X-Git-Url: http://git.joshuawise.com/firearm.git/blobdiff_plain/45fa96c0a2fd6e490690cff69dd694a3dce3ab35..2b5c79c05898ff20b0c04cd78bccb2580f6c8331:/BlockRAM.v diff --git a/BlockRAM.v b/BlockRAM.v index 85f8659..091c749 100644 --- a/BlockRAM.v +++ b/BlockRAM.v @@ -12,29 +12,30 @@ module BlockRAM( * 0x00004000. rdata and ready must be driven to zero if the * address is not within the range of this module. */ - wire decode = (bus_addr & ~32'h00003FFF) == 32'h00000000; - /* verilator lint_off WIDTH */ - wire [13:2] ramaddr = bus_addr & 32'h3FFC; /* mask off lower two bits + wire decode = bus_addr[31:14] == 18'b0; + wire [13:0] ramaddr = {bus_addr[13:2], 2'b0}; /* mask off lower two bits * for word alignment */ - /* verilator lint_on WIDTH */ + + reg [31:0] data [(16384 / 4 - 1):0]; - reg [31:0] data [0:(16384 / 4 - 1)]; - - reg [31:0] temprdata; - reg [13:2] lastread; + reg [31:0] temprdata = 0; + reg [13:0] lastread = 14'h3FFF; assign bus_rdata = (bus_rd && decode) ? temprdata : 32'h0; assign bus_ready = decode && (bus_wr || (bus_rd && (lastread == ramaddr))); + initial + $readmemh("ram.hex", data); + always @(posedge clk) begin if (bus_wr && decode) - data[ramaddr] <= bus_wdata; + data[ramaddr[13:2]] <= bus_wdata; /* This is not allowed to be conditional -- stupid Xilinx * blockram. */ - temprdata <= data[ramaddr]; + temprdata <= (bus_wr && decode) ? bus_wdata : data[ramaddr[13:2]]; lastread <= ramaddr; end endmodule