268 lines
7.0 KiB
C
268 lines
7.0 KiB
C
/* $Id$ */
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/*
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* This file is part of OpenTTD.
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* OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
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* OpenTTD 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.
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* See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
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*/
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/** @file direction_func.h Different functions related to conversions between directions. */
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#ifndef DIRECTION_FUNC_H
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#define DIRECTION_FUNC_H
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#include "direction_type.h"
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/**
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* Checks if an integer value is a valid DiagDirection
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*
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* @param d The value to check
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* @return True if the value belongs to a DiagDirection, else false
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*/
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static inline bool IsValidDiagDirection(DiagDirection d)
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{
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return d < DIAGDIR_END;
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}
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/**
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* Checks if an integer value is a valid Direction
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*
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* @param d The value to check
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* @return True if the value belongs to a Direction, else false
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*/
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static inline bool IsValidDirection(Direction d)
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{
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return d < DIR_END;
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}
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/**
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* Checks if an integer value is a valid Axis
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*
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* @param d The value to check
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* @return True if the value belongs to an Axis, else false
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*/
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static inline bool IsValidAxis(Axis d)
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{
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return d < AXIS_END;
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}
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/**
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* Return the reverse of a direction
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*
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* @param d The direction to get the reverse from
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* @return The reverse Direction
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*/
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static inline Direction ReverseDir(Direction d)
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{
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assert(IsValidDirection(d));
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return (Direction)(4 ^ d);
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}
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/**
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* Calculate the difference between to directions
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*
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* @param d0 The first direction as the base
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* @param d1 The second direction as the offset from the base
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* @return The difference how the second directions drifts of the first one.
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*/
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static inline DirDiff DirDifference(Direction d0, Direction d1)
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{
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assert(IsValidDirection(d0));
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assert(IsValidDirection(d1));
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/* Cast to uint so compiler can use bitmask. If the difference is negative
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* and we used int instead of uint, further "+ 8" would have to be added. */
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return (DirDiff)((uint)(d0 - d1) % 8);
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}
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/**
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* Applies two differences together
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*
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* This function adds two differences together and return the resulting
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* difference. So adding two DIRDIFF_REVERSE together results in the
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* DIRDIFF_SAME difference.
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*
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* @param d The first difference
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* @param delta The second difference to add on
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* @return The resulting difference
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*/
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static inline DirDiff ChangeDirDiff(DirDiff d, DirDiff delta)
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{
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/* Cast to uint so compiler can use bitmask. Result can never be negative. */
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return (DirDiff)((uint)(d + delta) % 8);
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}
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/**
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* Change a direction by a given difference
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*
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* This functions returns a new direction of the given direction
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* which is rotated by the given difference.
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*
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* @param d The direction to get a new direction from
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* @param delta The offset/drift applied to the direction
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* @return The new direction
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*/
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static inline Direction ChangeDir(Direction d, DirDiff delta)
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{
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assert(IsValidDirection(d));
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/* Cast to uint so compiler can use bitmask. Result can never be negative. */
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return (Direction)((uint)(d + delta) % 8);
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}
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/**
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* Returns the reverse direction of the given DiagDirection
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*
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* @param d The DiagDirection to get the reverse from
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* @return The reverse direction
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*/
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static inline DiagDirection ReverseDiagDir(DiagDirection d)
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{
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assert(IsValidDiagDirection(d));
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return (DiagDirection)(2 ^ d);
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}
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/**
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* Applies a difference on a DiagDirection
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*
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* This function applies a difference on a DiagDirection and returns
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* the new DiagDirection.
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*
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* @param d The DiagDirection
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* @param delta The difference to apply on
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* @return The new direction which was calculated
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*/
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static inline DiagDirection ChangeDiagDir(DiagDirection d, DiagDirDiff delta)
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{
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assert(IsValidDiagDirection(d));
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/* Cast to uint so compiler can use bitmask. Result can never be negative. */
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return (DiagDirection)((uint)(d + delta) % 4);
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}
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/**
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* Convert a Direction to a DiagDirection.
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*
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* This function can be used to convert the 8-way Direction to
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* the 4-way DiagDirection. If the direction cannot be mapped its
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* "rounded clockwise". So DIR_N becomes DIAGDIR_NE.
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*
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* @param dir The direction to convert
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* @return The resulting DiagDirection, maybe "rounded clockwise".
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*/
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static inline DiagDirection DirToDiagDir(Direction dir)
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{
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assert(IsValidDirection(dir));
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return (DiagDirection)(dir >> 1);
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}
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/**
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* Convert a DiagDirection to a Direction.
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*
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* This function can be used to convert the 4-way DiagDirection
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* to the 8-way Direction. As 4-way are less than 8-way not all
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* possible directions can be calculated.
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*
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* @param dir The direction to convert
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* @return The resulting Direction
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*/
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static inline Direction DiagDirToDir(DiagDirection dir)
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{
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assert(IsValidDiagDirection(dir));
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return (Direction)(dir * 2 + 1);
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}
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/**
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* Select the other axis as provided.
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*
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* This is basically the not-operator for the axis.
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*
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* @param a The given axis
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* @return The other axis
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*/
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static inline Axis OtherAxis(Axis a)
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{
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assert(IsValidAxis(a));
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return (Axis)(a ^ 1);
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}
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/**
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* Convert a DiagDirection to the axis.
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*
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* This function returns the axis which belongs to the given
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* DiagDirection. The axis X belongs to the DiagDirection
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* north-east and south-west.
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*
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* @param d The DiagDirection
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* @return The axis which belongs to the direction
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*/
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static inline Axis DiagDirToAxis(DiagDirection d)
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{
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assert(IsValidDiagDirection(d));
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return (Axis)(d & 1);
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}
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/**
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* Converts an Axis to a DiagDirection
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*
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* This function returns the DiagDirection which
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* belongs to the axis. As 2 directions are mapped to an axis
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* this function returns the one which points to south,
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* either south-west (on X axis) or south-east (on Y axis)
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*
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* @param a The axis
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* @return The direction pointed to south
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*/
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static inline DiagDirection AxisToDiagDir(Axis a)
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{
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assert(IsValidAxis(a));
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return (DiagDirection)(2 - a);
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}
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/**
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* Converts an Axis to a Direction
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*
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* This function returns the Direction which
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* belongs to the axis. As 2 directions are mapped to an axis
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* this function returns the one which points to south,
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* either south-west (on X axis) or south-east (on Y axis)
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*
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* @param a The axis
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* @return The direction pointed to south
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*/
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static inline Direction AxisToDirection(Axis a)
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{
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assert(IsValidAxis(a));
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return (Direction)(5 - 2 * a);
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}
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/**
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* Convert an axis and a flag for north/south into a DiagDirection
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* @param xy axis to convert
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* @param ns north -> 0, south -> 1
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* @return the desired DiagDirection
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*/
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static inline DiagDirection XYNSToDiagDir(Axis xy, uint ns)
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{
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assert(IsValidAxis(xy));
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return (DiagDirection)(xy * 3 ^ ns * 2);
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}
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/**
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* Checks if a given Direction is diagonal.
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*
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* @param dir The given direction.
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* @return True if the direction is diagonal.
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*/
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static inline bool IsDiagonalDirection(Direction dir)
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{
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assert(IsValidDirection(dir));
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return (dir & 1) != 0;
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}
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#endif /* DIRECTION_FUNC_H */
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