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root/radiance/ray/src/rt/ambient.c
Revision: 2.36
Committed: Wed Feb 14 15:43:22 1996 UTC (28 years, 2 months ago) by greg
Content type: text/plain
Branch: MAIN
Changes since 2.35: +3 -8 lines
Log Message:
added -aw option for ambient value weight

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 #ifndef OCTSCALE
22 #define OCTSCALE 1.0 /* ceil((valid rad.)/(cube size)) */
23 #endif
24
25 typedef struct ambtree {
26 AMBVAL *alist; /* ambient value list */
27 struct ambtree *kid; /* 8 child nodes */
28 } AMBTREE; /* ambient octree */
29
30 extern CUBE thescene; /* contains space boundaries */
31
32 extern char *shm_boundary; /* memory sharing boundary */
33
34 #define MAXASET 511 /* maximum number of elements in ambient set */
35 OBJECT ambset[MAXASET+1]={0}; /* ambient include/exclude set */
36
37 double maxarad; /* maximum ambient radius */
38 double minarad; /* minimum ambient radius */
39
40 static AMBTREE atrunk; /* our ambient trunk node */
41
42 static FILE *ambfp = NULL; /* ambient file pointer */
43 static int nunflshed = 0; /* number of unflushed ambient values */
44
45 #ifndef SORT_THRESH
46 #ifdef BIGMEM
47 #define SORT_THRESH ((9L<<20)/sizeof(AMBVAL))
48 #else
49 #define SORT_THRESH ((3L<<20)/sizeof(AMBVAL))
50 #endif
51 #endif
52 #ifndef SORT_INTVL
53 #define SORT_INTVL (SORT_THRESH*256)
54 #endif
55 #ifndef MAX_SORT_INTVL
56 #define MAX_SORT_INTVL (SORT_INTVL<<4)
57 #endif
58
59 static COLOR avsum = BLKCOLOR; /* computed ambient value sum */
60 static unsigned int nambvals = 0; /* total number of indirect values */
61 static unsigned int nambshare = 0; /* number of values from file */
62 static unsigned long ambclock = 0; /* ambient access clock */
63 static unsigned long lastsort = 0; /* time of last value sort */
64 static long sortintvl = SORT_INTVL; /* time until next sort */
65
66 #define MAXACLOCK (1L<<30) /* clock turnover value */
67 /*
68 * Track access times unless we are sharing ambient values
69 * through memory on a multiprocessor, when we want to avoid
70 * claiming our own memory (copy on write). Go ahead anyway
71 * if more than two thirds of our values are unshared.
72 */
73 #define tracktime (shm_boundary == NULL || nambvals > 3*nambshare)
74
75 #define AMBFLUSH (BUFSIZ/AMBVALSIZ)
76
77 #define newambval() (AMBVAL *)bmalloc(sizeof(AMBVAL))
78
79 extern long ftell(), lseek();
80 static int initambfile(), avsave(), avinsert(), sortambvals();
81 static AMBVAL *avstore();
82 #ifdef F_SETLKW
83 static aflock();
84 #endif
85
86
87 setambres(ar) /* set ambient resolution */
88 int ar;
89 {
90 ambres = ar < 0 ? 0 : ar; /* may be done already */
91 /* set min & max radii */
92 if (ar <= 0) {
93 minarad = 0;
94 maxarad = thescene.cusize / 2.0;
95 } else {
96 minarad = thescene.cusize / ar;
97 maxarad = 64 * minarad; /* heuristic */
98 if (maxarad > thescene.cusize / 2.0)
99 maxarad = thescene.cusize / 2.0;
100 }
101 if (minarad <= FTINY)
102 minarad = 10*FTINY;
103 if (maxarad <= minarad)
104 maxarad = 64 * minarad;
105 }
106
107
108 setambacc(newa) /* set ambient accuracy */
109 double newa;
110 {
111 double ambdiff;
112
113 if (newa < 0.0)
114 newa = 0.0;
115 ambdiff = fabs(newa - ambacc);
116 if (ambdiff >= .01 && (ambacc = newa) > FTINY && nambvals > 0)
117 sortambvals(1); /* rebuild tree */
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 nambshare = nambvals;
146 } else if ((ambfp = fopen(afile, "w+")) != NULL)
147 initambfile(1);
148 else {
149 sprintf(errmsg, "cannot open ambient file \"%s\"", afile);
150 error(SYSTEM, errmsg);
151 }
152 nunflshed++; /* lie */
153 ambsync();
154 }
155
156
157 ambnotify(obj) /* record new modifier */
158 OBJECT obj;
159 {
160 static int hitlimit = 0;
161 register OBJREC *o = objptr(obj);
162 register char **amblp;
163
164 if (hitlimit || !ismodifier(o->otype))
165 return;
166 for (amblp = amblist; *amblp != NULL; amblp++)
167 if (!strcmp(o->oname, *amblp)) {
168 if (ambset[0] >= MAXASET) {
169 error(WARNING, "too many modifiers in ambient list");
170 hitlimit++;
171 return; /* should this be fatal? */
172 }
173 insertelem(ambset, obj);
174 return;
175 }
176 }
177
178
179 ambient(acol, r, nrm) /* compute ambient component for ray */
180 COLOR acol;
181 register RAY *r;
182 FVECT nrm;
183 {
184 static int rdepth = 0; /* ambient recursion */
185 double d;
186
187 if (ambdiv <= 0) /* no ambient calculation */
188 goto dumbamb;
189 /* check number of bounces */
190 if (rdepth >= ambounce)
191 goto dumbamb;
192 /* check ambient list */
193 if (ambincl != -1 && r->ro != NULL &&
194 ambincl != inset(ambset, r->ro->omod))
195 goto dumbamb;
196
197 if (ambacc <= FTINY) { /* no ambient storage */
198 rdepth++;
199 d = doambient(acol, r, r->rweight, NULL, NULL);
200 rdepth--;
201 if (d <= FTINY)
202 goto dumbamb;
203 return;
204 }
205 /* resort memory? */
206 sortambvals(0);
207 /* get ambient value */
208 setcolor(acol, 0.0, 0.0, 0.0);
209 d = sumambient(acol, r, nrm, rdepth,
210 &atrunk, thescene.cuorg, thescene.cusize);
211 if (d > FTINY) {
212 scalecolor(acol, 1.0/d);
213 return;
214 }
215 rdepth++; /* need to cache new value */
216 d = makeambient(acol, r, nrm, rdepth-1);
217 rdepth--;
218 if (d > FTINY)
219 return;
220 dumbamb: /* return global value */
221 copycolor(acol, ambval);
222 if (ambvwt <= 0 | nambvals == 0)
223 return;
224 scalecolor(acol, (double)ambvwt);
225 addcolor(acol, avsum); /* average in computations */
226 d = 1.0/(ambvwt+nambvals);
227 scalecolor(acol, d);
228 }
229
230
231 double
232 sumambient(acol, r, rn, al, at, c0, s) /* get interpolated ambient value */
233 COLOR acol;
234 register RAY *r;
235 FVECT rn;
236 int al;
237 AMBTREE *at;
238 FVECT c0;
239 double s;
240 {
241 double d, e1, e2, wt, wsum;
242 COLOR ct;
243 FVECT ck0;
244 int i;
245 register int j;
246 register AMBVAL *av;
247
248 wsum = 0.0;
249 /* do this node */
250 for (av = at->alist; av != NULL; av = av->next) {
251 if (tracktime)
252 av->latick = ambclock++;
253 /*
254 * Ambient level test.
255 */
256 if (av->lvl > al) /* list sorted, so this works */
257 break;
258 if (av->weight < r->rweight-FTINY)
259 continue;
260 /*
261 * Ambient radius test.
262 */
263 d = av->pos[0] - r->rop[0];
264 e1 = d * d;
265 d = av->pos[1] - r->rop[1];
266 e1 += d * d;
267 d = av->pos[2] - r->rop[2];
268 e1 += d * d;
269 e1 /= av->rad * av->rad;
270 if (e1 > ambacc*ambacc*1.21)
271 continue;
272 /*
273 * Normal direction test.
274 */
275 e2 = (1.0 - DOT(av->dir, r->ron)) * r->rweight;
276 if (e2 < 0.0) e2 = 0.0;
277 if (e1 + e2 > ambacc*ambacc*1.21)
278 continue;
279 /*
280 * Ray behind test.
281 */
282 d = 0.0;
283 for (j = 0; j < 3; j++)
284 d += (r->rop[j] - av->pos[j]) *
285 (av->dir[j] + r->ron[j]);
286 if (d*0.5 < -minarad*ambacc-.001)
287 continue;
288 /*
289 * Jittering final test reduces image artifacts.
290 */
291 wt = sqrt(e1) + sqrt(e2);
292 if (wt > ambacc*(.9+.2*urand(9015+samplendx)))
293 continue;
294 if (wt <= 1e-3)
295 wt = 1e3;
296 else
297 wt = 1.0 / wt;
298 wsum += wt;
299 extambient(ct, av, r->rop, rn);
300 scalecolor(ct, wt);
301 addcolor(acol, ct);
302 }
303 if (at->kid == NULL)
304 return(wsum);
305 /* do children */
306 s *= 0.5;
307 for (i = 0; i < 8; i++) {
308 for (j = 0; j < 3; j++) {
309 ck0[j] = c0[j];
310 if (1<<j & i)
311 ck0[j] += s;
312 if (r->rop[j] < ck0[j] - OCTSCALE*s)
313 break;
314 if (r->rop[j] > ck0[j] + (1.0+OCTSCALE)*s)
315 break;
316 }
317 if (j == 3)
318 wsum += sumambient(acol, r, rn, al, at->kid+i, ck0, s);
319 }
320 return(wsum);
321 }
322
323
324 double
325 makeambient(acol, r, rn, al) /* make a new ambient value */
326 COLOR acol;
327 register RAY *r;
328 FVECT rn;
329 int al;
330 {
331 AMBVAL amb;
332 FVECT gp, gd;
333 /* compute weight */
334 amb.weight = pow(AVGREFL, (double)al);
335 if (r->rweight < 0.1*amb.weight) /* heuristic */
336 amb.weight = r->rweight;
337 /* compute ambient */
338 amb.rad = doambient(acol, r, amb.weight, gp, gd);
339 if (amb.rad <= FTINY)
340 return(0.0);
341 /* store it */
342 VCOPY(amb.pos, r->rop);
343 VCOPY(amb.dir, r->ron);
344 amb.lvl = al;
345 copycolor(amb.val, acol);
346 VCOPY(amb.gpos, gp);
347 VCOPY(amb.gdir, gd);
348 /* insert into tree */
349 avsave(&amb); /* and save to file */
350 if (rn != r->ron)
351 extambient(acol, &amb, r->rop, rn); /* texture */
352 return(amb.rad);
353 }
354
355
356 extambient(cr, ap, pv, nv) /* extrapolate value at pv, nv */
357 COLOR cr;
358 register AMBVAL *ap;
359 FVECT pv, nv;
360 {
361 FVECT v1, v2;
362 register int i;
363 double d;
364
365 d = 1.0; /* zeroeth order */
366 /* gradient due to translation */
367 for (i = 0; i < 3; i++)
368 d += ap->gpos[i]*(pv[i]-ap->pos[i]);
369 /* gradient due to rotation */
370 VCOPY(v1, ap->dir);
371 fcross(v2, v1, nv);
372 d += DOT(ap->gdir, v2);
373 if (d <= 0.0) {
374 setcolor(cr, 0.0, 0.0, 0.0);
375 return;
376 }
377 copycolor(cr, ap->val);
378 scalecolor(cr, d);
379 }
380
381
382 static
383 initambfile(creat) /* initialize ambient file */
384 int creat;
385 {
386 extern char *progname, *octname, VersionID[];
387
388 #ifdef F_SETLKW
389 aflock(creat ? F_WRLCK : F_RDLCK);
390 #endif
391 #ifdef MSDOS
392 setmode(fileno(ambfp), O_BINARY);
393 #endif
394 setbuf(ambfp, bmalloc(BUFSIZ+8));
395 if (creat) { /* new file */
396 newheader("RADIANCE", ambfp);
397 fprintf(ambfp, "%s -av %g %g %g -ab %d -aa %g ",
398 progname, colval(ambval,RED),
399 colval(ambval,GRN), colval(ambval,BLU),
400 ambounce, ambacc);
401 fprintf(ambfp, "-ad %d -as %d -ar %d %s\n",
402 ambdiv, ambssamp, ambres,
403 octname==NULL ? "" : octname);
404 fprintf(ambfp, "SOFTWARE= %s\n", VersionID);
405 fputformat(AMBFMT, ambfp);
406 putc('\n', ambfp);
407 putambmagic(ambfp);
408 } else if (checkheader(ambfp, AMBFMT, NULL) < 0 || !hasambmagic(ambfp))
409 error(USER, "bad ambient file");
410 }
411
412
413 static
414 avsave(av) /* insert and save an ambient value */
415 AMBVAL *av;
416 {
417 avinsert(avstore(av));
418 if (ambfp == NULL)
419 return;
420 if (writambval(av, ambfp) < 0)
421 goto writerr;
422 if (++nunflshed >= AMBFLUSH)
423 if (ambsync() == EOF)
424 goto writerr;
425 return;
426 writerr:
427 error(SYSTEM, "error writing ambient file");
428 }
429
430
431 static AMBVAL *
432 avstore(aval) /* allocate memory and store aval */
433 register AMBVAL *aval;
434 {
435 register AMBVAL *av;
436
437 if ((av = newambval()) == NULL)
438 error(SYSTEM, "out of memory in avstore");
439 copystruct(av, aval);
440 av->latick = ambclock;
441 av->next = NULL;
442 addcolor(avsum, av->val); /* add to sum for averaging */
443 nambvals++;
444 return(av);
445 }
446
447
448 #define ATALLOCSZ 512 /* #/8 trees to allocate at once */
449
450 static AMBTREE *atfreelist = NULL; /* free ambient tree structures */
451
452
453 static
454 AMBTREE *
455 newambtree() /* allocate 8 ambient tree structs */
456 {
457 register AMBTREE *atp, *upperlim;
458
459 if (atfreelist == NULL) { /* get more nodes */
460 atfreelist = (AMBTREE *)bmalloc(ATALLOCSZ*8*sizeof(AMBTREE));
461 if (atfreelist == NULL)
462 return(NULL);
463 /* link new free list */
464 upperlim = atfreelist + 8*(ATALLOCSZ-1);
465 for (atp = atfreelist; atp < upperlim; atp += 8)
466 atp->kid = atp + 8;
467 atp->kid = NULL;
468 }
469 atp = atfreelist;
470 atfreelist = atp->kid;
471 bzero((char *)atp, 8*sizeof(AMBTREE));
472 return(atp);
473 }
474
475
476 static
477 freeambtree(atp) /* free 8 ambient tree structs */
478 AMBTREE *atp;
479 {
480 atp->kid = atfreelist;
481 atfreelist = atp;
482 }
483
484
485 static
486 avinsert(av) /* insert ambient value in our tree */
487 register AMBVAL *av;
488 {
489 register AMBTREE *at;
490 register AMBVAL *ap;
491 AMBVAL avh;
492 FVECT ck0;
493 double s;
494 int branch;
495 register int i;
496
497 if (av->rad <= FTINY)
498 error(CONSISTENCY, "zero ambient radius in avinsert");
499 at = &atrunk;
500 VCOPY(ck0, thescene.cuorg);
501 s = thescene.cusize;
502 while (s*(OCTSCALE/2) > av->rad*ambacc) {
503 if (at->kid == NULL)
504 if ((at->kid = newambtree()) == NULL)
505 error(SYSTEM, "out of memory in avinsert");
506 s *= 0.5;
507 branch = 0;
508 for (i = 0; i < 3; i++)
509 if (av->pos[i] > ck0[i] + s) {
510 ck0[i] += s;
511 branch |= 1 << i;
512 }
513 at = at->kid + branch;
514 }
515 avh.next = at->alist; /* order by increasing level */
516 for (ap = &avh; ap->next != NULL; ap = ap->next)
517 if (ap->next->lvl >= av->lvl)
518 break;
519 av->next = ap->next;
520 ap->next = av;
521 at->alist = avh.next;
522 }
523
524
525 static
526 unloadatree(at, f) /* unload an ambient value tree */
527 register AMBTREE *at;
528 int (*f)();
529 {
530 register AMBVAL *av;
531 register int i;
532 /* transfer values at this node */
533 for (av = at->alist; av != NULL; av = at->alist) {
534 at->alist = av->next;
535 (*f)(av);
536 }
537 if (at->kid == NULL)
538 return;
539 for (i = 0; i < 8; i++) /* transfer and free children */
540 unloadatree(at->kid+i, f);
541 freeambtree(at->kid);
542 at->kid = NULL;
543 }
544
545
546 static AMBVAL **avlist1, **avlist2; /* ambient value lists for sorting */
547 static int i_avlist; /* index for lists */
548
549
550 static
551 av2list(av)
552 AMBVAL *av;
553 {
554 #ifdef DEBUG
555 if (i_avlist >= nambvals)
556 error(CONSISTENCY, "too many ambient values in av2list1");
557 #endif
558 avlist1[i_avlist] = avlist2[i_avlist] = av;
559 i_avlist++;
560 }
561
562
563 static int
564 alatcmp(avp1, avp2) /* compare ambient values for MRA */
565 AMBVAL **avp1, **avp2;
566 {
567 return((**avp2).latick - (**avp1).latick);
568 }
569
570
571 static int
572 aposcmp(avp1, avp2) /* compare ambient value positions */
573 AMBVAL **avp1, **avp2;
574 {
575 return(*avp1 - *avp2);
576 }
577
578
579 #ifdef DEBUG
580 static int
581 avlmemi(avaddr) /* find list position from address */
582 AMBVAL *avaddr;
583 {
584 register AMBVAL **avlpp;
585
586 avlpp = (AMBVAL **)bsearch((char *)&avaddr, (char *)avlist2,
587 nambvals, sizeof(AMBVAL *), aposcmp);
588 if (avlpp == NULL)
589 error(CONSISTENCY, "address not found in avlmemi");
590 return(avlpp - avlist2);
591 }
592 #else
593 #define avlmemi(avaddr) ((AMBVAL **)bsearch((char *)&avaddr,(char *)avlist2, \
594 nambvals,sizeof(AMBVAL *),aposcmp) - avlist2)
595 #endif
596
597
598 static
599 sortambvals(always) /* resort ambient values */
600 int always;
601 {
602 AMBTREE oldatrunk;
603 AMBVAL tav, *tap, *pnext;
604 register int i, j;
605 /* see if it's time yet */
606 if (!always && (ambclock < lastsort+sortintvl ||
607 nambvals < SORT_THRESH))
608 return;
609 /*
610 * The idea here is to minimize memory thrashing
611 * in VM systems by improving reference locality.
612 * We do this by periodically sorting our stored ambient
613 * values in memory in order of most recently to least
614 * recently accessed. This ordering was chosen so that new
615 * ambient values (which tend to be less important) go into
616 * higher memory with the infrequently accessed values.
617 * Since we expect our values to need sorting less
618 * frequently as the process continues, we double our
619 * waiting interval after each call.
620 * This routine is also called by setambacc() with
621 * the "always" parameter set to 1 so that the ambient
622 * tree will be rebuilt with the new accuracy parameter.
623 */
624 if (tracktime) { /* allocate pointer arrays to sort */
625 avlist1 = (AMBVAL **)malloc(nambvals*sizeof(AMBVAL *));
626 avlist2 = (AMBVAL **)malloc(nambvals*sizeof(AMBVAL *));
627 } else
628 avlist1 = avlist2 = NULL;
629 if (avlist2 == NULL) { /* no time tracking -- rebuild tree? */
630 if (avlist1 != NULL)
631 free((char *)avlist1);
632 if (always) { /* rebuild without sorting */
633 copystruct(&oldatrunk, &atrunk);
634 atrunk.alist = NULL;
635 atrunk.kid = NULL;
636 unloadatree(&oldatrunk, avinsert);
637 }
638 } else { /* sort memory by last access time */
639 /*
640 * Sorting memory is tricky because it isn't contiguous.
641 * We have to sort an array of pointers by MRA and also
642 * by memory position. We then copy values in "loops"
643 * to minimize memory hits. Nevertheless, we will visit
644 * everyone at least twice, and this is an expensive process
645 * when we're thrashing, which is when we need to do it.
646 */
647 #ifdef DEBUG
648 sprintf(errmsg, "sorting %u ambient values at ambclock=%lu...",
649 nambvals, ambclock);
650 eputs(errmsg);
651 #endif
652 i_avlist = 0;
653 unloadatree(&atrunk, av2list); /* empty current tree */
654 #ifdef DEBUG
655 if (i_avlist < nambvals)
656 error(CONSISTENCY, "missing ambient values in sortambvals");
657 #endif
658 qsort((char *)avlist1, nambvals, sizeof(AMBVAL *), alatcmp);
659 qsort((char *)avlist2, nambvals, sizeof(AMBVAL *), aposcmp);
660 for (i = 0; i < nambvals; i++) {
661 if (avlist1[i] == NULL)
662 continue;
663 tap = avlist2[i];
664 copystruct(&tav, tap);
665 for (j = i; (pnext = avlist1[j]) != tap;
666 j = avlmemi(pnext)) {
667 copystruct(avlist2[j], pnext);
668 avinsert(avlist2[j]);
669 avlist1[j] = NULL;
670 }
671 copystruct(avlist2[j], &tav);
672 avinsert(avlist2[j]);
673 avlist1[j] = NULL;
674 }
675 free((char *)avlist1);
676 free((char *)avlist2);
677 /* compute new sort interval */
678 sortintvl = ambclock - lastsort;
679 if (sortintvl >= MAX_SORT_INTVL/2)
680 sortintvl = MAX_SORT_INTVL;
681 else
682 sortintvl <<= 1; /* wait twice as long next */
683 #ifdef DEBUG
684 eputs("done\n");
685 #endif
686 }
687 if (ambclock >= MAXACLOCK)
688 ambclock = MAXACLOCK/2;
689 lastsort = ambclock;
690 }
691
692
693 #ifdef F_SETLKW
694
695 static
696 aflock(typ) /* lock/unlock ambient file */
697 int typ;
698 {
699 static struct flock fls; /* static so initialized to zeroes */
700
701 fls.l_type = typ;
702 if (fcntl(fileno(ambfp), F_SETLKW, &fls) < 0)
703 error(SYSTEM, "cannot (un)lock ambient file");
704 }
705
706
707 int
708 ambsync() /* synchronize ambient file */
709 {
710 static FILE *ambinp = NULL;
711 static long lastpos = -1;
712 long flen;
713 AMBVAL avs;
714 register int n;
715
716 if (nunflshed == 0)
717 return(0);
718 if (lastpos < 0) /* initializing (locked in initambfile) */
719 goto syncend;
720 /* gain exclusive access */
721 aflock(F_WRLCK);
722 /* see if file has grown */
723 if ((flen = lseek(fileno(ambfp), 0L, 2)) < 0)
724 goto seekerr;
725 if (n = flen - lastpos) { /* file has grown */
726 if (ambinp == NULL) { /* use duplicate filedes */
727 ambinp = fdopen(dup(fileno(ambfp)), "r");
728 if (ambinp == NULL)
729 error(SYSTEM, "fdopen failed in ambsync");
730 }
731 if (fseek(ambinp, lastpos, 0) < 0)
732 goto seekerr;
733 while (n >= AMBVALSIZ) { /* load contributed values */
734 readambval(&avs, ambinp);
735 avinsert(avstore(&avs));
736 n -= AMBVALSIZ;
737 }
738 /*** seek always as safety measure
739 if (n) ***/ /* alignment */
740 if (lseek(fileno(ambfp), flen-n, 0) < 0)
741 goto seekerr;
742 }
743 #ifdef DEBUG
744 if (ambfp->_ptr - ambfp->_base != nunflshed*AMBVALSIZ) {
745 sprintf(errmsg, "ambient file buffer at %d rather than %d",
746 ambfp->_ptr - ambfp->_base,
747 nunflshed*AMBVALSIZ);
748 error(CONSISTENCY, errmsg);
749 }
750 #endif
751 syncend:
752 n = fflush(ambfp); /* calls write() at last */
753 if ((lastpos = lseek(fileno(ambfp), 0L, 1)) < 0)
754 goto seekerr;
755 aflock(F_UNLCK); /* release file */
756 nunflshed = 0;
757 return(n);
758 seekerr:
759 error(SYSTEM, "seek failed in ambsync");
760 }
761
762 #else
763
764 int
765 ambsync() /* flush ambient file */
766 {
767 if (nunflshed == 0)
768 return(0);
769 nunflshed = 0;
770 return(fflush(ambfp));
771 }
772
773 #endif