fifo: Count bytes

1 files changed, 19 insertions, 3 deletions

diff --git a/fifo.v b/fifo.v
index d900155..ebc1eee 100644
--- a/fifo.v
+++ b/fifo.v
@@ -5,8 +5,8 @@ module fifo #(
   input rst_i,
   input clk_i,
 
-  input data_write_i,
-  input data_read_i,
+  input write_i,
+  input read_i,
 
   output empty_o,
   output full_o,
@@ -18,10 +18,26 @@ module fifo #(
 
 );
 
+reg [$clog2(DATA_DEPTH):0] r_count;
+
+initial begin
+  r_count = 0;
+end
+
 always @(posedge clk_i or negedge rst_i) begin
   if (!rst_i) begin
-    
+    r_count <= 0;
+  end else if (write_i && read_i) begin
+    // nothing to do
+  end else if (write_i && !full_o) begin
+    r_count <= r_count + 1;
+  end else if (read_i && !empty_o) begin
+    r_count <= r_count - 1;
   end
 end
 
+assign empty_o = r_count == 0;
+assign full_o = r_count >= DATA_DEPTH - 1;
+
+
 endmodule