Some experiments with dds. probably useless.

helpers.vhd

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+
+library IEEE;
+use IEEE.STD_LOGIC_1164.ALL;
+use IEEE.NUMERIC_STD.ALL;
+
+package helpers is
+    --helper function to calculate the log2 (truncated) of a integer
+    function log2_int(n:natural) return natural; 
+    function divide  (a : UNSIGNED; b : UNSIGNED) return UNSIGNED;
+end helpers;
+
+
+
+package body helpers is
+    function log2_int(n:natural) return natural is
+        begin
+          if(n>1) then --we can stil divide n by 2
+                return 1+log2_int(n/2); --recursivly call log2_int for the by two divided number.
+          end if;
+          return 1; --since we can no longer divide n, return 1
+    end log2_int;
+    
+    --Source: http://vhdlguru.blogspot.ch/2010/03/vhdl-function-for-division-two-signed.html
+    function  divide  (a : UNSIGNED; b : UNSIGNED) return UNSIGNED is
+    variable a1 : unsigned(a'length-1 downto 0):=a;
+    variable b1 : unsigned(b'length-1 downto 0):=b;
+    variable p1 : unsigned(b'length downto 0):= (others => '0');
+    variable i : integer:=0;
+
+    begin
+        for i in 0 to b'length-1 loop
+            p1(b'length-1 downto 1) := p1(b'length-2 downto 0);
+            p1(0) := a1(a'length-1);
+            a1(a'length-1 downto 1) := a1(a'length-2 downto 0);
+            p1 := p1-b1;
+            if(p1(b'length-1) ='1') then
+                a1(0) :='0';
+                p1 := p1+b1;
+            else
+                a1(0) :='1';
+            end if;
+        end loop;
+        return a1;
+    end divide;
+end helpers;
+