VHDL-200X-FT Meeting Minutes    20-Dec-04
----------------------------------------------------------
Peter Ashenden
Chuck Swart
Jim Lewis
David Bishop


Next Meeting:    January 10,  2pm - 4pm


Discussion of Status

1076 Package Integration Part 1:
  David wondered if we should include 1076.6 RTL
  attributes as part of 1076?   No.  Keep 1076.6 separate.
  Include VITAL packages also?  No.  Too much stuff in
  VITAL that are outside of the language.


Package Standard:
  David to update package standard to include
  boolean_vector, integer_vector, real_vector, time_vector
  in package standard (comming from ISAC approved issues).
  Will round up all package standard updates under FT30


Floating Point Standard
  Discussion about use model of floating point.
  For DSP type work are different sizes of floating
  point used within a single chip or in any given chip
  is only one size of floating point used?

  Currently the package architecture being considered
  is to constrain the width of the mantissa and exponent
  as package generics.  With this approach one package
  would need to be instantiated per size of floating point
  being used in the design.  Simple if only one size is
  being used.  More interesting if a design uses multiple
  different sizes of floating point - in addition it would
  be a significantly different use model from types signed
  and unsigned in numeric_std.

  For generalized floating point, do different operations
  require a different number of guard bits (add/sub vs.
  multiply vs. divide).  Do we need to specify these
  parameters separately?


  Discussion of call format for extended functions.  Should
  it be a named function such as:
  function add (
    l, r                 : floating_point;      -- floating point input
    constant round_style : round_type := round_nearest;  -- rounding option
    constant guard : natural := 3;      -- number of guard bits
    constant check_error : boolean    := true;  -- check for errors
    constant ieee_extend : boolean    := true)  -- Use IEEE extended FP
    return floating_point;

  or should the "+" be extended to allow optional parameters:
    function "+" ( L, R : FP;
                   round_style : round_type := default_round_style;
                   denormalize : BOOLEAN := default_denormalize;
                   check_error : BOOLEAN := default_check_error;
                   guard_bits :  NATURAL := default_guard_bits )
                 return FP;

   in this case,
   signal A, B, Y : FP(18 downto -7) ;

   Y <= A + B ; -- use the defaults

   Y <= "+"(A, B, ...) ; -- set values.


1076 Package Integration Part 2:
  Chuck wondered whether fixed point and floating point
  packages should be part of 1076 or a separate standard?

  Discussion as to what belongs to the standard and why.