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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, cached ram
module ram_harvard
#(parameter AWIDTH=15,
parameter RAM_SIZE=16384,
parameter ICWIDTH=6,
parameter DCWIDTH=6)
(input wb_clk_i,
input wb_rst_i,
// Firmware download port.
input [AWIDTH-1:0] ram_loader_adr_i,
input [31:0] ram_loader_dat_i,
input [3:0] ram_loader_sel_i,
input ram_loader_stb_i,
input ram_loader_we_i,
input ram_loader_done_i,
// Instruction fetch port.
input [AWIDTH-1:0] if_adr,
output [31:0] if_data,
// Data access port.
input [AWIDTH-1:0] dwb_adr_i,
input [31:0] dwb_dat_i,
output [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;
dpram32 #(.AWIDTH(AWIDTH),.RAM_SIZE(RAM_SIZE))
sys_ram
(.clk(wb_clk_i),
.adr1_i(ram_loader_done_i ? if_adr : ram_loader_adr_i),
.dat1_i(ram_loader_dat_i),
.dat1_o(if_data),
.we1_i(ram_loader_done_i ? 1'b0 : ram_loader_we_i),
.en1_i(ram_loader_done_i ? 1'b1 : ram_loader_stb_i),
//.sel1_i(ram_loader_done_i ? 4'hF : ram_loader_sel_i),
.sel1_i(ram_loader_sel_i), // Sel is only for writes anyway
.adr2_i(dwb_adr_i),
.dat2_i(dwb_dat_i),
.dat2_o(dwb_dat_o),
.we2_i(dwb_we_i),
.en2_i(dwb_stb_i),
.sel2_i(dwb_sel_i)
);
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;
endmodule // ram_harvard
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