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URL https://opencores.org/ocsvn/versatile_mem_ctrl/versatile_mem_ctrl/trunk

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Rev 44 → Rev 45

/versatile_mem_ctrl/trunk/rtl/verilog/egress_fifo.v
0,0 → 1,143
// async FIFO with multiple queues, multiple data
 
module egress_fifo (
d, fifo_full, write, write_enable, clk1, rst1,
q, fifo_empty, read_adr, read_data, read_enable, clk2, rst2
);
 
parameter a_hi_size = 4;
parameter a_lo_size = 4;
parameter nr_of_queues = 16;
parameter data_width = 36;
 
input [data_width*nr_of_queues-1:0] d;
output [0:nr_of_queues-1] fifo_full;
input write;
input [0:nr_of_queues-1] write_enable;
input clk1;
input rst1;
 
output [data_width-1:0] q;
output [0:nr_of_queues-1] fifo_empty;
input read_adr, read_data;
input [0:nr_of_queues-1] read_enable;
input clk2;
input rst2;
 
wire [a_lo_size-1:0] fifo_wadr_bin[0:nr_of_queues-1];
wire [a_lo_size-1:0] fifo_wadr_gray[0:nr_of_queues-1];
wire [a_lo_size-1:0] fifo_radr_bin[0:nr_of_queues-1];
wire [a_lo_size-1:0] fifo_radr_gray[0:nr_of_queues-1];
reg [a_lo_size-1:0] wadr;
reg [a_lo_size-1:0] radr;
reg [data_width-1:0] wdata;
wire [data_width-1:0] wdataa[0:nr_of_queues-1];
 
reg read_adr_reg;
reg [0:nr_of_queues-1] read_enable_reg;
 
genvar i;
integer j,k,l;
 
function [a_lo_size-1:0] onehot2bin;
input [0:nr_of_queues-1] a;
integer i;
begin
onehot2bin = {a_lo_size{1'b0}};
for (i=1;i<nr_of_queues;i=i+1) begin
if (a[i])
onehot2bin = i;
end
end
endfunction
 
// a pipeline stage for adress read gives higher clock frequency but adds one clock latency for adr read
always @ (posedge clk2 or posedge rst2)
if (rst2)
read_adr_reg <= 1'b0;
else
read_adr_reg <= read_adr;
always @ (posedge clk2 or posedge rst2)
if (rst2)
read_enable_reg <= {nr_of_queues{1'b0}};
else
if (read_adr)
read_enable_reg <= read_enable;
 
generate
for (i=0;i<nr_of_queues;i=i+1) begin : fifo_adr
gray_counter wadrcnt (
.cke(write & write_enable[i]),
.q(fifo_wadr_gray[i]),
.q_bin(fifo_wadr_bin[i]),
.rst(rst1),
.clk(clk1));
gray_counter radrcnt (
.cke((read_adr_reg | read_data) & read_enable_reg[i]),
.q(fifo_radr_gray[i]),
.q_bin(fifo_radr_bin[i]),
.rst(rst2),
.clk(clk2));
versatile_fifo_async_cmp
#(.ADDR_WIDTH(a_lo_size))
egresscmp (
.wptr(fifo_wadr_gray[i]),
.rptr(fifo_radr_gray[i]),
.fifo_empty(fifo_empty[i]),
.fifo_full(fifo_full[i]),
.wclk(clk1),
.rclk(clk2),
.rst(rst1));
end
endgenerate
 
// and-or mux write address
always @*
begin
wadr = {a_lo_size{1'b0}};
for (j=0;j<nr_of_queues;j=j+1) begin
wadr = (fifo_wadr_bin[j] & {a_lo_size{write_enable[j]}}) | wadr;
end
end
 
// and-or mux read address
always @*
begin
radr = {a_lo_size{1'b0}};
for (k=0;k<nr_of_queues;k=k+1) begin
radr = (fifo_radr_bin[k] & {a_lo_size{read_enable_reg[k]}}) | radr;
end
end
 
// and-or mux write data
generate
for (i=0;i<nr_of_queues;i=i+1) begin : vector2array
assign wdataa[i] = d[(nr_of_queues-i)*data_width-1:(nr_of_queues-1-i)*data_width];
end
endgenerate
 
always @*
begin
wdata = {data_width{1'b0}};
for (l=0;l<nr_of_queues;l=l+1) begin
wdata = (wdataa[l] & {data_width{write_enable[l]}}) | wdata;
end
end
 
vfifo_dual_port_ram_dc_sw # ( .DATA_WIDTH(data_width), .ADDR_WIDTH(a_hi_size+a_lo_size))
dpram (
.d_a(wdata),
.adr_a({onehot2bin(write_enable),wadr}),
.we_a(write),
.clk_a(clk1),
.q_b(q),
.adr_b({onehot2bin(read_enable_reg),radr}),
.clk_b(clk2) );
 
endmodule

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