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//
// Copyright 2012-2013 Ettus Research LLC
//
module gpif2_to_fifo64
#(
parameter FIFO_SIZE = 9
)
(
//input interface
input gpif_clk,
input gpif_rst,
input [31:0] i_tdata,
input i_tlast,
input i_tvalid,
output i_tready,
output fifo_has_space,
output fifo_nearly_full,
//output fifo interface
input fifo_clk,
input fifo_rst,
output [63:0] o_tdata,
output o_tlast,
output o_tvalid,
input o_tready,
output bus_error,
output [31:0] debug
);
wire [31:0] int_tdata;
wire int_tlast;
wire int_tvalid, int_tready;
wire [31:0] int0_tdata;
wire int0_tlast, int0_tvalid, int0_tready;
//
// Generate flags that show if initial FIFO's can accept a maximum sized burst from the FX3
// or if the FIFO is about to fill.
//
localparam BURST_SIZE = (FIFO_SIZE < 8)? FIFO_SIZE : 8;
wire [15:0] space;
assign fifo_has_space = space >= (1 << BURST_SIZE);
assign fifo_nearly_full = (space < 6); // 5 spaces left.
//
// This FIFO is provdied purely to easy FPGA timing closure as data is comming from I/O pins.
//
axi_fifo #(.WIDTH(33), .SIZE(0)) ingress_timing_fifo
(
.clk(gpif_clk), .reset(gpif_rst), .clear(1'b0),
.i_tdata({i_tlast, i_tdata}), .i_tvalid(i_tvalid), .i_tready(i_tready), .space(),
.o_tdata({int0_tlast, int0_tdata}), .o_tvalid(int0_tvalid), .o_tready(int0_tready), .occupied()
);
//
// This FIFO provides space to accept a single burst from FX3 and it's fullness drives flags to GPIF2 logic
//
axi_fifo #(.WIDTH(33), .SIZE(BURST_SIZE)) min_read_buff
(
.clk(gpif_clk), .reset(gpif_rst), .clear(1'b0),
.i_tdata({int0_tlast, int0_tdata}), .i_tvalid(int0_tvalid), .i_tready(int0_tready), .space(space),
.o_tdata({int_tlast, int_tdata}), .o_tvalid(int_tvalid), .o_tready(int_tready), .occupied()
);
//
// This logic allows signals to cross from the GPIF2 clock domain to the BUS clock domain.
// It may now be obselete if bus_clk and gpif_clk are merged
//
wire [31:0] chk_tdata;
wire chk_tlast;
wire chk_tvalid, chk_tready;
axi_fifo_2clk #(.WIDTH(33), .SIZE(0/*SRL*/)) cross_clock_fifo
(
.reset(fifo_rst | gpif_rst),
.i_aclk(gpif_clk), .i_tdata({int_tlast, int_tdata}), .i_tvalid(int_tvalid), .i_tready(int_tready),
.o_aclk(fifo_clk), .o_tdata({chk_tlast, chk_tdata}), .o_tvalid(chk_tvalid), .o_tready(chk_tready)
);
//
// Performs basic tests on incomming packets such as testing if size on the wire patches
// the internal size field. Uses axi_packet_gate internally so can back pressure upstream if
// packet needs to be dropped.
//
wire [31:0] o32_tdata;
wire o32_tlast;
wire o32_tvalid, o32_tready;
gpif2_error_checker #(.SIZE(FIFO_SIZE)) checker
(
.clk(fifo_clk), .reset(fifo_rst), .clear(1'b0),
.i_tdata(chk_tdata), .i_tlast(chk_tlast), .i_tvalid(chk_tvalid), .i_tready(chk_tready),
.o_tdata(o32_tdata), .o_tlast(o32_tlast), .o_tvalid(o32_tvalid), .o_tready(o32_tready),
.bus_error(bus_error), .debug()
);
//assign o32_tdata = chk_tdata;
//assign o32_tlast = chk_tlast;
//assign o32_tvalid = chk_tvalid;
//assign chk_tready = o32_tready;
//
// Convert 32bit AXIS bus to 64bit
//
axi_fifo32_to_fifo64 fifo32_to_fifo64
(
.clk(fifo_clk), .reset(fifo_rst), .clear(1'b0),
.i_tdata(o32_tdata), .i_tuser(2'b0/*always 32 bits*/), .i_tlast(o32_tlast), .i_tvalid(o32_tvalid), .i_tready(o32_tready),
.o_tdata(o_tdata), .o_tuser(/*ignored cuz vita has len*/), .o_tlast(o_tlast), .o_tvalid(o_tvalid), .o_tready(o_tready)
);
/////////////////////////////////////////////
//
// Debug logic only
//
/////////////////////////////////////////////
endmodule //fifo_to_gpif2
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