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// Dual ported RAM for Harvard architecture processors
// Does no forwarding
// Addresses are byte-oriented, so botton 2 address bits are ignored. FIXME
// AWIDTH of 13 gives 8K bytes. For Spartan 3, if the total RAM size is not a
// multiple of 8K then BRAM space is wasted
module ram_wb_harvard #(parameter AWIDTH=13)
(input wb_clk_i,
input wb_rst_i,
input [AWIDTH-1:0] iwb_adr_i,
input [31:0] iwb_dat_i,
output reg [31:0] iwb_dat_o,
input iwb_we_i,
output reg iwb_ack_o,
input iwb_stb_i,
input [3:0] iwb_sel_i,
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 reg dwb_ack_o,
input dwb_stb_i,
input [3:0] dwb_sel_i);
reg [7:0] ram0 [0:(1<<(AWIDTH-2))-1];
reg [7:0] ram1 [0:(1<<(AWIDTH-2))-1];
reg [7:0] ram2 [0:(1<<(AWIDTH-2))-1];
reg [7:0] ram3 [0:(1<<(AWIDTH-2))-1];
// Instruction Read Port
always @(posedge wb_clk_i)
iwb_ack_o <= iwb_stb_i & ~iwb_ack_o;
always @(posedge wb_clk_i)
iwb_dat_o[31:24] <= ram3[iwb_adr_i[AWIDTH-1:2]];
always @(posedge wb_clk_i)
iwb_dat_o[23:16] <= ram2[iwb_adr_i[AWIDTH-1:2]];
always @(posedge wb_clk_i)
iwb_dat_o[15:8] <= ram1[iwb_adr_i[AWIDTH-1:2]];
always @(posedge wb_clk_i)
iwb_dat_o[7:0] <= ram0[iwb_adr_i[AWIDTH-1:2]];
always @(posedge wb_clk_i)
if(iwb_we_i & iwb_stb_i & iwb_sel_i[3])
ram3[iwb_adr_i[AWIDTH-1:2]] <= iwb_dat_i[31:24];
always @(posedge wb_clk_i)
if(iwb_we_i & iwb_stb_i & iwb_sel_i[2])
ram2[iwb_adr_i[AWIDTH-1:2]] <= iwb_dat_i[23:16];
always @(posedge wb_clk_i)
if(iwb_we_i & iwb_stb_i & iwb_sel_i[1])
ram1[iwb_adr_i[AWIDTH-1:2]] <= iwb_dat_i[15:8];
always @(posedge wb_clk_i)
if(iwb_we_i & iwb_stb_i & iwb_sel_i[0])
ram0[iwb_adr_i[AWIDTH-1:2]] <= iwb_dat_i[7:0];
// Data Port
always @(posedge wb_clk_i)
dwb_ack_o <= dwb_stb_i & ~dwb_ack_o;
always @(posedge wb_clk_i)
dwb_dat_o[31:24] <= ram3[dwb_adr_i[AWIDTH-1:2]];
always @(posedge wb_clk_i)
dwb_dat_o[23:16] <= ram2[dwb_adr_i[AWIDTH-1:2]];
always @(posedge wb_clk_i)
dwb_dat_o[15:8] <= ram1[dwb_adr_i[AWIDTH-1:2]];
always @(posedge wb_clk_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_wb_harvard
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