Upd clogb2 info

Author: pConst

clogb2.svh

@@ -7,6 +7,28 @@
 // INFO ------------------------------------------------------------------------
 //  Calculates counter/address width based on specified vector/RAM depth
 //
+//  see also: http://www.sunburst-design.com/papers/CummingsHDLCON2001_Verilog2001.pdf
+//
+//  Compared with system function $clog2():
+//  =======================================
+//  $clog2(0) = 0;   clogb2(0) = 0;
+//  $clog2(1) = 0;   clogb2(1) = 1;
+//  $clog2(2) = 1;   clogb2(2) = 2;
+//  $clog2(3) = 2;   clogb2(3) = 2;
+//  $clog2(4) = 2;   clogb2(4) = 3;
+//  $clog2(5) = 3;   clogb2(5) = 3;
+//  $clog2(6) = 3;   clogb2(6) = 3;
+//  $clog2(7) = 3;   clogb2(7) = 3;
+//  $clog2(8) = 3;   clogb2(8) = 4;
+//  $clog2(9) = 4;   clogb2(9) = 4;
+//  $clog2(10)= 4;   clogb2(10)= 4;
+//  $clog2(11)= 4;   clogb2(11)= 4;
+//  $clog2(12)= 4;   clogb2(12)= 4;
+//  $clog2(13)= 4;   clogb2(13)= 4;
+//  $clog2(14)= 4;   clogb2(14)= 4;
+//  $clog2(15)= 4;   clogb2(15)= 4;
+//  $clog2(16)= 4;   clogb2(16)= 5;
+//
 //  Function should be instantiated inside a module
 //  But you are free to call it from anywhere by its hierarchical name
 //
@@ -15,10 +37,11 @@
 //
 
 function integer clogb2;
-  input integer depth;
+  input [31:0] depth;
 
   for( clogb2=0; depth>0; clogb2=clogb2+1 ) begin
     depth = depth >> 1;
   end
+
 endfunction