Squashed B200 FPGA Source. Code from Josh Blum, Ian Buckley, and Matt Ettus.

Original-commit: 0df4b801a34697f2058b4a7b95e08d2a0576c9db

lib/packet_proc/cvita_chunker.v

@@ -0,0 +1,91 @@
+//
+// Copyright 2013 Ettus Research LLC
+//
+
+// Quantize cvita packets to a configurable quantum value. o_tlast and 
+// i_tready will be held off until the entire quantized packet is xferred. 
+// If quantum is changed, it is the responsibility of the client to clear
+// this module. error is asserted if a packet is larger than the quantum
+// error can be reset by asserting reset or clear.
+
+module cvita_chunker # (
+   parameter PAD_VALUE = 64'hFFFFFFFF_FFFFFFFF
+) (
+   input          clk,
+   input          reset,
+   input          clear,
+   input [15:0]   frame_size,
+
+   input [63:0]   i_tdata,
+   input          i_tlast,
+   input          i_tvalid,
+   output         i_tready,
+   
+   output [63:0]  o_tdata,
+   output         o_tlast,
+   output         o_tvalid,
+   input          o_tready,
+   
+   output         error
+);
+
+   localparam ST_HEADER  = 2'd0;
+   localparam ST_DATA    = 2'd1;
+   localparam ST_PADDING = 2'd2;
+   localparam ST_ERROR   = 2'd3;
+
+   reg [1:0]   state;
+   reg [15:0]  frame_rem;
+
+   wire [15:0] cvita_len_ceil = i_tdata[47:32] + 7;
+   wire [15:0] axi_len = {3'b000, cvita_len_ceil[15:3]};
+
+   always @(posedge clk) begin
+      if (reset | clear) begin
+         state <= ST_HEADER;
+         frame_rem <= 16'd0;
+      end else if (o_tvalid & o_tready) begin
+         case (state)
+            ST_HEADER: begin
+               if (axi_len > frame_size)
+                  state <= ST_ERROR;
+               else if (i_tlast)
+                  state <= ST_PADDING;
+               else
+                  state <= ST_DATA;
+                  
+               frame_rem <= frame_size - 16'd1;
+            end
+
+            ST_DATA: begin
+               if (i_tlast) begin
+                  state   <= o_tlast ? ST_HEADER : ST_PADDING;
+                  frame_rem <= o_tlast ? 16'd0 : (frame_rem - 16'd1);
+               end else begin
+                  state <= ST_DATA;
+                  frame_rem <= frame_rem - 16'd1;
+               end
+            end
+
+            ST_PADDING: begin
+               if (o_tlast) begin
+                  state   <= ST_HEADER;
+                  frame_rem <= 16'd0;
+               end else begin
+                  state   <= ST_PADDING;
+                  frame_rem <= frame_rem - 16'd1;
+               end
+            end
+         endcase
+      end
+   end
+
+   assign i_tready = o_tready & (state != ST_PADDING);
+   
+   assign o_tvalid = i_tvalid | (state == ST_PADDING);
+   assign o_tlast = (frame_rem != 0) ? (frame_rem == 16'd1) : (axi_len == 16'd1);
+   assign o_tdata = (state == ST_PADDING) ? PAD_VALUE : i_tdata;
+
+   assign error = (state == ST_ERROR);
+
+endmodule // cvita_chunker