move stuff around

1 files changed, 90 insertions, 0 deletions

diff --git a/playground/fifo.v b/playground/fifo.v
new file mode 100644
index 0000000..bcc2d3f
--- /dev/null
+++ b/playground/fifo.v
@@ -0,0 +1,90 @@
+`timescale 1us/1us
+
+`include "my_mem.v"
+
+module fifo #(
+  parameter DATA_WIDTH = 8,
+  parameter DATA_DEPTH = 1024
+) (
+  input rst_i,
+  input clk_i,
+
+  input write_i,
+  input read_i,
+
+  output empty_o,
+  output full_o,
+
+  //output data_valid_o,
+
+  input [(DATA_WIDTH-1) : 0] data_i,
+  output reg [(DATA_WIDTH-1) : 0] data_o
+
+);
+
+localparam DATA_DEPTH_BITS = $clog2(DATA_DEPTH);
+
+// the -1 will make sure it fits
+/* verilator lint_off WIDTHTRUNC */
+localparam [DATA_DEPTH_BITS-1:0] MAX_ADDRESS = (DATA_DEPTH - 1);
+/* verilator lint_on WIDTHTRUNC */
+
+// need to "count" to number *including* depth
+reg [$clog2(DATA_DEPTH + 1)-1:0] r_count;
+reg [DATA_DEPTH_BITS-1:0] r_read_addr;
+reg [DATA_DEPTH_BITS-1:0] r_write_addr;
+
+assign empty_o = r_count == 0;
+assign full_o = r_count == DATA_DEPTH;
+
+wire int_wr_en = write_i && !full_o;
+wire int_rd_en = read_i && !empty_o;
+
+my_mem #(
+  .DATA_WIDTH(DATA_WIDTH),
+  .DATA_DEPTH(DATA_DEPTH)
+) fifo_mem (
+  .clk_i(clk_i),
+  .write_en_i(int_wr_en),
+  .read_en_i(int_rd_en),
+  .r_read_addr(r_read_addr),
+  .r_write_addr(r_write_addr),
+
+  .data_i(data_i),
+  .data_o(data_o)
+);
+
+initial begin
+  r_count = 0;
+  r_read_addr = 0;
+  r_write_addr = 0;
+end
+
+always @(posedge clk_i or negedge rst_i) begin
+  if (!rst_i)
+    r_count <= 0;
+  else if (write_i && read_i)
+    // nothing to do
+    // count stays the same
+    ;
+  else if (write_i && !full_o)
+    r_count <= r_count + 1;
+  else if (read_i && !empty_o)
+    r_count <= r_count - 1;
+end
+
+always @(posedge clk_i or negedge rst_i) begin
+  if (!rst_i)
+    r_read_addr <= 0;
+  else if (read_i && !empty_o)
+    r_read_addr <= (r_read_addr < MAX_ADDRESS) ? (r_read_addr + 1) : 0;
+end
+
+always @(posedge clk_i or negedge rst_i) begin
+  if (!rst_i)
+    r_write_addr <= 0;
+  else if (write_i && !full_o)
+    r_write_addr <= (r_write_addr < MAX_ADDRESS) ? (r_write_addr + 1) : 0;
+end
+
+endmodule