X-Git-Url: http://git.joshuawise.com/firearm.git/blobdiff_plain/c808669d58509186fededc868210747f78a52933..2f8f0594f45ef78f4f3c5c0c209c889c931bc863:/icache.v diff --git a/icache.v b/icache.v index 2c29a6c..3dd9cc3 100644 --- a/icache.v +++ b/icache.v @@ -13,12 +13,14 @@ module ICache( output reg bus_req, input bus_ack, output reg [31:0] bus_addr, - input [31:0] bus_data + input [31:0] bus_rdata, + output wire [31:0] bus_wdata, output reg bus_rd, output wire bus_wr, input bus_ready); assign bus_wr = 0; + assign bus_wdata = 0; /* [31 tag 10] [9 cache index 6] [5 data index 0] * so the data index is 6 bits long @@ -28,11 +30,12 @@ module ICache( reg cache_valid [15:0]; reg [21:0] cache_tags [15:0]; - reg [31:0] cache_data [15:0] [7:0]; + reg [31:0] cache_data [15:0 /* line */] [15:0 /* word */]; + reg [4:0] i; initial for (i = 0; i < 16; i = i + 1) - cache_valid[i] <= 0; + cache_valid[i[3:0]] = 0; wire [5:0] rd_didx = rd_addr[5:0]; wire [3:0] rd_didx_word = rd_didx[5:2]; @@ -42,18 +45,33 @@ 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 + always @(*) + 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 == 15) begin /* Done? */ + cache_tags[rd_idx] = rd_tag; + cache_valid[rd_idx] = 1; + end + end end endmodule