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Diffstat (limited to 'fpga/usrp2/fifo/fifo_short.v')
-rw-r--r-- | fpga/usrp2/fifo/fifo_short.v | 112 |
1 files changed, 112 insertions, 0 deletions
diff --git a/fpga/usrp2/fifo/fifo_short.v b/fpga/usrp2/fifo/fifo_short.v new file mode 100644 index 000000000..32f26beef --- /dev/null +++ b/fpga/usrp2/fifo/fifo_short.v @@ -0,0 +1,112 @@ +// +// 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/>. +// + + +module fifo_short + #(parameter WIDTH=32) + (input clk, input reset, input clear, + input [WIDTH-1:0] datain, + input src_rdy_i, + output dst_rdy_o, + output [WIDTH-1:0] dataout, + output src_rdy_o, + input dst_rdy_i, + + output reg [4:0] space, + output reg [4:0] occupied); + + reg full, empty; + wire write = src_rdy_i & dst_rdy_o; + wire read = dst_rdy_i & src_rdy_o; + + assign dst_rdy_o = ~full; + assign src_rdy_o = ~empty; + + reg [3:0] a; + genvar i; + + generate + for (i=0;i<WIDTH;i=i+1) + begin : gen_srl16 + SRL16E + srl16e(.Q(dataout[i]), + .A0(a[0]),.A1(a[1]),.A2(a[2]),.A3(a[3]), + .CE(write),.CLK(clk),.D(datain[i])); + end + endgenerate + + always @(posedge clk) + if(reset) + begin + a <= 0; + empty <= 1; + full <= 0; + end + else if(clear) + begin + a <= 0; + empty <= 1; + full<= 0; + end + else if(read & ~write) + begin + full <= 0; + if(a==0) + empty <= 1; + else + a <= a - 1; + end + else if(write & ~read) + begin + empty <= 0; + if(~empty) + a <= a + 1; + if(a == 14) + full <= 1; + end + + // NOTE will fail if you write into a full fifo or read from an empty one + + ////////////////////////////////////////////////////////////// + // space and occupied are used for diagnostics, not + // guaranteed correct + + //assign space = full ? 0 : empty ? 16 : 15-a; + //assign occupied = empty ? 0 : full ? 16 : a+1; + + always @(posedge clk) + if(reset) + space <= 16; + else if(clear) + space <= 16; + else if(read & ~write) + space <= space + 1; + else if(write & ~read) + space <= space - 1; + + always @(posedge clk) + if(reset) + occupied <= 0; + else if(clear) + occupied <= 0; + else if(read & ~write) + occupied <= occupied - 1; + else if(write & ~read) + occupied <= occupied + 1; + +endmodule // fifo_short + |