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pmutil.c
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	#ifndef lint
	static const char RCSid[] = "$Id: pmutil.c,v 2.5 2020/04/08 15:14:21 rschregle Exp $";
	#endif

	/*
	======================================================================
	Auxiliary photon map utilities

	Roland Schregle (roland.schregle@{hslu.ch, gmail.com})
	(c) Fraunhofer Institute for Solar Energy Systems,
	(c) Lucerne University of Applied Sciences and Arts,
	supported by the Swiss National Science Foundation (SNSF, #147053)
	======================================================================

	$Id: pmutil.c,v 2.5 2020/04/08 15:14:21 rschregle Exp $
	*/

	#include "pmutil.h"
	#if NIX
	#include <fcntl.h>
	#endif



	void colorNorm (COLOR c)
	/* Normalise colour channels to average of 1 */
	{
	const float avg = colorAvg(c);

	if (!avg)
	return;

	c [0] /= avg;
	c [1] /= avg;
	c [2] /= avg;
	}



	void cleanUpPmaps (PhotonMap **pmaps)
	{
	unsigned t;

	for (t = 0; t < NUM_PMAP_TYPES; t++) {
	if (pmaps [t]) {
	deletePhotons(pmaps [t]);
	free(pmaps [t]);
	}
	}
	}



	#if NIX
	void shmLock (int shmFile, int type)
	/* Set/release record lock on shared memory file,
	where type is either F_RDLCK, F_WRLCK or F_UNLCK*/
	{
	struct flock lock;

	lock.l_type = type;
	lock.l_whence = SEEK_SET;
	lock.l_start = lock.l_len = 0;

	/* F_SETLKW waits until file is released by other process. A loop
	* handles interrupt by a signal (error EINTR). */
	do
	if (fcntl(shmFile, F_SETLKW, &lock) >= 0)
	/* Okie dokie */
	return;
	while (errno == EINTR);

	error(SYSTEM,
	"failed to (un)lock shared memory in distribPhotonContrib()"
	);
	}
	#endif