work in progress

git-svn-id: http://gnuradio.org/svn/gnuradio/trunk@10358 221aa14e-8319-0410-a670-987f0aec2ac5

1 files changed, 209 insertions, 0 deletions

diff --git a/usrp2/fpga/control_lib/giantfifo.v b/usrp2/fpga/control_lib/giantfifo.v
new file mode 100644
index 000000000..dba330b8a
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+++ b/usrp2/fpga/control_lib/giantfifo.v
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+
+
+
+module giantfifo
+  #(parameter WIDTH=36)
+    (input clk, input rst,
+     input [WIDTH-1:0] datain,
+     output [WIDTH-1:0] dataout,
+     input read,
+     input write,
+     input clear,
+     output full,
+     output empty,
+     output [15:0] space,
+     output [15:0] occupied,
+     
+     // External RAM
+     inout [17:0] RAM_D,
+     output reg [18:0] RAM_A,
+     output RAM_CE1n,
+     output RAM_CENn,
+     output reg RAM_CLK,
+     output reg RAM_WEn,
+     output RAM_OEn,
+     output RAM_LDn
+     );
+
+   wire [4:0] path1_occ, path2_space;
+   wire [35:0] path1_dat, path2_dat;
+   
+   shortfifo #(.WIDTH(WIDTH)) sf1
+     (.clk(clk),.rst(rst),.clear(clear),
+      .datain(datain),.write(write),.full(full),
+      .dataout(path1_dat),.read(path1_read),.empty(path1_empty),
+      .space(),.occupied(path1_occ) );
+   wire       path1_almost_empty = (path1_occ == 5'd1);
+   
+   shortfifo #(.WIDTH(WIDTH)) sf2
+     (.clk(clk),.rst(rst),.clear(clear),
+      .datain(path2_dat),.write(path2_write),.full(path2_full),
+      .dataout(dataout),.read(read),.empty(empty),
+      .space(path2_space),.occupied() );
+   wire       path2_almost_full = (path2_space == 5'd1);
+	
+   assign     RAM_CE1n = 1'b0;
+   assign     RAM_CENn = 1'b0;
+   always @(clk)
+     RAM_CLK <= #2 clk;
+   assign     RAM_LDn = 1'b0;
+
+   // State machine
+   wire       write_now, read_now, idle, phase;
+   reg 	      ram_full, ram_empty;
+   
+   reg [17:0] read_ptr, write_ptr;
+   reg [2:0]  zbt_state;
+
+   localparam ZBT_IDLE = 0;
+   localparam ZBT_WRITE_UPPER = 2;
+   localparam ZBT_WRITE_LOWER = 3;
+   localparam ZBT_READ_UPPER = 4;
+   localparam ZBT_READ_LOWER = 5;
+
+   wire       can_write = ~ram_full & ~path1_empty;
+   wire       can_write_chain = can_write & ~path1_almost_empty;
+
+   wire       can_read = ~ram_empty & ~path2_full;
+   wire       can_read_chain = can_read & ~path2_almost_full;
+   
+   assign     phase = zbt_state[0];
+
+   reg [17:0] ram_occupied;
+   wire       ram_almost_empty = (write_ptr == (read_ptr+1'b1));
+   wire       ram_almost_full = ((write_ptr+1'b1) == read_ptr);
+
+   always @(posedge clk)
+     if(rst | clear)
+       begin
+	  zbt_state <= ZBT_IDLE;
+	  write_ptr <= 0;
+	  read_ptr <= 0;
+	  ram_full <= 0;
+	  ram_empty <= 1;
+	  ram_occupied <= 0;
+       end
+     else
+       case(zbt_state)
+	 ZBT_IDLE : 
+	   if(can_read) 
+	     zbt_state <= ZBT_READ_UPPER;
+	   else if(can_write)
+	     zbt_state <= ZBT_WRITE_UPPER;
+	 
+	 ZBT_WRITE_UPPER : 
+	   begin
+	      zbt_state <= ZBT_WRITE_LOWER;
+	      ram_occupied <= ram_occupied + 1;
+	      ram_empty <= 0;
+	      if(ram_occupied == 18'd10)
+		ram_full <= 1;
+	   end
+	 ZBT_WRITE_LOWER : 
+	   begin
+	      write_ptr <= write_ptr + 1;
+	      if(can_read_chain) 
+		zbt_state <= ZBT_READ_UPPER;
+	      else if(can_write_chain)
+		zbt_state <= ZBT_WRITE_UPPER;
+	      else
+		zbt_state <= ZBT_IDLE;
+	   end
+	 ZBT_READ_UPPER : 
+	   begin
+	      zbt_state <= ZBT_READ_LOWER;
+	      ram_occupied <= ram_occupied - 1;
+	      ram_full <= 0;
+	      if(ram_occupied == 18'd1)
+		ram_empty <= 1;
+	   end
+	 ZBT_READ_LOWER :
+	   begin
+	      read_ptr <= read_ptr + 1;
+	      if(can_read_chain) 
+		zbt_state <= ZBT_READ_UPPER;
+	      else if(can_write_chain)
+		zbt_state <= ZBT_WRITE_UPPER;
+	      else
+		zbt_state <= ZBT_IDLE;
+	   end
+	 default :
+	   zbt_state <= ZBT_IDLE;
+       endcase // case(zbt_state)
+
+   // Need to generate RAM_WEn, RAM_OEn, RAM_D, RAM_A;
+   assign path1_read = (zbt_state == ZBT_WRITE_LOWER);
+   reg 	  path2_write, delayed_read_upper, delayed_read_lower, delayed_write;
+
+   always @(posedge clk)
+     if(delayed_read_upper)
+       path2_dat[35:18] <= RAM_D;
+   always @(posedge clk)
+     if(delayed_read_lower)
+       path2_dat[17:0] <= RAM_D;
+
+   always @(posedge clk)
+     if(rst)
+       begin
+	  delayed_read_upper <= 0;
+	  delayed_read_lower <= 0;
+	  path2_write <= 0;
+       end
+     else 
+       begin
+	  delayed_read_upper <= (zbt_state == ZBT_READ_LOWER);
+	  delayed_read_lower <= delayed_read_upper;
+	  path2_write <= delayed_read_lower;
+       end
+   
+   reg [17:0] RAM_D_pre2, RAM_D_pre1, RAM_D_out;
+   
+   always @(posedge clk)
+     RAM_D_pre2 <= phase ? path1_dat[17:0] : path1_dat[35:18];
+
+   always @(posedge clk)  RAM_D_pre1 <= RAM_D_pre2;
+   always @(posedge clk)  RAM_D_out <= RAM_D_pre1;
+   reg 	      wr_del_1, wr_del_2; 	      
+   always @(posedge clk)
+     if(rst)
+       begin
+	  wr_del_1 <= 0;	  
+	  wr_del_2 <= 0;
+	  delayed_write <= 0;
+       end
+     else
+       begin
+	  delayed_write <= wr_del_2;
+	  wr_del_2 <= wr_del_1;
+	  wr_del_1 <= write_now;
+       end
+
+   reg delayed_read, rd_del_1, rd_del_2;
+   always @(posedge clk)
+     if(rst)
+       begin
+	  rd_del_1 <= 0;	  
+	  rd_del_2 <= 0;
+	  delayed_read <= 0;
+       end
+     else
+       begin
+	  delayed_read <= rd_del_2;
+	  rd_del_2 <= rd_del_1;
+	  rd_del_1 <= read_now;
+       end
+	  
+   assign     RAM_D = delayed_write ? RAM_D_out : 18'bzzzzzzzzzzzzzzzzzz;
+   assign     write_now = (zbt_state == ZBT_WRITE_UPPER) || (zbt_state == ZBT_WRITE_LOWER);
+   assign     read_now =  (zbt_state == ZBT_READ_UPPER) || (zbt_state == ZBT_READ_LOWER);
+   
+   always @(posedge clk)
+     RAM_A <= write_now ? {write_ptr,phase} : {read_ptr,phase};
+
+   always @(posedge clk)
+     RAM_WEn <= ~write_now;
+
+   assign     RAM_OEn = ~delayed_read;
+   assign     RAM_OEn = 0;
+   
+endmodule // giantfifo