alu/div: dision in hardwaregerechte art und weise

[hwmod.git] / src / gen_pkg.vhd

diff --git a/src/gen_pkg.vhd b/src/gen_pkg.vhd
index f2f48712d7bac1efb3b2603c91cadabd5e3d071f..6f1ff43d48089bff05b40bd342d988ff68407efa 100644 (file)
--- a/src/gen_pkg.vhd
+++ b/src/gen_pkg.vhd
@@ -1,4 +1,33 @@
+library ieee;
+use ieee.std_logic_1164.all;
+use ieee.numeric_std.all;
+
 package gen_pkg is
        type alu_ops is (NOP, SUB, ADD, MUL, DIV, DONE);
+       constant CBITS : integer := 32;
+       subtype csigned is signed((CBITS-1) downto 0);
+       --TODO: bei CBITS-1 gibts einen overflow :/
+       subtype cinteger is integer range -(2**(CBITS-2)) to ((2**(CBITS-2))-1);
+       function find_msb(a : csigned) return natural;
 end package gen_pkg;
 
+package body gen_pkg is
+       function find_msb(a : csigned) return natural is
+               variable r : natural := 0;
+               variable count : boolean := true;
+       begin
+               for i in (CBITS-1) downto 0 loop
+                       if count then
+                               if a(i) = '1' then
+                                       count := false;
+                               else
+                                       r := r+1;
+                               end if;
+                       else
+                               null;
+                       end if;
+               end loop;
+               return (CBITS - r);
+       end function find_msb;
+end package body gen_pkg;
+