src/common/caldefn.c

/* Copyright (c) 1986 Regents of the University of California */

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

/*
 *  Store variable definitions.
 *
 *  7/1/85  Greg Ward
 *
 *  11/11/85  Added conditional compiles (OUTCHAN) for control output.
 *
 *  4/2/86  Added conditional compiles for function definitions (FUNCTION).
 *
 *  1/15/88  Added clock for caching of variable values.
 *
 *  11/16/88  Added VARDEF structure for hard linking.
 *
 *  5/31/90  Added conditional compile (REDEFW) for redefinition warning.
 */

#include  <stdio.h>

#include  <ctype.h>

#include  "calcomp.h"

#ifndef  NHASH
#define  NHASH          521             /* hash size (a prime!) */
#endif

#define  newnode()      (EPNODE *)ecalloc(1, sizeof(EPNODE))

extern char  *ecalloc(), *savestr();

static double  dvalue();

long  eclock = -1;                      /* value storage timer */

static VARDEF  *hashtbl[NHASH];         /* definition list */
static int  htndx;                      /* index for */         
static VARDEF  *htpos;                  /* ...dfirst() and */
#ifdef  OUTCHAN
static EPNODE  *ochpos;                 /* ...dnext */
static EPNODE  *outchan;
#endif

#ifdef  FUNCTION
EPNODE  *curfunc;
#define  dname(ep)      ((ep)->v.kid->type == SYM ? \
                        (ep)->v.kid->v.name : \
                        (ep)->v.kid->v.kid->v.name)
#else
#define  dname(ep)      ((ep)->v.kid->v.name)
#endif


fcompile(fname)                 /* get definitions from a file */
char  *fname;
{
    FILE  *fp;

    if (fname == NULL)
        fp = stdin;
    else if ((fp = fopen(fname, "r")) == NULL) {
        eputs(fname);
        eputs(": cannot open\n");
        quit(1);
    }
    initfile(fp, fname, 0);
    while (nextc != EOF)
        loaddefn();
    if (fname != NULL)
        fclose(fp);
}


scompile(str, fn, ln)           /* get definitions from a string */
char  *str;
char  *fn;
int  ln;
{
    initstr(str, fn, ln);
    while (nextc != EOF)
        loaddefn();
}


double
varvalue(vname)                 /* return a variable's value */
char  *vname;
{
    return(dvalue(vname, dlookup(vname)));
}


double
evariable(ep)                   /* evaluate a variable */
EPNODE  *ep;
{
    register VARDEF  *dp = ep->v.ln;

    return(dvalue(dp->name, dp->def));
}


varset(vname, val)              /* set a variable's value */
char  *vname;
double  val;
{
    register EPNODE  *ep1, *ep2;
                                        /* check for quick set */
    if ((ep1 = dlookup(vname)) != NULL && ep1->v.kid->type == SYM) {
        ep2 = ep1->v.kid->sibling;
        if (ep2->type == NUM) {
            ep2->v.num = val;
            return;
        }
    }
                                        /* hand build definition */
    ep1 = newnode();
    ep1->type = '=';
    ep2 = newnode();
    ep2->type = SYM;
    ep2->v.name = savestr(vname);
    addekid(ep1, ep2);
    ep2 = newnode();
    ep2->type = NUM;
    ep2->v.num = val;
    addekid(ep1, ep2);
    dclear(vname);
    dpush(ep1);
}


dclear(name)                    /* delete all definitions of name */
char  *name;
{
    register EPNODE  *ep;

    while ((ep = dpop(name)) != NULL)
        epfree(ep);
}


vardefined(name)        /* return non-zero if variable defined */
char  *name;
{
    register EPNODE  *dp;

    return((dp = dlookup(name)) != NULL && dp->v.kid->type == SYM);
}


#ifdef  OUTCHAN
chanout()                       /* set output channels */
{
    register EPNODE  *ep;

    for (ep = outchan; ep != NULL; ep = ep->sibling)
        chanset(ep->v.kid->v.chan, evalue(ep->v.kid->sibling));

}
#endif


dclearall()                     /* clear all definitions */
{
    register int  i;
    register VARDEF  *vp;
    register EPNODE  *ep;

    for (i = 0; i < NHASH; i++)
        for (vp = hashtbl[i]; vp != NULL; vp = vp->next)
            dclear(vp->name);
#ifdef  OUTCHAN
    for (ep = outchan; ep != NULL; ep = ep->sibling)
        epfree(ep);
    outchan = NULL;
#endif
}


EPNODE *
dlookup(name)                   /* look up a definition */
char  *name;
{
    register VARDEF  *vp;
    
    if ((vp = varlookup(name)) == NULL)
        return(NULL);
    return(vp->def);
}


VARDEF *
varlookup(name)                 /* look up a variable */
char  *name;
{
    register VARDEF  *vp;
    
    for (vp = hashtbl[hash(name)]; vp != NULL; vp = vp->next)
        if (!strcmp(vp->name, name))
            return(vp);
    return(NULL);
}


VARDEF *
varinsert(name)                 /* get a link to a variable */
char  *name;
{
    register VARDEF  *vp;
    int  hv;
    
    hv = hash(name);
    for (vp = hashtbl[hv]; vp != NULL; vp = vp->next)
        if (!strcmp(vp->name, name)) {
            vp->nlinks++;
            return(vp);
        }
    vp = (VARDEF *)emalloc(sizeof(VARDEF));
    vp->name = savestr(name);
    vp->nlinks = 1;
    vp->def = NULL;
    vp->lib = NULL;
    vp->next = hashtbl[hv];
    hashtbl[hv] = vp;
    return(vp);
}


varfree(ln)                             /* release link to variable */
register VARDEF  *ln;
{
    register VARDEF  *vp;
    int  hv;

    if (--ln->nlinks > 0)
        return;                         /* still active */

    hv = hash(ln->name);
    vp = hashtbl[hv];
    if (vp == ln)
        hashtbl[hv] = vp->next;
    else {
        while (vp->next != ln)          /* must be in list */
                vp = vp->next;
        vp->next = ln->next;
    }
    freestr(ln->name);
    efree((char *)ln);
}


EPNODE *
dfirst()                        /* return pointer to first definition */
{
    htndx = 0;
    htpos = NULL;
#ifdef  OUTCHAN
    ochpos = outchan;
#endif
    return(dnext());
}


EPNODE *
dnext()                         /* return pointer to next definition */
{
    register EPNODE  *ep;

    while (htndx < NHASH) {
        if (htpos == NULL)
                htpos = hashtbl[htndx++];
        while (htpos != NULL) {
            ep = htpos->def;
            htpos = htpos->next;
            if (ep != NULL)
                return(ep);
        }
    }
#ifdef  OUTCHAN
    if ((ep = ochpos) != NULL)
        ochpos = ep->sibling;
    return(ep);
#else
    return(NULL);
#endif
}


EPNODE *
dpop(name)                      /* pop a definition */
char  *name;
{
    register VARDEF  *vp;
    register EPNODE  *dp;
    
    if ((vp = varlookup(name)) == NULL || vp->def == NULL)
        return(NULL);
    dp = vp->def;
    vp->def = dp->sibling;
    varfree(vp);
    return(dp);
}


dpush(ep)                       /* push on a definition */
register EPNODE  *ep;
{
    register VARDEF  *vp;

    vp = varinsert(dname(ep));
    ep->sibling = vp->def;
    vp->def = ep;
}


#ifdef  OUTCHAN
addchan(sp)                     /* add an output channel assignment */
EPNODE  *sp;
{
    int  ch = sp->v.kid->v.chan;
    register EPNODE  *ep, *epl;

    for (epl = NULL, ep = outchan; ep != NULL; epl = ep, ep = ep->sibling)
        if (ep->v.kid->v.chan >= ch) {
            if (epl != NULL)
                epl->sibling = sp;
            else
                outchan = sp;
            if (ep->v.kid->v.chan > ch)
                sp->sibling = ep;
            else {
                sp->sibling = ep->sibling;
                epfree(ep);
            }
            return;
        }
    if (epl != NULL)
        epl->sibling = sp;
    else
        outchan = sp;
    sp->sibling = NULL;

}
#endif


loaddefn()                      /* load next definition */
{
    register EPNODE  *ep;

    if (nextc == ';') {         /* empty statement */
        scan();
        return;
    }
#ifdef  OUTCHAN
    if (nextc == '$') {         /* channel assignment */
        ep = getchan();
        addchan(ep);
    } else
#endif
    {                           /* ordinary definition */
        ep = getdefn();
#ifdef  REDEFW
        if (dlookup(dname(ep)) != NULL) {
                dclear(dname(ep));
                wputs(dname(ep));
                wputs(": redefined\n");
        }
#else
        dclear(dname(ep));
#endif
        dpush(ep);
    }
    if (nextc != EOF) {
        if (nextc != ';')
            syntax("';' expected");
        scan();
    }
}


EPNODE *
getdefn()                       /* A -> SYM = E1 */
                                /*      FUNC(SYM,..) = E1 */
{
    register EPNODE  *ep1, *ep2;

    if (!isalpha(nextc))
        syntax("illegal variable name");

    ep1 = newnode();
    ep1->type = SYM;
    ep1->v.name = savestr(getname());

#ifdef  FUNCTION
    if (nextc == '(') {
        ep2 = newnode();
        ep2->type = FUNC;
        addekid(ep2, ep1);
        ep1 = ep2;
        do {
            scan();
            if (!isalpha(nextc))
                syntax("illegal variable name");
            ep2 = newnode();
            ep2->type = SYM;
            ep2->v.name = savestr(getname());
            addekid(ep1, ep2);
        } while (nextc == ',');
        if (nextc != ')')
            syntax("')' expected");
        scan();
        curfunc = ep1;
    } else
        curfunc = NULL;
#endif

    if (nextc != '=')
        syntax("'=' expected");
    scan();

    ep2 = newnode();
    ep2->type = '=';
    addekid(ep2, ep1);
    addekid(ep2, getE1());

#ifdef  FUNCTION
    if (ep1->type == SYM)
#endif
    {
        ep1 = newnode();
        ep1->type = TICK;
        ep1->v.tick = -1;
        addekid(ep2, ep1);
        ep1 = newnode();
        ep1->type = NUM;
        addekid(ep2, ep1);
    }

    return(ep2);
}


#ifdef  OUTCHAN
EPNODE *
getchan()                       /* A -> $N = E1 */
{
    register EPNODE  *ep1, *ep2;

    if (nextc != '$')
        syntax("missing '$'");
    scan();

    ep1 = newnode();
    ep1->type = CHAN;
    ep1->v.chan = getinum();

    if (nextc != '=')
        syntax("'=' expected");
    scan();

    ep2 = newnode();
    ep2->type = '=';
    addekid(ep2, ep1);
    addekid(ep2, getE1());

    return(ep2);
}
#endif


/*
 *  The following routines are for internal use only:
 */


static double
dvalue(name, d)                 /* evaluate a variable */
char  *name;
EPNODE  *d;
{
    register EPNODE  *ep1, *ep2;
    
    if (d == NULL || d->v.kid->type != SYM) {
        eputs(name);
        eputs(": undefined variable\n");
        quit(1);
    }
    ep1 = d->v.kid->sibling;                    /* get expression */
    if (ep1->type == NUM)
        return(ep1->v.num);                     /* return if number */
    ep2 = ep1->sibling;                         /* check time */
    if (ep2->v.tick < 0 || ep2->v.tick < eclock) {
        ep2->v.tick = eclock;
        ep2 = ep2->sibling;
        ep2->v.num = evalue(ep1);               /* needs new value */
    } else
        ep2 = ep2->sibling;                     /* else reuse old value */

    return(ep2->v.num);
}


static int
hash(s)                         /* hash a string */
register char  *s;
{
    register int  rval = 0;

    while (*s)
        rval += *s++;
    
    return(rval % NHASH);
}
Revision:	1.5
Committed:	Thu Jul 19 11:15:31 1990 UTC (33 years, 9 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 1.4:	+4 -10 lines
Log Message:	eliminated cache for numeric definitions
#	User	Rev	Content
1	greg	1.1	/* Copyright (c) 1986 Regents of the University of California */
2
3			#ifndef lint
4			static char SCCSid[] = "$SunId$ LBL";
5			#endif
6
7			/*
8			* Store variable definitions.
9			*
10			* 7/1/85 Greg Ward
11			*
12			* 11/11/85 Added conditional compiles (OUTCHAN) for control output.
13			*
14			* 4/2/86 Added conditional compiles for function definitions (FUNCTION).
15			*
16			* 1/15/88 Added clock for caching of variable values.
17			*
18			* 11/16/88 Added VARDEF structure for hard linking.
19	greg	1.2	*
20			* 5/31/90 Added conditional compile (REDEFW) for redefinition warning.
21	greg	1.1	*/
22
23			#include <stdio.h>
24
25			#include <ctype.h>
26
27			#include "calcomp.h"
28
29			#ifndef NHASH
30			#define NHASH 521 /* hash size (a prime!) */
31			#endif
32
33			#define newnode() (EPNODE *)ecalloc(1, sizeof(EPNODE))
34
35			extern char ecalloc(), savestr();
36
37	greg	1.3	static double dvalue();
38	greg	1.1
39			long eclock = -1; /* value storage timer */
40
41			static VARDEF hashtbl[NHASH]; / definition list */
42			static int htndx; /* index for */
43			static VARDEF htpos; / ...dfirst() and */
44			#ifdef OUTCHAN
45			static EPNODE ochpos; / ...dnext */
46			static EPNODE *outchan;
47			#endif
48
49			#ifdef FUNCTION
50			EPNODE *curfunc;
51			#define dname(ep) ((ep)->v.kid->type == SYM ? \
52			(ep)->v.kid->v.name : \
53			(ep)->v.kid->v.kid->v.name)
54			#else
55			#define dname(ep) ((ep)->v.kid->v.name)
56			#endif
57
58
59			fcompile(fname) /* get definitions from a file */
60			char *fname;
61			{
62			FILE *fp;
63
64			if (fname == NULL)
65			fp = stdin;
66			else if ((fp = fopen(fname, "r")) == NULL) {
67			eputs(fname);
68			eputs(": cannot open\n");
69			quit(1);
70			}
71	greg	1.4	initfile(fp, fname, 0);
72	greg	1.1	while (nextc != EOF)
73			loaddefn();
74			if (fname != NULL)
75			fclose(fp);
76			}
77
78
79	greg	1.4	scompile(str, fn, ln) /* get definitions from a string */
80	greg	1.1	char *str;
81	greg	1.4	char *fn;
82			int ln;
83	greg	1.1	{
84	greg	1.4	initstr(str, fn, ln);
85	greg	1.1	while (nextc != EOF)
86			loaddefn();
87			}
88
89
90			double
91			varvalue(vname) /* return a variable's value */
92			char *vname;
93			{
94			return(dvalue(vname, dlookup(vname)));
95			}
96
97
98			double
99			evariable(ep) /* evaluate a variable */
100			EPNODE *ep;
101			{
102			register VARDEF *dp = ep->v.ln;
103
104			return(dvalue(dp->name, dp->def));
105			}
106
107
108			varset(vname, val) /* set a variable's value */
109			char *vname;
110			double val;
111			{
112			register EPNODE ep1, ep2;
113			/* check for quick set */
114			if ((ep1 = dlookup(vname)) != NULL && ep1->v.kid->type == SYM) {
115			ep2 = ep1->v.kid->sibling;
116			if (ep2->type == NUM) {
117			ep2->v.num = val;
118			return;
119			}
120			}
121			/* hand build definition */
122			ep1 = newnode();
123			ep1->type = '=';
124			ep2 = newnode();
125			ep2->type = SYM;
126			ep2->v.name = savestr(vname);
127			addekid(ep1, ep2);
128			ep2 = newnode();
129			ep2->type = NUM;
130			ep2->v.num = val;
131			addekid(ep1, ep2);
132			dclear(vname);
133			dpush(ep1);
134			}
135
136
137			dclear(name) /* delete all definitions of name */
138			char *name;
139			{
140			register EPNODE *ep;
141
142			while ((ep = dpop(name)) != NULL)
143			epfree(ep);
144			}
145
146
147			vardefined(name) /* return non-zero if variable defined */
148			char *name;
149			{
150			register EPNODE *dp;
151
152			return((dp = dlookup(name)) != NULL && dp->v.kid->type == SYM);
153			}
154
155
156			#ifdef OUTCHAN
157			chanout() /* set output channels */
158			{
159			register EPNODE *ep;
160
161			for (ep = outchan; ep != NULL; ep = ep->sibling)
162			chanset(ep->v.kid->v.chan, evalue(ep->v.kid->sibling));
163
164			}
165			#endif
166
167
168			dclearall() /* clear all definitions */
169			{
170			register int i;
171			register VARDEF *vp;
172			register EPNODE *ep;
173
174			for (i = 0; i < NHASH; i++)
175			for (vp = hashtbl[i]; vp != NULL; vp = vp->next)
176			dclear(vp->name);
177			#ifdef OUTCHAN
178			for (ep = outchan; ep != NULL; ep = ep->sibling)
179			epfree(ep);
180			outchan = NULL;
181			#endif
182			}
183
184
185			EPNODE *
186			dlookup(name) /* look up a definition */
187			char *name;
188			{
189			register VARDEF *vp;
190
191			if ((vp = varlookup(name)) == NULL)
192			return(NULL);
193			return(vp->def);
194			}
195
196
197			VARDEF *
198			varlookup(name) /* look up a variable */
199			char *name;
200			{
201			register VARDEF *vp;
202
203			for (vp = hashtbl[hash(name)]; vp != NULL; vp = vp->next)
204			if (!strcmp(vp->name, name))
205			return(vp);
206			return(NULL);
207			}
208
209
210			VARDEF *
211			varinsert(name) /* get a link to a variable */
212			char *name;
213			{
214			register VARDEF *vp;
215			int hv;
216
217			hv = hash(name);
218			for (vp = hashtbl[hv]; vp != NULL; vp = vp->next)
219			if (!strcmp(vp->name, name)) {
220			vp->nlinks++;
221			return(vp);
222			}
223			vp = (VARDEF *)emalloc(sizeof(VARDEF));
224			vp->name = savestr(name);
225			vp->nlinks = 1;
226			vp->def = NULL;
227			vp->lib = NULL;
228			vp->next = hashtbl[hv];
229			hashtbl[hv] = vp;
230			return(vp);
231			}
232
233
234			varfree(ln) /* release link to variable */
235			register VARDEF *ln;
236			{
237			register VARDEF *vp;
238			int hv;
239
240			if (--ln->nlinks > 0)
241			return; /* still active */
242
243			hv = hash(ln->name);
244			vp = hashtbl[hv];
245			if (vp == ln)
246			hashtbl[hv] = vp->next;
247			else {
248			while (vp->next != ln) /* must be in list */
249			vp = vp->next;
250			vp->next = ln->next;
251			}
252			freestr(ln->name);
253			efree((char *)ln);
254			}
255
256
257			EPNODE *
258			dfirst() /* return pointer to first definition */
259			{
260			htndx = 0;
261			htpos = NULL;
262			#ifdef OUTCHAN
263			ochpos = outchan;
264			#endif
265			return(dnext());
266			}
267
268
269			EPNODE *
270			dnext() /* return pointer to next definition */
271			{
272			register EPNODE *ep;
273
274			while (htndx < NHASH) {
275			if (htpos == NULL)
276			htpos = hashtbl[htndx++];
277			while (htpos != NULL) {
278			ep = htpos->def;
279			htpos = htpos->next;
280			if (ep != NULL)
281			return(ep);
282			}
283			}
284			#ifdef OUTCHAN
285			if ((ep = ochpos) != NULL)
286			ochpos = ep->sibling;
287			return(ep);
288			#else
289			return(NULL);
290			#endif
291			}
292
293
294			EPNODE *
295			dpop(name) /* pop a definition */
296			char *name;
297			{
298			register VARDEF *vp;
299			register EPNODE *dp;
300
301			if ((vp = varlookup(name)) == NULL \|\| vp->def == NULL)
302			return(NULL);
303			dp = vp->def;
304			vp->def = dp->sibling;
305			varfree(vp);
306			return(dp);
307			}
308
309
310			dpush(ep) /* push on a definition */
311			register EPNODE *ep;
312			{
313			register VARDEF *vp;
314
315			vp = varinsert(dname(ep));
316			ep->sibling = vp->def;
317			vp->def = ep;
318			}
319
320
321			#ifdef OUTCHAN
322			addchan(sp) /* add an output channel assignment */
323			EPNODE *sp;
324			{
325			int ch = sp->v.kid->v.chan;
326			register EPNODE ep, epl;
327
328			for (epl = NULL, ep = outchan; ep != NULL; epl = ep, ep = ep->sibling)
329			if (ep->v.kid->v.chan >= ch) {
330			if (epl != NULL)
331			epl->sibling = sp;
332			else
333			outchan = sp;
334			if (ep->v.kid->v.chan > ch)
335			sp->sibling = ep;
336			else {
337			sp->sibling = ep->sibling;
338			epfree(ep);
339			}
340			return;
341			}
342			if (epl != NULL)
343			epl->sibling = sp;
344			else
345			outchan = sp;
346			sp->sibling = NULL;
347
348			}
349			#endif
350
351
352			loaddefn() /* load next definition */
353			{
354			register EPNODE *ep;
355
356			if (nextc == ';') { /* empty statement */
357			scan();
358			return;
359			}
360			#ifdef OUTCHAN
361			if (nextc == '$') { /* channel assignment */
362			ep = getchan();
363			addchan(ep);
364			} else
365			#endif
366			{ /* ordinary definition */
367			ep = getdefn();
368	greg	1.2	#ifdef REDEFW
369			if (dlookup(dname(ep)) != NULL) {
370			dclear(dname(ep));
371			wputs(dname(ep));
372			wputs(": redefined\n");
373			}
374			#else
375	greg	1.1	dclear(dname(ep));
376	greg	1.2	#endif
377	greg	1.1	dpush(ep);
378			}
379			if (nextc != EOF) {
380			if (nextc != ';')
381			syntax("';' expected");
382			scan();
383			}
384			}
385
386
387			EPNODE *
388			getdefn() /* A -> SYM = E1 */
389			/* FUNC(SYM,..) = E1 */
390			{
391			register EPNODE ep1, ep2;
392
393			if (!isalpha(nextc))
394			syntax("illegal variable name");
395
396			ep1 = newnode();
397			ep1->type = SYM;
398			ep1->v.name = savestr(getname());
399
400			#ifdef FUNCTION
401			if (nextc == '(') {
402			ep2 = newnode();
403			ep2->type = FUNC;
404			addekid(ep2, ep1);
405			ep1 = ep2;
406			do {
407			scan();
408			if (!isalpha(nextc))
409			syntax("illegal variable name");
410			ep2 = newnode();
411			ep2->type = SYM;
412			ep2->v.name = savestr(getname());
413			addekid(ep1, ep2);
414			} while (nextc == ',');
415			if (nextc != ')')
416			syntax("')' expected");
417			scan();
418			curfunc = ep1;
419			} else
420			curfunc = NULL;
421			#endif
422
423			if (nextc != '=')
424			syntax("'=' expected");
425			scan();
426
427			ep2 = newnode();
428			ep2->type = '=';
429			addekid(ep2, ep1);
430			addekid(ep2, getE1());
431
432			#ifdef FUNCTION
433			if (ep1->type == SYM)
434			#endif
435			{
436			ep1 = newnode();
437			ep1->type = TICK;
438			ep1->v.tick = -1;
439			addekid(ep2, ep1);
440			ep1 = newnode();
441			ep1->type = NUM;
442			addekid(ep2, ep1);
443			}
444
445			return(ep2);
446			}
447
448
449			#ifdef OUTCHAN
450			EPNODE *
451			getchan() /* A -> $N = E1 */
452			{
453			register EPNODE ep1, ep2;
454
455			if (nextc != '$')
456			syntax("missing '$'");
457			scan();
458
459			ep1 = newnode();
460			ep1->type = CHAN;
461			ep1->v.chan = getinum();
462
463			if (nextc != '=')
464			syntax("'=' expected");
465			scan();
466
467			ep2 = newnode();
468			ep2->type = '=';
469			addekid(ep2, ep1);
470			addekid(ep2, getE1());
471
472			return(ep2);
473			}
474			#endif
475
476
477
478			/*
479			* The following routines are for internal use only:
480			*/
481
482
483			static double
484			dvalue(name, d) /* evaluate a variable */
485			char *name;
486			EPNODE *d;
487			{
488			register EPNODE ep1, ep2;
489
490			if (d == NULL \|\| d->v.kid->type != SYM) {
491			eputs(name);
492			eputs(": undefined variable\n");
493			quit(1);
494			}
495			ep1 = d->v.kid->sibling; /* get expression */
496	greg	1.5	if (ep1->type == NUM)
497			return(ep1->v.num); /* return if number */
498	greg	1.1	ep2 = ep1->sibling; /* check time */
499			if (ep2->v.tick < 0 \|\| ep2->v.tick < eclock) {
500			ep2->v.tick = eclock;
501			ep2 = ep2->sibling;
502	greg	1.5	ep2->v.num = evalue(ep1); /* needs new value */
503	greg	1.1	} else
504	greg	1.5	ep2 = ep2->sibling; /* else reuse old value */
505	greg	1.1
506			return(ep2->v.num);
507			}
508
509
510			static int
511			hash(s) /* hash a string */
512			register char *s;
513			{
514			register int rval = 0;
515
516			while (*s)
517			rval += *s++;
518
519			return(rval % NHASH);
520			}