VHDL-200X-FT review meeting.  7-Feb-2005

Attendees:
  Chuck Swart
  Charlie Guy
  David Bishop
  Jim Lewis
  Depack Pant
  Ajay Varikat
  Karl Eisenhofer

Next Phone Meeting:
  Monday Feb 28th, 2005
   2-4 PM PST

Agenda
  Review of FT 26
  Fixed Point Package Issues

Discussion
  FT 26 looks good

  In numeric_std, the functions to_unsigned and to_signed currently
    provide an assertion of level warning if the integer value to
    be represented is too large for the corresponding unsigned/signed
    value.

  In fixed point point package:
    to_unsigned(ufixed, ...)
    to_signed(sfixed, ...)
        Will saturate or do modulo math based on parameters
        _Currently produces warnings if wraps or saturates_

    to_ufixed(...)  (integer, real, unsigned, signed, ...)
    to_sfixed(...)
    to_float(...)
        Will saturate or modulo based on parameters, but
        no warnings when wraps or saturates

  In numeric_std when a signed value wraps from a negative
    number to a positive number the result is adjusted so
    that it will be negative.  Similarly when it wraps from
    a positive number to a negative number, the result is
    adjusted so that it will be positive.

  In fixed point package when a sfixed value wraps from
    a negative number to a positive number the result
    remains positive.  Likewise when a sfixed value wraps
    from a positive number to a negative number the result
    remains negative.

  Functions:   to_ufix, to_fix, to_ufix_high, to_ufix_low, ...
    Are intended as a special interface to some DSP packages
    and a note will be added to guide a user to the corresponding
    to_ufixed and to_sfixed functions.
    Names to be changed to "to_ufix, to_sfix, ufix_high, ufix_low, ....

  Add functions:
     ufixed_high, ufixed_low, sfixed_high, sfixed_low

  Review:  from_string, ...
     Used for providing a literal value for fixed point types

  Have a version of abs(sfixed) that returns ufixed
    Size of values shall be such that they retain full precision
    of the number.
    Remove the "remove_sign (sfixed)" function as it will be redundant
    with the ABS(sfixed) added above.