diff options
Diffstat (limited to 'fpga/usrp2/fifo/fifo_2clock.v')
| -rw-r--r-- | fpga/usrp2/fifo/fifo_2clock.v | 139 |
1 files changed, 139 insertions, 0 deletions
diff --git a/fpga/usrp2/fifo/fifo_2clock.v b/fpga/usrp2/fifo/fifo_2clock.v new file mode 100644 index 000000000..756ad508f --- /dev/null +++ b/fpga/usrp2/fifo/fifo_2clock.v @@ -0,0 +1,139 @@ +// +// Copyright 2011 Ettus Research LLC +// +// This program is free software: you can redistribute it and/or modify +// it under the terms of the GNU General Public License as published by +// the Free Software Foundation, either version 3 of the License, or +// (at your option) any later version. +// +// This program is distributed in the hope that it will be useful, +// but WITHOUT ANY WARRANTY; without even the implied warranty of +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +// GNU General Public License for more details. +// +// You should have received a copy of the GNU General Public License +// along with this program. If not, see <http://www.gnu.org/licenses/>. +// + + +// FIXME ignores the AWIDTH (fifo size) parameter + +module fifo_2clock + #(parameter WIDTH=36, SIZE=6) + (input wclk, input [WIDTH-1:0] datain, input src_rdy_i, output dst_rdy_o, output [15:0] space, + input rclk, output [WIDTH-1:0] dataout, output src_rdy_o, input dst_rdy_i, output [15:0] occupied, + input arst); + + wire [SIZE:0] level_rclk, level_wclk; // xilinx adds an extra bit if you ask for accurate levels + wire full, empty, write, read; + + assign dst_rdy_o = ~full; + assign src_rdy_o = ~empty; + assign write = src_rdy_i & dst_rdy_o; + assign read = src_rdy_o & dst_rdy_i; + wire dummy; + + generate + if(WIDTH==36) + if(SIZE==9) + fifo_xlnx_512x36_2clk fifo_xlnx_512x36_2clk + (.rst(arst), + .wr_clk(wclk),.din(datain),.full(full),.wr_en(write),.wr_data_count(level_wclk), + .rd_clk(rclk),.dout(dataout),.empty(empty),.rd_en(read),.rd_data_count(level_rclk) ); + else if(SIZE==11) + fifo_xlnx_2Kx36_2clk fifo_xlnx_2Kx36_2clk + (.rst(arst), + .wr_clk(wclk),.din(datain),.full(full),.wr_en(write),.wr_data_count(level_wclk), + .rd_clk(rclk),.dout(dataout),.empty(empty),.rd_en(read),.rd_data_count(level_rclk) ); + else if(SIZE==6) + fifo_xlnx_64x36_2clk fifo_xlnx_64x36_2clk + (.rst(arst), + .wr_clk(wclk),.din(datain),.full(full),.wr_en(write),.wr_data_count(level_wclk), + .rd_clk(rclk),.dout(dataout),.empty(empty),.rd_en(read),.rd_data_count(level_rclk) ); + else + fifo_xlnx_512x36_2clk fifo_xlnx_512x36_2clk + (.rst(arst), + .wr_clk(wclk),.din(datain),.full(full),.wr_en(write),.wr_data_count(level_wclk), + .rd_clk(rclk),.dout(dataout),.empty(empty),.rd_en(read),.rd_data_count(level_rclk) ); + else if((WIDTH==19) & (SIZE==4)) + fifo_xlnx_16x19_2clk fifo_xlnx_16x19_2clk + (.rst(arst), + .wr_clk(wclk),.din(datain),.full(full),.wr_en(write),.wr_data_count(level_wclk), + .rd_clk(rclk),.dout(dataout),.empty(empty),.rd_en(read),.rd_data_count(level_rclk) ); + else if((WIDTH==18) & (SIZE==4)) + fifo_xlnx_16x19_2clk fifo_xlnx_16x19_2clk + (.rst(arst), + .wr_clk(wclk),.din({1'b0,datain}),.full(full),.wr_en(write),.wr_data_count(level_wclk), + .rd_clk(rclk),.dout({dummy,dataout}),.empty(empty),.rd_en(read),.rd_data_count(level_rclk) ); + endgenerate + + assign occupied = {{(16-SIZE-1){1'b0}},level_rclk}; + assign space = ((1<<SIZE)+1)-level_wclk; + +endmodule // fifo_2clock + +/* +`else + // ISE sucks, so the following doesn't work properly + + reg [AWIDTH-1:0] wr_addr, rd_addr; + wire [AWIDTH-1:0] wr_addr_rclk, rd_addr_wclk; + wire [AWIDTH-1:0] next_rd_addr; + wire enb_read; + + // Write side management + wire [AWIDTH-1:0] next_wr_addr = wr_addr + 1; + always @(posedge wclk or posedge arst) + if(arst) + wr_addr <= 0; + else if(write) + wr_addr <= next_wr_addr; + assign full = (next_wr_addr == rd_addr_wclk); + + // RAM for data storage. Data out is registered, complicating the + // read side logic + ram_2port #(.DWIDTH(DWIDTH),.AWIDTH(AWIDTH)) mac_rx_ff_ram + (.clka(wclk),.ena(1'b1),.wea(write),.addra(wr_addr),.dia(datain),.doa(), + .clkb(rclk),.enb(enb_read),.web(1'b0),.addrb(next_rd_addr),.dib(0),.dob(dataout) ); + + // Read side management + reg data_valid; + assign empty = ~data_valid; + assign next_rd_addr = rd_addr + data_valid; + assign enb_read = read | ~data_valid; + + always @(posedge rclk or posedge arst) + if(arst) + rd_addr <= 0; + else if(read) + rd_addr <= rd_addr + 1; + + always @(posedge rclk or posedge arst) + if(arst) + data_valid <= 0; + else + if(read & (next_rd_addr == wr_addr_rclk)) + data_valid <= 0; + else if(next_rd_addr != wr_addr_rclk) + data_valid <= 1; + + // Send pointers across clock domains via gray code + gray_send #(.WIDTH(AWIDTH)) send_wr_addr + (.clk_in(wclk),.addr_in(wr_addr), + .clk_out(rclk),.addr_out(wr_addr_rclk) ); + + gray_send #(.WIDTH(AWIDTH)) send_rd_addr + (.clk_in(rclk),.addr_in(rd_addr), + .clk_out(wclk),.addr_out(rd_addr_wclk) ); + + // Generate fullness info, these are approximate and may be delayed + // and are only for higher-level flow control. + // Only full and empty are guaranteed exact. + always @(posedge wclk) + level_wclk <= wr_addr - rd_addr_wclk; + always @(posedge rclk) + level_rclk <= wr_addr_rclk - rd_addr; +`endif +endmodule // fifo_2clock + +*/ |