blobbuffer.h

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/*
* Copyright 2016 Autodesk, Inc. All rights reserved.
* Use of this software is subject to the terms of the Autodesk license agreement and any attachments or Appendices thereto provided at the time of installation or download,
* or which otherwise accompanies this software in either electronic or hard copy form, or which is signed by you and accepted by Autodesk.
*/

#pragma once

#include "gwnavruntime/blob/blobarray.h"
#include "gwnavruntime/blob/blobref.h"
#include "gwnavruntime/blob/blobhandler.h"
#include "gwnavruntime/kernel/SF_Debug.h"
#include <string.h>

namespace Kaim
{


class BlobRefInfo
{
public:
    BlobRefInfo() { Clear(); }

    void Clear() { Set(nullptr, nullptr, 0); }

    void Set(KyUInt32* shallowBlobSizePtr, KyInt32* offsetPtr, KyInt32 blobGlobalOffset)
    {
        m_shallowBlobSizePtr = shallowBlobSizePtr;
        m_offsetPtr          = offsetPtr;
        m_blobGlobalOffset   = blobGlobalOffset;
    }

    bool IsValid() { return m_shallowBlobSizePtr != nullptr; }

public:
    KyUInt32* m_shallowBlobSizePtr;
    KyInt32* m_offsetPtr;
    KyInt32 m_blobGlobalOffset;
};


/*
BlobBuffer is used in conjunction with derivations of BaseBlobBuilder to build Blobs.
A given succession of calls to Alloc...() functions must be called twice,
once in COUNT mode (the default), once in WRITE mode (set by a call to SwitchToWriteMode()).
In COUNT mode (IsWriteMode() == false): Alloc(), AllocArray(), AllocAndCopyArray() do not write to m_buffer memory,
they just increment the size needed to fit the Blob.
In WRITE mode (IsWriteMode() == true ): Alloc(), AllocArray(), AllocAndCopyArray() do write to m_buffer memory.
You should not use BlobBuffer directly, use a derivation of BaseBlobBuilder instead
and its accompanying macros: BLOB_SET, BLOB_ARRAY, BLOB_ARRAY_COPY, BLOB_STRING, BLOB_BUILD.
*/
class BlobBuffer
{
    KY_DEFINE_NEW_DELETE_OPERATORS(Stat_Default_Mem)

public:
    BlobBuffer() : m_offset(0), m_buffer(nullptr) {}

    /* returns true when BlobBuffer is in write mode */
    bool IsWriteMode() { return m_buffer != nullptr; }

    /*  In COUNT mode: increment the size by sizeof(T).
        In WRITE mode: call the T default constructor on the current position in buffer.*/
    template<class T> T* Alloc();

    /*  In COUNT mode: increment the size by sizeof(T) * count.
        In WRITE mode: call count times the T default constructor on the current position in buffer. */
    template<class T> T* AllocArray(BlobArray<T>* blobArray, KyUInt32 count)
    {
        return AllocAndCopyArray<T>(blobArray, nullptr, count);
    }

    /*  In COUNT mode: increment the size by sizeof(T) * count.
        In WRITE mode: call count times the T default constructor on the current position in buffer. */
    template<class T> T* AllocAndCopyArray(BlobArray<T>* blobArray, const T* src, KyUInt32 count);

    template<class T> T* AllocAndCopyReferencedBlob(BlobRef<T>* blobRef, void* srcBlob, KyUInt32 srcBlobDeepSize, KyUInt32 srcBlobShallowSize);

    template<class T> T* AllocAndCopyReferencedBlobFromBlobHandler(BlobRef<T>* blobRef, const BlobHandler<T>& blobHandler);

    /* called in BaseBlobBuilder<T>::Build() */
    void SwitchToWriteMode(BaseBlobHandler& baseBlobHandler, KyUInt32 rootShallowBlobSize, MemoryHeap* heap, KyInt32 memStat);

    KyUInt32 GetAlignedSize(KyUInt32 size) { return ((size + 4 - 1) / 4) * 4; }

    template<class T> void BeginBlobRefBuffer(BlobRef<T>* blobRef);

    void SetBlobRefInfoFromCurrentOffset();

    void SetBlobRefInfoFromCopiedBlobRef(KyUInt32 shallowBlobSize);

public:
    KyUInt32 m_offset;
    char* m_buffer;
    BlobRefInfo m_blobRefInfo;
};


// --------------------------------- inline implementation ---------------------------------

template<class T>
T* BlobBuffer::Alloc()
{
    KY_ASSERT(sizeof(T) % 4 == 0);

    if (IsWriteMode() == false)
    {
        m_offset += sizeof(T);
        return nullptr;
    }

    T* ptr = (T*)(m_buffer + m_offset);
    ::new(ptr) T(); // placement new
    m_offset += sizeof(T);
    return ptr;
}


template<class T>
T* BlobBuffer::AllocAndCopyArray(BlobArray<T>* blobArray, const T* src, KyUInt32 count)
{
    KyUInt32 size = sizeof(T) * count;
    KyUInt32 alignedSize = GetAlignedSize(size);
    KyUInt32 paddingSize = alignedSize - size;

    if (IsWriteMode() == false)
    {
        m_offset += alignedSize;
        return nullptr;
    }

    if (count == 0)
    {
        blobArray->m_count = count;
        blobArray->m_offset = 0; // force m_offset = 0 when count = 0
        return nullptr;
    }

    // get destArray
    T* dest = (T*)(m_buffer + m_offset);

    // initialize blobArray
    blobArray->m_count = count;
    blobArray->m_offset = (KyInt32)((char*)dest - (char*)&blobArray->m_offset);

    if (src != nullptr)
    {
        memcpy(dest, src, size);
    }
    else
    {
        memset(dest, 0, size);
        // TODO check if this is necessary
        // call default constructor on each element
        for (KyUInt32 i = 0; i < count; ++i)
            ::new(dest + i) T;
    }
    for (KyUInt32 i = 0; i < paddingSize; ++i)
        ((char*)dest)[size + i] = 0;

    m_offset += alignedSize;
    return dest;
}


template<class T>
void BlobBuffer::BeginBlobRefBuffer(BlobRef<T>* blobRef)
{
    if (blobRef == nullptr)
        return;
    SetBlobRefInfoFromCurrentOffset(); // set the previous BlobRefInfo
    m_blobRefInfo.Set(&blobRef->m_impl.m_shallowBlobSize, &blobRef->m_impl.m_offset, m_offset);
}


template<class T>
T* BlobBuffer::AllocAndCopyReferencedBlob(BlobRef<T>* blobRef, void* srcBlob, KyUInt32 srcBlobDeepSize, KyUInt32 srcBlobShallowSize)
{
    BeginBlobRefBuffer(blobRef);

    KyUInt32 alignedSize = GetAlignedSize(srcBlobDeepSize);
    KyUInt32 paddingSize = alignedSize - srcBlobDeepSize;

    if (IsWriteMode() == false || srcBlob == nullptr || blobRef == nullptr)
    {
        m_offset += alignedSize;
        SetBlobRefInfoFromCopiedBlobRef(srcBlobShallowSize);
        return nullptr;
    }

    char* dest = m_buffer + m_offset;
    memcpy(dest, srcBlob, srcBlobDeepSize);

    // nullify paddingSize
    for (KyUInt32 i = 0; i < paddingSize; ++i)
        ((char*)dest)[srcBlobDeepSize + i] = 0;

    m_offset += alignedSize;
    SetBlobRefInfoFromCopiedBlobRef(srcBlobShallowSize);
    return (T*)dest;
}


template<class T>
T* BlobBuffer::AllocAndCopyReferencedBlobFromBlobHandler(BlobRef<T>* blobRef, const BlobHandler<T>& blobHandler)
{
    return AllocAndCopyReferencedBlob(blobRef, (void*)blobHandler.VoidBlob(), blobHandler.GetDeepBlobSize(), blobHandler.GetShallowBlobSize());
}



}