Fix tag position
[firearm.git] / icache.v
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7e757d70
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1/* 16 cache entries, 64-byte long cache lines */
2
3module ICache(
4 input clk,
5 input [31:0] rd_addr,
6 input rd_req,
7 output reg rd_wait,
8 output reg [31:0] rd_data);
9
f83818d5 10 /* [31 tag 10] [9 cache index 6] [5 data index 0]
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11 * so the data index is 6 bits long
12 * so the cache index is 4 bits long
f83818d5 13 * so the tag is 22 bits long. c.c
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14 */
15
16 reg cache_valid [15:0];
f83818d5 17 reg [21:0] cache_tags [15:0];
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18 reg [31:0] cache_data [15:0] [7:0];
19
20 initial
21 for (i = 0; i < 16; i = i + 1)
22 cache_valid[i] <= 0;
23
24 wire [5:0] rd_didx = rd_addr[5:0];
25 wire [3:0] rd_didx_word = rd_didx[5:2];
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26 wire [3:0] rd_idx = rd_addr[9:6];
27 wire [21:0] rd_tag = rd_addr[31:10];
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28
29 always @(*) begin /* XXX does this work nowadays? */
30 rd_wait = !(cache_valid[rd_idx] && (cache_tags[rd_idx] == rd_tag));
31 rd_data = cache_data[rd_idx][rd_didx_word];
32 end
33endmodule
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