sbgSplitBuffer.h

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#ifndef SBG_SPLIT_BUFFER_H
#define SBG_SPLIT_BUFFER_H

#include <sbgCommon.h>

//----------------------------------------------------------------------//
//- Header (open extern C block)                                       -//
//----------------------------------------------------------------------//
#ifdef __cplusplus
extern "C" {
#endif

//----------------------------------------------------------------------//
//- Structs definitions                                                -//
//----------------------------------------------------------------------//

typedef struct _SbgSplitBuffer
{
        uint8_t *pLinkedBuffer;                                 
        size_t   linkedBufferSize;                              
        size_t   subBufferSize;                                 
        size_t   subBufferNbr;                                  
} SbgSplitBuffer;

//----------------------------------------------------------------------//
//- Public methods definitions                                                         -//
//----------------------------------------------------------------------//

SBG_INLINE void sbgSplitBufferInitForRead(SbgSplitBuffer *pSplitBuffer, const void *pBuffer, size_t bufferSize, size_t subBufferSize)
{
        //
        //      Test input arguments
        //
        assert(pSplitBuffer);

        //
        // Initialize split buffer parameters
        //
        pSplitBuffer->pLinkedBuffer = (uint8_t*)pBuffer;
        pSplitBuffer->linkedBufferSize = bufferSize;
        pSplitBuffer->subBufferSize = subBufferSize;

        //
        // Compute sub buffer number
        //
        pSplitBuffer->subBufferNbr = (bufferSize + (subBufferSize - 1)) / subBufferSize;
}

SBG_INLINE void sbgSplitBufferInitForWrite(SbgSplitBuffer *pSplitBuffer, void *pBuffer, size_t bufferSize, size_t subBufferSize)
{
        //
        //      Test input arguments
        //
        assert(pSplitBuffer);

        //
        // Initialize split buffer parameters
        //
        pSplitBuffer->pLinkedBuffer = (uint8_t*)pBuffer;
        pSplitBuffer->linkedBufferSize = bufferSize;
        pSplitBuffer->subBufferSize = subBufferSize;

        //
        // Compute sub buffer number
        //
        pSplitBuffer->subBufferNbr = (bufferSize + (subBufferSize - 1)) / subBufferSize;
}

SBG_INLINE size_t sbgSplitBufferGetSubBufferNbr(const SbgSplitBuffer *pSplitBuffer)
{
        //
        //      Test input arguments
        //
        assert(pSplitBuffer);

        //
        // Return subBufferNbr parameter
        //
        return pSplitBuffer->subBufferNbr;
}

SBG_INLINE void *sbgSplitBufferGetSubBuffer(const SbgSplitBuffer *pSplitBuffer, size_t subBufferIdx)
{
        //
        //      Test input arguments
        //
        assert(pSplitBuffer);

        //
        // Test input parameters
        //
        if (subBufferIdx < pSplitBuffer->subBufferNbr)
        {
                //
                // Return pointer to buffer
                //
                return ((uint8_t*)pSplitBuffer->pLinkedBuffer + pSplitBuffer->subBufferSize*subBufferIdx);
        }
        else
        {
                //
                // Invalid index
                //
                return NULL;
        }
}

SBG_INLINE size_t sbgSplitBufferGetSubBufferOffset(const SbgSplitBuffer *pSplitBuffer, size_t subBufferIdx)
{
        //
        //      Test input arguments
        //
        assert(pSplitBuffer);

        //
        // Test input parameters
        //
        if (subBufferIdx < pSplitBuffer->subBufferNbr)
        {
                //
                // Return pointer to buffer
                //
                return (pSplitBuffer->subBufferSize * subBufferIdx);
        }
        else
        {
                //
                // Invalid index
                //
                return 0;
        }
}

SBG_INLINE size_t sbgSplitBufferGetSubBufferSize(const SbgSplitBuffer *pSplitBuffer, size_t subBufferIdx)
{
        size_t subBufferSize = 0;

        //
        //      Test input arguments
        //
        assert(pSplitBuffer);

        //
        // Test input parameters
        //
        if (pSplitBuffer->subBufferNbr > 0)
        {
                //
                // Test that the sub buffer index is not the last one
                //
                if (subBufferIdx < (pSplitBuffer->subBufferNbr-1))
                {
                        //
                        // We can just return the sub buffer size because it's not the last sub buffer
                        //
                        subBufferSize =  pSplitBuffer->subBufferSize;
                }
                else if (subBufferIdx == (pSplitBuffer->subBufferNbr-1) )
                {
                        //
                        // It's the last sub buffer so return the remaining size
                        //
                        subBufferSize = pSplitBuffer->linkedBufferSize - (subBufferIdx * pSplitBuffer->subBufferSize);
                }
        }

        //
        // Return computed size
        //
        return subBufferSize;
}

//----------------------------------------------------------------------//
//- Footer (close extern C block)                                      -//
//----------------------------------------------------------------------//
#ifdef __cplusplus
}
#endif

#endif /* SBG_SPLIT_BUFFER_H */