void DoAdjustGain(void)
{
        /**********************************************************/
        /******************* to do ********************************/
        // you have to control the volume variables (left and right) and mute
        // are in their range and adjust the sound card sound using the 'AdjustLevel' function:
    //     parameters (channel left value = 1, channel right value = 0)
        //
        : You have to check that volume variables value is between minimum
         maximum value [0,255]. We can simulate a Mute with
        // right and left channel to 0;
        /***********************************************************/

    // Si no está muteado...
        if (MasterMute == 0) {

        // Volumen del canal izquierdo
        if (LeftVolume < VolumeMin)
            LeftVolume = 0;
        else if (LeftVolume > VolumeMax)
            LeftVolume = 255;

        // Volumen del canal derecho
        if (RightVolume < VolumeMin)
            RightVolume = 0;
        else if (RightVolume > VolumeMax)
            RightVolume = 255;

        // Ajuste del canal izquierdo
        AdjustLevel(0, LeftVolume);

        // Ajuste del canal derecho
        AdjustLevel(1, RightVolume);

    // Si está muteado...
    }else{

        // Ajuste del canal izquierdo
        AdjustLevel(0, VolumeMin);

        // Ajuste del canal derecho
        AdjustLevel(1, VolumeMin);
    }

}