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Diffstat (limited to 'fpga/usrp2/control_lib/icache.v')
| -rw-r--r-- | fpga/usrp2/control_lib/icache.v | 152 |
1 files changed, 152 insertions, 0 deletions
diff --git a/fpga/usrp2/control_lib/icache.v b/fpga/usrp2/control_lib/icache.v new file mode 100644 index 000000000..810b5fa64 --- /dev/null +++ b/fpga/usrp2/control_lib/icache.v @@ -0,0 +1,152 @@ +// +// Copyright 2011 Ettus Research LLC +// +// This program is free software: you can redistribute it and/or modify +// it under the terms of the GNU General Public License as published by +// the Free Software Foundation, either version 3 of the License, or +// (at your option) any later version. +// +// This program is distributed in the hope that it will be useful, +// but WITHOUT ANY WARRANTY; without even the implied warranty of +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +// GNU General Public License for more details. +// +// You should have received a copy of the GNU General Public License +// along with this program. If not, see <http://www.gnu.org/licenses/>. +// + + +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 |