unsigned long ulTemp;

    //
    // Return iff SSI port is not enabled for OSRAM.
    //
    if(!g_bSSIEnabled)
    {
        return;
    }

    //
    // Clear the command/control bit to enable command mode.
    //
    GPIOPinWrite(GPIO_PORTC_BASE, GPIO_PIN_7, 0);

    //
    // Loop while there are more bytes left to be transferred.
    //
    while(ulCount != 0)
    {
        //
        // Write the next byte to the controller.
        //
        SSIDataPut(SSI0_BASE, *pucBuffer++);

        //
        // Dummy read to drain the fifo and time the GPIO signal.
        //
        SSIDataGet(SSI0_BASE, &ulTemp);

        //
        // Decrement the BYTE counter.
        //
        ulCount--;
    }
}

//*****************************************************************************
//
//! \internal
//!
//! Write a sequence of data bytes to the SSD0323 controller.
//!
//! The data is written in a polled fashion; this function will not return
//! until the entire byte sequence has been written to the controller.
//!
//! \return None.
//
//*****************************************************************************
static void
OSRAMWriteData(const unsigned char *pucBuffer, unsigned long ulCount)
{
    unsigned long ulTemp;

    //
    // Return iff SSI port is not enabled for OSRAM.
    //
    if(!g_bSSIEnabled)
    {
        return;
    }

    //
    // Set the command/control bit to enable data mode.
    //
    GPIOPinWrite(GPIO_PORTC_BASE, GPIO_PIN_7, GPIO_PIN_7);

    //
    // Loop while there are more bytes left to be transferred.
    //
    while(ulCount != 0)
    {
        //
        // Write the next byte to the controller.
        //
        SSIDataPut(SSI0_BASE, *pucBuffer++);

        //
        // Dummy read to drain the fifo and time the GPIO signal.
        //
        SSIDataGet(SSI0_BASE, &ulTemp);

        //
        // Decrement the BYTE counter.
        //
        ulCount--;
    }
}

//*****************************************************************************
//
//! Clears the OLED display.
//!
//! This function will clear the display RAM.  All pixels in the display will
//! be turned off.
//!
//! This function is contained in <tt>osram128x64x4.c</tt>, with
//! <tt>osram128x64x4.h</tt> containing the API definition for use by
//! applications.
//!
//! \return None.
//
//*****************************************************************************
void
OSRAM128x64x4Clear(void)
{
    static const unsigned char pucCommand1[] = { 0x15, 0, 63 };
    static const unsigned char pucCommand2[] = { 0x75, 0, 79 };
    unsigned long ulRow, ulColumn;
    static unsigned char pucZeroBuffer[8] = { 0, 0, 0, 0, 0, 0, 0, 0};

    //
    // Set the window to fill the entire display.
    //
    OSRAMWriteCommand(pucCommand1, sizeof(pucCommand1));
    OSRAMWriteCommand(pucCommand2, sizeof(pucCommand2));
    OSRAMWriteCommand(g_pucOSRAM128x64x4VerticalInc,
                      sizeof(g_pucOSRAM128x64x4VerticalInc));

    //
    // In vertical address increment mode, loop through each column, filling
    // each row with 0.
    //
    for(ulColumn = 0; ulColumn < (128/2); ulColumn++)
    {
        //
        // 8 rows (bytes) per row of text.
        //
        for(ulRow = 0; ulRow < 80; ulRow += 8)
        {
            OSRAMWriteData(pucZeroBuffer, sizeof(pucZeroBuffer));
        }
    }
}

//*****************************************************************************
//
//! Displays a string on the OLED display.
//!
//! \param pcStr is a pointer to the string to display.
//! \param ulX is the horizontal position to display the string, specified in
//! columns from the left edge of the display.
//! \param ulY is the vertical position to display the string, specified in
//! rows from the top edge of the display.
//! \param ucLevel is the 4-bit grey scale value to be used for displayed text.
//!
//! This function will draw a string on the display.  Only the ASCII characters
//! between 32 (space) and 126 (tilde) are supported; other characters will
//! result in random data being draw on the display (based on whatever appears
//! before/after the font in memory).  The font is mono-spaced, so characters
//! such as "i" and "l" have more white space around them than characters such
//! as "m" or "w".
//!
//! If the drawing of the string reaches the right edge of the display, no more
//! characters will be drawn.  Therefore, special care is not required to avoid
//! supplying a string that is "too long" to display.
//!
//! This function is contained in <tt>osram128x64x4.c</tt>, with
//! <tt>osram128x64x4.h</tt> containing the API definition for use by
//! applications.
//!
//! \note Because the OLED display packs 2 pixels of data in a single byte, the
//! parameter \e ulX must be an even column number (e.g. 0, 2, 4, etc).
//!
//! \return None.
//
//*****************************************************************************
void
OSRAM128x64x4StringDraw(const char *pcStr, unsigned long ulX,
                        unsigned long ulY, unsigned char ucLevel)
{
    static unsigned char pucBuffer[8];
    unsigned long ulIdx1, ulIdx2;
    unsigned char ucTemp;

    //
    // Check the arguments.
    //
    ASSERT(ulX < 128);
    ASSERT((ulX & 1) == 0);
    ASSERT(ulY < 64);
    ASSERT(ucLevel < 16);

    //
    // Setup a window starting at the specified column and row, ending
    // at the right edge of the display and 8 rows down (single character row).
    //
    pucBuffer[0] = 0x15;
    pucBuffer[1] = ulX / 2;
    pucBuffer[2] = 63;
    OSRAMWriteCommand(pucBuffer, 3);
    pucBuffer[0] = 0x75;
    pucBuffer[1] = ulY;
    pucBuffer[2] = ulY + 7;
    OSRAMWriteCommand(pucBuffer, 3);
    OSRAMWriteCommand(g_pucOSRAM128x64x4VerticalInc,
                      sizeof(g_pucOSRAM128x64x4VerticalInc));

    //
    // Loop while there are more characters in the string.
    //
    while(*pcStr != 0)
    {
        //
        // Get a working copy of the current character and convert to an
        // index into the character bit-map array.
        //
        ucTemp = *pcStr;
        ucTemp &= 0x7F;
        if(ucTemp < ' ')
        {
            ucTemp = ' ';
        }
        else
        {
            ucTemp -= ' ';
        }

        //
        // Build and display the character buffer.
        //
        for(ulIdx1 = 0; ulIdx1 < 3; ulIdx1++)
        {
            //
            // Convert two columns of 1-bit font data into a single data
            // byte column of 4-bit font data.
            //
            for(ulIdx2 = 0; ulIdx2 < 8; ulIdx2++)
            {
                pucBuffer[ulIdx2] = 0;
                if(g_pucFont[ucTemp][ulIdx1*2] & (1 << ulIdx2))
                {
                    pucBuffer[ulIdx2] = ((ucLevel << 4) & 0xf0);
                }
                if((ulIdx1 < 2) &&
                    (g_pucFont[ucTemp][ulIdx1*2+1] & (1 << ulIdx2)))
                {
                    pucBuffer[ulIdx2] |= ((ucLevel << 0) & 0x0f);
                }
            }

            //
            // If there is room, dump the single data byte column to the
            // display.  Otherwise, bail out.
            //
            if(ulX < 126)
            {
                OSRAMWriteData(pucBuffer, 8);
                ulX += 2;
            }
            else
            {
                return;
            }
        }

        //
        // Advance to the next character.
        //
        pcStr++;
    }
}

//*****************************************************************************
//
//! Displays an image on the OLED display.
//!
//! \param pucImage is a pointer to the image data.
//! \param ulX is the horizontal position to display this image, specified in
//! columns from the left edge of the display.
//! \param ulY is the vertical position to display this image, specified in
//! rows from the top of the display.
//! \param ulWidth is the width of the image, specified in columns.
//! \param ulHeight is the height of the image, specified in rows.
//!
//! This function will display a bitmap graphic on the display.  Because of the
//! format of the display RAM, the starting column (/e ulX) and the number of
//! columns (/e ulWidth) must be an integer multiple of two.
//!
//! The image data is organized with the first row of image data appearing left
//! to right, followed immediately by the second row of image data.  Each byte
//! contains the data for two columns in the current row, with the leftmost
//! column being contained in bits 7:4 and the rightmost column being contained
//! in bits 3:0.
//!
//! For example, an image six columns wide and seven scan lines tall would
//! be arranged as follows (showing how the twenty one bytes of the image would
//! appear on the display):
//!
//! \verbatim
//!     +-------------------+-------------------+-------------------+
//!     |      Byte 0       |      Byte 1       |      Byte 2       |
//!     +---------+---------+---------+---------+---------+---------+
//!     | 7 6 5 4 | 3 2 1 0 | 7 6 5 4 | 3 2 1 0 | 7 6 5 4 | 3 2 1 0 |
//!     +---------+---------+---------+---------+---------+---------+
//!     |      Byte 3       |      Byte 4       |      Byte 5       |
//!     +---------+---------+---------+---------+---------+---------+
//!     | 7 6 5 4 | 3 2 1 0 | 7 6 5 4 | 3 2 1 0 | 7 6 5 4 | 3 2 1 0 |
//!     +---------+---------+---------+---------+---------+---------+
//!     |      Byte 6       |      Byte 7       |      Byte 8       |
//!     +---------+---------+---------+---------+---------+---------+
//!     | 7 6 5 4 | 3 2 1 0 | 7 6 5 4 | 3 2 1 0 | 7 6 5 4 | 3 2 1 0 |
//!     +---------+---------+---------+---------+---------+---------+
//!     |      Byte 9       |      Byte 10      |      Byte 11      |
//!     +---------+---------+---------+---------+---------+---------+
//!     | 7 6 5 4 | 3 2 1 0 | 7 6 5 4 | 3 2 1 0 | 7 6 5 4 | 3 2 1 0 |
//!     +---------+---------+---------+---------+---------+---------+
//!     |      Byte 12      |      Byte 13      |      Byte 14      |
//!     +---------+---------+---------+--3------+---------+---------+
//!     | 7 6 5 4 | 3 2 1 0 | 7 6 5 4 | 3 2 1 0 | 7 6 5 4 | 3 2 1 0 |
//!     +---------+---------+---------+---------+---------+---------+
//!     |      Byte 15      |      Byte 16      |      Byte 17      |