rubidium@9723: /* $Id$ */
rubidium@9723: 
rubidium@9723: /** @file direction_func.h Different functions related to conversions between directions. */
rubidium@9723: 
rubidium@9723: #ifndef DIRECTION_FUNC_H
rubidium@9723: #define DIRECTION_FUNC_H
rubidium@9723: 
rubidium@9723: #include "direction_type.h"
rubidium@9723: 
rubidium@9723: /**
rubidium@9723:  * Return the reverse of a direction
rubidium@9723:  *
rubidium@9723:  * @param d The direction to get the reverse from
rubidium@9723:  * @return The reverse Direction
rubidium@9723:  */
rubidium@9723: static inline Direction ReverseDir(Direction d)
rubidium@9723: {
rubidium@9723: 	return (Direction)(4 ^ d);
rubidium@9723: }
rubidium@9723: 
rubidium@9723: 
rubidium@9723: /**
rubidium@9723:  * Calculate the difference between to directions
rubidium@9723:  *
rubidium@9723:  * @param d0 The first direction as the base
rubidium@9723:  * @param d1 The second direction as the offset from the base
rubidium@9723:  * @return The difference how the second directions drifts of the first one.
rubidium@9723:  */
rubidium@9723: static inline DirDiff DirDifference(Direction d0, Direction d1)
rubidium@9723: {
rubidium@9723: 	return (DirDiff)((d0 + 8 - d1) % 8);
rubidium@9723: }
rubidium@9723: 
rubidium@9723: /**
rubidium@9723:  * Applies two differences together
rubidium@9723:  *
rubidium@9723:  * This function adds two differences together and return the resulting
rubidium@9723:  * difference. So adding two DIRDIFF_REVERSE together results in the
rubidium@9723:  * DIRDIFF_SAME difference.
rubidium@9723:  *
rubidium@9723:  * @param d The first difference
rubidium@9723:  * @param delta The second difference to add on
rubidium@9723:  * @return The resulting difference
rubidium@9723:  */
rubidium@9723: static inline DirDiff ChangeDirDiff(DirDiff d, DirDiff delta)
rubidium@9723: {
rubidium@9723: 	return (DirDiff)((d + delta) % 8);
rubidium@9723: }
rubidium@9723: 
rubidium@9723: /**
rubidium@9723:  * Change a direction by a given difference
rubidium@9723:  *
rubidium@9723:  * This functions returns a new direction of the given direction
rubidium@9723:  * which is rotated by the given difference.
rubidium@9723:  *
rubidium@9723:  * @param d The direction to get a new direction from
rubidium@9723:  * @param delta The offset/drift applied to the direction
rubidium@9723:  * @return The new direction
rubidium@9723:  */
rubidium@9723: static inline Direction ChangeDir(Direction d, DirDiff delta)
rubidium@9723: {
rubidium@9723: 	return (Direction)((d + delta) % 8);
rubidium@9723: }
rubidium@9723: 
rubidium@9723: 
rubidium@9723: /**
rubidium@9723:  * Returns the reverse direction of the given DiagDirection
rubidium@9723:  *
rubidium@9723:  * @param d The DiagDirection to get the reverse from
rubidium@9723:  * @return The reverse direction
rubidium@9723:  */
rubidium@9723: static inline DiagDirection ReverseDiagDir(DiagDirection d)
rubidium@9723: {
rubidium@9723: 	return (DiagDirection)(2 ^ d);
rubidium@9723: }
rubidium@9723: 
rubidium@9723: 
rubidium@9723: /**
rubidium@9723:  * Applies a difference on a DiagDirection
rubidium@9723:  *
rubidium@9723:  * This function applies a difference on a DiagDirection and returns
rubidium@9723:  * the new DiagDirection.
rubidium@9723:  *
rubidium@9723:  * @param d The DiagDirection
rubidium@9723:  * @param delta The difference to applie on
rubidium@9723:  * @return The new direction which was calculated
rubidium@9723:  */
rubidium@9723: static inline DiagDirection ChangeDiagDir(DiagDirection d, DiagDirDiff delta)
rubidium@9723: {
rubidium@9723: 	return (DiagDirection)((d + delta) % 4);
rubidium@9723: }
rubidium@9723: 
rubidium@9723: /**
rubidium@9723:  * Convert a Direction to a DiagDirection.
rubidium@9723:  *
rubidium@9723:  * This function can be used to convert the 8-way Direction to
rubidium@9723:  * the 4-way DiagDirection. If the direction cannot be mapped its
rubidium@9723:  * "rounded clockwise". So DIR_N becomes DIAGDIR_NE.
rubidium@9723:  *
rubidium@9723:  * @param dir The direction to convert
rubidium@9723:  * @return The resulting DiagDirection, maybe "rounded clockwise".
rubidium@9723:  */
rubidium@9723: static inline DiagDirection DirToDiagDir(Direction dir)
rubidium@9723: {
rubidium@9723: 	return (DiagDirection)(dir >> 1);
rubidium@9723: }
rubidium@9723: 
rubidium@9723: /**
rubidium@9723:  * Convert a DiagDirection to a Direction.
rubidium@9723:  *
rubidium@9723:  * This function can be used to convert the 4-way DiagDirection
rubidium@9723:  * to the 8-way Direction. As 4-way are less than 8-way not all
rubidium@9723:  * possible directions can be calculated.
rubidium@9723:  *
rubidium@9723:  * @param dir The direction to convert
rubidium@9723:  * @return The resulting Direction
rubidium@9723:  */
rubidium@9723: static inline Direction DiagDirToDir(DiagDirection dir)
rubidium@9723: {
rubidium@9723: 	return (Direction)(dir * 2 + 1);
rubidium@9723: }
rubidium@9723: 
rubidium@9723: 
rubidium@9723: /**
rubidium@9723:  * Select the other axis as provided.
rubidium@9723:  *
rubidium@9723:  * This is basically the not-operator for the axis.
rubidium@9723:  *
rubidium@9723:  * @param a The given axis
rubidium@9723:  * @return The other axis
rubidium@9723:  */
rubidium@9723: static inline Axis OtherAxis(Axis a)
rubidium@9723: {
rubidium@9723: 	return (Axis)(a ^ 1);
rubidium@9723: }
rubidium@9723: 
rubidium@9723: 
rubidium@9723: /**
rubidium@9723:  * Convert a DiagDirection to the axis.
rubidium@9723:  *
rubidium@9723:  * This function returns the axis which belongs to the given
rubidium@9723:  * DiagDirection. The axis X belongs to the DiagDirection
rubidium@9723:  * north-east and south-west.
rubidium@9723:  *
rubidium@9723:  * @param d The DiagDirection
rubidium@9723:  * @return The axis which belongs to the direction
rubidium@9723:  */
rubidium@9723: static inline Axis DiagDirToAxis(DiagDirection d)
rubidium@9723: {
rubidium@9723: 	return (Axis)(d & 1);
rubidium@9723: }
rubidium@9723: 
rubidium@9723: 
rubidium@9723: /**
rubidium@9723:  * Converts an Axis to a DiagDirection
rubidium@9723:  *
rubidium@9723:  * This function returns the DiagDirection which
rubidium@9723:  * belongs to the axis. As 2 directions are mapped to an axis
rubidium@9723:  * this function returns the one which points to south,
rubidium@9723:  * either south-west (on X axis) or south-east (on Y axis)
rubidium@9723:  *
rubidium@9723:  * @param a The axis
rubidium@9723:  * @return The direction pointed to south
rubidium@9723:  */
rubidium@9723: static inline DiagDirection AxisToDiagDir(Axis a)
rubidium@9723: {
rubidium@9723: 	return (DiagDirection)(2 - a);
rubidium@9723: }
rubidium@9723: 
rubidium@9723: /**
rubidium@10355:  * Converts an Axis to a Direction
rubidium@10355:  *
rubidium@10355:  * This function returns the Direction which
rubidium@10355:  * belongs to the axis. As 2 directions are mapped to an axis
rubidium@10355:  * this function returns the one which points to south,
rubidium@10355:  * either south-west (on X axis) or south-east (on Y axis)
rubidium@10355:  *
rubidium@10355:  * @param a The axis
rubidium@10355:  * @return The direction pointed to south
rubidium@10355:  */
rubidium@10355: static inline Direction AxisToDirection(Axis a)
rubidium@10355: {
rubidium@10355: 	return (Direction)(5 - 2 * a);
rubidium@10355: }
rubidium@10355: 
rubidium@10355: /**
rubidium@9723:  * Convert an axis and a flag for north/south into a DiagDirection
rubidium@9723:  * @param xy axis to convert
rubidium@9723:  * @param ns north -> 0, south -> 1
rubidium@9723:  * @return the desired DiagDirection
rubidium@9723:  */
rubidium@9723: static inline DiagDirection XYNSToDiagDir(Axis xy, uint ns)
rubidium@9723: {
rubidium@9723: 	return (DiagDirection)(xy * 3 ^ ns * 2);
rubidium@9723: }
rubidium@9723: 
rubidium@9723: /**
rubidium@9723:  * Checks if an interger value is a valid DiagDirection
rubidium@9723:  *
rubidium@9723:  * @param d The value to check
rubidium@9723:  * @return True if the value belongs to a DiagDirection, else false
rubidium@9723:  */
rubidium@9723: static inline bool IsValidDiagDirection(DiagDirection d)
rubidium@9723: {
rubidium@9723: 	return d < DIAGDIR_END;
rubidium@9723: }
rubidium@9723: 
rubidium@9723: /**
rubidium@9723:  * Checks if an integer value is a valid Direction
rubidium@9723:  *
rubidium@9723:  * @param d The value to check
rubidium@9723:  * @return True if the value belongs to a Direction, else false
rubidium@9723:  */
rubidium@9723: static inline bool IsValidDirection(Direction d)
rubidium@9723: {
rubidium@9723: 	return d < DIR_END;
rubidium@9723: }
rubidium@9723: 
rubidium@9723: /**
rubidium@9723:  * Checks if an integer value is a valid Axis
rubidium@9723:  *
rubidium@9723:  * @param d The value to check
rubidium@9723:  * @return True if the value belongs to an Axis, else false
rubidium@9723:  */
rubidium@9723: static inline bool IsValidAxis(Axis d)
rubidium@9723: {
rubidium@9723: 	return d < AXIS_END;
rubidium@9723: }
rubidium@9723: 
rubidium@9723: #endif /* DIRECTION_H */