ViewVC Help
View File | Revision Log | Show Annotations | Download File | Root Listing
root/radiance/ray/src/rt/ambient.c
Revision: 2.40
Committed: Tue Jul 9 21:56:44 1996 UTC (27 years, 9 months ago) by greg
Content type: text/plain
Branch: MAIN
Changes since 2.39: +8 -7 lines
Log Message:
made ambclock advance more slowly

File Contents

# Content
1 /* Copyright (c) 1996 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<<4)
54 #endif
55 #ifndef MAX_SORT_INTVL
56 #define MAX_SORT_INTVL (SORT_INTVL<<8)
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(), avlmemi();
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 pos, flen;
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 pos = ftell(ambfp);
141 while (readambval(&amb, ambfp))
142 avinsert(avstore(&amb));
143 /* align */
144 pos += (long)nambvals*AMBVALSIZ;
145 flen = lseek(fileno(ambfp), 0L, 2);
146 if (flen != pos) {
147 error(WARNING,
148 "ignoring last %ld values in ambient file (corrupted)",
149 (flen - pos)/AMBVALSIZ);
150 fseek(ambfp, pos, 0);
151 ftruncate(fileno(ambfp), pos);
152 }
153 nambshare = nambvals;
154 } else if ((ambfp = fopen(afile, "w+")) != NULL)
155 initambfile(1);
156 else {
157 sprintf(errmsg, "cannot open ambient file \"%s\"", afile);
158 error(SYSTEM, errmsg);
159 }
160 nunflshed++; /* lie */
161 ambsync();
162 }
163
164
165 ambnotify(obj) /* record new modifier */
166 OBJECT obj;
167 {
168 static int hitlimit = 0;
169 register OBJREC *o = objptr(obj);
170 register char **amblp;
171
172 if (hitlimit || !ismodifier(o->otype))
173 return;
174 for (amblp = amblist; *amblp != NULL; amblp++)
175 if (!strcmp(o->oname, *amblp)) {
176 if (ambset[0] >= MAXASET) {
177 error(WARNING, "too many modifiers in ambient list");
178 hitlimit++;
179 return; /* should this be fatal? */
180 }
181 insertelem(ambset, obj);
182 return;
183 }
184 }
185
186
187 ambient(acol, r, nrm) /* compute ambient component for ray */
188 COLOR acol;
189 register RAY *r;
190 FVECT nrm;
191 {
192 static int rdepth = 0; /* ambient recursion */
193 double d;
194
195 if (ambdiv <= 0) /* no ambient calculation */
196 goto dumbamb;
197 /* check number of bounces */
198 if (rdepth >= ambounce)
199 goto dumbamb;
200 /* check ambient list */
201 if (ambincl != -1 && r->ro != NULL &&
202 ambincl != inset(ambset, r->ro->omod))
203 goto dumbamb;
204
205 if (ambacc <= FTINY) { /* no ambient storage */
206 rdepth++;
207 d = doambient(acol, r, r->rweight, NULL, NULL);
208 rdepth--;
209 if (d <= FTINY)
210 goto dumbamb;
211 return;
212 }
213
214 if (tracktime) /* sort to minimize thrashing */
215 sortambvals(0);
216 /* get ambient value */
217 setcolor(acol, 0.0, 0.0, 0.0);
218 d = sumambient(acol, r, nrm, rdepth,
219 &atrunk, thescene.cuorg, thescene.cusize);
220 if (d > FTINY) {
221 scalecolor(acol, 1.0/d);
222 return;
223 }
224 rdepth++; /* need to cache new value */
225 d = makeambient(acol, r, nrm, rdepth-1);
226 rdepth--;
227 if (d > FTINY)
228 return;
229 dumbamb: /* return global value */
230 copycolor(acol, ambval);
231 if (ambvwt <= 0 | nambvals == 0)
232 return;
233 scalecolor(acol, (double)ambvwt);
234 addcolor(acol, avsum); /* average in computations */
235 d = 1.0/(ambvwt+nambvals);
236 scalecolor(acol, d);
237 }
238
239
240 double
241 sumambient(acol, r, rn, al, at, c0, s) /* get interpolated ambient value */
242 COLOR acol;
243 register RAY *r;
244 FVECT rn;
245 int al;
246 AMBTREE *at;
247 FVECT c0;
248 double s;
249 {
250 double d, e1, e2, wt, wsum;
251 COLOR ct;
252 FVECT ck0;
253 int i;
254 register int j;
255 register AMBVAL *av;
256
257 wsum = 0.0;
258 /* do this node */
259 for (av = at->alist; av != NULL; av = av->next) {
260 if (tracktime)
261 av->latick = ambclock;
262 /*
263 * Ambient level test.
264 */
265 if (av->lvl > al) /* list sorted, so this works */
266 break;
267 if (av->weight < r->rweight-FTINY)
268 continue;
269 /*
270 * Ambient radius test.
271 */
272 d = av->pos[0] - r->rop[0];
273 e1 = d * d;
274 d = av->pos[1] - r->rop[1];
275 e1 += d * d;
276 d = av->pos[2] - r->rop[2];
277 e1 += d * d;
278 e1 /= av->rad * av->rad;
279 if (e1 > ambacc*ambacc*1.21)
280 continue;
281 /*
282 * Normal direction test.
283 */
284 e2 = (1.0 - DOT(av->dir, r->ron)) * r->rweight;
285 if (e2 < 0.0) e2 = 0.0;
286 if (e1 + e2 > ambacc*ambacc*1.21)
287 continue;
288 /*
289 * Ray behind test.
290 */
291 d = 0.0;
292 for (j = 0; j < 3; j++)
293 d += (r->rop[j] - av->pos[j]) *
294 (av->dir[j] + r->ron[j]);
295 if (d*0.5 < -minarad*ambacc-.001)
296 continue;
297 /*
298 * Jittering final test reduces image artifacts.
299 */
300 wt = sqrt(e1) + sqrt(e2);
301 if (wt > ambacc*(.9+.2*urand(9015+samplendx)))
302 continue;
303 if (wt <= 1e-3)
304 wt = 1e3;
305 else
306 wt = 1.0 / wt;
307 wsum += wt;
308 extambient(ct, av, r->rop, rn);
309 scalecolor(ct, wt);
310 addcolor(acol, ct);
311 }
312 if (at->kid == NULL)
313 return(wsum);
314 /* do children */
315 s *= 0.5;
316 for (i = 0; i < 8; i++) {
317 for (j = 0; j < 3; j++) {
318 ck0[j] = c0[j];
319 if (1<<j & i)
320 ck0[j] += s;
321 if (r->rop[j] < ck0[j] - OCTSCALE*s)
322 break;
323 if (r->rop[j] > ck0[j] + (1.0+OCTSCALE)*s)
324 break;
325 }
326 if (j == 3)
327 wsum += sumambient(acol, r, rn, al, at->kid+i, ck0, s);
328 }
329 return(wsum);
330 }
331
332
333 double
334 makeambient(acol, r, rn, al) /* make a new ambient value */
335 COLOR acol;
336 register RAY *r;
337 FVECT rn;
338 int al;
339 {
340 AMBVAL amb;
341 FVECT gp, gd;
342 /* compute weight */
343 amb.weight = pow(AVGREFL, (double)al);
344 if (r->rweight < 0.1*amb.weight) /* heuristic */
345 amb.weight = r->rweight;
346 /* compute ambient */
347 amb.rad = doambient(acol, r, amb.weight, gp, gd);
348 if (amb.rad <= FTINY)
349 return(0.0);
350 /* store it */
351 VCOPY(amb.pos, r->rop);
352 VCOPY(amb.dir, r->ron);
353 amb.lvl = al;
354 copycolor(amb.val, acol);
355 VCOPY(amb.gpos, gp);
356 VCOPY(amb.gdir, gd);
357 /* insert into tree */
358 avsave(&amb); /* and save to file */
359 if (rn != r->ron)
360 extambient(acol, &amb, r->rop, rn); /* texture */
361 return(amb.rad);
362 }
363
364
365 extambient(cr, ap, pv, nv) /* extrapolate value at pv, nv */
366 COLOR cr;
367 register AMBVAL *ap;
368 FVECT pv, nv;
369 {
370 FVECT v1, v2;
371 register int i;
372 double d;
373
374 d = 1.0; /* zeroeth order */
375 /* gradient due to translation */
376 for (i = 0; i < 3; i++)
377 d += ap->gpos[i]*(pv[i]-ap->pos[i]);
378 /* gradient due to rotation */
379 VCOPY(v1, ap->dir);
380 fcross(v2, v1, nv);
381 d += DOT(ap->gdir, v2);
382 if (d <= 0.0) {
383 setcolor(cr, 0.0, 0.0, 0.0);
384 return;
385 }
386 copycolor(cr, ap->val);
387 scalecolor(cr, d);
388 }
389
390
391 static
392 initambfile(creat) /* initialize ambient file */
393 int creat;
394 {
395 extern char *progname, *octname, VersionID[];
396
397 #ifdef F_SETLKW
398 aflock(creat ? F_WRLCK : F_RDLCK);
399 #endif
400 #ifdef MSDOS
401 setmode(fileno(ambfp), O_BINARY);
402 #endif
403 setbuf(ambfp, bmalloc(BUFSIZ+8));
404 if (creat) { /* new file */
405 newheader("RADIANCE", ambfp);
406 fprintf(ambfp, "%s -av %g %g %g -ab %d -aa %g ",
407 progname, colval(ambval,RED),
408 colval(ambval,GRN), colval(ambval,BLU),
409 ambounce, ambacc);
410 fprintf(ambfp, "-ad %d -as %d -ar %d %s\n",
411 ambdiv, ambssamp, ambres,
412 octname==NULL ? "" : octname);
413 fprintf(ambfp, "SOFTWARE= %s\n", VersionID);
414 fputformat(AMBFMT, ambfp);
415 putc('\n', ambfp);
416 putambmagic(ambfp);
417 } else if (checkheader(ambfp, AMBFMT, NULL) < 0 || !hasambmagic(ambfp))
418 error(USER, "bad ambient file");
419 }
420
421
422 static
423 avsave(av) /* insert and save an ambient value */
424 AMBVAL *av;
425 {
426 avinsert(avstore(av));
427 if (ambfp == NULL)
428 return;
429 if (writambval(av, ambfp) < 0)
430 goto writerr;
431 if (++nunflshed >= AMBFLUSH)
432 if (ambsync() == EOF)
433 goto writerr;
434 return;
435 writerr:
436 error(SYSTEM, "error writing ambient file");
437 }
438
439
440 static AMBVAL *
441 avstore(aval) /* allocate memory and store aval */
442 register AMBVAL *aval;
443 {
444 register AMBVAL *av;
445
446 if ((av = newambval()) == NULL)
447 error(SYSTEM, "out of memory in avstore");
448 copystruct(av, aval);
449 av->latick = ambclock;
450 av->next = NULL;
451 addcolor(avsum, av->val); /* add to sum for averaging */
452 nambvals++;
453 return(av);
454 }
455
456
457 #define ATALLOCSZ 512 /* #/8 trees to allocate at once */
458
459 static AMBTREE *atfreelist = NULL; /* free ambient tree structures */
460
461
462 static
463 AMBTREE *
464 newambtree() /* allocate 8 ambient tree structs */
465 {
466 register AMBTREE *atp, *upperlim;
467
468 if (atfreelist == NULL) { /* get more nodes */
469 atfreelist = (AMBTREE *)bmalloc(ATALLOCSZ*8*sizeof(AMBTREE));
470 if (atfreelist == NULL)
471 return(NULL);
472 /* link new free list */
473 upperlim = atfreelist + 8*(ATALLOCSZ-1);
474 for (atp = atfreelist; atp < upperlim; atp += 8)
475 atp->kid = atp + 8;
476 atp->kid = NULL;
477 }
478 atp = atfreelist;
479 atfreelist = atp->kid;
480 bzero((char *)atp, 8*sizeof(AMBTREE));
481 return(atp);
482 }
483
484
485 static
486 freeambtree(atp) /* free 8 ambient tree structs */
487 AMBTREE *atp;
488 {
489 atp->kid = atfreelist;
490 atfreelist = atp;
491 }
492
493
494 static
495 avinsert(av) /* insert ambient value in our tree */
496 register AMBVAL *av;
497 {
498 register AMBTREE *at;
499 register AMBVAL *ap;
500 AMBVAL avh;
501 FVECT ck0;
502 double s;
503 int branch;
504 register int i;
505
506 if (av->rad <= FTINY)
507 error(CONSISTENCY, "zero ambient radius in avinsert");
508 at = &atrunk;
509 VCOPY(ck0, thescene.cuorg);
510 s = thescene.cusize;
511 while (s*(OCTSCALE/2) > av->rad*ambacc) {
512 if (at->kid == NULL)
513 if ((at->kid = newambtree()) == NULL)
514 error(SYSTEM, "out of memory in avinsert");
515 s *= 0.5;
516 branch = 0;
517 for (i = 0; i < 3; i++)
518 if (av->pos[i] > ck0[i] + s) {
519 ck0[i] += s;
520 branch |= 1 << i;
521 }
522 at = at->kid + branch;
523 }
524 avh.next = at->alist; /* order by increasing level */
525 for (ap = &avh; ap->next != NULL; ap = ap->next)
526 if (ap->next->lvl >= av->lvl)
527 break;
528 av->next = ap->next;
529 ap->next = av;
530 at->alist = avh.next;
531 }
532
533
534 static
535 unloadatree(at, f) /* unload an ambient value tree */
536 register AMBTREE *at;
537 int (*f)();
538 {
539 register AMBVAL *av;
540 register int i;
541 /* transfer values at this node */
542 for (av = at->alist; av != NULL; av = at->alist) {
543 at->alist = av->next;
544 (*f)(av);
545 }
546 if (at->kid == NULL)
547 return;
548 for (i = 0; i < 8; i++) /* transfer and free children */
549 unloadatree(at->kid+i, f);
550 freeambtree(at->kid);
551 at->kid = NULL;
552 }
553
554
555 static struct avl {
556 AMBVAL *p;
557 unsigned long t;
558 } *avlist1; /* ambient value list with ticks */
559 static AMBVAL **avlist2; /* memory positions for sorting */
560 static int i_avlist; /* index for lists */
561
562
563 static
564 av2list(av)
565 register AMBVAL *av;
566 {
567 #ifdef DEBUG
568 if (i_avlist >= nambvals)
569 error(CONSISTENCY, "too many ambient values in av2list1");
570 #endif
571 avlist1[i_avlist].p = avlist2[i_avlist] = av;
572 avlist1[i_avlist++].t = av->latick;
573 }
574
575
576 static int
577 alatcmp(av1, av2) /* compare ambient values for MRA */
578 struct avl *av1, *av2;
579 {
580 register long lc = av2->t - av1->t;
581 return(lc<0 ? -1 : lc>0 ? 1 : 0);
582 }
583
584
585 static int
586 aposcmp(avp1, avp2) /* compare ambient value positions */
587 AMBVAL **avp1, **avp2;
588 {
589 return(*avp1 - *avp2);
590 }
591
592
593 #if 1
594 static int
595 avlmemi(avaddr) /* find list position from address */
596 AMBVAL *avaddr;
597 {
598 register AMBVAL **avlpp;
599
600 avlpp = (AMBVAL **)bsearch((char *)&avaddr, (char *)avlist2,
601 nambvals, sizeof(AMBVAL *), aposcmp);
602 if (avlpp == NULL)
603 error(CONSISTENCY, "address not found in avlmemi");
604 return(avlpp - avlist2);
605 }
606 #else
607 #define avlmemi(avaddr) ((AMBVAL **)bsearch((char *)&avaddr,(char *)avlist2, \
608 nambvals,sizeof(AMBVAL *),aposcmp) - avlist2)
609 #endif
610
611
612 static
613 sortambvals(always) /* resort ambient values */
614 int always;
615 {
616 AMBTREE oldatrunk;
617 AMBVAL tav, *tap, *pnext;
618 register int i, j;
619 /* see if it's time yet */
620 if (!always && (ambclock++ < lastsort+sortintvl ||
621 nambvals < SORT_THRESH))
622 return;
623 /*
624 * The idea here is to minimize memory thrashing
625 * in VM systems by improving reference locality.
626 * We do this by periodically sorting our stored ambient
627 * values in memory in order of most recently to least
628 * recently accessed. This ordering was chosen so that new
629 * ambient values (which tend to be less important) go into
630 * higher memory with the infrequently accessed values.
631 * Since we expect our values to need sorting less
632 * frequently as the process continues, we double our
633 * waiting interval after each call.
634 * This routine is also called by setambacc() with
635 * the "always" parameter set to 1 so that the ambient
636 * tree will be rebuilt with the new accuracy parameter.
637 */
638 if (tracktime) { /* allocate pointer arrays to sort */
639 avlist2 = (AMBVAL **)malloc(nambvals*sizeof(AMBVAL *));
640 avlist1 = (struct avl *)malloc(nambvals*sizeof(struct avl));
641 } else {
642 avlist2 = NULL;
643 avlist1 = NULL;
644 }
645 if (avlist1 == NULL) { /* no time tracking -- rebuild tree? */
646 if (avlist2 != NULL)
647 free((char *)avlist2);
648 if (always) { /* rebuild without sorting */
649 copystruct(&oldatrunk, &atrunk);
650 atrunk.alist = NULL;
651 atrunk.kid = NULL;
652 unloadatree(&oldatrunk, avinsert);
653 }
654 } else { /* sort memory by last access time */
655 /*
656 * Sorting memory is tricky because it isn't contiguous.
657 * We have to sort an array of pointers by MRA and also
658 * by memory position. We then copy values in "loops"
659 * to minimize memory hits. Nevertheless, we will visit
660 * everyone at least twice, and this is an expensive process
661 * when we're thrashing, which is when we need to do it.
662 */
663 #ifdef DEBUG
664 sprintf(errmsg, "sorting %u ambient values at ambclock=%lu...",
665 nambvals, ambclock);
666 eputs(errmsg);
667 #endif
668 i_avlist = 0;
669 unloadatree(&atrunk, av2list); /* empty current tree */
670 #ifdef DEBUG
671 if (i_avlist < nambvals)
672 error(CONSISTENCY, "missing ambient values in sortambvals");
673 #endif
674 qsort((char *)avlist1, nambvals, sizeof(struct avl), alatcmp);
675 qsort((char *)avlist2, nambvals, sizeof(AMBVAL *), aposcmp);
676 for (i = 0; i < nambvals; i++) {
677 if (avlist1[i].p == NULL)
678 continue;
679 tap = avlist2[i];
680 copystruct(&tav, tap);
681 for (j = i; (pnext = avlist1[j].p) != tap;
682 j = avlmemi(pnext)) {
683 copystruct(avlist2[j], pnext);
684 avinsert(avlist2[j]);
685 avlist1[j].p = NULL;
686 }
687 copystruct(avlist2[j], &tav);
688 avinsert(avlist2[j]);
689 avlist1[j].p = NULL;
690 }
691 free((char *)avlist1);
692 free((char *)avlist2);
693 /* compute new sort interval */
694 sortintvl = ambclock - lastsort;
695 if (sortintvl >= MAX_SORT_INTVL/2)
696 sortintvl = MAX_SORT_INTVL;
697 else
698 sortintvl <<= 1; /* wait twice as long next */
699 #ifdef DEBUG
700 eputs("done\n");
701 #endif
702 }
703 if (ambclock >= MAXACLOCK)
704 ambclock = MAXACLOCK/2;
705 lastsort = ambclock;
706 }
707
708
709 #ifdef F_SETLKW
710
711 static
712 aflock(typ) /* lock/unlock ambient file */
713 int typ;
714 {
715 static struct flock fls; /* static so initialized to zeroes */
716
717 fls.l_type = typ;
718 if (fcntl(fileno(ambfp), F_SETLKW, &fls) < 0)
719 error(SYSTEM, "cannot (un)lock ambient file");
720 }
721
722
723 int
724 ambsync() /* synchronize ambient file */
725 {
726 static FILE *ambinp = NULL;
727 static long lastpos = -1;
728 long flen;
729 AMBVAL avs;
730 register int n;
731
732 if (nunflshed == 0)
733 return(0);
734 if (lastpos < 0) /* initializing (locked in initambfile) */
735 goto syncend;
736 /* gain exclusive access */
737 aflock(F_WRLCK);
738 /* see if file has grown */
739 if ((flen = lseek(fileno(ambfp), 0L, 2)) < 0)
740 goto seekerr;
741 if (n = flen - lastpos) { /* file has grown */
742 if (ambinp == NULL) { /* use duplicate filedes */
743 ambinp = fdopen(dup(fileno(ambfp)), "r");
744 if (ambinp == NULL)
745 error(SYSTEM, "fdopen failed in ambsync");
746 }
747 if (fseek(ambinp, lastpos, 0) < 0)
748 goto seekerr;
749 while (n >= AMBVALSIZ) { /* load contributed values */
750 if (!readambval(&avs, ambinp)) {
751 sprintf(errmsg,
752 "ambient file corrupted near character %ld",
753 flen - n);
754 error(WARNING, errmsg);
755 break;
756 }
757 avinsert(avstore(&avs));
758 n -= AMBVALSIZ;
759 }
760 /*** seek always as safety measure
761 if (n) ***/ /* alignment */
762 if (lseek(fileno(ambfp), flen-n, 0) < 0)
763 goto seekerr;
764 }
765 #ifdef DEBUG
766 if (ambfp->_ptr - ambfp->_base != nunflshed*AMBVALSIZ) {
767 sprintf(errmsg, "ambient file buffer at %d rather than %d",
768 ambfp->_ptr - ambfp->_base,
769 nunflshed*AMBVALSIZ);
770 error(CONSISTENCY, errmsg);
771 }
772 #endif
773 syncend:
774 n = fflush(ambfp); /* calls write() at last */
775 if ((lastpos = lseek(fileno(ambfp), 0L, 1)) < 0)
776 goto seekerr;
777 aflock(F_UNLCK); /* release file */
778 nunflshed = 0;
779 return(n);
780 seekerr:
781 error(SYSTEM, "seek failed in ambsync");
782 }
783
784 #else
785
786 int
787 ambsync() /* flush ambient file */
788 {
789 if (nunflshed == 0)
790 return(0);
791 nunflshed = 0;
792 return(fflush(ambfp));
793 }
794
795 #endif