Merge pull request #9 from oswald3141/sizing_new_funcs

Add resizing functions to sizing package

rtl/extras/sizing.vhdl

@@ -47,6 +47,12 @@
 --#  For convenenience, base-2 functions are also provided along with the array
 --#  sizing functions.
 --#
+--#  Additionally the package provides functions for vectors resizing with
+--#  interfaces which show clearly, how resizing should be performed (extending
+--#  or truncating, most significant bits or least significant bits).
+--#  
+--#  This package does not supports VHDL-2008. Use sizing_2008 instead.
+--#
 --# EXAMPLE USAGE:
 --#  constant MAX_COUNT  : natural := 1000;
 --#  constant COUNT_SIZE : natural := bit_size(MAX_COUNT);
@@ -56,6 +62,10 @@
 --#  -- counter will resize itself as MAX_COUNT is changed
 --------------------------------------------------------------------
 
+library ieee;
+use ieee.std_logic_1164.all;
+use ieee.numeric_std.all;
+
 package sizing is
   --## Compute the integer result of the function floor(log(n)).
   --#
@@ -125,6 +135,58 @@ package sizing is
   --# Returns:
   --#   Number of bits.
   function signed_size(n : integer) return natural;
+
+  type resize_method is (truncate_LSBs, truncate_MSBs, extend_LSBs, extend_MSBs);
+  --## Resizizng function for std_ulogic_vector clearly stating how exactly the 
+  --# resizing will be done.
+  --#
+  --# Args:
+  --#   s: Vector to  resize
+  --#   new_size: New vector size
+  --#   method: Resizizng method
+  --#   extension: Bit used for extension
+  --# Returns:
+  --#   Resized vector.
+  function change_size (s : std_ulogic_vector; new_size : positive; method : resize_method;
+    extension : std_ulogic := '0' ) return std_ulogic_vector;
+
+  --## Resizizng function for std_logic_vector clearly stating how exactly the 
+  --# resizing will be done.
+  --#
+  --# Args:
+  --#   s: Vector to  resize
+  --#   new_size: New vector size
+  --#   method: Resizizng method
+  --#   extension: Bit used for extension
+  --# Returns:
+  --#   Resized vector.
+  function change_size (s : std_logic_vector; new_size : positive; method : resize_method;
+    extension : std_ulogic := '0' ) return std_logic_vector;
+
+  --## Resizizng function for unsigned number clearly stating how exactly the 
+  --# resizing will be done. Extends numbers with zeros.
+  --#
+  --# Args:
+  --#   s: Vector to  resize
+  --#   new_size: New vector size
+  --#   method: Resizizng method
+  --# Returns:
+  --#   Resized number.
+  function change_size (s : unsigned; new_size : positive; method : resize_method)
+    return unsigned;
+
+  --## Resizizng function for signed number clearly stating how exactly the 
+  --# resizing will be done. Extends most significant bits with a sign bit,
+  --# and least significant bits with zeros.
+  --#
+  --# Args:
+  --#   s: Vector to  resize
+  --#   new_size: New vector size
+  --#   method: Resizizng method
+  --# Returns:
+  --#   Resized number.
+  function change_size (s : signed; new_size : positive; method : resize_method)
+    return signed;
 
 end package;
 
@@ -210,5 +272,67 @@ package body sizing is
       return bit_size(-1 - n) + 1;
     end if;
   end function;
+
+
+  --## Resizizng function for std_ulogic_vector clearly stating how exactly the 
+  --# resizing will be done.
+  function change_size (s : std_ulogic_vector; new_size : positive; method : resize_method;
+      extension : std_ulogic := '0' ) return std_ulogic_vector is
+
+    variable v : std_ulogic_vector(new_size-1 downto 0);
+  begin
+
+    case method is
+      when truncate_LSBs =>
+        return s( s'high downto (s'length - new_size) );
+      when truncate_MSBs =>
+        return s(new_size-1 downto 0);
+      when extend_LSBs   =>
+        v(v'high downto new_size - s'length) := s;
+        v(new_size - s'length - 1 downto 0) := (others => extension);
+        return v;
+      when extend_MSBs   =>
+        v(new_size-1 downto s'high+1) := (others => extension);
+        v(s'high downto 0) := s;
+        return v;
+    end case;
+
+  end function;
 
+  --## Resizizng function for std_logic_vector clearly stating how exactly the 
+  --# resizing will be done.
+  function change_size (s : std_logic_vector; new_size : positive; method : resize_method;
+    extension : std_ulogic := '0' ) return std_logic_vector is
+  begin
+    return std_logic_vector(
+      change_size(std_ulogic_vector(s), new_size, method, extension));
+  end function;
+
+  --## Resizizng function for unsigned number clearly stating how exactly the 
+  --# resizing will be done. Extends numbers with zeros.
+  function change_size (s : unsigned; new_size : positive; method : resize_method)
+    return unsigned is
+  begin
+    return unsigned(
+      change_size(std_ulogic_vector(s), new_size, method, '0'));
+  end function;
+
+  --## Resizizng function for signed number clearly stating how exactly the 
+  --# resizing will be done. Extends most significant bits with a sign bit,
+  --# and least significant bits with zeros.
+  function change_size (s : signed; new_size : positive; method : resize_method)
+    return signed is
+  begin
+
+    case method is
+      when extend_MSBs   =>
+        return signed(
+          change_size(std_ulogic_vector(s), new_size, method, s(s'high)));
+      when others =>
+        return signed(
+          change_size(std_ulogic_vector(s), new_size, method, '0'));
+    end case;
+
+  end function;
+
 end package body;