2 * Copyright (c) 1983, 1993
3 * The Regents of the University of California. All rights reserved.
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15 * This product includes software developed by the University of
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33 * @(#)dfn.c 8.1 (Berkeley) 6/6/93
44 typedef struct dfnstruct dfntype;
46 dfntype dfn_stack[ DFN_DEPTH ];
55 dfn_counter = DFN_NAN;
59 * given this parent, depth first number its children.
67 if ( debug & DFNDEBUG ) {
68 printf( "[dfn] dfn(" );
74 * if we're already numbered, no need to look any furthur.
76 if ( dfn_numbered( parentp ) ) {
80 * if we're already busy, must be a cycle
82 if ( dfn_busy( parentp ) ) {
83 dfn_findcycle( parentp );
87 * visit yourself before your children
89 dfn_pre_visit( parentp );
93 for ( arcp = parentp -> children ; arcp ; arcp = arcp -> arc_childlist ) {
94 if ( arcp -> arc_flags & DEADARC )
96 dfn( arcp -> arc_childp );
99 * visit yourself after your children
101 dfn_post_visit( parentp );
105 * push a parent onto the stack and mark it busy
107 dfn_pre_visit( parentp )
112 if ( dfn_depth >= DFN_DEPTH ) {
113 fprintf( stderr , "[dfn] out of my depth (dfn_stack overflow)\n" );
116 dfn_stack[ dfn_depth ].nlentryp = parentp;
117 dfn_stack[ dfn_depth ].cycletop = dfn_depth;
118 parentp -> toporder = DFN_BUSY;
120 if ( debug & DFNDEBUG ) {
121 printf( "[dfn_pre_visit]\t\t%d:" , dfn_depth );
122 printname( parentp );
129 * are we already numbered?
132 dfn_numbered( childp )
136 return ( childp -> toporder != DFN_NAN && childp -> toporder != DFN_BUSY );
140 * are we already busy?
147 if ( childp -> toporder == DFN_NAN ) {
154 * MISSING: an explanation
156 dfn_findcycle( childp )
164 for ( cycletop = dfn_depth ; cycletop > 0 ; cycletop -= 1 ) {
165 cycleheadp = dfn_stack[ cycletop ].nlentryp;
166 if ( childp == cycleheadp ) {
169 if ( childp -> cyclehead != childp &&
170 childp -> cyclehead == cycleheadp ) {
174 if ( cycletop <= 0 ) {
175 fprintf( stderr , "[dfn_findcycle] couldn't find head of cycle\n" );
179 if ( debug & DFNDEBUG ) {
180 printf( "[dfn_findcycle] dfn_depth %d cycletop %d " ,
181 dfn_depth , cycletop );
182 printname( cycleheadp );
186 if ( cycletop == dfn_depth ) {
188 * this is previous function, e.g. this calls itself
191 dfn_self_cycle( childp );
194 * glom intervening functions that aren't already
195 * glommed into this cycle.
196 * things have been glommed when their cyclehead field
197 * points to the head of the cycle they are glommed into.
199 for ( tailp = cycleheadp ; tailp -> cnext ; tailp = tailp -> cnext ) {
200 /* void: chase down to tail of things already glommed */
202 if ( debug & DFNDEBUG ) {
203 printf( "[dfn_findcycle] tail " );
210 * if what we think is the top of the cycle
211 * has a cyclehead field, then it's not really the
212 * head of the cycle, which is really what we want
214 if ( cycleheadp -> cyclehead != cycleheadp ) {
215 cycleheadp = cycleheadp -> cyclehead;
217 if ( debug & DFNDEBUG ) {
218 printf( "[dfn_findcycle] new cyclehead " );
219 printname( cycleheadp );
224 for ( index = cycletop + 1 ; index <= dfn_depth ; index += 1 ) {
225 childp = dfn_stack[ index ].nlentryp;
226 if ( childp -> cyclehead == childp ) {
228 * not yet glommed anywhere, glom it
229 * and fix any children it has glommed
231 tailp -> cnext = childp;
232 childp -> cyclehead = cycleheadp;
234 if ( debug & DFNDEBUG ) {
235 printf( "[dfn_findcycle] glomming " );
238 printname( cycleheadp );
242 for ( tailp = childp ; tailp->cnext ; tailp = tailp->cnext ) {
243 tailp -> cnext -> cyclehead = cycleheadp;
245 if ( debug & DFNDEBUG ) {
246 printf( "[dfn_findcycle] and its tail " );
247 printname( tailp -> cnext );
249 printname( cycleheadp );
254 } else if ( childp -> cyclehead != cycleheadp /* firewall */ ) {
256 "[dfn_busy] glommed, but not to cyclehead\n" );
263 * deal with self-cycles
266 dfn_self_cycle( parentp )
270 * since we are taking out self-cycles elsewhere
271 * no need for the special case, here.
274 if ( debug & DFNDEBUG ) {
275 printf( "[dfn_self_cycle] " );
276 printname( parentp );
283 * visit a node after all its children
284 * [MISSING: an explanation]
285 * and pop it off the stack
287 dfn_post_visit( parentp )
293 if ( debug & DFNDEBUG ) {
294 printf( "[dfn_post_visit]\t%d: " , dfn_depth );
295 printname( parentp );
300 * number functions and things in their cycles
301 * unless the function is itself part of a cycle
303 if ( parentp -> cyclehead == parentp ) {
305 for ( memberp = parentp ; memberp ; memberp = memberp -> cnext ) {
306 memberp -> toporder = dfn_counter;
308 if ( debug & DFNDEBUG ) {
309 printf( "[dfn_post_visit]\t\tmember " );
310 printname( memberp );
311 printf( " -> toporder = %d\n" , dfn_counter );
317 if ( debug & DFNDEBUG ) {
318 printf( "[dfn_post_visit]\t\tis part of a cycle\n" );