From 05d77f772317de5d925301aa11bb9a880656dd05 Mon Sep 17 00:00:00 2001
From: Josh Blum <josh@joshknows.com>
Date: Thu, 15 Apr 2010 11:24:24 -0700
Subject: moved usrp1 and usrp2 fpga dirs into fpga subdirectory

---
 fpga/usrp2/control_lib/icache.v | 135 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 135 insertions(+)
 create mode 100644 fpga/usrp2/control_lib/icache.v

(limited to 'fpga/usrp2/control_lib/icache.v')

diff --git a/fpga/usrp2/control_lib/icache.v b/fpga/usrp2/control_lib/icache.v
new file mode 100644
index 000000000..bd21f47cc
--- /dev/null
+++ b/fpga/usrp2/control_lib/icache.v
@@ -0,0 +1,135 @@
+
+module icache
+  #(parameter AWIDTH=14,
+    parameter CWIDTH=6)
+
+    (input wb_clk_i,
+     input wb_rst_i,
+     input [AWIDTH-1:0] iwb_adr_i,
+     input iwb_stb_i,
+     output [31:0] iwb_dat_o,
+     output iwb_ack_o,
+     input [31:0] iram_dat_i,
+     output [AWIDTH-1:0] iram_adr_o,
+     output iram_en_o,
+     input flush);
+
+   localparam TAGWIDTH = AWIDTH-CWIDTH-2;
+   reg 	      stb_d1, ack_d1, miss_d1;
+   reg [AWIDTH-1:0] held_addr;
+   reg [31:0] 	    idata [0:(1<<CWIDTH)-1];
+   reg [TAGWIDTH-1:0] itags [0:(1<<CWIDTH)-1];
+   reg 		      ivalid [0:(1<<CWIDTH)-1];
+   
+   wire [CWIDTH-1:0]  rd_line, wr_line;
+   wire [TAGWIDTH-1:0] wr_tags;
+   wire 	       store_in_cache;
+
+   // /////////////////////////////////////
+   // Write into cache
+   integer 	      i;
+   always @(posedge wb_clk_i)
+     if(wb_rst_i | flush)
+       for(i=0;i<(1<<CWIDTH);i=i+1)
+	 ivalid[i] <= 0;
+     else
+       if(store_in_cache)
+	 ivalid[wr_line] <= 1'b1;
+   
+   always @(posedge wb_clk_i)
+     if(store_in_cache)
+       begin
+	  idata[wr_line] <= iram_dat_i;
+	  itags[wr_line] <= wr_tags;
+       end
+   
+   // //////////////////////////////////////
+   // Read from Cache
+   wire [TAGWIDTH-1:0] tag_out = itags[rd_line];
+   wire 	       valid_out = ivalid[rd_line];
+   wire [31:0] 	       data_out	= idata[rd_line];
+   wire 	       cache_hit = valid_out & (tag_out == iwb_adr_i[AWIDTH-1:CWIDTH+2]);
+   wire 	       cache_miss = ~cache_hit;
+
+   // //////////////////////////////////////
+   // Handle 1-cycle delay of Block-RAM
+   always @(posedge wb_clk_i)
+     if(wb_rst_i)
+       stb_d1 <= 0;
+     else
+       stb_d1 <= iwb_stb_i;
+   
+   always @(posedge wb_clk_i)
+     if(wb_rst_i)
+       held_addr <= 0;
+     else
+       held_addr <= iwb_adr_i;
+   
+   always @(posedge wb_clk_i) 
+     if(wb_rst_i)
+       ack_d1 <= 1'b0;
+     else 
+       ack_d1 <= iwb_ack_o;
+
+   always @(posedge wb_clk_i) 
+     if(wb_rst_i)
+       miss_d1 <= 0;
+     else 
+       miss_d1 <= cache_miss;
+
+//`define IC_NOCACHE
+//`define IC_BASIC
+//`define IC_FORWARDING_DP
+`define IC_FORWARDING_SP
+//`define IC_PREFETCH
+
+`ifdef IC_NOCACHE
+   assign 	       iwb_dat_o = iram_dat_i;
+   assign 	       iwb_ack_o = iwb_stb_i & (stb_d1 & ~ack_d1);
+   assign 	       iram_adr_o = iwb_adr_i;
+   assign 	       iram_en_o = 1'b1;
+   assign 	       rd_line = 0;
+   assign 	       wr_line = 0;
+   assign 	       wr_tags = 0;
+   assign 	       store_in_cache = 0;
+`endif
+   
+`ifdef IC_BASIC    // Very basic, no forwarding, 2 wait states on miss
+   assign 	       iwb_dat_o = data_out;
+   assign 	       iwb_ack_o = iwb_stb_i & cache_hit;
+   assign 	       iram_adr_o = iwb_adr_i;
+   assign 	       iram_en_o = 1'b1;
+   assign 	       rd_line = iwb_adr_i[CWIDTH+1:2];
+   assign 	       wr_line = rd_line;
+   assign 	       wr_tags = iwb_adr_i[AWIDTH-1:CWIDTH+2];
+   assign 	       store_in_cache = stb_d1 & miss_d1;
+`endif
+   
+`ifdef IC_FORWARDING_DP   // Simple forwarding, 1 wait state on miss, dual-port ram
+   assign 	       iwb_dat_o = cache_hit ? data_out : iram_dat_i;
+   assign 	       iwb_ack_o = iwb_stb_i & (cache_hit | (stb_d1 & ~ack_d1));
+   assign 	       iram_adr_o = iwb_adr_i;
+   assign 	       iram_en_o = 1'b1;
+   assign 	       rd_line = iwb_adr_i[CWIDTH+1:2];
+   assign 	       wr_line = held_addr[CWIDTH+1:2];
+   assign 	       wr_tags = held_addr[AWIDTH-1:CWIDTH+2];	       
+   assign 	       store_in_cache = iwb_stb_i & stb_d1 & miss_d1 & ~ack_d1;
+`endif
+
+`ifdef IC_FORWARDING_SP   // Simple forwarding, 1 wait state on miss, single-port ram
+   assign 	       iwb_dat_o = cache_hit ? data_out : iram_dat_i;
+   assign 	       iwb_ack_o = iwb_stb_i & (cache_hit | (stb_d1 & ~ack_d1));
+   assign 	       iram_adr_o = iwb_adr_i;
+   assign 	       iram_en_o = 1'b1;
+   assign 	       rd_line = iwb_adr_i[CWIDTH+1:2];
+   assign 	       wr_line = rd_line;
+   assign 	       wr_tags = iwb_adr_i[AWIDTH-1:CWIDTH+2];
+   assign 	       store_in_cache = iwb_stb_i & stb_d1 & miss_d1 & ~ack_d1;
+`endif
+
+`ifdef IC_PREFETCH   // Forwarding plus prefetch
+
+`endif
+   
+   
+endmodule // icache
-- 
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