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//
// 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/>.
//
// Dual ported, Harvard architecture
module ram_harvard2
#(parameter AWIDTH=15,
parameter RAM_SIZE=32768)
(input wb_clk_i,
input wb_rst_i,
// Instruction fetch port.
input [AWIDTH-1:0] if_adr,
output reg [31:0] if_data,
// Data access port.
input [AWIDTH-1:0] dwb_adr_i,
input [31:0] dwb_dat_i,
output reg [31:0] dwb_dat_o,
input dwb_we_i,
output dwb_ack_o,
input dwb_stb_i,
input [3:0] dwb_sel_i);
reg ack_d1;
reg stb_d1;
assign dwb_ack_o = dwb_stb_i & (dwb_we_i | (stb_d1 & ~ack_d1));
always @(posedge wb_clk_i)
if(wb_rst_i)
ack_d1 <= 1'b0;
else
ack_d1 <= dwb_ack_o;
always @(posedge wb_clk_i)
if(wb_rst_i)
stb_d1 <= 0;
else
stb_d1 <= dwb_stb_i;
reg [7:0] ram0 [0:(RAM_SIZE/4)-1];
reg [7:0] ram1 [0:(RAM_SIZE/4)-1];
reg [7:0] ram2 [0:(RAM_SIZE/4)-1];
reg [7:0] ram3 [0:(RAM_SIZE/4)-1];
// Port 1, Read only
always @(posedge wb_clk_i)
if_data[31:24] <= ram3[if_adr[AWIDTH-1:2]];
always @(posedge wb_clk_i)
if_data[23:16] <= ram2[if_adr[AWIDTH-1:2]];
always @(posedge wb_clk_i)
if_data[15:8] <= ram1[if_adr[AWIDTH-1:2]];
always @(posedge wb_clk_i)
if_data[7:0] <= ram0[if_adr[AWIDTH-1:2]];
// Port 2, R/W
always @(posedge wb_clk_i)
if(dwb_stb_i) dwb_dat_o[31:24] <= ram3[dwb_adr_i[AWIDTH-1:2]];
always @(posedge wb_clk_i)
if(dwb_stb_i) dwb_dat_o[23:16] <= ram2[dwb_adr_i[AWIDTH-1:2]];
always @(posedge wb_clk_i)
if(dwb_stb_i) dwb_dat_o[15:8] <= ram1[dwb_adr_i[AWIDTH-1:2]];
always @(posedge wb_clk_i)
if(dwb_stb_i) dwb_dat_o[7:0] <= ram0[dwb_adr_i[AWIDTH-1:2]];
always @(posedge wb_clk_i)
if(dwb_we_i & dwb_stb_i & dwb_sel_i[3])
ram3[dwb_adr_i[AWIDTH-1:2]] <= dwb_dat_i[31:24];
always @(posedge wb_clk_i)
if(dwb_we_i & dwb_stb_i & dwb_sel_i[2])
ram2[dwb_adr_i[AWIDTH-1:2]] <= dwb_dat_i[23:16];
always @(posedge wb_clk_i)
if(dwb_we_i & dwb_stb_i & dwb_sel_i[1])
ram1[dwb_adr_i[AWIDTH-1:2]] <= dwb_dat_i[15:8];
always @(posedge wb_clk_i)
if(dwb_we_i & dwb_stb_i & dwb_sel_i[0])
ram0[dwb_adr_i[AWIDTH-1:2]] <= dwb_dat_i[7:0];
endmodule // ram_harvard
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