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Diffstat (limited to 'fpga/usrp2/udp/prot_eng_rx.v')
| -rw-r--r-- | fpga/usrp2/udp/prot_eng_rx.v | 138 |
1 files changed, 138 insertions, 0 deletions
diff --git a/fpga/usrp2/udp/prot_eng_rx.v b/fpga/usrp2/udp/prot_eng_rx.v new file mode 100644 index 000000000..ccb59b7ff --- /dev/null +++ b/fpga/usrp2/udp/prot_eng_rx.v @@ -0,0 +1,138 @@ +// +// 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/>. +// + + + + +// Protocol Engine Receiver +// Checks each line (16 bits) against values in setting regs +// 3 options for each line -- +// Error if mismatch, Slowpath if mismatch, or ignore line +// The engine increases the length of each packet by 32 or 48 bits, +// bringing the total length to a multiple of 32 bits. The last line +// is entirely new, and contains the results of the matching operation: +// 16 bits of flags, 16 bits of data. Flags indicate error or slowpath +// Data indicates line that caused mismatch if any. + + +// Flags[2:0] is {occ, eop, sop} +// Protocol word format is: +// 22 Last Header Line +// 21 SLOWPATH if mismatch +// 20 ERROR if mismatch +// 19 This is the IP checksum +// 18 This is the UDP checksum +// 17 Compute IP checksum on this word +// 16 Compute UDP checksum on this word +// 15:0 data word to be matched + +module prot_eng_rx + #(parameter BASE=0) + (input clk, input reset, input clear, + input set_stb, input [7:0] set_addr, input [31:0] set_data, + input [18:0] datain, input src_rdy_i, output dst_rdy_o, + output [18:0] dataout, output src_rdy_o, input dst_rdy_i); + + localparam HDR_WIDTH = 16 + 7; // 16 bits plus flags + localparam HDR_LEN = 32; // Up to 64 bytes of protocol + + // Store header values in a small dual-port (distributed) ram + reg [HDR_WIDTH-1:0] header_ram[0:HDR_LEN-1]; + wire [HDR_WIDTH-1:0] header_word; + + always @(posedge clk) + if(set_stb & ((set_addr & 8'hE0) == BASE)) + header_ram[set_addr[4:0]] <= set_data; + + assign header_word = header_ram[state]; + + wire consume_input = src_rdy_i & dst_rdy_o; + wire produce_output = src_rdy_o & dst_rdy_i; + + // Main State Machine + reg [15:0] pkt_length, fail_word, dataout_int; + + reg slowpath, error, sof_o, eof_o, occ_o, odd; + + assign dataout = {occ_o, eof_o, sof_o, dataout_int}; + + wire [15:0] calc_ip_checksum, calc_udp_checksum; + reg [15:0] rx_ip_checksum, rx_udp_checksum; + + always @(posedge clk) + if(header_word[19]) + rx_ip_checksum <= datain[15:0]; + always @(posedge clk) + if(header_word[18]) + rx_udp_checksum <= datain[15:0]; + + always @(posedge clk) + if(reset | clear) + begin + slowpath <= 0; + error <= 0; + state <= 0; + fail_word <= 0; + eof_o <= 0; + occ_o <= 0; + end + else if(src_rdy_i & dst_rdy_i) + case (state) + 0 : + begin + slowpath <= 0; + error <= 0; + eof_o <= 0; + occ_o <= 0; + state <= 1; + end + + ST_SLOWPATH : + ; + ST_ERROR : + ; + ST_PAYLOAD : + ; + ST_FILLER : + ; + ST_END1 : + ; + ST_END2 : + ; + default : + if(header_word[21] && mismatch) + state <= ST_SLOWPATH; + else if(header_word[20] && mismatch) + state <= ST_ERROR; + else if(header_word[22]) + state <= ST_PAYLOAD; + else + state <= state + 1; + endcase // case (state) + + + + // IP + UDP checksum state machines + checksum_sm ip_chk + (.clk(clk), .reset(reset), .in(datain), + .calc(consume_input & header_word[17]), .clear(state==0), .checksum(ip_checksum)); + + checksum_sm udp_chk + (.clk(clk), .reset(reset), .in(datain), + .calc(consume_input & header_word[16]), .clear(state==0), .checksum(udp_checksum)); + +endmodule // prot_eng_rx |