RAW to G711(μ-Law) encoding algorithm

/* ===================================================================
 *  @func     ALG_G711ulawEncode
 *
 *  @desc     G711 Encode
 *
 *  @inputs   This function takes the following inputs
 *            src - RAW data buffer
 *            bufsize - Size of RAW data
 *
 *  @outputs  dst - G711 encoded Data
 *
 *  @return   Size of Encoded Data
 *  ==================================================================
int ALG_G711ulawEncode(short *dst, short *src, Int32 bufsize)
{
    unsigned short i;

    short data;

    unsigned short isNegative;

    short nOut;

    short lowByte = 1;

    int outputSize = bufsize / 2;

    for (i = 0; i < outputSize; i++)
    {
        data = *(src + i);
        data >>= 2;
        isNegative = (data < 0 ? 1 : 0);

        if (isNegative)
            data = -data;

        if (data <= 1)
        {
            nOut = (char) data;
        }
        else if (data <= 31)
        {
            nOut = ((data - 1) >> 1) + 1;
        }
        else if (data <= 95)
        {
            nOut = ((data - 31) >> 2) + 16;
        }
        else if (data <= 223)
        {
            nOut = ((data - 95) >> 3) + 32;
        }
        else if (data <= 479)
        {
            nOut = ((data - 223) >> 4) + 48;
        }
        else if (data <= 991)
        {
            nOut = ((data - 479) >> 5) + 64;
        }
        else if (data <= 2015)
        {
            nOut = ((data - 991) >> 6) + 80;
        }
        else if (data <= 4063)
        {
            nOut = ((data - 2015) >> 7) + 96;
        }
        else if (data <= 7903)
        {
            nOut = ((data - 4063) >> 8) + 112;
        }
        else
        {
            nOut = 127;
        }

        if (isNegative)
        {
            nOut = 127 - nOut;
        }
        else
        {
            nOut = 255 - nOut;
        }

        // Pack the bytes in a word
        if (lowByte)
        {
            *(dst + (i >> 1)) = (nOut & 0x00FF);
        }
        else
        {
            *(dst + (i >> 1)) |= ((nOut << 8) & 0xFF00);
        }

        lowByte ^= 0x1;
    }

    return (outputSize);
}

G711(μ-Law) to RAW decoding Algorithm

/* ===================================================================
 *  @func     AUDIO_audioDecode
 *
 *  @desc     Function does the following
 *
 *  @inputs   This function takes the following inputs
 *            src - G711 data buffer
 *            bufsize - Size of G711 data
 *
 *  @outputs  dst - RAW Data
 *
 *  @return   SUCCESS
 *  ==================================================================
 */
int AUDIO_audioDecode(char *src, short *dst,
                      int bufsize)
{
    int sizeConsumed = 0, i = 0;

    sizeConsumed = bufsize;

    for (i = 0; i < sizeConsumed; i++)
    {
        *((unsigned short *) (dst) + i) =
            ALG_G711ulawDecode(*((unsigned char *) (src) + i));
    }
   
    return TRUE;
}

/* ===================================================================
 *  @func     ALG_G711ulawDecode
 *
 *  @desc     Decode G711 Audio
 *
 *  @inputs   This function takes the following inputs
 *            input - G711 data
 *
 *  @return   RAW Data
 *  ==================================================================
 */
short ALG_G711ulawDecode(unsigned short input)
{
    unsigned short isNegative;

    short nOut;

    isNegative = ((input & 0x80) == 0);
    if (isNegative)
        nOut = 127 - input;
    else
        nOut = 255 - input;
    if (nOut < 2)
        nOut *= 2;
    else if (nOut < 16)
        nOut = ((nOut - 1) << 1) + 1 + 1;
    else if (nOut < 32)
        nOut = ((nOut - 16) << 2) + 2 + 31;
    else if (nOut < 48)
        nOut = ((nOut - 32) << 3) + 4 + 95;
    else if (nOut < 64)
        nOut = ((nOut - 48) << 4) + 8 + 223;
    else if (nOut < 80)
        nOut = ((nOut - 64) << 5) + 16 + 479;
    else if (nOut < 96)
        nOut = ((nOut - 80) << 6) + 32 + 991;
    else if (nOut < 112)
        nOut = ((nOut - 96) << 7) + 64 + 2015;
    else
        nOut = ((nOut - 112) << 8) + 128 + 4063;
    if (isNegative)
        nOut = -nOut;
    nOut <<= 2;
    return nOut;
}