source: downloads/RenderSystems/GL/src/OgreGLHardwareBufferManager.cpp @ 3

/*
-----------------------------------------------------------------------------
This source file is part of OGRE
    (Object-oriented Graphics Rendering Engine)
For the latest info, see http://www.ogre3d.org/

Copyright (c) 2000-2006 Torus Knot Software Ltd
Also see acknowledgements in Readme.html

This program is free software; you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License as published by the Free Software
Foundation; either version 2 of the License, or (at your option) any later
version.

This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with
this program; if not, write to the Free Software Foundation, Inc., 59 Temple
Place - Suite 330, Boston, MA 02111-1307, USA, or go to
http://www.gnu.org/copyleft/lesser.txt.

You may alternatively use this source under the terms of a specific version of
the OGRE Unrestricted License provided you have obtained such a license from
Torus Knot Software Ltd.
-----------------------------------------------------------------------------
*/
#include "OgreGLHardwareBufferManager.h"
#include "OgreGLHardwareVertexBuffer.h"
#include "OgreGLHardwareIndexBuffer.h"
#include "OgreHardwareBuffer.h"
#include "OgreAlignedAllocator.h"

namespace Ogre {
    //-----------------------------------------------------------------------
        // Scratch pool management (32 bit structure)
        struct GLScratchBufferAlloc
        {
                /// Size in bytes
                uint32 size: 31;
                /// Free? (pack with size)
                uint32 free: 1;
        };
        #define SCRATCH_POOL_SIZE 1 * 1024 * 1024
        //---------------------------------------------------------------------
    GLHardwareBufferManager::GLHardwareBufferManager()
    {
                // Init scratch pool
                // TODO make it a configurable size?
                // 32-bit aligned buffer
                mScratchBufferPool = static_cast<char*>(AlignedMemory::allocate(SCRATCH_POOL_SIZE, 32));
                GLScratchBufferAlloc* ptrAlloc = (GLScratchBufferAlloc*)mScratchBufferPool;
                ptrAlloc->size = SCRATCH_POOL_SIZE - sizeof(GLScratchBufferAlloc);
                ptrAlloc->free = 1;
    }
    //-----------------------------------------------------------------------
    GLHardwareBufferManager::~GLHardwareBufferManager()
    {
        destroyAllDeclarations();
        destroyAllBindings();

                AlignedMemory::deallocate(mScratchBufferPool);
    }
    //-----------------------------------------------------------------------
    HardwareVertexBufferSharedPtr GLHardwareBufferManager::createVertexBuffer(
        size_t vertexSize, size_t numVerts, HardwareBuffer::Usage usage, bool useShadowBuffer)
    {
                GLHardwareVertexBuffer* buf = 
                        new GLHardwareVertexBuffer(vertexSize, numVerts, usage, useShadowBuffer);
                {
                        OGRE_LOCK_MUTEX(mVertexBuffersMutex)
                        mVertexBuffers.insert(buf);
                }
                return HardwareVertexBufferSharedPtr(buf);
    }
    //-----------------------------------------------------------------------
    HardwareIndexBufferSharedPtr 
    GLHardwareBufferManager::createIndexBuffer(
        HardwareIndexBuffer::IndexType itype, size_t numIndexes, 
        HardwareBuffer::Usage usage, bool useShadowBuffer)
    {
                GLHardwareIndexBuffer* buf = 
                        new GLHardwareIndexBuffer(itype, numIndexes, usage, useShadowBuffer);
                {
                        OGRE_LOCK_MUTEX(mIndexBuffersMutex)
                        mIndexBuffers.insert(buf);
                }
                return HardwareIndexBufferSharedPtr(buf);
    }
    //---------------------------------------------------------------------
    GLenum GLHardwareBufferManager::getGLUsage(unsigned int usage)
    {
        switch(usage)
        {
        case HardwareBuffer::HBU_STATIC:
        case HardwareBuffer::HBU_STATIC_WRITE_ONLY:
            return GL_STATIC_DRAW_ARB;
        case HardwareBuffer::HBU_DYNAMIC:
        case HardwareBuffer::HBU_DYNAMIC_WRITE_ONLY:
            return GL_DYNAMIC_DRAW_ARB;
        case HardwareBuffer::HBU_DYNAMIC_WRITE_ONLY_DISCARDABLE:
            return GL_STREAM_DRAW_ARB;
        default:
            return GL_DYNAMIC_DRAW_ARB;
        };
    }
    //---------------------------------------------------------------------
    GLenum GLHardwareBufferManager::getGLType(unsigned int type)
    {
        switch(type)
        {
            case VET_FLOAT1:
            case VET_FLOAT2:
            case VET_FLOAT3:
            case VET_FLOAT4:
                return GL_FLOAT;
            case VET_SHORT1:
            case VET_SHORT2:
            case VET_SHORT3:
            case VET_SHORT4:
                return GL_SHORT;
            case VET_COLOUR:
                        case VET_COLOUR_ABGR:
                        case VET_COLOUR_ARGB:
            case VET_UBYTE4:
                return GL_UNSIGNED_BYTE;
            default:
                return 0;
        };
    }
        //---------------------------------------------------------------------
        //---------------------------------------------------------------------
        void* GLHardwareBufferManager::allocateScratch(uint32 size)
        {
                // simple forward link search based on alloc sizes
                // not that fast but the list should never get that long since not many
                // locks at once (hopefully)
                OGRE_LOCK_MUTEX(mScratchMutex)


                // Alignment - round up the size to 32 bits
                // control blocks are 32 bits too so this packs nicely
                if (size % 4 != 0)
                {
                        size += 4 - (size % 4);
                }

                uint32 bufferPos = 0;
                while (bufferPos < SCRATCH_POOL_SIZE)
                {
                        GLScratchBufferAlloc* pNext = (GLScratchBufferAlloc*)(mScratchBufferPool + bufferPos);
                        // Big enough?
                        if (pNext->free && pNext->size >= size)
                        {
                                // split? And enough space for control block
                                if(pNext->size > size + sizeof(GLScratchBufferAlloc))
                                {
                                        uint32 offset = sizeof(GLScratchBufferAlloc) + size;

                                        GLScratchBufferAlloc* pSplitAlloc = (GLScratchBufferAlloc*)
                                                (mScratchBufferPool + bufferPos + offset);
                                        pSplitAlloc->free = 1;
                                        // split size is remainder minus new control block
                                        pSplitAlloc->size = pNext->size - size - sizeof(GLScratchBufferAlloc);

                                        // New size of current
                                        pNext->size = size;
                                }
                                // allocate and return
                                pNext->free = 0;

                                // return pointer just after this control block (++ will do that for us)
                                return ++pNext;

                        }

                        bufferPos += sizeof(GLScratchBufferAlloc) + pNext->size;

                }

                // no available alloc
                return 0;

        }
        //---------------------------------------------------------------------
        void GLHardwareBufferManager::deallocateScratch(void* ptr)
        {
                OGRE_LOCK_MUTEX(mScratchMutex)

                // Simple linear search dealloc
                uint32 bufferPos = 0;
                GLScratchBufferAlloc* pLast = 0;
                while (bufferPos < SCRATCH_POOL_SIZE)
                {
                        GLScratchBufferAlloc* pCurrent = (GLScratchBufferAlloc*)(mScratchBufferPool + bufferPos);
                        
                        // Pointers match?
                        if ((mScratchBufferPool + bufferPos + sizeof(GLScratchBufferAlloc))
                                == ptr)
                        {
                                // dealloc
                                pCurrent->free = 1;
                                
                                // merge with previous
                                if (pLast && pLast->free)
                                {
                                        // adjust buffer pos
                                        bufferPos -= (pLast->size + sizeof(GLScratchBufferAlloc));
                                        // merge free space
                                        pLast->size += pCurrent->size + sizeof(GLScratchBufferAlloc);
                                        pCurrent = pLast;
                                }

                                // merge with next
                                uint32 offset = bufferPos + pCurrent->size + sizeof(GLScratchBufferAlloc);
                                if (offset < SCRATCH_POOL_SIZE)
                                {
                                        GLScratchBufferAlloc* pNext = (GLScratchBufferAlloc*)(
                                                mScratchBufferPool + offset);
                                        if (pNext->free)
                                        {
                                                pCurrent->size += pNext->size + sizeof(GLScratchBufferAlloc);
                                        }
                                }

                                // done
                                return;
                        }

                        bufferPos += sizeof(GLScratchBufferAlloc) + pCurrent->size;
                        pLast = pCurrent;

                }

                // Should never get here unless there's a corruption
                assert (false && "Memory deallocation error");


        }
}