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(*
* 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.
* - Changes and updates by the UltraStar Deluxe Team
*)
(*
* Conversion of libavutil/rational.h
* avutil max. version 50.15.2, revision 23059, Tue May 11 22:10:00 2010 CET
*
*)
unit rational;
{$IFDEF FPC}
{$MODE DELPHI}
{$PACKENUM 4} (* use 4-byte enums *)
{$PACKRECORDS C} (* C/C++-compatible record packing *)
{$ELSE}
{$MINENUMSIZE 4} (* use 4-byte enums *)
{$ENDIF}
{$I switches.inc}
interface
uses
ctypes,
UConfig;
type
(*
* rational number numerator/denominator
*)
PAVRational = ^TAVRational;
TAVRational = record
num: cint; ///< numerator
den: cint; ///< denominator
end;
TAVRationalArray = array[0 .. (MaxInt div SizeOf(TAVRational))-1] of TAVRational;
PAVRationalArray = ^TAVRationalArray;
(**
* Compares two rationals.
* @param a first rational
* @param b second rational
* @return 0 if a==b, 1 if a>b and -1 if a<b
*)
function av_cmp_q(a: TAVRational; b: TAVRational): cint; {$IFDEF HasInline}inline;{$ENDIF}
(**
* Converts rational to double.
* @param a rational to convert
* @return (double) a
*)
function av_q2d(a: TAVRational): cdouble; {$IFDEF HasInline}inline;{$ENDIF}
(**
* Reduces a fraction.
* This is useful for framerate calculations.
* @param dst_num destination numerator
* @param dst_den destination denominator
* @param num source numerator
* @param den source denominator
* @param max the maximum allowed for dst_num & dst_den
* @return 1 if exact, 0 otherwise
*)
function av_reduce(dst_num: PCint; dst_den: PCint; num: cint64; den: cint64; max: cint64): cint;
cdecl; external av__util;
(**
* Multiplies two rationals.
* @param b first rational
* @param c second rational
* @return b*c
*)
function av_mul_q(b: TAVRational; c: TAVRational): TAVRational;
cdecl; external av__util; {av_const}
(**
* Divides one rational by another.
* @param b first rational
* @param c second rational
* @return b/c
*)
function av_div_q(b: TAVRational; c: TAVRational): TAVRational;
cdecl; external av__util; {av_const}
(**
* Adds two rationals.
* @param b first rational
* @param c second rational
* @return b+c
*)
function av_add_q(b: TAVRational; c: TAVRational): TAVRational;
cdecl; external av__util; {av_const}
(**
* Subtracts one rational from another.
* @param b first rational
* @param c second rational
* @return b-c
*)
function av_sub_q(b: TAVRational; c: TAVRational): TAVRational;
cdecl; external av__util; {av_const}
(**
* Converts a double precision floating point number to a rational.
* @param d double to convert
* @param max the maximum allowed numerator and denominator
* @return (AVRational) d
*)
function av_d2q(d: cdouble; max: cint): TAVRational;
cdecl; external av__util; {av_const}
{$IF LIBAVUTIL_VERSION >= 49011000} // 49.11.0
(**
* @return 1 if q1 is nearer to q than q2, -1 if q2 is nearer
* than q1, 0 if they have the same distance.
*)
function av_nearer_q(q, q1, q2: TAVRational): cint;
cdecl; external av__util;
(**
* Finds the nearest value in q_list to q.
* @param q_list an array of rationals terminated by {0, 0}
* @return the index of the nearest value found in the array
*)
function av_find_nearest_q_idx(q: TAVRational; q_list: {const} PAVRationalArray): cint;
cdecl; external av__util;
{$IFEND}
implementation
function av_cmp_q (a: TAVRational; b: TAVRational): cint;
var
tmp: cint64;
begin
tmp := a.num * cint64(b.den) - b.num * cint64(a.den);
if (tmp <> 0) then
Result := (tmp shr 63) or 1
else
Result := 0
end;
function av_q2d(a: TAVRational): cdouble;
begin
Result := a.num / a.den;
end;
end.
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