alu: bessere find_msb, von 1295 auf 1054 logic cells (fuer alu)

[hwmod.git] / src / gen_pkg.vhd

diff --git a/src/gen_pkg.vhd b/src/gen_pkg.vhd
index cb87dbab6d977aed99c2750d5559556f4b7fc850..c990f1b2f5354aa2c4670a9bcfbf53d310eb41ae 100644 (file)
--- a/src/gen_pkg.vhd
+++ b/src/gen_pkg.vhd
@@ -1,9 +1,110 @@
 library ieee;
 use ieee.std_logic_1164.all;
 use ieee.numeric_std.all;
+use work.math_pkg.all;
 
 package gen_pkg is
-       type alu_ops is (NOP, SUB, ADD, MUL, DIV, DONE);
-       subtype csigned is signed(31 downto 0);
+       subtype alu_ops is std_logic_vector(2 downto 0);
+       constant ALU_NOP : alu_ops := "000";
+       constant ALU_SUB : alu_ops := "001";
+       constant ALU_ADD : alu_ops := "010";
+       constant ALU_MUL : alu_ops := "011";
+       constant ALU_DIV : alu_ops := "100";
+       constant ALU_DONE : alu_ops := "101";
+
+       constant CBITS : integer := 32;
+       subtype csigned is signed((CBITS-1) downto 0);
+       subtype divinteger is unsigned(4 downto 0);
+       -- integer ist 32bit (31bit + sign)
+       subtype cinteger is integer;
+
+       -- 50 zeilen * 71 zeichen * 2 (berechnung + ergebnis) = 7100 bytes
+       constant H_RAM_SIZE : integer := 7100;
+       constant H_RAM_WIDTH : integer := log2c(H_RAM_SIZE);
+       subtype hspalte is std_logic_vector(6 downto 0);
+       subtype hzeile is std_logic_vector(6 downto 0);
+       subtype hbyte is std_logic_vector(7 downto 0);
+       subtype hstring is string(1 to 72);
+       subtype hstr_int is integer range 0 to 72;
+
+       function find_msb(a : std_logic_vector) return std_logic_vector;
+       procedure icwait(signal clk_i : IN std_logic; cycles: natural);
+
+       -- http://www.marjorie.de/ps2/scancode-set2.htm
+       constant SC_KP_0 : std_logic_vector(7 downto 0) := x"70";
+       constant SC_KP_1 : std_logic_vector(7 downto 0) := x"69";
+       constant SC_KP_2 : std_logic_vector(7 downto 0) := x"72";
+       constant SC_KP_3 : std_logic_vector(7 downto 0) := x"7a";
+       constant SC_KP_4 : std_logic_vector(7 downto 0) := x"6b";
+       constant SC_KP_5 : std_logic_vector(7 downto 0) := x"73";
+       constant SC_KP_6 : std_logic_vector(7 downto 0) := x"74";
+       constant SC_KP_7 : std_logic_vector(7 downto 0) := x"6c";
+       constant SC_KP_8 : std_logic_vector(7 downto 0) := x"75";
+       constant SC_KP_9 : std_logic_vector(7 downto 0) := x"7d";
+
+       constant SC_KP_PLUS : std_logic_vector(7 downto 0) := x"79";
+       constant SC_KP_MINUS : std_logic_vector(7 downto 0) := x"7b";
+       constant SC_KP_MUL : std_logic_vector(7 downto 0) := x"7c";
+       constant SC_KP_DIV : std_logic_vector(7 downto 0) := x"4a"; -- inkl. 0xe0!
+
+       constant SC_ENTER : std_logic_vector(7 downto 0) := x"5a";
+       constant SC_BKSP : std_logic_vector(7 downto 0) := x"66";
+       constant SC_SPACE : std_logic_vector(7 downto 0) := x"29";
 end package gen_pkg;
 
+package body gen_pkg is
+       -- http://www.velocityreviews.com/forums/showpost.php?p=137148&postcount=5
+       function find_msb(a : std_logic_vector) return std_logic_vector is
+               function bits_to_fit(n : positive) return natural is
+                       variable nn, bits : natural := 0;
+               begin
+                       nn := n;
+                       while nn > 0 loop
+                               bits := bits + 1;
+                               nn := nn/2;
+                       end loop;
+                       return bits;
+               end;
+
+               function or_all(p : std_logic_vector) return std_logic is
+                       variable r : std_logic;
+               begin
+                       r := '0';
+                       for i in p'range loop
+                               r := r or p(i);
+                       end loop;
+                       return r;
+               end;
+
+               constant wN : positive := bits_to_fit(a'length - 1);
+               constant wP : positive := 2 ** wN;
+               variable pv : std_logic_vector(wP-1 downto 0);
+               variable n : std_logic_vector(wN downto 1);
+       begin
+               if a'length <= 2 then
+                       n(n'right) := a(a'left);
+               else
+                       pv(a'length-1 downto 0) := a;
+                       if or_all(pv(wP-1 downto wP/2)) = '1' then
+                               n := '1' & find_msb((pv(wP-1 downto wP/2)));
+                       else
+                               n := '0' & find_msb((pv(wP/2-1 downto 0)));
+                       end if;
+               end if;
+               return n;
+       end function find_msb;
+       -- -- alternativ: eleganter, braucht aber mehr logic cells
+       -- for i in (CBITS-1) downto 0 loop
+       --       exit when a(i) = '1';
+       --       r := r+1;
+       -- end loop;
+       -- return (CBITS - r);
+
+       procedure icwait(signal clk_i : IN std_logic; cycles: Natural) is
+       begin
+               for i in 1 to cycles loop
+                       wait until clk_i= '0' and clk_i'event;
+               end loop;
+       end;
+end package body gen_pkg;
+