image.c

基于TI公司Cortex-M3的uart超级通信开发

        {
            *(unsigned long *)(g_pucDictionary + ulBits) = 0;
        }

        //
        // Determine the number of bytes of data to decompress.
        //
        ulCount = (((lWidth * lBPP) + 7) / 8) * lHeight;

        //
        // Initialize the pointer into the dictionary.
        //
        ulIdx = 0;

        //
        // Start off with no encoding byte.
        //
        ulBits = 0;
        ulByte = 0;

        //
        // Start from the upper left corner of the image.
        //
        lX1 = 0;

        //
        // Loop while there are more rows or more data in the image.
        //
        while(lHeight && ulCount)
        {
            //
            // See if an encoding byte needs to be read.
            //
            if(ulBits == 0)
            {
                //
                // Read the encoding byte, which indicates if each of the
                // following eight bytes are encoded or literal.
                //
                ulByte = *pucImage++;
                ulBits = 8;
            }

            //
            // See if the next byte is encoded or literal.
            //
            if(ulByte & (1 << (ulBits - 1)))
            {
                //
                // This byte is encoded, so extract the location and size of
                // the encoded data within the dictionary.
                //
                ulMatch = *pucImage >> 3;
                ulSize = (*pucImage++ & 7) + 2;

                //
                // Decrement the count of bytes to decode by the number of
                // copied bytes.
                //
                ulCount -= ulSize;
            }
            else
            {
                //
                // This byte is a literal, so copy it into the dictionary.
                //
                g_pucDictionary[ulIdx++] = *pucImage++;

                //
                // Decrement the count of bytes to decode.
                //
                ulCount--;

                //
                // Clear any previous encoded data information.
                //
                ulMatch = 0;
                ulSize = 0;
            }

            //
            // Loop while there are bytes to copy for the encoded data, or
            // once for literal data.
            //
            while(ulSize || !(ulByte & (1 << (ulBits - 1))))
            {
                //
                // Set the encoded data bit for this data so that this loop
                // will only be executed once for literal data.
                //
                ulByte |= 1 << (ulBits - 1);

                //
                // Loop while there is more encoded data to copy and there is
                // additional space in the dictionary (before the buffer
                // wraps).
                //
                while(ulSize && (ulIdx != sizeof(g_pucDictionary)))
                {
                    //
                    // Copy this byte.
                    //
                    g_pucDictionary[ulIdx] =
                        g_pucDictionary[(ulIdx + ulMatch) %
                                        sizeof(g_pucDictionary)];

                    //
                    // Increment the dictionary pointer.
                    //
                    ulIdx++;

                    //
                    // Decrement the encoded data size.
                    //
                    ulSize--;
                }

                //
                // See if the dictionary pointer is about to wrap, or if there
                // is no more data to decompress.
                //
                if((ulIdx == sizeof(g_pucDictionary)) || !ulCount)
                {
                    //
                    // Loop through the data in the dictionary buffer.
                    //
                    for(ulIdx = 0;
                        (ulIdx < sizeof(g_pucDictionary)) && lHeight; )
                    {
                        //
                        // Compute the number of pixels that remain in the
                        // dictionary buffer.
                        //
                        ulNum = ((sizeof(g_pucDictionary) - ulIdx) * 8) / lBPP;

                        //
                        // See if any of the pixels in the dictionary buffer
                        // are within the clipping region.
                        //
                        if((lY >= pContext->sClipRegion.sYMin) &&
                           ((lX1 + ulNum) >= lX0) && (lX1 <= lX2))
                        {
                            //
                            // Skip some pixels at the start of the scan line
                            // if required to stay within the clipping region.
                            //
                            if(lX1 < lX0)
                            {
                                ulIdx += ((lX0 - lX1) * lBPP) / 8;
                                lX1 = lX0;
                            }

                            //
                            // Shorten the scan line if required to stay within
                            // the clipping region.
                            //
                            if(ulNum > (lX2 - lX1 + 1))
                            {
                                ulNum = lX2 - lX1 + 1;
                            }

                            //
                            // Draw this row of image pixels.
                            //
                            DpyPixelDrawMultiple(pContext->pDisplay, lX + lX1,
                                                 lY, lX1 & 7, ulNum, lBPP,
                                                 g_pucDictionary + ulIdx,
                                                 pucPalette);
                        }

                        //
                        // Move the X coordinate back to the start of the first
                        // data byte in this portion of the dictionary buffer.
                        //
                        lX1 = ((lX1 * lBPP) & ~7) / lBPP;

                        //
                        // See if the remainder of this scan line resides
                        // within the dictionary buffer.
                        //
                        if(((((lWidth - lX1) * lBPP) + 7) / 8) >
                           (sizeof(g_pucDictionary) - ulIdx))
                        {
                            //
                            // There is more to this scan line than is in the
                            // dictionary buffer at this point, so move the
                            // X coordinate by by the number of pixels in the
                            // dictionary buffer.
                            //
                            lX1 += (((sizeof(g_pucDictionary) - ulIdx) * 8) /
                                    lBPP);

                            //
                            // The entire dictionary buffer has been scanned.
                            //
                            ulIdx = sizeof(g_pucDictionary);
                        }
                        else
                        {
                            //
                            // The remainder of this scan line resides in the
                            // dictionary buffer, so skip past it.
                            //
                            ulIdx += (((lWidth - lX1) * lBPP) + 7) / 8;

                            //
                            // Move to the start of the next scan line.
                            //
                            lX1 = 0;
                            lY++;

                            //
                            // There is one less scan line to process.
                            //
                            lHeight--;
                        }
                    }

                    //
                    // Start over from the beginning of the dictionary buffer.
                    //
                    ulIdx = 0;
                }
            }

            //
            // Advance to the next bit in the encoding byte.
            //
            ulBits--;
        }
    }
}

//*****************************************************************************
//
// Close the Doxygen group.
//! @}
//
//*****************************************************************************