCache_Slot *Slot) */
LPDIRECTDRAWSURFACE7 D3DCache_SlotGetSurface(D3DCache_Slot *Slot)
{
        assert(D3DCache_SlotIsValid(Slot));

        return Slot->Surface;
}

//=====================================================================================
//      Log2
//      Return the log of a size
//=====================================================================================
uint32 Log2(uint32 P2)
{
        uint32          p = 0;
        int32           i = 0;
        
        for (i = P2; i > 0; i>>=1)
                p++;

        return (p-1);
}

//=====================================================================================
//      SnapToPower2
//      Snaps a number to a power of 2
//=====================================================================================
int32 SnapToPower2(int32 Width)
{
#if 1
        if (Width > 0 && Width <= 1) Width = 1;
        else if (Width > 1 && Width <= 2) Width = 2;
        else if (Width > 2 && Width <= 4) Width = 4;
        else if (Width > 4 && Width <= 8) Width = 8;
        else if (Width > 8 && Width <= 16) Width =16;
        else if (Width > 16 && Width <= 32) Width = 32;
        else if (Width > 32 && Width <= 64) Width = 64;
        else if (Width > 64 && Width <= 128) Width = 128;
        else if (Width > 128 && Width <= 256) Width = 256;
        else 
                return -1;
#else
        
        if (Width > 1 && Width <= 8) Width = 8;
        else if (Width > 8 && Width <= 16) Width =16;
        else if (Width > 16 && Width <= 32) Width = 32;
        else if (Width > 32 && Width <= 64) Width = 64;
        else if (Width > 64 && Width <= 128) Width = 128;
        else if (Width > 128 && Width <= 256) Width = 256;
        else 
                return -1;
#endif

        return Width;
}

//=====================================================================================
//      Return the max log of a (power of 2) width and height
//=====================================================================================
int32 GetLog(int32 Width, int32 Height)
{
        int32   LWidth = SnapToPower2(max(Width, Height));
        
        return Log2(LWidth);
}

---