(*
 * Rational numbers
 * Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 *)
(* This is a part of Pascal porting of ffmpeg.  Originally by Victor Zinetz for Delphi and Free Pascal on Windows.
For Mac OS X, some modifications were made by The Creative CAT, denoted as CAT
in the source codes *)

unit rational;
{$IFDEF FPC}
  {$MODE DELPHI}  (* CAT *)
  {$PACKENUM 4}    (* every enum type variables uses 4 bytes, CAT *)
  {$PACKRECORDS C}    (* GCC compatible, Record Packing, CAT *)
{$ENDIF}

interface		(* unit windows is deleted by CAT *)

const
  {$IFDEF win32}
    av__util = 'avutil-49.dll';
  {$ELSE}
    av__util = 'libavutil.so';  // .0d
//    av__util = 'libavutil.49';
  {$ENDIF}
type

(*
 * Rational number num/den. *)
  PAVRational = ^TAVRational;
  TAVRational = record
    num: integer; ///< numerator
    den: integer; ///< denominator
  end;

(**
 * returns 0 if a==b, 1 if a>b and -1 if a<b.
 *)
function av_cmp_q(a: TAVRational; b: TAVRational): integer;

(**
 * converts the given AVRational to a double.
 *)
function av_q2d(a: TAVRational): double;

(**
 * reduce a fraction.
 * this is usefull for framerate calculations
 * @param max the maximum allowed for dst_nom & dst_den
 * @return 1 if exact, 0 otherwise
 *)
function av_reduce(dst_nom: pinteger; dst_den: PInteger; nom: int64; den: int64; max: int64): integer;
  cdecl; external av__util;

function av_mul_q(b: TAVRational; c: TAVRational): TAVRational;
  cdecl; external av__util;
function av_div_q(b: TAVRational; c: TAVRational): TAVRational;
  cdecl; external av__util;
function av_add_q(b: TAVRational; c: TAVRational): TAVRational;
  cdecl; external av__util;
function av_sub_q(b: TAVRational; c: TAVRational): TAVRational;
  cdecl; external av__util;
function av_d2q(d: double; max: integer): TAVRational;
  cdecl; external av__util;

implementation

function av_cmp_q (a: TAVRational; b: TAVRational): integer;
var
  tmp: int64;
begin
  tmp := a.num * b.den - b.num * a.den;

  if tmp <> 0 then Result := (tmp shr 63) or 1 (* fixed by CAT *)
              else Result := 0
end;

function av_q2d(a: TAVRational): double;
begin
  Result := a.num / a.den;
end;

end.