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/******************************************************************************
 *                                                                            *
 *   This module counts which bits for serial audio transfers. The module     *
 * assume that the data format is I2S, as it is described in the audio        *
 * chip's datasheet.                                                          *
 *                                                                            *
 ******************************************************************************/

module altera_up_audio_bit_counter (
	// Inputs
	clk,
	reset,
	
	bit_clk_rising_edge,
	bit_clk_falling_edge,
	left_right_clk_rising_edge,
	left_right_clk_falling_edge,
	
	// Bidirectionals

	// Outputs
	counting
);

/*****************************************************************************
 *                           Parameter Declarations                          *
 *****************************************************************************/

parameter BIT_COUNTER_INIT	= 5'h0F;

/*****************************************************************************
 *                             Port Declarations                             *
 *****************************************************************************/

// Inputs
input				clk;
input				reset;
	
input				bit_clk_rising_edge;
input				bit_clk_falling_edge;
input				left_right_clk_rising_edge;
input				left_right_clk_falling_edge;

// Bidirectionals

// Outputs
output	reg			counting;

/*****************************************************************************
 *                           Constant Declarations                           *
 *****************************************************************************/


/*****************************************************************************
 *                 Internal wires and registers Declarations                 *
 *****************************************************************************/

// Internal Wires
wire				reset_bit_counter;

// Internal Registers
reg			[4:0]	bit_counter;

// State Machine Registers


/*****************************************************************************
 *                         Finite State Machine(s)                           *
 *****************************************************************************/


/*****************************************************************************
 *                             Sequential logic                              *
 *****************************************************************************/

always @(posedge clk)
begin
	if (reset == 1'b1)
		bit_counter <= 5'h00;
	else if (reset_bit_counter == 1'b1)
		bit_counter <= BIT_COUNTER_INIT;
	else if ((bit_clk_falling_edge == 1'b1) && (bit_counter != 5'h00))
		bit_counter <= bit_counter - 5'h01;
end

always @(posedge clk)
begin
	if (reset == 1'b1)
		counting <= 1'b0;
	else if (reset_bit_counter == 1'b1)
		counting <= 1'b1;
	else if ((bit_clk_falling_edge == 1'b1) && (bit_counter == 5'h00))
		counting <= 1'b0;
end

/*****************************************************************************
 *                            Combinational logic                            *
 *****************************************************************************/

assign reset_bit_counter = left_right_clk_rising_edge | 
							left_right_clk_falling_edge;

/*****************************************************************************
 *                              Internal Modules                             *
 *****************************************************************************/

endmodule

