actually fill the cache?
authorJoshua Wise <joshua@rebirth.joshuawise.com>
Fri, 19 Dec 2008 07:47:00 +0000 (02:47 -0500)
committerJoshua Wise <joshua@rebirth.joshuawise.com>
Fri, 19 Dec 2008 07:47:00 +0000 (02:47 -0500)
icache.v

index 2c29a6c..4dce41d 100644 (file)
--- a/icache.v
+++ b/icache.v
@@ -42,18 +42,33 @@ module ICache(
        wire cache_hit = cache_valid[rd_idx] && (cache_tags[rd_idx] == rd_tag);
        
        always @(*) begin       /* XXX does this work nowadays? */
-               rd_wait = !cache_hit;
+               rd_wait = rd_req && !cache_hit;
                rd_data = cache_data[rd_idx][rd_didx_word];
        end
        
        reg [3:0] cache_fill_pos = 0;
-       reg cache_filling = 0;
        always @(*) begin
-               if (!cache_hit) begin
+               if (rd_req && !cache_hit) begin
                        bus_req = 1;
                        if (bus_ack) begin
                                bus_addr = {rd_addr[31:6], cache_fill_pos[3:0], 2'b00 /* reads are 32-bits */};
                                bus_rd = 1;
                        end
+               end else begin
+                       bus_req = 0;
+                       bus_addr = 0;
+                       bus_rd = 0;
+               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_data;
+                               cache_fill_pos <= cache_fill_pos + 1;
+                               if ((cache_fill_pos + 1) == 0) begin    /* Done? */
+                                       cache_tags[rd_idx] = rd_tag;
+                                       cache_valid[rd_idx] = 1;
+                               end
+                       end
                end
 endmodule
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