DCache, ICache: Make cache_data a 1-D array to enable better synthesizability on...

[firearm.git] / ICache.v

diff --git a/ICache.v b/ICache.v
index 3a9f14481be7a2cc9c92dcbd036d7193602cf9ae..8b9eac34f5c5a8e62be1c117d6eaec173070a9b6 100644 (file)
--- a/ICache.v
+++ b/ICache.v
@@ -10,7 +10,7 @@ module ICache(
        output reg [31:0] rd_data,
        
        /* bus interface */
-       output reg bus_req,
+       output wire bus_req,
        input bus_ack,
        output reg [31:0] bus_addr,
        input [31:0] bus_rdata,
@@ -30,24 +30,24 @@ module ICache(
        
        reg cache_valid [15:0];
        reg [21:0] cache_tags [15:0];
-       reg [31:0] cache_data [15:0 /* line */] [15:0 /* word */];
+       reg [31:0] cache_data [255:0 /* {line, word} */];       //synthesis attribute ram_style of cache_data is distributed
        
-       reg [4:0] i;
+       integer i;
        initial
                for (i = 0; i < 16; i = i + 1)
+               begin
                        cache_valid[i[3:0]] = 0;
+                       cache_tags[i[3:0]] = 0;
+               end
        
        wire [5:0] rd_didx = rd_addr[5:0];
        wire [3:0] rd_didx_word = rd_didx[5:2];
        wire [3:0] rd_idx = rd_addr[9:6];
        wire [21:0] rd_tag = rd_addr[31:10];
        
-       wire cache_hit = cache_valid[rd_idx] && (cache_tags[rd_idx] == rd_tag);
+       reg [31:0] prev_rd_addr = 32'hFFFFFFFF;
        
-       always @(*) begin       /* XXX does this work nowadays? */
-               rd_wait = rd_req && !cache_hit;
-               rd_data = cache_data[rd_idx][rd_didx_word];
-       end
+       wire cache_hit = cache_valid[rd_idx] && (cache_tags[rd_idx] == rd_tag);
        
        reg [3:0] cache_fill_pos = 0;
        assign bus_req = rd_req && !cache_hit; /* xxx, needed for Verilator */
@@ -59,16 +59,27 @@ module ICache(
                        bus_addr = 0;
                        bus_rd = 0;
                end
+
+       wire [31:0] curdata = cache_data[{rd_idx,rd_didx_word}];
+       always @(*) begin
+               rd_wait = rd_req && !cache_hit;
+               rd_data = curdata;
+       end
        
-       always @(posedge clk)
-               if (rd_req && !cache_hit) begin
-                       if (bus_ready) begin    /* Started the fill, and we have data. */
-                               cache_data[rd_idx][cache_fill_pos] <= bus_rdata;
-                               cache_fill_pos <= cache_fill_pos + 1;
-                               if (cache_fill_pos == 15) begin /* Done? */
-                                       cache_tags[rd_idx] <= rd_tag;
-                                       cache_valid[rd_idx] <= 1;
-                               end
-                       end
+       always @(posedge clk) begin
+               prev_rd_addr <= {rd_addr[31:6], 6'b0};
+               if (cache_fill_pos != 0 && ((prev_rd_addr != {rd_addr[31:6], 6'b0}) || cache_hit))      /* If this wasn't from the same line, or we've moved on somehow, reset the fill circuitry. */
+                       cache_fill_pos <= 0;
+               else if (rd_req && !cache_hit && bus_ack && bus_ready) begin
+                       $display("ICACHE: FILL: rd addr %08x; bus addr %08x; bus data %08x", rd_addr, bus_addr, bus_rdata);
+                       cache_data[{rd_idx,cache_fill_pos}] <= bus_rdata;
+                       cache_fill_pos <= cache_fill_pos + 1;
+                       if (cache_fill_pos == 15) begin /* Done? */
+                               cache_tags[rd_idx] <= rd_tag;
+                               cache_valid[rd_idx] <= 1;
+                               $display("ICACHE: Fill complete for line %x, tag %x", rd_idx, rd_tag);
+                       end else
+                               cache_valid[rd_idx] <= 0;
                end
+       end
 endmodule