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//
// Copyright 2020 Ettus Research, a National Instruments Brand
//
// SPDX-License-Identifier: LGPL-3.0-or-later
//
// Description:
//
// Windowing module. Multiplies each input packet by the coefficients loaded
// into an internal memory.
//
// Parameters:
//
// WINDOW_SIZE : Sets the maximum window size to 2^WINDOW_SIZE samples.
// COEFF_WIDTH : The bit width of coefficients.
//
module window #(
parameter WINDOW_SIZE = 10,
parameter COEFF_WIDTH = 16
) (
input wire clk,
input wire rst,
// Window size to use
input wire [WINDOW_SIZE:0] window_size,
// Coefficient input
input wire [COEFF_WIDTH-1:0] m_axis_coeff_tdata,
input wire m_axis_coeff_tlast,
input wire m_axis_coeff_tvalid,
output wire m_axis_coeff_tready,
// Input data stream
input wire [31:0] i_tdata,
input wire i_tlast,
input wire i_tvalid,
output wire i_tready,
// Output data stream
output wire [31:0] o_tdata,
output wire o_tlast,
output wire o_tvalid,
input wire o_tready
);
// Sample data stream (from i_tdata)
wire [ 31:0] stream_tdata;
wire stream_tlast;
wire stream_tvalid;
wire stream_tready;
// RAM output data stream (saved coefficients)
wire [ 15:0] ram_tdata;
wire ram_tvalid;
wire ram_tready;
// Counter data stream (RAM address for coefficient lookup)
wire [WINDOW_SIZE-1:0] count_tdata;
wire count_tvalid;
wire count_tready;
// Flow control stream. This keeps the counter stream in sync with the
// sample data stream.
wire flow_tvalid;
wire flow_tready;
wire clear_counter;
// Restart the address counter whenever we load a new set of coefficients.
assign clear_counter = m_axis_coeff_tlast &
m_axis_coeff_tvalid &
m_axis_coeff_tready;
// Split the incoming data stream into two
split_stream_fifo #(
.WIDTH (32),
.ACTIVE_MASK (4'b0011)
) split_stream_fifo_i (
.clk (clk),
.reset (rst),
.clear (1'b0),
.i_tdata (i_tdata),
.i_tlast (i_tlast),
.i_tvalid (i_tvalid),
.i_tready (i_tready),
.o0_tdata (stream_tdata),
.o0_tlast (stream_tlast),
.o0_tvalid (stream_tvalid),
.o0_tready (stream_tready),
.o1_tdata (),
.o1_tlast (),
.o1_tvalid (flow_tvalid),
.o1_tready (flow_tready),
.o2_tdata (),
.o2_tlast (),
.o2_tvalid (),
.o2_tready (1'b0),
.o3_tdata (),
.o3_tlast (),
.o3_tvalid (),
.o3_tready (1'b0)
);
// Address generation
counter #(
.WIDTH (WINDOW_SIZE)
) counter_i (
.clk (clk),
.reset (rst),
.clear (clear_counter),
.max (window_size),
.i_tlast (1'b0),
.i_tvalid (flow_tvalid),
.i_tready (flow_tready),
.o_tdata (count_tdata),
.o_tlast (),
.o_tvalid (count_tvalid),
.o_tready (count_tready)
);
// RAM to store window coefficients
ram_to_fifo #(
.DWIDTH (COEFF_WIDTH),
.AWIDTH (WINDOW_SIZE)
) ram_to_fifo_i (
.clk (clk),
.reset (rst),
.clear (1'b0),
.config_tdata (m_axis_coeff_tdata),
.config_tlast (m_axis_coeff_tlast),
.config_tvalid (m_axis_coeff_tvalid),
.config_tready (m_axis_coeff_tready),
.i_tdata (count_tdata),
.i_tlast (1'b0),
.i_tvalid (count_tvalid),
.i_tready (count_tready),
.o_tdata (ram_tdata),
.o_tlast (),
.o_tvalid (ram_tvalid),
.o_tready (ram_tready)
);
// Real by complex multiplier. This multiplier is configured for signed
// fixed point with 15 fractional bits. For N fractional bits (a right-shift
// by N in the multiplication result), set:
// DROP_TOP_P = (WIDTH_REAL + WIDTH_CPLX - WIDTH_P + 5) - N
mult_rc #(
.WIDTH_REAL (COEFF_WIDTH),
.WIDTH_CPLX (16),
.WIDTH_P (16),
.DROP_TOP_P (6)
) mult_rc_i (
.clk (clk),
.reset (rst),
.real_tdata (ram_tdata),
.real_tlast (1'b0),
.real_tvalid (ram_tvalid),
.real_tready (ram_tready),
.cplx_tdata (stream_tdata),
.cplx_tlast (stream_tlast),
.cplx_tvalid (stream_tvalid),
.cplx_tready (stream_tready),
.p_tdata (o_tdata),
.p_tlast (o_tlast),
.p_tvalid (o_tvalid),
.p_tready (o_tready)
);
endmodule
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