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GitHub Repository: att/ast
 Path: blob/master/src/lib/librecsort/rsdisc.c
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/***********************************************************************

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*                                                                      *

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*               This software is part of the ast package               *

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*          Copyright (c) 1996-2011 AT&T Intellectual Property          *

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*                      and is licensed under the                       *

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*                 Eclipse Public License, Version 1.0                  *

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*                    by AT&T Intellectual Property                     *

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*                                                                      *

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*                A copy of the License is available at                 *

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*          http://www.eclipse.org/org/documents/epl-v10.html           *

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*         (with md5 checksum b35adb5213ca9657e911e9befb180842)         *

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*                                                                      *

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*              Information and Software Systems Research               *

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*                            AT&T Research                             *

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*                           Florham Park NJ                            *

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*                                                                      *

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*                   Phong Vo <[email protected]>                    *

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*                 Glenn Fowler <[email protected]>                  *

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*                                                                      *

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***********************************************************************/

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#include	"rshdr.h"

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/*	Change discipline for a context

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**

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**	Written by Kiem-Phong Vo (07/29/96).

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*/

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#if __STD_C

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Rsdisc_t* rsdisc(Rs_t* rs, Rsdisc_t* disc, int op)

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#else

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Rsdisc_t* rsdisc(rs, disc, op)

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Rs_t*		rs;

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Rsdisc_t*	disc;

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int		op;

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#endif

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{

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	reg Rsdisc_t*	old;

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	reg Rsdisc_t*	cur;

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	reg Rsdisc_t*	prv;

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	reg Rsdisc_t*	top;

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	switch (op)

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	{

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	case RS_DISC:

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		old = rs->disc;

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		if(disc)

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		{	if(old && (old->events & RS_DISC) &&

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			   (*old->eventf)(rs,RS_DISC,(Void_t*)disc,(Void_t*)0,old) < 0)

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				return NIL(Rsdisc_t*);

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			rs->type &= ~(RS_DSAMELEN|RS_KSAMELEN);

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			rs->type |= disc->type&(RS_DSAMELEN|RS_KSAMELEN);

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			if((disc->type&RS_DSAMELEN) && !disc->defkeyf)

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				rs->type |= RS_KSAMELEN;

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			rs->disc = disc;

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			rs->events = rs->disc->events;

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			for (cur = rs->disc; cur; cur = cur->disc)

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				rs->events |= cur->events;

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		}

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		return old;

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	case RS_NEXT:

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		cur = rs->disc;

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		if (disc)

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			while (top = cur)

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			{

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				cur = cur->disc;

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				if (disc == top)

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					break;

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			}

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		return cur;

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	case RS_POP:

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		prv = 0;

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		cur = rs->disc;

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		if (disc)

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			while (cur && cur != disc)

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				cur = (prv = cur)->disc;

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		if (cur)

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		{

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			disc = cur;

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			if (prv)

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				prv->disc = cur->disc;

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			else

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				rs->disc = cur->disc;

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			if ((disc->events & RS_POP) &&

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			    (*disc->eventf)(rs, RS_POP, (Void_t*)0, (Void_t*)0, disc) < 0)

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				return 0;

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			if (rs->disc)

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			{

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				rs->events = rs->disc->events;

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				for (cur = rs->disc; cur; cur = cur->disc)

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					rs->events |= cur->events;

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			}

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		}

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		else

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			disc = 0;

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		return disc;

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	case RS_PUSH:

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		if (!disc)

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			return 0;

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		for (prv = 0, cur = rs->disc; cur; cur = (prv = cur)->disc)

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			if (cur == disc)

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			{

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				if (prv)

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				{

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					/*

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					 * move to front

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					 */

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					prv->disc = cur->disc;

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					cur->disc = rs->disc;

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					rs->disc = cur;

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				}

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				return disc;

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			}

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		disc->disc = rs->disc;

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		rs->disc = disc;

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		rs->events |= disc->events;

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		return disc;

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	}

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	return 0;

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}

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