src/util/glareval.c

/* Copyright (c) 1991 Regents of the University of California */

#ifndef lint
static char SCCSid[] = "$SunId$ LBL";
#endif

/*
 * Compute pixels for glare calculation
 */

#include "glare.h"
#include <sys/param.h>
                                        /* compute rtrace buffer size */
#ifndef PIPE_BUF
#define PIPE_BUF        512             /* hyperconservative */
#endif
#define MAXPIX          (PIPE_BUF/(6*sizeof(float)) - 1)

#ifndef BSD
#define vfork           fork
#endif

#define MAXSBUF         524268  /* maximum total size of scanline buffer */
#define HSIZE           317     /* size of scanline hash table */
#define NRETIRE         16      /* number of scanlines to retire at once */

int     rt_pid = -1;            /* process id for rtrace */
int     fd_tort, fd_fromrt;     /* pipe descriptors */

FILE    *pictfp = NULL;         /* picture file pointer */
double  exposure;               /* picture exposure */
int     pxsiz, pysiz;           /* picture dimensions */

static int      curpos;         /* current scanline */
static long     *scanpos;       /* scanline positions */

typedef struct scan {
        int     y;              /* scanline position */
        long    lused;          /* for LRU replacement */
        struct scan     *next;  /* next in this hash or free list */
        /* followed by the scanline data */
} SCAN;                 /* buffered scanline */

#define scandata(sl)    ((COLR *)((sl)+1))
#define shash(y)        ((y)%HSIZE)

static SCAN     *freelist;              /* scanline free list */
static SCAN     *hashtab[HSIZE];        /* scanline hash table */

static long     ncall = 0L;     /* number of calls to getpictscan */
static long     nread = 0L;     /* number of scanlines read */

SCAN    *scanretire();

extern long     ftell();


SCAN *
claimscan(y)                    /* claim scanline from buffers */
int     y;
{
        int     hi = shash(y);
        SCAN    *slast;
        register SCAN   *sl;

        for (sl = hashtab[hi]; sl != NULL; sl = sl->next)
                if (sl->y == y)                         /* active scanline */
                        return(sl);
        for (slast = NULL, sl = freelist; sl != NULL; slast = sl, sl = sl->next)
                if (sl->y == -1 || sl->y == y || sl->next == NULL) {
                        if (slast == NULL)              /* remove from free */
                                freelist = sl->next;
                        else
                                slast->next = sl->next;
                        if (sl->y == y) {               /* reclaim */
                                sl->next = hashtab[hi];
                                hashtab[hi] = sl;
#ifdef DEBUG
                                if (verbose)
                                        fprintf(stderr,
                                                "%s: scanline %d reclaimed\n",
                                                        progname, y);
#endif
                        }
                        return(sl);
                }
        return(scanretire());           /* need more free scanlines */
}


COLR *
getpictscan(y)                  /* get picture scanline */
int     y;
{
        register SCAN   *sl;
        register int    i;
                                        /* first check our buffers */
        sl = claimscan(y);
        if (sl == NULL)
                memerr("claimscan()");
        sl->lused = ncall++;
        if (sl->y == y)                 /* scan hit */
                return(scandata(sl));
                                        /* else read in replacement */
        if (scanpos[y] < 0) {                   /* need to search */
                for (i = y+1; i < curpos; i++)
                        if (scanpos[i] >= 0) {
                                if (fseek(pictfp, scanpos[i], 0) < 0)
                                        goto seekerr;
                                curpos = i;
                                break;
                        }
                while (curpos >= y) {
                        scanpos[curpos] = ftell(pictfp);
                        if (freadcolrs(scandata(sl), pxsiz, pictfp) < 0)
                                goto readerr;
                        nread++;
                        curpos--;
                }
        } else {
                if (curpos != y && fseek(pictfp, scanpos[y], 0) < 0)
                        goto seekerr;
                if (freadcolrs(scandata(sl), pxsiz, pictfp) < 0)
                        goto readerr;
                nread++;
                curpos = y-1;
        }
        sl->y = y;
        i = shash(y);                   /* add to hash list */
        sl->next = hashtab[i];
        hashtab[i] = sl;
        return(scandata(sl));
readerr:
        fprintf(stderr, "%s: picture read error\n", progname);
        exit(1);
seekerr:
        fprintf(stderr, "%s: picture seek error\n", progname);
        exit(1);
}


#ifdef DEBUG
pict_stats()                    /* print out picture read statistics */
{
        static long     lastcall = 0L;  /* ncall at last report */
        static long     lastread = 0L;  /* nread at last report */

        if (ncall == lastcall)
                return;
        fprintf(stderr, "%s: %ld scanlines read in %ld calls\n",
                        progname, nread-lastread, ncall-lastcall);
        lastcall = ncall;
        lastread = nread;
}
#endif


double
pict_val(vd)                    /* find picture value for view direction */
FVECT   vd;
{
        FVECT   pp;
        double  vpx, vpy, vpz;
        COLOR   res;

        if (pictfp == NULL)
                return(-1.0);
        pp[0] = pictview.vp[0] + vd[0];
        pp[1] = pictview.vp[1] + vd[1];
        pp[2] = pictview.vp[2] + vd[2];
        viewpixel(&vpx, &vpy, &vpz, &pictview, pp);
        if (vpz <= FTINY || vpx < 0. || vpx >= 1. || vpy < 0. || vpy >= 1.)
                return(-1.0);
        colr_color(res, getpictscan((int)(vpy*pysiz))[(int)(vpx*pxsiz)]);
        return(luminance(res)/exposure);
}


double
getviewpix(vh, vv)              /* compute single view pixel */
int     vh, vv;
{
        FVECT   dir;
        float   rt_buf[6];
        double  res;

        if (compdir(dir, vh, vv) < 0)
                return(-1.0);
        npixinvw++;
        if ((res = pict_val(dir)) >= 0.0)
                return(res);
        if (rt_pid == -1) {
                npixmiss++;
                return(-1.0);
        }
        rt_buf[0] = ourview.vp[0];
        rt_buf[1] = ourview.vp[1];
        rt_buf[2] = ourview.vp[2];
        rt_buf[3] = dir[0];
        rt_buf[4] = dir[1];
        rt_buf[5] = dir[2];
        rt_compute(rt_buf, 1);
        return(luminance(rt_buf));
}


getviewspan(vv, vb)             /* compute a span of view pixels */
int     vv;
float   *vb;
{
        float   rt_buf[6*MAXPIX];       /* rtrace send/receive buffer */
        register int    n;              /* number of pixels in buffer */
        short   buf_vh[MAXPIX];         /* pixel positions */
        FVECT   dir;
        register int    vh;

#ifdef DEBUG
        if (verbose)
                fprintf(stderr, "%s: computing view span at %d...\n",
                                progname, vv);
#endif
        n = 0;
        for (vh = -hsize; vh <= hsize; vh++) {
                if (compdir(dir, vh, vv) < 0) { /* off viewable region */
                        vb[vh+hsize] = -1.0;
                        continue;
                }
                npixinvw++;
                if ((vb[vh+hsize] = pict_val(dir)) >= 0.0)
                        continue;
                if (rt_pid == -1) {             /* missing information */
                        npixmiss++;
                        continue;
                }
                                                /* send to rtrace */
                if (n >= MAXPIX) {                      /* flush */
                        rt_compute(rt_buf, n);
                        while (n-- > 0)
                                vb[buf_vh[n]+hsize] = luminance(rt_buf+3*n);
                }
                rt_buf[6*n] = ourview.vp[0];
                rt_buf[6*n+1] = ourview.vp[1];
                rt_buf[6*n+2] = ourview.vp[2];
                rt_buf[6*n+3] = dir[0];
                rt_buf[6*n+4] = dir[1];
                rt_buf[6*n+5] = dir[2];
                buf_vh[n++] = vh;
        }
#ifdef DEBUG
        if (verbose)
                pict_stats();
#endif
        if (n > 0) {                            /* process pending buffer */
                rt_compute(rt_buf, n);
                while (n-- > 0)
                        vb[buf_vh[n]+hsize] = luminance(rt_buf+3*n);
        }
}


rt_compute(pb, np)              /* process buffer through rtrace */
float   *pb;
int     np;
{
        static float    nbuf[6] = {0.,0.,0.,0.,0.,0.};

#ifdef DEBUG
        if (verbose && np > 1)
                fprintf(stderr, "%s: sending %d samples to rtrace...\n",
                                progname, np);
#endif
        if (writebuf(fd_tort,(char *)pb,6*sizeof(float)*np) < 6*sizeof(float)*np
                || writebuf(fd_tort,(char *)nbuf,sizeof(nbuf)) < sizeof(nbuf)) {
                fprintf(stderr, "%s: error writing to rtrace process\n",
                                progname);
                exit(1);
        }
        if (readbuf(fd_fromrt, (char *)pb, 3*sizeof(float)*np)
                        < 3*sizeof(float)*np) {
                fprintf(stderr, "%s: error reading from rtrace process\n",
                                progname);
                exit(1);
        }
}


getexpos(s)                     /* get exposure from header line */
char    *s;
{
        if (isexpos(s))
                exposure *= exposval(s);
}


open_pict(fn)                   /* open picture file */
char    *fn;
{
        register int    i;

        if ((pictfp = fopen(fn, "r")) == NULL) {
                fprintf("%s: cannot open\n", fn);
                exit(1);
        }
        exposure = 1.0;
        getheader(pictfp, getexpos);
        if (fgetresolu(&pxsiz, &pysiz, pictfp) != (YMAJOR|YDECR)) {
                fprintf("%s: bad picture resolution\n", fn);
                exit(1);
        }
        initscans();
}


close_pict()                    /* done with picture */
{
        register int    i;

        if (pictfp == NULL)
                return;
        fclose(pictfp);
        donescans();
        pictfp = NULL;
}


fork_rtrace(av)                 /* open pipe and start rtrace */
char    *av[];
{
        int     p0[2], p1[2];

        if (pipe(p0) < 0 || pipe(p1) < 0) {
                perror(progname);
                exit(1);
        }
        if ((rt_pid = vfork()) == 0) {          /* if child */
                close(p0[1]);
                close(p1[0]);
                if (p0[0] != 0) {       /* connect p0 to stdin */
                        dup2(p0[0], 0);
                        close(p0[0]);
                }
                if (p1[1] != 0) {       /* connect p1 to stdout */
                        dup2(p1[1], 1);
                        close(p1[1]);
                }
                execvp(av[0], av);
                perror(av[0]);
                _exit(127);
        }
        if (rt_pid == -1) {
                perror(progname);
                exit(1);
        }
        close(p0[0]);
        close(p1[1]);
        fd_tort = p0[1];
        fd_fromrt = p1[0];
}


done_rtrace()                   /* wait for rtrace to finish */
{
        int     pid, status;

        if (rt_pid == -1)
                return;
        close(fd_tort);
        close(fd_fromrt);
        while ((pid = wait(&status)) != -1 && pid != rt_pid)
                ;
        if (pid == rt_pid && status != 0) {
                fprintf(stderr, "%s: bad status (%d) from rtrace\n",
                                progname, status);
                exit(1);
        }
        rt_pid = -1;
}


int
readbuf(fd, bpos, siz)
int     fd;
char    *bpos;
int     siz;
{
        register int    cc, nrem = siz;

        while (nrem > 0 && (cc = read(fd, bpos, nrem)) > 0) {
                bpos += cc;
                nrem -= cc;
        }
        if (cc < 0)
                return(cc);
        return(siz-nrem);
}


int
writebuf(fd, bpos, siz)
char    *bpos;
int     siz;
{
        register int    cc, nrem = siz;

        while (nrem > 0 && (cc = write(fd, bpos, nrem)) > 0) {
                bpos += cc;
                nrem -= cc;
        }
        if (cc < 0)
                return(cc);
        return(siz-nrem);
}


SCAN *
scanretire()                    /* retire old scanlines to free list */
{
        SCAN    *sold[NRETIRE];
        int     n;
        int     h;
        register SCAN   *sl;
        register int    i;
                                        /* grab the NRETIRE oldest scanlines */
        sold[n = 0] = NULL;
        for (h = 0; h < HSIZE; h++)
                for (sl = hashtab[h]; sl != NULL; sl = sl->next) {
                        for (i = n; i && sold[i-1]->lused > sl->lused; i--)
                                if (i < NRETIRE)
                                        sold[i] = sold[i-1];
                        if (i < NRETIRE) {
                                sold[i] = sl;
                                if (n < NRETIRE)        /* grow list */
                                        n++;
                        }
                }
                                        /* put scanlines into free list */
        for (i = 0; i < n; i++) {
                h = shash(sold[i]->y);
                sl = hashtab[h];
                if (sl == sold[i])
                        hashtab[h] = sl->next;
                else {
                        while (sl->next != sold[i])     /* IS in list */
                                sl = sl->next;
                        sl->next = sold[i]->next;
                }
                if (i > 0) {            /* save oldest as return value */
                        sold[i]->next = freelist;
                        freelist = sold[i];
                }
        }
        return(sold[0]);
}


static char     *scan_buf;


initscans()                             /* initialize scanline buffers */
{
        int     scansize;
        register SCAN   *ptr;
        register int    i;
                                        /* initialize positions */
        scanpos = (long *)malloc(pysiz*sizeof(long));
        if (scanpos == NULL)
                memerr("scanline positions");
        for (i = pysiz-1; i >= 0; i--)
                scanpos[i] = -1L;
        curpos = pysiz-1;
                                        /* clear hash table */
        for (i = 0; i < HSIZE; i++)
                hashtab[i] = NULL;
                                        /* allocate scanline buffers */
        scansize = sizeof(SCAN) + pxsiz*sizeof(COLR);
#ifdef ALIGN
        scansize = scansize+(sizeof(ALIGN)-1)) & ~(sizeof(ALIGN)-1);
#endif
        i = MAXSBUF / scansize;         /* compute number to allocate */
        if (i > HSIZE)
                i = HSIZE;
        scan_buf = malloc(i*scansize);  /* get in one big chunk */
        if (scan_buf == NULL)
                memerr("scanline buffers");
        ptr = (SCAN *)scan_buf;
        freelist = NULL;                /* build our free list */
        while (i-- > 0) {
                ptr->y = -1;
                ptr->lused = -1;
                ptr->next = freelist;
                freelist = ptr;
                ptr = (SCAN *)((char *)ptr + scansize); /* beware of C bugs */
        }
}


donescans()                             /* free up scanlines */
{
        free(scan_buf);
        free((char *)scanpos);
}
Revision:	1.11
Committed:	Fri Apr 5 14:57:28 1991 UTC (33 years ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 1.10:	+7 -1 lines
Log Message:	reduced scanline buffer size and added debugging output for reclaims
#	User	Rev	Content
1	greg	1.1	/* Copyright (c) 1991 Regents of the University of California */
2
3			#ifndef lint
4			static char SCCSid[] = "$SunId$ LBL";
5			#endif
6
7			/*
8			* Compute pixels for glare calculation
9			*/
10
11			#include "glare.h"
12			#include <sys/param.h>
13			/* compute rtrace buffer size */
14			#ifndef PIPE_BUF
15			#define PIPE_BUF 512 /* hyperconservative */
16			#endif
17			#define MAXPIX (PIPE_BUF/(6*sizeof(float)) - 1)
18
19			#ifndef BSD
20			#define vfork fork
21			#endif
22
23	greg	1.11	#define MAXSBUF 524268 /* maximum total size of scanline buffer */
24	greg	1.9	#define HSIZE 317 /* size of scanline hash table */
25	greg	1.8	#define NRETIRE 16 /* number of scanlines to retire at once */
26	greg	1.1
27			int rt_pid = -1; /* process id for rtrace */
28			int fd_tort, fd_fromrt; /* pipe descriptors */
29
30			FILE pictfp = NULL; / picture file pointer */
31			double exposure; /* picture exposure */
32			int pxsiz, pysiz; /* picture dimensions */
33	greg	1.8
34			static int curpos; /* current scanline */
35			static long scanpos; / scanline positions */
36
37			typedef struct scan {
38			int y; /* scanline position */
39	greg	1.1	long lused; /* for LRU replacement */
40	greg	1.8	struct scan next; / next in this hash or free list */
41			/* followed by the scanline data */
42			} SCAN; /* buffered scanline */
43	greg	1.1
44	greg	1.8	#define scandata(sl) ((COLR *)((sl)+1))
45			#define shash(y) ((y)%HSIZE)
46
47			static SCAN freelist; / scanline free list */
48			static SCAN hashtab[HSIZE]; / scanline hash table */
49
50	greg	1.2	static long ncall = 0L; /* number of calls to getpictscan */
51			static long nread = 0L; /* number of scanlines read */
52	greg	1.1
53	greg	1.8	SCAN *scanretire();
54
55	greg	1.5	extern long ftell();
56	greg	1.2
57	greg	1.5
58	greg	1.8	SCAN *
59			claimscan(y) /* claim scanline from buffers */
60			int y;
61			{
62			int hi = shash(y);
63			SCAN *slast;
64			register SCAN *sl;
65
66			for (sl = hashtab[hi]; sl != NULL; sl = sl->next)
67			if (sl->y == y) /* active scanline */
68			return(sl);
69			for (slast = NULL, sl = freelist; sl != NULL; slast = sl, sl = sl->next)
70			if (sl->y == -1 \|\| sl->y == y \|\| sl->next == NULL) {
71			if (slast == NULL) /* remove from free */
72			freelist = sl->next;
73			else
74			slast->next = sl->next;
75			if (sl->y == y) { /* reclaim */
76			sl->next = hashtab[hi];
77			hashtab[hi] = sl;
78	greg	1.11	#ifdef DEBUG
79			if (verbose)
80			fprintf(stderr,
81			"%s: scanline %d reclaimed\n",
82			progname, y);
83			#endif
84	greg	1.8	}
85			return(sl);
86			}
87			return(scanretire()); /* need more free scanlines */
88			}
89
90
91	greg	1.1	COLR *
92			getpictscan(y) /* get picture scanline */
93			int y;
94			{
95	greg	1.8	register SCAN *sl;
96	greg	1.1	register int i;
97			/* first check our buffers */
98	greg	1.8	sl = claimscan(y);
99			if (sl == NULL)
100			memerr("claimscan()");
101			sl->lused = ncall++;
102			if (sl->y == y) /* scan hit */
103			return(scandata(sl));
104			/* else read in replacement */
105	greg	1.5	if (scanpos[y] < 0) { /* need to search */
106			for (i = y+1; i < curpos; i++)
107			if (scanpos[i] >= 0) {
108			if (fseek(pictfp, scanpos[i], 0) < 0)
109			goto seekerr;
110			curpos = i;
111			break;
112			}
113			while (curpos >= y) {
114	greg	1.1	scanpos[curpos] = ftell(pictfp);
115	greg	1.8	if (freadcolrs(scandata(sl), pxsiz, pictfp) < 0)
116	greg	1.1	goto readerr;
117	greg	1.5	nread++;
118	greg	1.1	curpos--;
119			}
120	greg	1.5	} else {
121			if (curpos != y && fseek(pictfp, scanpos[y], 0) < 0)
122			goto seekerr;
123	greg	1.8	if (freadcolrs(scandata(sl), pxsiz, pictfp) < 0)
124	greg	1.5	goto readerr;
125			nread++;
126			curpos = y-1;
127	greg	1.1	}
128	greg	1.8	sl->y = y;
129			i = shash(y); /* add to hash list */
130			sl->next = hashtab[i];
131			hashtab[i] = sl;
132			return(scandata(sl));
133	greg	1.1	readerr:
134			fprintf(stderr, "%s: picture read error\n", progname);
135			exit(1);
136	greg	1.5	seekerr:
137			fprintf(stderr, "%s: picture seek error\n", progname);
138			exit(1);
139	greg	1.1	}
140
141
142	greg	1.6	#ifdef DEBUG
143	greg	1.2	pict_stats() /* print out picture read statistics */
144			{
145			static long lastcall = 0L; /* ncall at last report */
146			static long lastread = 0L; /* nread at last report */
147
148			if (ncall == lastcall)
149			return;
150	greg	1.6	fprintf(stderr, "%s: %ld scanlines read in %ld calls\n",
151			progname, nread-lastread, ncall-lastcall);
152	greg	1.2	lastcall = ncall;
153			lastread = nread;
154			}
155	greg	1.6	#endif
156	greg	1.2
157
158	greg	1.1	double
159			pict_val(vd) /* find picture value for view direction */
160			FVECT vd;
161			{
162			FVECT pp;
163			double vpx, vpy, vpz;
164			COLOR res;
165
166			if (pictfp == NULL)
167			return(-1.0);
168			pp[0] = pictview.vp[0] + vd[0];
169			pp[1] = pictview.vp[1] + vd[1];
170			pp[2] = pictview.vp[2] + vd[2];
171			viewpixel(&vpx, &vpy, &vpz, &pictview, pp);
172			if (vpz <= FTINY \|\| vpx < 0. \|\| vpx >= 1. \|\| vpy < 0. \|\| vpy >= 1.)
173			return(-1.0);
174			colr_color(res, getpictscan((int)(vpypysiz))[(int)(vpxpxsiz)]);
175			return(luminance(res)/exposure);
176			}
177
178
179			double
180			getviewpix(vh, vv) /* compute single view pixel */
181			int vh, vv;
182			{
183			FVECT dir;
184			float rt_buf[6];
185			double res;
186
187			if (compdir(dir, vh, vv) < 0)
188			return(-1.0);
189	greg	1.7	npixinvw++;
190	greg	1.1	if ((res = pict_val(dir)) >= 0.0)
191			return(res);
192	greg	1.7	if (rt_pid == -1) {
193			npixmiss++;
194	greg	1.1	return(-1.0);
195	greg	1.7	}
196	greg	1.1	rt_buf[0] = ourview.vp[0];
197			rt_buf[1] = ourview.vp[1];
198			rt_buf[2] = ourview.vp[2];
199			rt_buf[3] = dir[0];
200			rt_buf[4] = dir[1];
201			rt_buf[5] = dir[2];
202			rt_compute(rt_buf, 1);
203			return(luminance(rt_buf));
204			}
205
206
207			getviewspan(vv, vb) /* compute a span of view pixels */
208			int vv;
209			float *vb;
210			{
211			float rt_buf[6MAXPIX]; / rtrace send/receive buffer */
212	greg	1.3	register int n; /* number of pixels in buffer */
213	greg	1.1	short buf_vh[MAXPIX]; /* pixel positions */
214			FVECT dir;
215			register int vh;
216
217	greg	1.4	#ifdef DEBUG
218	greg	1.1	if (verbose)
219			fprintf(stderr, "%s: computing view span at %d...\n",
220			progname, vv);
221	greg	1.4	#endif
222	greg	1.3	n = 0;
223	greg	1.1	for (vh = -hsize; vh <= hsize; vh++) {
224			if (compdir(dir, vh, vv) < 0) { /* off viewable region */
225			vb[vh+hsize] = -1.0;
226			continue;
227			}
228	greg	1.7	npixinvw++;
229	greg	1.1	if ((vb[vh+hsize] = pict_val(dir)) >= 0.0)
230			continue;
231	greg	1.7	if (rt_pid == -1) { /* missing information */
232			npixmiss++;
233	greg	1.1	continue;
234	greg	1.7	}
235	greg	1.1	/* send to rtrace */
236	greg	1.3	if (n >= MAXPIX) { /* flush */
237			rt_compute(rt_buf, n);
238			while (n-- > 0)
239			vb[buf_vh[n]+hsize] = luminance(rt_buf+3*n);
240	greg	1.1	}
241	greg	1.3	rt_buf[6*n] = ourview.vp[0];
242			rt_buf[6*n+1] = ourview.vp[1];
243			rt_buf[6*n+2] = ourview.vp[2];
244			rt_buf[6*n+3] = dir[0];
245			rt_buf[6*n+4] = dir[1];
246			rt_buf[6*n+5] = dir[2];
247			buf_vh[n++] = vh;
248	greg	1.1	}
249	greg	1.4	#ifdef DEBUG
250	greg	1.2	if (verbose)
251			pict_stats();
252	greg	1.4	#endif
253	greg	1.3	if (n > 0) { /* process pending buffer */
254			rt_compute(rt_buf, n);
255			while (n-- > 0)
256			vb[buf_vh[n]+hsize] = luminance(rt_buf+3*n);
257			}
258	greg	1.1	}
259
260
261			rt_compute(pb, np) /* process buffer through rtrace */
262			float *pb;
263			int np;
264			{
265			static float nbuf[6] = {0.,0.,0.,0.,0.,0.};
266
267	greg	1.4	#ifdef DEBUG
268	greg	1.1	if (verbose && np > 1)
269			fprintf(stderr, "%s: sending %d samples to rtrace...\n",
270			progname, np);
271	greg	1.4	#endif
272	greg	1.1	if (writebuf(fd_tort,(char )pb,6sizeof(float)np) < 6sizeof(float)*np
273			\|\| writebuf(fd_tort,(char *)nbuf,sizeof(nbuf)) < sizeof(nbuf)) {
274			fprintf(stderr, "%s: error writing to rtrace process\n",
275			progname);
276			exit(1);
277			}
278			if (readbuf(fd_fromrt, (char )pb, 3sizeof(float)*np)
279			< 3sizeof(float)np) {
280			fprintf(stderr, "%s: error reading from rtrace process\n",
281			progname);
282			exit(1);
283			}
284			}
285
286
287			getexpos(s) /* get exposure from header line */
288			char *s;
289			{
290			if (isexpos(s))
291			exposure *= exposval(s);
292			}
293
294
295			open_pict(fn) /* open picture file */
296			char *fn;
297			{
298			register int i;
299
300			if ((pictfp = fopen(fn, "r")) == NULL) {
301			fprintf("%s: cannot open\n", fn);
302			exit(1);
303			}
304			exposure = 1.0;
305			getheader(pictfp, getexpos);
306			if (fgetresolu(&pxsiz, &pysiz, pictfp) != (YMAJOR\|YDECR)) {
307			fprintf("%s: bad picture resolution\n", fn);
308			exit(1);
309			}
310	greg	1.8	initscans();
311	greg	1.1	}
312
313
314			close_pict() /* done with picture */
315			{
316			register int i;
317
318			if (pictfp == NULL)
319			return;
320			fclose(pictfp);
321	greg	1.8	donescans();
322	greg	1.1	pictfp = NULL;
323			}
324
325
326			fork_rtrace(av) /* open pipe and start rtrace */
327			char *av[];
328			{
329			int p0[2], p1[2];
330
331			if (pipe(p0) < 0 \|\| pipe(p1) < 0) {
332			perror(progname);
333			exit(1);
334			}
335			if ((rt_pid = vfork()) == 0) { /* if child */
336			close(p0[1]);
337			close(p1[0]);
338			if (p0[0] != 0) { /* connect p0 to stdin */
339			dup2(p0[0], 0);
340			close(p0[0]);
341			}
342			if (p1[1] != 0) { /* connect p1 to stdout */
343			dup2(p1[1], 1);
344			close(p1[1]);
345			}
346			execvp(av[0], av);
347			perror(av[0]);
348			_exit(127);
349			}
350			if (rt_pid == -1) {
351			perror(progname);
352			exit(1);
353			}
354	greg	1.3	close(p0[0]);
355			close(p1[1]);
356	greg	1.1	fd_tort = p0[1];
357			fd_fromrt = p1[0];
358			}
359
360
361			done_rtrace() /* wait for rtrace to finish */
362			{
363			int pid, status;
364
365			if (rt_pid == -1)
366			return;
367			close(fd_tort);
368			close(fd_fromrt);
369			while ((pid = wait(&status)) != -1 && pid != rt_pid)
370			;
371			if (pid == rt_pid && status != 0) {
372			fprintf(stderr, "%s: bad status (%d) from rtrace\n",
373			progname, status);
374			exit(1);
375			}
376			rt_pid = -1;
377			}
378
379
380			int
381			readbuf(fd, bpos, siz)
382			int fd;
383			char *bpos;
384			int siz;
385			{
386			register int cc, nrem = siz;
387
388			while (nrem > 0 && (cc = read(fd, bpos, nrem)) > 0) {
389			bpos += cc;
390			nrem -= cc;
391			}
392			if (cc < 0)
393			return(cc);
394			return(siz-nrem);
395			}
396
397
398			int
399			writebuf(fd, bpos, siz)
400			char *bpos;
401			int siz;
402			{
403			register int cc, nrem = siz;
404
405			while (nrem > 0 && (cc = write(fd, bpos, nrem)) > 0) {
406			bpos += cc;
407			nrem -= cc;
408			}
409			if (cc < 0)
410			return(cc);
411			return(siz-nrem);
412	greg	1.8	}
413
414
415			SCAN *
416			scanretire() /* retire old scanlines to free list */
417			{
418			SCAN *sold[NRETIRE];
419			int n;
420			int h;
421			register SCAN *sl;
422			register int i;
423			/* grab the NRETIRE oldest scanlines */
424			sold[n = 0] = NULL;
425	greg	1.10	for (h = 0; h < HSIZE; h++)
426			for (sl = hashtab[h]; sl != NULL; sl = sl->next) {
427			for (i = n; i && sold[i-1]->lused > sl->lused; i--)
428			if (i < NRETIRE)
429	greg	1.8	sold[i] = sold[i-1];
430			if (i < NRETIRE) {
431	greg	1.10	sold[i] = sl;
432	greg	1.8	if (n < NRETIRE) /* grow list */
433			n++;
434	greg	1.10	}
435			}
436			/* put scanlines into free list */
437			for (i = 0; i < n; i++) {
438			h = shash(sold[i]->y);
439			sl = hashtab[h];
440			if (sl == sold[i])
441			hashtab[h] = sl->next;
442			else {
443			while (sl->next != sold[i]) /* IS in list */
444	greg	1.8	sl = sl->next;
445	greg	1.10	sl->next = sold[i]->next;
446	greg	1.8	}
447	greg	1.10	if (i > 0) { /* save oldest as return value */
448			sold[i]->next = freelist;
449			freelist = sold[i];
450			}
451	greg	1.8	}
452			return(sold[0]);
453			}
454
455
456			static char *scan_buf;
457
458
459			initscans() /* initialize scanline buffers */
460			{
461			int scansize;
462			register SCAN *ptr;
463			register int i;
464			/* initialize positions */
465			scanpos = (long )malloc(pysizsizeof(long));
466			if (scanpos == NULL)
467			memerr("scanline positions");
468			for (i = pysiz-1; i >= 0; i--)
469			scanpos[i] = -1L;
470			curpos = pysiz-1;
471			/* clear hash table */
472			for (i = 0; i < HSIZE; i++)
473			hashtab[i] = NULL;
474			/* allocate scanline buffers */
475			scansize = sizeof(SCAN) + pxsiz*sizeof(COLR);
476			#ifdef ALIGN
477			scansize = scansize+(sizeof(ALIGN)-1)) & ~(sizeof(ALIGN)-1);
478			#endif
479			i = MAXSBUF / scansize; /* compute number to allocate */
480			if (i > HSIZE)
481			i = HSIZE;
482			scan_buf = malloc(iscansize); / get in one big chunk */
483			if (scan_buf == NULL)
484			memerr("scanline buffers");
485			ptr = (SCAN *)scan_buf;
486			freelist = NULL; /* build our free list */
487			while (i-- > 0) {
488			ptr->y = -1;
489			ptr->lused = -1;
490			ptr->next = freelist;
491			freelist = ptr;
492			ptr = (SCAN )((char )ptr + scansize); /* beware of C bugs */
493			}
494			}
495
496
497			donescans() /* free up scanlines */
498			{
499			free(scan_buf);
500			free((char *)scanpos);
501	greg	1.1	}