[hdl] clean-up log2 ceiling functions.

Reported by Olof Olof Kindgren (@olofk). See also merge request !4

.

Signed-off-by: Dimitris Lampridis <dimitris.lampridis@cern.ch>

modules/common/gencores_pkg.vhd

@@ -27,8 +27,6 @@ library ieee;
 use ieee.std_logic_1164.all;
 use ieee.numeric_std.all;
 
-use work.genram_pkg.all;
-
 package gencores_pkg is
 
   --============================================================================
@@ -342,7 +340,7 @@ package gencores_pkg is
       d_req_o      : out std_logic_vector(g_num_inputs-1 downto 0);
       q_o          : out std_logic_vector(g_width-1 downto 0);
       q_valid_o    : out std_logic;
-      q_input_id_o : out std_logic_vector(f_log2_size(g_num_inputs)-1 downto 0));
+      q_input_id_o : out std_logic_vector(f_log2_ceil(g_num_inputs)-1 downto 0));
   end component;
 
   ------------------------------------------------------------------------------
@@ -838,17 +836,22 @@ package body gencores_pkg is
   ------------------------------------------------------------------------------
   -- Returns log of 2 of a natural number
   ------------------------------------------------------------------------------
-  function log2_ceil(N : natural) return positive is
+  function f_log2_ceil(N : natural) return positive is
   begin
     if N <= 2 then
       return 1;
     elsif N mod 2 = 0 then
-      return 1 + log2_ceil(N/2);
+      return 1 + f_log2_ceil(N/2);
     else
-      return 1 + log2_ceil((N+1)/2);
+      return 1 + f_log2_ceil((N+1)/2);
     end if;
   end;
 
+  -- kept for backwards compatibility
+  function log2_ceil(N : natural) return positive is
+  begin
+    return f_log2_ceil(N);
+  end;
 
   ------------------------------------------------------------------------------
   -- Converts a boolean to natural integer (false -> 0, true -> 1)

modules/genrams/genram_pkg.vhd

@@ -248,14 +248,10 @@ end genram_pkg;
 
 package body genram_pkg is
 
+  -- kept for backwards compatibility
   function f_log2_size (A : natural) return natural is
   begin
-    for I in 1 to 64 loop               -- Works for up to 64 bits
-      if (2**I >= A) then
-        return(I);
-      end if;
-    end loop;
-    return(63);
+    return f_log2_ceil(N);
   end function f_log2_size;
 
   function f_gen_dummy_vec (val : std_logic; size : natural) return std_logic_vector is