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root/radiance/ray/src/rt/ambient.c
Revision: 2.33
Committed: Tue Oct 24 13:33:23 1995 UTC (28 years, 6 months ago) by greg
Content type: text/plain
Branch: MAIN
Changes since 2.32: +9 -14 lines
Log Message:
made setambacc() a little simpler

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 #ifndef AMBVWT
25 #define AMBVWT 250 /* relative ambient value weight (# calcs) */
26 #endif
27
28 typedef struct ambtree {
29 AMBVAL *alist; /* ambient value list */
30 struct ambtree *kid; /* 8 child nodes */
31 } AMBTREE; /* ambient octree */
32
33 extern CUBE thescene; /* contains space boundaries */
34
35 extern char *shm_boundary; /* memory sharing boundary */
36
37 #define MAXASET 511 /* maximum number of elements in ambient set */
38 OBJECT ambset[MAXASET+1]={0}; /* ambient include/exclude set */
39
40 double maxarad; /* maximum ambient radius */
41 double minarad; /* minimum ambient radius */
42
43 static AMBTREE atrunk; /* our ambient trunk node */
44
45 static FILE *ambfp = NULL; /* ambient file pointer */
46 static int nunflshed = 0; /* number of unflushed ambient values */
47
48 #ifndef SORT_THRESH
49 #ifdef BIGMEM
50 #define SORT_THRESH ((9L<<20)/sizeof(AMBVAL))
51 #else
52 #define SORT_THRESH ((3L<<20)/sizeof(AMBVAL))
53 #endif
54 #endif
55 #ifndef SORT_INTVL
56 #define SORT_INTVL (SORT_THRESH*256)
57 #endif
58 #ifndef MAX_SORT_INTVL
59 #define MAX_SORT_INTVL (SORT_INTVL<<4)
60 #endif
61
62 static COLOR avsum = BLKCOLOR; /* computed ambient value sum */
63 static unsigned int nambvals = 0; /* number of computed ambient values */
64 static unsigned long ambclock = 0; /* ambient access clock */
65 static unsigned long lastsort = 0; /* time of last value sort */
66 static long sortintvl = SORT_INTVL; /* time until next sort */
67
68 #define MAXACLOCK (1L<<30) /* clock turnover value */
69 /*
70 * Track access times unless we are sharing ambient values
71 * through memory on a multiprocessor, when we want to avoid
72 * claiming our own memory (copy on write).
73 */
74 #define tracktime (shm_boundary == NULL || ambfp == NULL)
75
76 #define AMBFLUSH (BUFSIZ/AMBVALSIZ)
77
78 #define newambval() (AMBVAL *)bmalloc(sizeof(AMBVAL))
79
80 extern long ftell(), lseek();
81 static int initambfile(), avsave(), avinsert(), sortambvals();
82 static AMBVAL *avstore();
83 #ifdef F_SETLKW
84 static aflock();
85 #endif
86
87
88 setambres(ar) /* set ambient resolution */
89 int ar;
90 {
91 ambres = ar < 0 ? 0 : ar; /* may be done already */
92 /* set min & max radii */
93 if (ar <= 0) {
94 minarad = 0;
95 maxarad = thescene.cusize / 2.0;
96 } else {
97 minarad = thescene.cusize / ar;
98 maxarad = 64 * minarad; /* heuristic */
99 if (maxarad > thescene.cusize / 2.0)
100 maxarad = thescene.cusize / 2.0;
101 }
102 if (minarad <= FTINY)
103 minarad = 10*FTINY;
104 if (maxarad <= minarad)
105 maxarad = 64 * minarad;
106 }
107
108
109 setambacc(newa) /* set ambient accuracy */
110 double newa;
111 {
112 double ambdiff;
113
114 if (newa < 0.0)
115 newa = 0.0;
116 ambdiff = fabs(newa - ambacc);
117 if (ambdiff >= .01 && (ambacc = newa) > FTINY && nambvals > 0)
118 sortambvals(1); /* rebuild tree */
119 }
120
121
122 setambient(afile) /* initialize calculation */
123 char *afile;
124 {
125 long headlen;
126 AMBVAL amb;
127 /* init ambient limits */
128 setambres(ambres);
129 setambacc(ambacc);
130 if (afile == NULL)
131 return;
132 if (ambacc <= FTINY) {
133 sprintf(errmsg, "zero ambient accuracy so \"%s\" not opened",
134 afile);
135 error(WARNING, errmsg);
136 return;
137 }
138 /* open ambient file */
139 if ((ambfp = fopen(afile, "r+")) != NULL) {
140 initambfile(0);
141 headlen = ftell(ambfp);
142 while (readambval(&amb, ambfp))
143 avinsert(avstore(&amb));
144 /* align */
145 fseek(ambfp, -((ftell(ambfp)-headlen)%AMBVALSIZ), 1);
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) /* compute ambient component for ray */
180 COLOR acol;
181 register RAY *r;
182 {
183 static int rdepth = 0; /* ambient recursion */
184 double d;
185
186 if (ambdiv <= 0) /* no ambient calculation */
187 goto dumbamb;
188 /* check number of bounces */
189 if (rdepth >= ambounce)
190 goto dumbamb;
191 /* check ambient list */
192 if (ambincl != -1 && r->ro != NULL &&
193 ambincl != inset(ambset, r->ro->omod))
194 goto dumbamb;
195
196 if (ambacc <= FTINY) { /* no ambient storage */
197 rdepth++;
198 d = doambient(acol, r, r->rweight, NULL, NULL);
199 rdepth--;
200 if (d <= FTINY)
201 goto dumbamb;
202 return;
203 }
204 /* resort memory? */
205 sortambvals(0);
206 /* get ambient value */
207 setcolor(acol, 0.0, 0.0, 0.0);
208 d = sumambient(acol, r, rdepth,
209 &atrunk, thescene.cuorg, thescene.cusize);
210 if (d > FTINY) {
211 scalecolor(acol, 1.0/d);
212 return;
213 }
214 rdepth++; /* need to cache new value */
215 d = makeambient(acol, r, rdepth-1);
216 rdepth--;
217 if (d > FTINY)
218 return;
219 dumbamb: /* return global value */
220 copycolor(acol, ambval);
221 #if AMBVWT
222 if (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 #endif
229 }
230
231
232 double
233 sumambient(acol, r, al, at, c0, s) /* get interpolated ambient value */
234 COLOR acol;
235 register RAY *r;
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, r->ron);
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, al, at->kid+i, ck0, s);
319 }
320 return(wsum);
321 }
322
323
324 double
325 makeambient(acol, r, al) /* make a new ambient value */
326 COLOR acol;
327 register RAY *r;
328 int al;
329 {
330 AMBVAL amb;
331 FVECT gp, gd;
332 /* compute weight */
333 amb.weight = pow(AVGREFL, (double)al);
334 if (r->rweight < 0.1*amb.weight) /* heuristic */
335 amb.weight = r->rweight;
336 /* compute ambient */
337 amb.rad = doambient(acol, r, amb.weight, gp, gd);
338 if (amb.rad <= FTINY)
339 return(0.0);
340 /* store it */
341 VCOPY(amb.pos, r->rop);
342 VCOPY(amb.dir, r->ron);
343 amb.lvl = al;
344 copycolor(amb.val, acol);
345 VCOPY(amb.gpos, gp);
346 VCOPY(amb.gdir, gd);
347 /* insert into tree */
348 avsave(&amb); /* and save to file */
349 return(amb.rad);
350 }
351
352
353 extambient(cr, ap, pv, nv) /* extrapolate value at pv, nv */
354 COLOR cr;
355 register AMBVAL *ap;
356 FVECT pv, nv;
357 {
358 FVECT v1, v2;
359 register int i;
360 double d;
361
362 d = 1.0; /* zeroeth order */
363 /* gradient due to translation */
364 for (i = 0; i < 3; i++)
365 d += ap->gpos[i]*(pv[i]-ap->pos[i]);
366 /* gradient due to rotation */
367 VCOPY(v1, ap->dir);
368 fcross(v2, v1, nv);
369 d += DOT(ap->gdir, v2);
370 if (d <= 0.0) {
371 setcolor(cr, 0.0, 0.0, 0.0);
372 return;
373 }
374 copycolor(cr, ap->val);
375 scalecolor(cr, d);
376 }
377
378
379 static
380 initambfile(creat) /* initialize ambient file */
381 int creat;
382 {
383 extern char *progname, *octname, VersionID[];
384
385 #ifdef F_SETLKW
386 aflock(creat ? F_WRLCK : F_RDLCK);
387 #endif
388 #ifdef MSDOS
389 setmode(fileno(ambfp), O_BINARY);
390 #endif
391 setbuf(ambfp, bmalloc(BUFSIZ+8));
392 if (creat) { /* new file */
393 newheader("RADIANCE", ambfp);
394 fprintf(ambfp, "%s -av %g %g %g -ab %d -aa %g ",
395 progname, colval(ambval,RED),
396 colval(ambval,GRN), colval(ambval,BLU),
397 ambounce, ambacc);
398 fprintf(ambfp, "-ad %d -as %d -ar %d %s\n",
399 ambdiv, ambssamp, ambres,
400 octname==NULL ? "" : octname);
401 fprintf(ambfp, "SOFTWARE= %s\n", VersionID);
402 fputformat(AMBFMT, ambfp);
403 putc('\n', ambfp);
404 putambmagic(ambfp);
405 } else if (checkheader(ambfp, AMBFMT, NULL) < 0 || !hasambmagic(ambfp))
406 error(USER, "bad ambient file");
407 }
408
409
410 static
411 avsave(av) /* insert and save an ambient value */
412 AMBVAL *av;
413 {
414 avinsert(avstore(av));
415 if (ambfp == NULL)
416 return;
417 if (writambval(av, ambfp) < 0)
418 goto writerr;
419 if (++nunflshed >= AMBFLUSH)
420 if (ambsync() == EOF)
421 goto writerr;
422 return;
423 writerr:
424 error(SYSTEM, "error writing ambient file");
425 }
426
427
428 static AMBVAL *
429 avstore(aval) /* allocate memory and store aval */
430 register AMBVAL *aval;
431 {
432 register AMBVAL *av;
433
434 if ((av = newambval()) == NULL)
435 error(SYSTEM, "out of memory in avstore");
436 copystruct(av, aval);
437 av->latick = ambclock;
438 av->next = NULL;
439 addcolor(avsum, av->val); /* add to sum for averaging */
440 nambvals++;
441 return(av);
442 }
443
444
445 #define ATALLOCSZ 512 /* #/8 trees to allocate at once */
446
447 static AMBTREE *atfreelist = NULL; /* free ambient tree structures */
448
449
450 static
451 AMBTREE *
452 newambtree() /* allocate 8 ambient tree structs */
453 {
454 register AMBTREE *atp, *upperlim;
455
456 if (atfreelist == NULL) { /* get more nodes */
457 atfreelist = (AMBTREE *)bmalloc(ATALLOCSZ*8*sizeof(AMBTREE));
458 if (atfreelist == NULL)
459 return(NULL);
460 /* link new free list */
461 upperlim = atfreelist + 8*(ATALLOCSZ-1);
462 for (atp = atfreelist; atp < upperlim; atp += 8)
463 atp->kid = atp + 8;
464 atp->kid = NULL;
465 }
466 atp = atfreelist;
467 atfreelist = atp->kid;
468 bzero((char *)atp, 8*sizeof(AMBTREE));
469 return(atp);
470 }
471
472
473 static
474 freeambtree(atp) /* free 8 ambient tree structs */
475 AMBTREE *atp;
476 {
477 atp->kid = atfreelist;
478 atfreelist = atp;
479 }
480
481
482 static
483 avinsert(av) /* insert ambient value in our tree */
484 register AMBVAL *av;
485 {
486 register AMBTREE *at;
487 register AMBVAL *ap;
488 AMBVAL avh;
489 FVECT ck0;
490 double s;
491 int branch;
492 register int i;
493
494 if (av->rad <= FTINY)
495 error(CONSISTENCY, "zero ambient radius in avinsert");
496 at = &atrunk;
497 VCOPY(ck0, thescene.cuorg);
498 s = thescene.cusize;
499 while (s*(OCTSCALE/2) > av->rad*ambacc) {
500 if (at->kid == NULL)
501 if ((at->kid = newambtree()) == NULL)
502 error(SYSTEM, "out of memory in avinsert");
503 s *= 0.5;
504 branch = 0;
505 for (i = 0; i < 3; i++)
506 if (av->pos[i] > ck0[i] + s) {
507 ck0[i] += s;
508 branch |= 1 << i;
509 }
510 at = at->kid + branch;
511 }
512 avh.next = at->alist; /* order by increasing level */
513 for (ap = &avh; ap->next != NULL; ap = ap->next)
514 if (ap->next->lvl >= av->lvl)
515 break;
516 av->next = ap->next;
517 ap->next = av;
518 at->alist = avh.next;
519 }
520
521
522 static
523 unloadatree(at, f) /* unload an ambient value tree */
524 register AMBTREE *at;
525 int (*f)();
526 {
527 register AMBVAL *av;
528 register int i;
529 /* transfer values at this node */
530 for (av = at->alist; av != NULL; av = at->alist) {
531 at->alist = av->next;
532 (*f)(av);
533 }
534 if (at->kid == NULL)
535 return;
536 for (i = 0; i < 8; i++) /* transfer and free children */
537 unloadatree(at->kid+i, f);
538 freeambtree(at->kid);
539 at->kid = NULL;
540 }
541
542
543 static AMBVAL **avlist1, **avlist2; /* ambient value lists for sorting */
544 static int i_avlist; /* index for lists */
545
546
547 static
548 av2list(av)
549 AMBVAL *av;
550 {
551 #ifdef DEBUG
552 if (i_avlist >= nambvals)
553 error(CONSISTENCY, "too many ambient values in av2list1");
554 #endif
555 avlist1[i_avlist] = avlist2[i_avlist] = av;
556 i_avlist++;
557 }
558
559
560 static int
561 alatcmp(avp1, avp2) /* compare ambient values for MRA */
562 AMBVAL **avp1, **avp2;
563 {
564 return((**avp2).latick - (**avp1).latick);
565 }
566
567
568 static int
569 aposcmp(avp1, avp2) /* compare ambient value positions */
570 AMBVAL **avp1, **avp2;
571 {
572 return(*avp1 - *avp2);
573 }
574
575
576 #ifdef DEBUG
577 static int
578 avlmemi(avaddr) /* find list position from address */
579 AMBVAL *avaddr;
580 {
581 register AMBVAL **avlpp;
582
583 avlpp = (AMBVAL **)bsearch((char *)&avaddr, (char *)avlist2,
584 nambvals, sizeof(AMBVAL *), aposcmp);
585 if (avlpp == NULL)
586 error(CONSISTENCY, "address not found in avlmemi");
587 return(avlpp - avlist2);
588 }
589 #else
590 #define avlmemi(avaddr) ((AMBVAL **)bsearch((char *)&avaddr,(char *)avlist2, \
591 nambvals,sizeof(AMBVAL *),aposcmp) - avlist2)
592 #endif
593
594
595 static
596 sortambvals(always) /* resort ambient values */
597 int always;
598 {
599 AMBTREE oldatrunk;
600 AMBVAL tav, *tap, *pnext;
601 register int i, j;
602 /* see if it's time yet */
603 if (!always && (ambclock < lastsort+sortintvl ||
604 nambvals < SORT_THRESH))
605 return;
606 /*
607 * The idea here is to minimize memory thrashing
608 * in VM systems by improving reference locality.
609 * We do this by periodically sorting our stored ambient
610 * values in memory in order of most recently to least
611 * recently accessed. This ordering was chosen so that new
612 * ambient values (which tend to be less important) go into
613 * higher memory with the infrequently accessed values.
614 * Since we expect our values to need sorting less
615 * frequently as the process continues, we double our
616 * waiting interval after each call.
617 * This routine is also called by setambacc() with
618 * the "always" parameter set to 1 so that the ambient
619 * tree will be rebuilt with the new accuracy parameter.
620 */
621 if (tracktime) { /* allocate pointer arrays to sort */
622 avlist1 = (AMBVAL **)malloc(nambvals*sizeof(AMBVAL *));
623 avlist2 = (AMBVAL **)malloc(nambvals*sizeof(AMBVAL *));
624 } else
625 avlist1 = avlist2 = NULL;
626 if (avlist2 == NULL) { /* no time tracking -- rebuild tree? */
627 if (avlist1 != NULL)
628 free((char *)avlist1);
629 if (always) { /* rebuild without sorting */
630 copystruct(&oldatrunk, &atrunk);
631 atrunk.alist = NULL;
632 atrunk.kid = NULL;
633 unloadatree(&oldatrunk, avinsert);
634 }
635 } else { /* sort memory by last access time */
636 /*
637 * Sorting memory is tricky because it isn't contiguous.
638 * We have to sort an array of pointers by MRA and also
639 * by memory position. We then copy values in "loops"
640 * to minimize memory hits. Nevertheless, we will visit
641 * everyone at least twice, and this is an expensive process
642 * when we're thrashing, which is when we need to do it.
643 */
644 #ifdef DEBUG
645 sprintf(errmsg, "sorting %u ambient values at ambclock=%lu...",
646 nambvals, ambclock);
647 eputs(errmsg);
648 #endif
649 i_avlist = 0;
650 unloadatree(&atrunk, av2list); /* empty current tree */
651 #ifdef DEBUG
652 if (i_avlist < nambvals)
653 error(CONSISTENCY, "missing ambient values in sortambvals");
654 #endif
655 qsort((char *)avlist1, nambvals, sizeof(AMBVAL *), alatcmp);
656 qsort((char *)avlist2, nambvals, sizeof(AMBVAL *), aposcmp);
657 for (i = 0; i < nambvals; i++) {
658 if (avlist1[i] == NULL)
659 continue;
660 tap = avlist2[i];
661 copystruct(&tav, tap);
662 for (j = i; (pnext = avlist1[j]) != tap;
663 j = avlmemi(pnext)) {
664 copystruct(avlist2[j], pnext);
665 avinsert(avlist2[j]);
666 avlist1[j] = NULL;
667 }
668 copystruct(avlist2[j], &tav);
669 avinsert(avlist2[j]);
670 avlist1[j] = NULL;
671 }
672 free((char *)avlist1);
673 free((char *)avlist2);
674 /* compute new sort interval */
675 sortintvl = ambclock - lastsort;
676 if (sortintvl >= MAX_SORT_INTVL/2)
677 sortintvl = MAX_SORT_INTVL;
678 else
679 sortintvl <<= 1; /* wait twice as long next */
680 #ifdef DEBUG
681 eputs("done\n");
682 #endif
683 }
684 if (ambclock >= MAXACLOCK)
685 ambclock = MAXACLOCK/2;
686 lastsort = ambclock;
687 }
688
689
690 #ifdef F_SETLKW
691
692 static
693 aflock(typ) /* lock/unlock ambient file */
694 int typ;
695 {
696 static struct flock fls; /* static so initialized to zeroes */
697
698 fls.l_type = typ;
699 if (fcntl(fileno(ambfp), F_SETLKW, &fls) < 0)
700 error(SYSTEM, "cannot (un)lock ambient file");
701 }
702
703
704 int
705 ambsync() /* synchronize ambient file */
706 {
707 static FILE *ambinp = NULL;
708 static long lastpos = -1;
709 long flen;
710 AMBVAL avs;
711 register int n;
712
713 if (nunflshed == 0)
714 return(0);
715 if (lastpos < 0) /* initializing (locked in initambfile) */
716 goto syncend;
717 /* gain exclusive access */
718 aflock(F_WRLCK);
719 /* see if file has grown */
720 if ((flen = lseek(fileno(ambfp), 0L, 2)) < 0)
721 goto seekerr;
722 if (n = flen - lastpos) { /* file has grown */
723 if (ambinp == NULL) { /* use duplicate filedes */
724 ambinp = fdopen(dup(fileno(ambfp)), "r");
725 if (ambinp == NULL)
726 error(SYSTEM, "fdopen failed in ambsync");
727 }
728 if (fseek(ambinp, lastpos, 0) < 0)
729 goto seekerr;
730 while (n >= AMBVALSIZ) { /* load contributed values */
731 readambval(&avs, ambinp);
732 avinsert(avstore(&avs));
733 n -= AMBVALSIZ;
734 }
735 /*** seek always as safety measure
736 if (n) ***/ /* alignment */
737 if (lseek(fileno(ambfp), flen-n, 0) < 0)
738 goto seekerr;
739 }
740 #ifdef DEBUG
741 if (ambfp->_ptr - ambfp->_base != nunflshed*AMBVALSIZ) {
742 sprintf(errmsg, "ambient file buffer at %d rather than %d",
743 ambfp->_ptr - ambfp->_base,
744 nunflshed*AMBVALSIZ);
745 error(CONSISTENCY, errmsg);
746 }
747 #endif
748 syncend:
749 n = fflush(ambfp); /* calls write() at last */
750 if ((lastpos = lseek(fileno(ambfp), 0L, 1)) < 0)
751 goto seekerr;
752 aflock(F_UNLCK); /* release file */
753 nunflshed = 0;
754 return(n);
755 seekerr:
756 error(SYSTEM, "seek failed in ambsync");
757 }
758
759 #else
760
761 int
762 ambsync() /* flush ambient file */
763 {
764 if (nunflshed == 0)
765 return(0);
766 nunflshed = 0;
767 return(fflush(ambfp));
768 }
769
770 #endif