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root/radiance/ray/src/rt/ambient.c
Revision: 2.31
Committed: Tue Oct 3 11:53:30 1995 UTC (28 years, 7 months ago) by greg
Content type: text/plain
Branch: MAIN
Changes since 2.30: +1 -2 lines
Log Message:
undid artifact of ancient change (1.6) that caused unnec. noise

File Contents

# Content
1 /* Copyright (c) 1995 Regents of the University of California */
2
3 #ifndef lint
4 static char SCCSid[] = "$SunId$ LBL";
5 #endif
6
7 /*
8 * ambient.c - routines dealing with ambient (inter-reflected) component.
9 */
10
11 #include "ray.h"
12
13 #include "octree.h"
14
15 #include "otypes.h"
16
17 #include "ambient.h"
18
19 #include "random.h"
20
21 #define OCTSCALE 1.0 /* ceil((valid rad.)/(cube size)) */
22
23 typedef struct ambtree {
24 AMBVAL *alist; /* ambient value list */
25 struct ambtree *kid; /* 8 child nodes */
26 } AMBTREE; /* ambient octree */
27
28 extern CUBE thescene; /* contains space boundaries */
29
30 extern char *shm_boundary; /* memory sharing boundary */
31
32 #define MAXASET 511 /* maximum number of elements in ambient set */
33 OBJECT ambset[MAXASET+1]={0}; /* ambient include/exclude set */
34
35 double maxarad; /* maximum ambient radius */
36 double minarad; /* minimum ambient radius */
37
38 static AMBTREE atrunk; /* our ambient trunk node */
39
40 static FILE *ambfp = NULL; /* ambient file pointer */
41 static int nunflshed = 0; /* number of unflushed ambient values */
42
43 #ifndef SORT_THRESH
44 #ifdef BIGMEM
45 #define SORT_THRESH ((9L<<20)/sizeof(AMBVAL))
46 #else
47 #define SORT_THRESH ((3L<<20)/sizeof(AMBVAL))
48 #endif
49 #endif
50 #ifndef SORT_INTVL
51 #define SORT_INTVL (SORT_THRESH*256)
52 #endif
53 #ifndef MAX_SORT_INTVL
54 #define MAX_SORT_INTVL (SORT_INTVL<<4)
55 #endif
56
57 static unsigned long ambclock = 0; /* ambient access clock */
58 static unsigned int nambvals = 0; /* number of stored ambient values */
59 static unsigned long lastsort = 0; /* time of last value sort */
60 static long sortintvl = SORT_INTVL; /* time until next sort */
61
62 #define MAXACLOCK (1L<<30) /* clock turnover value */
63 /*
64 * Track access times unless we are sharing ambient values
65 * through memory on a multiprocessor, when we want to avoid
66 * claiming our own memory (copy on write).
67 */
68 #define tracktime (shm_boundary == NULL || ambfp == NULL)
69
70 #define AMBFLUSH (BUFSIZ/AMBVALSIZ)
71
72 #define newambval() (AMBVAL *)bmalloc(sizeof(AMBVAL))
73
74 extern long ftell(), lseek();
75 static int initambfile(), avsave(), avinsert(), sortambvals();
76 static AMBVAL *avstore();
77 #ifdef F_SETLKW
78 static aflock();
79 #endif
80
81
82 setambres(ar) /* set ambient resolution */
83 int ar;
84 {
85 ambres = ar < 0 ? 0 : ar; /* may be done already */
86 /* set min & max radii */
87 if (ar <= 0) {
88 minarad = 0;
89 maxarad = thescene.cusize / 2.0;
90 } else {
91 minarad = thescene.cusize / ar;
92 maxarad = 64 * minarad; /* heuristic */
93 if (maxarad > thescene.cusize / 2.0)
94 maxarad = thescene.cusize / 2.0;
95 }
96 if (minarad <= FTINY)
97 minarad = 10*FTINY;
98 if (maxarad <= minarad)
99 maxarad = 64 * minarad;
100 }
101
102
103 setambacc(newa) /* set ambient accuracy */
104 double newa;
105 {
106 static double oldambacc = -1.0;
107
108 ambacc = newa < 0.0 ? 0.0 : newa; /* may be done already */
109 if (oldambacc < -FTINY)
110 oldambacc = ambacc; /* do nothing first call */
111 if (fabs(newa - oldambacc) < 0.01)
112 return; /* insignificant -- don't bother */
113 if (ambacc <= FTINY)
114 return; /* cannot build new tree */
115 /* else need to rebuild tree */
116 sortambvals(1);
117 oldambacc = ambacc; /* remeber setting for next call */
118 }
119
120
121 setambient(afile) /* initialize calculation */
122 char *afile;
123 {
124 long headlen;
125 AMBVAL amb;
126 /* init ambient limits */
127 setambres(ambres);
128 setambacc(ambacc);
129 if (afile == NULL)
130 return;
131 if (ambacc <= FTINY) {
132 sprintf(errmsg, "zero ambient accuracy so \"%s\" not opened",
133 afile);
134 error(WARNING, errmsg);
135 return;
136 }
137 /* open ambient file */
138 if ((ambfp = fopen(afile, "r+")) != NULL) {
139 initambfile(0);
140 headlen = ftell(ambfp);
141 while (readambval(&amb, ambfp))
142 avinsert(avstore(&amb));
143 /* align */
144 fseek(ambfp, -((ftell(ambfp)-headlen)%AMBVALSIZ), 1);
145 } else if ((ambfp = fopen(afile, "w+")) != NULL)
146 initambfile(1);
147 else {
148 sprintf(errmsg, "cannot open ambient file \"%s\"", afile);
149 error(SYSTEM, errmsg);
150 }
151 nunflshed++; /* lie */
152 ambsync();
153 }
154
155
156 ambnotify(obj) /* record new modifier */
157 OBJECT obj;
158 {
159 static int hitlimit = 0;
160 register OBJREC *o = objptr(obj);
161 register char **amblp;
162
163 if (hitlimit || !ismodifier(o->otype))
164 return;
165 for (amblp = amblist; *amblp != NULL; amblp++)
166 if (!strcmp(o->oname, *amblp)) {
167 if (ambset[0] >= MAXASET) {
168 error(WARNING, "too many modifiers in ambient list");
169 hitlimit++;
170 return; /* should this be fatal? */
171 }
172 insertelem(ambset, obj);
173 return;
174 }
175 }
176
177
178 ambient(acol, r) /* compute ambient component for ray */
179 COLOR acol;
180 register RAY *r;
181 {
182 static int rdepth = 0; /* ambient recursion */
183 double d;
184
185 if (ambdiv <= 0) /* no ambient calculation */
186 goto dumbamb;
187 /* check number of bounces */
188 if (rdepth >= ambounce)
189 goto dumbamb;
190 /* check ambient list */
191 if (ambincl != -1 && r->ro != NULL &&
192 ambincl != inset(ambset, r->ro->omod))
193 goto dumbamb;
194
195 if (ambacc <= FTINY) { /* no ambient storage */
196 rdepth++;
197 d = doambient(acol, r, r->rweight, NULL, NULL);
198 rdepth--;
199 if (d == 0.0)
200 goto dumbamb;
201 return;
202 }
203 /* resort memory? */
204 sortambvals(0);
205 /* get ambient value */
206 setcolor(acol, 0.0, 0.0, 0.0);
207 d = sumambient(acol, r, rdepth,
208 &atrunk, thescene.cuorg, thescene.cusize);
209 if (d > FTINY)
210 scalecolor(acol, 1.0/d);
211 else {
212 d = makeambient(acol, r, rdepth++);
213 rdepth--;
214 }
215 if (d > FTINY)
216 return;
217 dumbamb: /* return global value */
218 copycolor(acol, ambval);
219 }
220
221
222 double
223 sumambient(acol, r, al, at, c0, s) /* get interpolated ambient value */
224 COLOR acol;
225 register RAY *r;
226 int al;
227 AMBTREE *at;
228 FVECT c0;
229 double s;
230 {
231 double d, e1, e2, wt, wsum;
232 COLOR ct;
233 FVECT ck0;
234 int i;
235 register int j;
236 register AMBVAL *av;
237
238 wsum = 0.0;
239 /* do this node */
240 for (av = at->alist; av != NULL; av = av->next) {
241 if (tracktime)
242 av->latick = ambclock++;
243 /*
244 * Ambient level test.
245 */
246 if (av->lvl > al) /* list sorted, so this works */
247 break;
248 if (av->weight < r->rweight-FTINY)
249 continue;
250 /*
251 * Ambient radius test.
252 */
253 d = av->pos[0] - r->rop[0];
254 e1 = d * d;
255 d = av->pos[1] - r->rop[1];
256 e1 += d * d;
257 d = av->pos[2] - r->rop[2];
258 e1 += d * d;
259 e1 /= av->rad * av->rad;
260 if (e1 > ambacc*ambacc*1.21)
261 continue;
262 /*
263 * Normal direction test.
264 */
265 e2 = (1.0 - DOT(av->dir, r->ron)) * r->rweight;
266 if (e2 < 0.0) e2 = 0.0;
267 if (e1 + e2 > ambacc*ambacc*1.21)
268 continue;
269 /*
270 * Ray behind test.
271 */
272 d = 0.0;
273 for (j = 0; j < 3; j++)
274 d += (r->rop[j] - av->pos[j]) *
275 (av->dir[j] + r->ron[j]);
276 if (d*0.5 < -minarad*ambacc-.001)
277 continue;
278 /*
279 * Jittering final test reduces image artifacts.
280 */
281 wt = sqrt(e1) + sqrt(e2);
282 if (wt > ambacc*(.9+.2*urand(9015+samplendx)))
283 continue;
284 if (wt <= 1e-3)
285 wt = 1e3;
286 else
287 wt = 1.0 / wt;
288 wsum += wt;
289 extambient(ct, av, r->rop, r->ron);
290 scalecolor(ct, wt);
291 addcolor(acol, ct);
292 }
293 if (at->kid == NULL)
294 return(wsum);
295 /* do children */
296 s *= 0.5;
297 for (i = 0; i < 8; i++) {
298 for (j = 0; j < 3; j++) {
299 ck0[j] = c0[j];
300 if (1<<j & i)
301 ck0[j] += s;
302 if (r->rop[j] < ck0[j] - OCTSCALE*s)
303 break;
304 if (r->rop[j] > ck0[j] + (1.0+OCTSCALE)*s)
305 break;
306 }
307 if (j == 3)
308 wsum += sumambient(acol, r, al, at->kid+i, ck0, s);
309 }
310 return(wsum);
311 }
312
313
314 double
315 makeambient(acol, r, al) /* make a new ambient value */
316 COLOR acol;
317 register RAY *r;
318 int al;
319 {
320 AMBVAL amb;
321 FVECT gp, gd;
322 /* compute weight */
323 amb.weight = pow(AVGREFL, (double)al);
324 if (r->rweight < 0.2*amb.weight) /* heuristic */
325 amb.weight = r->rweight;
326 /* compute ambient */
327 amb.rad = doambient(acol, r, amb.weight, gp, gd);
328 if (amb.rad == 0.0)
329 return(0.0);
330 /* store it */
331 VCOPY(amb.pos, r->rop);
332 VCOPY(amb.dir, r->ron);
333 amb.lvl = al;
334 copycolor(amb.val, acol);
335 VCOPY(amb.gpos, gp);
336 VCOPY(amb.gdir, gd);
337 /* insert into tree */
338 avsave(&amb); /* and save to file */
339 return(amb.rad);
340 }
341
342
343 extambient(cr, ap, pv, nv) /* extrapolate value at pv, nv */
344 COLOR cr;
345 register AMBVAL *ap;
346 FVECT pv, nv;
347 {
348 FVECT v1, v2;
349 register int i;
350 double d;
351
352 d = 1.0; /* zeroeth order */
353 /* gradient due to translation */
354 for (i = 0; i < 3; i++)
355 d += ap->gpos[i]*(pv[i]-ap->pos[i]);
356 /* gradient due to rotation */
357 VCOPY(v1, ap->dir);
358 fcross(v2, v1, nv);
359 d += DOT(ap->gdir, v2);
360 if (d <= 0.0) {
361 setcolor(cr, 0.0, 0.0, 0.0);
362 return;
363 }
364 copycolor(cr, ap->val);
365 scalecolor(cr, d);
366 }
367
368
369 static
370 initambfile(creat) /* initialize ambient file */
371 int creat;
372 {
373 extern char *progname, *octname, VersionID[];
374
375 #ifdef F_SETLKW
376 aflock(creat ? F_WRLCK : F_RDLCK);
377 #endif
378 #ifdef MSDOS
379 setmode(fileno(ambfp), O_BINARY);
380 #endif
381 setbuf(ambfp, bmalloc(BUFSIZ+8));
382 if (creat) { /* new file */
383 newheader("RADIANCE", ambfp);
384 fprintf(ambfp, "%s -av %g %g %g -ab %d -aa %g ",
385 progname, colval(ambval,RED),
386 colval(ambval,GRN), colval(ambval,BLU),
387 ambounce, ambacc);
388 fprintf(ambfp, "-ad %d -as %d -ar %d %s\n",
389 ambdiv, ambssamp, ambres,
390 octname==NULL ? "" : octname);
391 fprintf(ambfp, "SOFTWARE= %s\n", VersionID);
392 fputformat(AMBFMT, ambfp);
393 putc('\n', ambfp);
394 putambmagic(ambfp);
395 } else if (checkheader(ambfp, AMBFMT, NULL) < 0 || !hasambmagic(ambfp))
396 error(USER, "bad ambient file");
397 }
398
399
400 static
401 avsave(av) /* insert and save an ambient value */
402 AMBVAL *av;
403 {
404 avinsert(avstore(av));
405 if (ambfp == NULL)
406 return;
407 if (writambval(av, ambfp) < 0)
408 goto writerr;
409 if (++nunflshed >= AMBFLUSH)
410 if (ambsync() == EOF)
411 goto writerr;
412 return;
413 writerr:
414 error(SYSTEM, "error writing ambient file");
415 }
416
417
418 static AMBVAL *
419 avstore(aval) /* allocate memory and store aval */
420 register AMBVAL *aval;
421 {
422 register AMBVAL *av;
423
424 if ((av = newambval()) == NULL)
425 error(SYSTEM, "out of memory in avstore");
426 copystruct(av, aval);
427 av->latick = ambclock;
428 av->next = NULL;
429 nambvals++;
430 return(av);
431 }
432
433
434 #define ATALLOCSZ 512 /* #/8 trees to allocate at once */
435
436 static AMBTREE *atfreelist = NULL; /* free ambient tree structures */
437
438
439 static
440 AMBTREE *
441 newambtree() /* allocate 8 ambient tree structs */
442 {
443 register AMBTREE *atp, *upperlim;
444
445 if (atfreelist == NULL) { /* get more nodes */
446 atfreelist = (AMBTREE *)bmalloc(ATALLOCSZ*8*sizeof(AMBTREE));
447 if (atfreelist == NULL)
448 return(NULL);
449 /* link new free list */
450 upperlim = atfreelist + 8*(ATALLOCSZ-1);
451 for (atp = atfreelist; atp < upperlim; atp += 8)
452 atp->kid = atp + 8;
453 atp->kid = NULL;
454 }
455 atp = atfreelist;
456 atfreelist = atp->kid;
457 bzero((char *)atp, 8*sizeof(AMBTREE));
458 return(atp);
459 }
460
461
462 static
463 freeambtree(atp) /* free 8 ambient tree structs */
464 AMBTREE *atp;
465 {
466 atp->kid = atfreelist;
467 atfreelist = atp;
468 }
469
470
471 static
472 avinsert(av) /* insert ambient value in our tree */
473 register AMBVAL *av;
474 {
475 register AMBTREE *at;
476 register AMBVAL *ap;
477 AMBVAL avh;
478 FVECT ck0;
479 double s;
480 int branch;
481 register int i;
482
483 if (av->rad <= FTINY)
484 error(CONSISTENCY, "zero ambient radius in avinsert");
485 at = &atrunk;
486 VCOPY(ck0, thescene.cuorg);
487 s = thescene.cusize;
488 while (s*(OCTSCALE/2) > av->rad*ambacc) {
489 if (at->kid == NULL)
490 if ((at->kid = newambtree()) == NULL)
491 error(SYSTEM, "out of memory in avinsert");
492 s *= 0.5;
493 branch = 0;
494 for (i = 0; i < 3; i++)
495 if (av->pos[i] > ck0[i] + s) {
496 ck0[i] += s;
497 branch |= 1 << i;
498 }
499 at = at->kid + branch;
500 }
501 avh.next = at->alist; /* order by increasing level */
502 for (ap = &avh; ap->next != NULL; ap = ap->next)
503 if (ap->next->lvl >= av->lvl)
504 break;
505 av->next = ap->next;
506 ap->next = av;
507 at->alist = avh.next;
508 }
509
510
511 static
512 unloadatree(at, f) /* unload an ambient value tree */
513 register AMBTREE *at;
514 int (*f)();
515 {
516 register AMBVAL *av;
517 register int i;
518 /* transfer values at this node */
519 for (av = at->alist; av != NULL; av = at->alist) {
520 at->alist = av->next;
521 (*f)(av);
522 }
523 if (at->kid == NULL)
524 return;
525 for (i = 0; i < 8; i++) /* transfer and free children */
526 unloadatree(at->kid+i, f);
527 freeambtree(at->kid);
528 at->kid = NULL;
529 }
530
531
532 static AMBVAL **avlist1, **avlist2; /* ambient value lists for sorting */
533 static int i_avlist; /* index for lists */
534
535
536 static
537 av2list(av)
538 AMBVAL *av;
539 {
540 #ifdef DEBUG
541 if (i_avlist >= nambvals)
542 error(CONSISTENCY, "too many ambient values in av2list1");
543 #endif
544 avlist1[i_avlist] = avlist2[i_avlist] = av;
545 i_avlist++;
546 }
547
548
549 static int
550 alatcmp(avp1, avp2) /* compare ambient values for MRA */
551 AMBVAL **avp1, **avp2;
552 {
553 return((**avp2).latick - (**avp1).latick);
554 }
555
556
557 static int
558 aposcmp(avp1, avp2) /* compare ambient value positions */
559 AMBVAL **avp1, **avp2;
560 {
561 return(*avp1 - *avp2);
562 }
563
564
565 #ifdef DEBUG
566 static int
567 avlmemi(avaddr) /* find list position from address */
568 AMBVAL *avaddr;
569 {
570 register AMBVAL **avlpp;
571
572 avlpp = (AMBVAL **)bsearch((char *)&avaddr, (char *)avlist2,
573 nambvals, sizeof(AMBVAL *), aposcmp);
574 if (avlpp == NULL)
575 error(CONSISTENCY, "address not found in avlmemi");
576 return(avlpp - avlist2);
577 }
578 #else
579 #define avlmemi(avaddr) ((AMBVAL **)bsearch((char *)&avaddr,(char *)avlist2, \
580 nambvals,sizeof(AMBVAL *),aposcmp) - avlist2)
581 #endif
582
583
584 static
585 sortambvals(always) /* resort ambient values */
586 int always;
587 {
588 AMBTREE oldatrunk;
589 AMBVAL tav, *tap, *pnext;
590 register int i, j;
591 /* see if it's time yet */
592 if (!always && (ambclock < lastsort+sortintvl ||
593 nambvals < SORT_THRESH))
594 return;
595 /*
596 * The idea here is to minimize memory thrashing
597 * in VM systems by improving reference locality.
598 * We do this by periodically sorting our stored ambient
599 * values in memory in order of most recently to least
600 * recently accessed. This ordering was chosen so that new
601 * ambient values (which tend to be less important) go into
602 * higher memory with the infrequently accessed values.
603 * Since we expect our values to need sorting less
604 * frequently as the process continues, we double our
605 * waiting interval after each call.
606 * This routine is also called by setambacc() with
607 * the "always" parameter set to 1 so that the ambient
608 * tree will be rebuilt with the new accuracy parameter.
609 */
610 if (tracktime) { /* allocate pointer arrays to sort */
611 avlist1 = (AMBVAL **)malloc(nambvals*sizeof(AMBVAL *));
612 avlist2 = (AMBVAL **)malloc(nambvals*sizeof(AMBVAL *));
613 } else
614 avlist1 = avlist2 = NULL;
615 if (avlist2 == NULL) { /* no time tracking -- rebuild tree? */
616 if (avlist1 != NULL)
617 free((char *)avlist1);
618 if (always) { /* rebuild without sorting */
619 copystruct(&oldatrunk, &atrunk);
620 atrunk.alist = NULL;
621 atrunk.kid = NULL;
622 unloadatree(&oldatrunk, avinsert);
623 }
624 } else { /* sort memory by last access time */
625 /*
626 * Sorting memory is tricky because it isn't contiguous.
627 * We have to sort an array of pointers by MRA and also
628 * by memory position. We then copy values in "loops"
629 * to minimize memory hits. Nevertheless, we will visit
630 * everyone at least twice, and this is an expensive process
631 * when we're thrashing, which is when we need to do it.
632 */
633 #ifdef DEBUG
634 sprintf(errmsg, "sorting %u ambient values at ambclock=%lu...",
635 nambvals, ambclock);
636 eputs(errmsg);
637 #endif
638 i_avlist = 0;
639 unloadatree(&atrunk, av2list); /* empty current tree */
640 #ifdef DEBUG
641 if (i_avlist < nambvals)
642 error(CONSISTENCY, "missing ambient values in sortambvals");
643 #endif
644 qsort((char *)avlist1, nambvals, sizeof(AMBVAL *), alatcmp);
645 qsort((char *)avlist2, nambvals, sizeof(AMBVAL *), aposcmp);
646 for (i = 0; i < nambvals; i++) {
647 if (avlist1[i] == NULL)
648 continue;
649 tap = avlist2[i];
650 copystruct(&tav, tap);
651 for (j = i; (pnext = avlist1[j]) != tap;
652 j = avlmemi(pnext)) {
653 copystruct(avlist2[j], pnext);
654 avinsert(avlist2[j]);
655 avlist1[j] = NULL;
656 }
657 copystruct(avlist2[j], &tav);
658 avinsert(avlist2[j]);
659 avlist1[j] = NULL;
660 }
661 free((char *)avlist1);
662 free((char *)avlist2);
663 /* compute new sort interval */
664 sortintvl = ambclock - lastsort;
665 if (sortintvl > MAX_SORT_INTVL)
666 sortintvl = MAX_SORT_INTVL;
667 else
668 sortintvl <<= 1; /* wait twice as long next */
669 #ifdef DEBUG
670 eputs("done\n");
671 #endif
672 }
673 if (ambclock >= MAXACLOCK)
674 ambclock = MAXACLOCK/2;
675 lastsort = ambclock;
676 }
677
678
679 #ifdef F_SETLKW
680
681 static
682 aflock(typ) /* lock/unlock ambient file */
683 int typ;
684 {
685 static struct flock fls; /* static so initialized to zeroes */
686
687 fls.l_type = typ;
688 if (fcntl(fileno(ambfp), F_SETLKW, &fls) < 0)
689 error(SYSTEM, "cannot (un)lock ambient file");
690 }
691
692
693 int
694 ambsync() /* synchronize ambient file */
695 {
696 static FILE *ambinp = NULL;
697 static long lastpos = -1;
698 long flen;
699 AMBVAL avs;
700 register int n;
701
702 if (nunflshed == 0)
703 return(0);
704 if (lastpos < 0) /* initializing (locked in initambfile) */
705 goto syncend;
706 /* gain exclusive access */
707 aflock(F_WRLCK);
708 /* see if file has grown */
709 if ((flen = lseek(fileno(ambfp), 0L, 2)) < 0)
710 goto seekerr;
711 if (n = flen - lastpos) { /* file has grown */
712 if (ambinp == NULL) { /* use duplicate filedes */
713 ambinp = fdopen(dup(fileno(ambfp)), "r");
714 if (ambinp == NULL)
715 error(SYSTEM, "fdopen failed in ambsync");
716 }
717 if (fseek(ambinp, lastpos, 0) < 0)
718 goto seekerr;
719 while (n >= AMBVALSIZ) { /* load contributed values */
720 readambval(&avs, ambinp);
721 avinsert(avstore(&avs));
722 n -= AMBVALSIZ;
723 }
724 /*** seek always as safety measure
725 if (n) ***/ /* alignment */
726 if (lseek(fileno(ambfp), flen-n, 0) < 0)
727 goto seekerr;
728 }
729 #ifdef DEBUG
730 if (ambfp->_ptr - ambfp->_base != nunflshed*AMBVALSIZ) {
731 sprintf(errmsg, "ambient file buffer at %d rather than %d",
732 ambfp->_ptr - ambfp->_base,
733 nunflshed*AMBVALSIZ);
734 error(CONSISTENCY, errmsg);
735 }
736 #endif
737 syncend:
738 n = fflush(ambfp); /* calls write() at last */
739 if ((lastpos = lseek(fileno(ambfp), 0L, 1)) < 0)
740 goto seekerr;
741 aflock(F_UNLCK); /* release file */
742 nunflshed = 0;
743 return(n);
744 seekerr:
745 error(SYSTEM, "seek failed in ambsync");
746 }
747
748 #else
749
750 int
751 ambsync() /* flush ambient file */
752 {
753 if (nunflshed == 0)
754 return(0);
755 nunflshed = 0;
756 return(fflush(ambfp));
757 }
758
759 #endif