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authorMatt Ettus <matt@ettus.com>2010-06-14 13:23:18 -0700
committerMatt Ettus <matt@ettus.com>2010-06-14 13:23:18 -0700
commita97707caa8e9f19fdc81061ac11a73f41aab2704 (patch)
treec75983a4caff316fe1c64cdba047229ac4584cc7 /usrp2/fifo/fifo_long.v
parenta4b11332ab4f6a24bf4645c0b2770f9578a36f45 (diff)
parent9445315e6a5cdfb29c4ead73b0fcd4d5fd75b900 (diff)
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Merge branch 'master' into u1e_newbuild
Made so Makefile changes as well to get it to build * master: new make works on ise12 produces good bin files first attempt at cleaning up the build system get rid of debug stuff to help timing move u2_core into u2_rev3 directory to simplify directory structure and save headaches Conflicts: usrp2/fifo/fifo36_to_fifo18.v usrp2/top/u2_rev3/Makefile usrp2/top/u2_rev3/Makefile.udp usrp2/top/u2_rev3/u2_core_udp.v
Diffstat (limited to 'usrp2/fifo/fifo_long.v')
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diff --git a/usrp2/fifo/fifo_long.v b/usrp2/fifo/fifo_long.v
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+
+// FIFO intended to be interchangeable with shortfifo, but
+// based on block ram instead of SRL16's
+// only one clock domain
+
+// Port A is write port, Port B is read port
+
+module fifo_long
+ #(parameter WIDTH=32, SIZE=9)
+ (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 [15:0] space,
+ output reg [15:0] occupied);
+
+ wire write = src_rdy_i & dst_rdy_o;
+ wire read = dst_rdy_i & src_rdy_o;
+ wire full, empty;
+
+ assign dst_rdy_o = ~full;
+ assign src_rdy_o = ~empty;
+
+ // Read side states
+ localparam EMPTY = 0;
+ localparam PRE_READ = 1;
+ localparam READING = 2;
+
+ reg [SIZE-1:0] wr_addr, rd_addr;
+ reg [1:0] read_state;
+
+ reg empty_reg, full_reg;
+ always @(posedge clk)
+ if(reset)
+ wr_addr <= 0;
+ else if(clear)
+ wr_addr <= 0;
+ else if(write)
+ wr_addr <= wr_addr + 1;
+
+ ram_2port #(.DWIDTH(WIDTH),.AWIDTH(SIZE))
+ ram (.clka(clk),
+ .ena(1'b1),
+ .wea(write),
+ .addra(wr_addr),
+ .dia(datain),
+ .doa(),
+
+ .clkb(clk),
+ .enb((read_state==PRE_READ)|read),
+ .web(0),
+ .addrb(rd_addr),
+ .dib(0),
+ .dob(dataout));
+
+ always @(posedge clk)
+ if(reset)
+ begin
+ read_state <= EMPTY;
+ rd_addr <= 0;
+ empty_reg <= 1;
+ end
+ else
+ if(clear)
+ begin
+ read_state <= EMPTY;
+ rd_addr <= 0;
+ empty_reg <= 1;
+ end
+ else
+ case(read_state)
+ EMPTY :
+ if(write)
+ begin
+ //rd_addr <= wr_addr;
+ read_state <= PRE_READ;
+ end
+ PRE_READ :
+ begin
+ read_state <= READING;
+ empty_reg <= 0;
+ rd_addr <= rd_addr + 1;
+ end
+
+ READING :
+ if(read)
+ if(rd_addr == wr_addr)
+ begin
+ empty_reg <= 1;
+ if(write)
+ read_state <= PRE_READ;
+ else
+ read_state <= EMPTY;
+ end
+ else
+ rd_addr <= rd_addr + 1;
+ endcase // case(read_state)
+
+ wire [SIZE-1:0] dont_write_past_me = rd_addr - 3;
+ wire becoming_full = wr_addr == dont_write_past_me;
+
+ always @(posedge clk)
+ if(reset)
+ full_reg <= 0;
+ else if(clear)
+ full_reg <= 0;
+ else if(read & ~write)
+ full_reg <= 0;
+ //else if(write & ~read & (wr_addr == (rd_addr-3)))
+ else if(write & ~read & becoming_full)
+ full_reg <= 1;
+
+ //assign empty = (read_state != READING);
+ assign empty = empty_reg;
+
+ // assign full = ((rd_addr - 1) == wr_addr);
+ assign full = full_reg;
+
+ //////////////////////////////////////////////
+ // space and occupied are for diagnostics only
+ // not guaranteed exact
+
+ localparam NUMLINES = (1<<SIZE)-2;
+ always @(posedge clk)
+ if(reset)
+ space <= NUMLINES;
+ else if(clear)
+ space <= NUMLINES;
+ 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_long