PCM轉G711的JAVA代碼

能跑，沒測試。心情問題……

private final static short SHORT_MAX = 0x7FFF;
    public static byte[] convertPcmToG711(byte[] pcmBuffer, int length, byte[] g711Buffer)
    {
        length = length/2;
        if (pcmBuffer == null)
        {
            pcmBuffer = new byte[length];
        }
        for (int i=0; i<length; i++)
        {
            short pcm = ToolKit.getShort(pcmBuffer, i*2);
            
            int sign = (pcm & 0x8000) >> 8;
            if (sign != 0)
            {
                pcm = (short)-pcm;
            }
            if (pcm > SHORT_MAX)
            {
                pcm = SHORT_MAX;
            }
            int exponent = 7;
            int expMask;
            //有的使用數組來代替這個步驟。
            for (expMask = 0x4000; (pcm & expMask) == 0 && exponent>0; exponent--, expMask >>= 1)
            {
                //
            }
            int mantissa = (pcm >> ((exponent == 0) ? 4 : (exponent + 3))) & 0x0F;
            byte alaw = (byte)(sign | exponent << 4 | mantissa);
            g711Buffer[i] = (byte)(alaw^0xD5);
        }
        return g711Buffer;
    }