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Diffstat (limited to 'fpga/usrp2/fifo/buffer_int.v')
| -rw-r--r-- | fpga/usrp2/fifo/buffer_int.v | 184 |
1 files changed, 184 insertions, 0 deletions
diff --git a/fpga/usrp2/fifo/buffer_int.v b/fpga/usrp2/fifo/buffer_int.v new file mode 100644 index 000000000..c068226ec --- /dev/null +++ b/fpga/usrp2/fifo/buffer_int.v @@ -0,0 +1,184 @@ +// +// 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/>. +// + + +// FIFO Interface to the 2K buffer RAMs +// Read port is read-acknowledge +// FIXME do we want to be able to interleave reads and writes? + +module buffer_int + #(parameter BUF_NUM = 0, + parameter BUF_SIZE = 9) + (// Control Interface + input clk, + input rst, + input [31:0] ctrl_word, + input go, + output done, + output error, + output idle, + + // Buffer Interface + output en_o, + output we_o, + output reg [BUF_SIZE-1:0] addr_o, + output [31:0] dat_to_buf, + input [31:0] dat_from_buf, + + // Write FIFO Interface + input [31:0] wr_data_i, + input [3:0] wr_flags_i, + input wr_ready_i, + output wr_ready_o, + + // Read FIFO Interface + output [31:0] rd_data_o, + output [3:0] rd_flags_o, + output rd_ready_o, + input rd_ready_i + ); + + reg [31:0] ctrl_reg; + reg go_reg; + + always @(posedge clk) + go_reg <= go; + + always @(posedge clk) + if(rst) + ctrl_reg <= 0; + else + if(go & (ctrl_word[31:28] == BUF_NUM)) + ctrl_reg <= ctrl_word; + + wire [BUF_SIZE-1:0] firstline = ctrl_reg[BUF_SIZE-1:0]; + wire [BUF_SIZE-1:0] lastline = ctrl_reg[2*BUF_SIZE-1:BUF_SIZE]; + + wire read = ctrl_reg[22]; + wire write = ctrl_reg[23]; + wire clear = ctrl_reg[24]; + //wire [2:0] port = ctrl_reg[27:25]; // Ignored in this block + //wire [3:0] buff_num = ctrl_reg[31:28]; // Ignored here ? + + localparam IDLE = 3'd0; + localparam PRE_READ = 3'd1; + localparam READING = 3'd2; + localparam WRITING = 3'd3; + localparam ERROR = 3'd4; + localparam DONE = 3'd5; + + reg [2:0] state; + reg rd_sop, rd_eop; + wire wr_sop, wr_eop, wr_error; + reg [1:0] rd_occ; + wire [1:0] wr_occ; + + always @(posedge clk) + if(rst) + begin + state <= IDLE; + rd_sop <= 0; + rd_eop <= 0; + rd_occ <= 0; + end + else + if(clear) + begin + state <= IDLE; + rd_sop <= 0; + rd_eop <= 0; + rd_occ <= 0; + end + else + case(state) + IDLE : + if(go_reg & read) + begin + addr_o <= firstline; + state <= PRE_READ; + end + else if(go_reg & write) + begin + addr_o <= firstline; + state <= WRITING; + end + + PRE_READ : + begin + state <= READING; + addr_o <= addr_o + 1; + rd_occ <= 2'b00; + rd_sop <= 1; + rd_eop <= 0; + end + + READING : + if(rd_ready_i) + begin + rd_sop <= 0; + addr_o <= addr_o + 1; + if(addr_o == lastline) + begin + rd_eop <= 1; + // FIXME assign occ here + rd_occ <= 0; + end + else + rd_eop <= 0; + if(rd_eop) + state <= DONE; + end + + WRITING : + begin + if(wr_ready_i) + begin + addr_o <= addr_o + 1; + if(wr_error) + begin + state <= ERROR; + // Save OCC flags here + end + else if((addr_o == lastline)||wr_eop) + state <= DONE; + end // if (wr_ready_i) + end // case: WRITING + + endcase // case(state) + + assign dat_to_buf = wr_data_i; + assign rd_data_o = dat_from_buf; + + assign rd_flags_o = { rd_occ[1:0], rd_eop, rd_sop }; + assign rd_ready_o = (state == READING); + + assign wr_sop = wr_flags_i[0]; + assign wr_eop = wr_flags_i[1]; + assign wr_occ = wr_flags_i[3:2]; + assign wr_error = wr_sop & wr_eop; + assign wr_ready_o = (state == WRITING); + + assign we_o = (state == WRITING); + //assign we_o = (state == WRITING) && wr_ready_i; // always write to avoid timing issue + + assign en_o = ~((state==READING)& ~rd_ready_i); // FIXME potential critical path + + assign done = (state == DONE); + assign error = (state == ERROR); + assign idle = (state == IDLE); + +endmodule // buffer_int |