src/common/caldefn.c

#ifndef lint
static const char       RCSid[] = "$Id: caldefn.c,v 2.21 2003/10/27 10:19:31 schorsch Exp $";
#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.
 *
 *  4/23/91  Added ':' assignment for constant expressions
 *
 *  8/7/91  Added optional context path to append to variable names
 *
 *  5/17/2001  Fixed clock counter wrapping behavior
 *
 *  2/19/03     Eliminated conditional compiles in favor of esupport extern.
 */

#include "copyright.h"

#include  <stdio.h>
#include  <string.h>
#include  <ctype.h>

#include  "rterror.h"
#include  "rtio.h"
#include  "rtmisc.h"
#include  "calcomp.h"

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

#define  hash(s)        (shash(s)%NHASH)

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

static double  dvalue(char  *name, EPNODE *d);

#define  MAXCLOCK       (1L<<31)        /* clock wrap value */

unsigned long  eclock = 0;              /* value storage timer */

#define  MAXCNTX        1023            /* maximum context length */

static char  context[MAXCNTX+1];        /* current context path */

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

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


void
fcompile(                       /* 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)
        getstatement();
    if (fname != NULL)
        fclose(fp);
}


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


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


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

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


void
varset(         /* set a variable's value */
        char  *vname,
        int  assign,
        double  val
)
{
    char  *qname;
    register EPNODE  *ep1, *ep2;
                                        /* get qualified name */
    qname = qualname(vname, 0);
                                        /* check for quick set */
    if ((ep1 = dlookup(qname)) != NULL && ep1->v.kid->type == SYM) {
        ep2 = ep1->v.kid->sibling;
        if (ep2->type == NUM) {
            ep2->v.num = val;
            ep1->type = assign;
            return;
        }
    }
                                        /* hand build definition */
    ep1 = newnode();
    ep1->type = assign;
    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);
    dremove(qname);
    dpush(qname, ep1);
}


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

    while ((ep = dpop(name)) != NULL) {
        if (ep->type == ':') {
            dpush(name, ep);            /* don't clear constants */
            return;
        }
        epfree(ep);
    }
}


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

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


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

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


char *
setcontext(                     /* set a new context path */
        register char  *ctx
)
{
    register char  *cpp;

    if (ctx == NULL)
        return(context);                /* just asking */
    while (*ctx == CNTXMARK)
        ctx++;                          /* skip past marks */
    if (!*ctx) {
        context[0] = '\0';              /* empty means clear context */
        return(context);
    }
    cpp = context;                      /* start context with mark */
    *cpp++ = CNTXMARK;
    do {                                /* carefully copy new context */
        if (cpp >= context+MAXCNTX)
            break;                      /* just copy what we can */
        if (isid(*ctx))
            *cpp++ = *ctx++;
        else {
            *cpp++ = '_'; ctx++;
        }
    } while (*ctx);
    while (cpp[-1] == CNTXMARK)         /* cannot end in context mark */
        cpp--;
    *cpp = '\0';
    return(context);
}


char *
pushcontext(            /* push on another context */
        char  *ctx
)
{
    char  oldcontext[MAXCNTX+1];
    register int  n;

    strcpy(oldcontext, context);        /* save old context */
    setcontext(ctx);                    /* set new context */
    n = strlen(context);                /* tack on old */
    if (n+strlen(oldcontext) > MAXCNTX) {
        strncpy(context+n, oldcontext, MAXCNTX-n);
        context[MAXCNTX] = '\0';
    } else
        strcpy(context+n, oldcontext);
    return(context);
}


char *
popcontext(void)                        /* pop off top context */
{
    register char  *cp1, *cp2;

    if (!context[0])                    /* nothing left to pop */
        return(context);
    cp2 = context;                      /* find mark */
    while (*++cp2 && *cp2 != CNTXMARK)
        ;
    cp1 = context;                      /* copy tail to front */
    while ( (*cp1++ = *cp2++) )
        ;
    return(context);
}


char *
qualname(               /* get qualified name */
        register char  *nam,
        int  lvl
)
{
    static char  nambuf[RMAXWORD+1];
    register char  *cp = nambuf, *cpp;
                                /* check for explicit local */
    if (*nam == CNTXMARK)
        if (lvl > 0)            /* only action is to refuse search */
            return(NULL);
        else
            nam++;
    else if (nam == nambuf)     /* check for repeat call */
        return(lvl > 0 ? NULL : nam);
                                /* copy name to static buffer */
    while (*nam) {
        if (cp >= nambuf+RMAXWORD)
                goto toolong;
        *cp++ = *nam++;
    }
                                /* check for explicit global */
    if (cp > nambuf && cp[-1] == CNTXMARK) {
        if (lvl > 0)
            return(NULL);
        *--cp = '\0';
        return(nambuf);         /* already qualified */
    }
    cpp = context;              /* else skip the requested levels */
    while (lvl-- > 0) {
        if (!*cpp)
            return(NULL);       /* return NULL if past global level */
        while (*++cpp && *cpp != CNTXMARK)
            ;
    }
    while (*cpp) {              /* copy context to static buffer */
        if (cp >= nambuf+RMAXWORD)
            goto toolong;
        *cp++ = *cpp++;
    }
toolong:
    *cp = '\0';
    return(nambuf);             /* return qualified name */
}


int
incontext(                      /* is qualified name in current context? */
        register char  *qn
)
{
    if (!context[0])                    /* global context accepts all */
        return(1);
    while (*qn && *qn != CNTXMARK)      /* find context mark */
        qn++;
    return(!strcmp(qn, context));
}


void
chanout(                        /* set output channels */
        void  (*cs)(int n, double v)
)
{
    register EPNODE  *ep;

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

}


void
dcleanup(               /* clear definitions (0->vars,1->output,2->consts) */
        int  lvl
)
{
    register int  i;
    register VARDEF  *vp;
    register EPNODE  *ep;
                                /* if context is global, clear all */
    for (i = 0; i < NHASH; i++)
        for (vp = hashtbl[i]; vp != NULL; vp = vp->next)
            if (incontext(vp->name)) {
                if (lvl >= 2)
                    dremove(vp->name);
                else
                    dclear(vp->name);
            }
    if (lvl >= 1) {
        for (ep = outchan; ep != NULL; ep = ep->sibling)
            epfree(ep);
        outchan = NULL;
    }
}


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


VARDEF *
varlookup(                      /* look up a variable */
        char  *name
)
{
    int  lvl = 0;
    register char  *qname;
    register VARDEF  *vp;
                                /* find most qualified match */
    while ((qname = qualname(name, lvl++)) != NULL)
        for (vp = hashtbl[hash(qname)]; vp != NULL; vp = vp->next)
            if (!strcmp(vp->name, qname))
                return(vp);
    return(NULL);
}


VARDEF *
varinsert(                      /* get a link to a variable */
        char  *name
)
{
    register VARDEF  *vp;
    int  hv;
    
    if ((vp = varlookup(name)) != NULL) {
        vp->nlinks++;
        return(vp);
    }
    vp = (VARDEF *)emalloc(sizeof(VARDEF));
    vp->lib = liblookup(name);
    if (vp->lib == NULL)                /* if name not in library */
        name = qualname(name, 0);       /* use fully qualified version */
    hv = hash(name);
    vp->name = savestr(name);
    vp->nlinks = 1;
    vp->def = NULL;
    vp->next = hashtbl[hv];
    hashtbl[hv] = vp;
    return(vp);
}


void
libupdate(                      /* update library links */
        char  *fn
)
{
    register int  i;
    register VARDEF  *vp;
                                        /* if fn is NULL then relink all */
    for (i = 0; i < NHASH; i++)
        for (vp = hashtbl[i]; vp != NULL; vp = vp->next)
            if (vp->lib != NULL || fn == NULL || !strcmp(fn, vp->name))
                vp->lib = liblookup(vp->name);
}


void
varfree(                                /* 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(void)                    /* return pointer to first definition */
{
    htndx = 0;
    htpos = NULL;
    ochpos = outchan;
    return(dnext());
}


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

    while (htndx < NHASH) {
        if (htpos == NULL)
                htpos = hashtbl[htndx++];
        while (htpos != NULL) {
            ep = htpos->def;
            nm = htpos->name;
            htpos = htpos->next;
            if (ep != NULL && incontext(nm))
                return(ep);
        }
    }
    if ((ep = ochpos) != NULL)
        ochpos = ep->sibling;
    return(ep);
}


EPNODE *
dpop(                   /* 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);
}


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

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


void
addchan(                        /* 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;

}


void
getstatement(void)                      /* get next statement */
{
    register EPNODE  *ep;
    char  *qname;
    register VARDEF  *vdef;

    if (nextc == ';') {         /* empty statement */
        scan();
        return;
    }
    if (esupport&E_OUTCHAN &&
                nextc == '$') {         /* channel assignment */
        ep = getchan();
        addchan(ep);
    } else {                            /* ordinary definition */
        ep = getdefn();
        qname = qualname(dname(ep), 0);
        if (esupport&E_REDEFW && (vdef = varlookup(qname)) != NULL) {
            if (vdef->def != NULL && epcmp(ep, vdef->def)) {
                wputs(qname);
                if (vdef->def->type == ':')
                    wputs(": redefined constant expression\n");
                else
                    wputs(": redefined\n");
            } else if (ep->v.kid->type == FUNC && vdef->lib != NULL) {
                wputs(qname);
                wputs(": definition hides library function\n");
            }
        }
        if (ep->type == ':')
            dremove(qname);
        else
            dclear(qname);
        dpush(qname, ep);
    }
    if (nextc != EOF) {
        if (nextc != ';')
            syntax("';' expected");
        scan();
    }
}


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

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

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

    if (esupport&E_FUNCTION && 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;
    }

    if (nextc != '=' && nextc != ':')
        syntax("'=' or ':' expected");

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

    if (ep1->type == SYM && ep1->sibling->type != NUM) {
        ep1 = newnode();
        ep1->type = TICK;
        ep1->v.tick = 0;
        addekid(ep2, ep1);
        ep1 = newnode();
        ep1->type = NUM;
        addekid(ep2, ep1);
    }
    curfunc = NULL;

    return(ep2);
}


EPNODE *
getchan(void)                   /* 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);
}


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


static double                   /* evaluate a variable */
dvalue(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 (eclock >= MAXCLOCK)
        eclock = 1;                             /* wrap clock counter */
    if (ep2->v.tick < MAXCLOCK &&
                (ep2->v.tick == 0) | (ep2->v.tick != eclock)) {
        ep2->v.tick = d->type == ':' ? MAXCLOCK : eclock;
        ep2 = ep2->sibling;
        ep2->v.num = evalue(ep1);               /* needs new value */
    } else
        ep2 = ep2->sibling;                     /* else reuse old value */

    return(ep2->v.num);
}
Revision:	2.22
Committed:	Sun Mar 28 20:33:12 2004 UTC (21 years, 7 months ago) by schorsch
Content type:	text/plain
Branch:	MAIN
CVS Tags:	rad3R7P2, rad3R7P1, rad3R6, rad3R6P1, rad3R8, rad3R9
Changes since 2.21:	+2 -1 lines
Log Message:	Continued ANSIfication, and other fixes and clarifications.
#	User	Rev	Content
1	greg	1.1	#ifndef lint
2	schorsch	2.22	static const char RCSid[] = "$Id: caldefn.c,v 2.21 2003/10/27 10:19:31 schorsch Exp $";
3	greg	1.1	#endif
4			/*
5			* Store variable definitions.
6			*
7			* 7/1/85 Greg Ward
8			*
9			* 11/11/85 Added conditional compiles (OUTCHAN) for control output.
10			*
11			* 4/2/86 Added conditional compiles for function definitions (FUNCTION).
12			*
13			* 1/15/88 Added clock for caching of variable values.
14			*
15			* 11/16/88 Added VARDEF structure for hard linking.
16	greg	1.2	*
17			* 5/31/90 Added conditional compile (REDEFW) for redefinition warning.
18	greg	1.8	*
19	greg	1.10	* 4/23/91 Added ':' assignment for constant expressions
20	greg	1.13	*
21			* 8/7/91 Added optional context path to append to variable names
22	greg	2.12	*
23			* 5/17/2001 Fixed clock counter wrapping behavior
24			*
25			* 2/19/03 Eliminated conditional compiles in favor of esupport extern.
26			*/
27
28	greg	2.13	#include "copyright.h"
29	greg	1.1
30			#include <stdio.h>
31	greg	2.12	#include <string.h>
32	greg	1.1	#include <ctype.h>
33
34	schorsch	2.18	#include "rterror.h"
35	schorsch	2.22	#include "rtio.h"
36	schorsch	2.21	#include "rtmisc.h"
37	greg	1.1	#include "calcomp.h"
38
39	greg	2.4	#ifndef NHASH
40			#define NHASH 521 /* hash size (a prime!) */
41	greg	1.1	#endif
42
43	greg	2.5	#define hash(s) (shash(s)%NHASH)
44
45	greg	2.4	#define newnode() (EPNODE *)ecalloc(1, sizeof(EPNODE))
46	greg	1.1
47	schorsch	2.18	static double dvalue(char name, EPNODE d);
48	greg	1.1
49	greg	2.12	#define MAXCLOCK (1L<<31) /* clock wrap value */
50	greg	1.1
51	greg	2.8	unsigned long eclock = 0; /* value storage timer */
52	greg	1.1
53	greg	2.11	#define MAXCNTX 1023 /* maximum context length */
54	greg	1.13
55	greg	2.11	static char context[MAXCNTX+1]; /* current context path */
56
57	greg	1.1	static VARDEF hashtbl[NHASH]; / definition list */
58			static int htndx; /* index for */
59			static VARDEF htpos; / ...dfirst() and */
60			static EPNODE ochpos; / ...dnext */
61			static EPNODE *outchan;
62
63	greg	2.10	EPNODE *curfunc = NULL;
64	greg	2.4	#define dname(ep) ((ep)->v.kid->type == SYM ? \
65	greg	1.1	(ep)->v.kid->v.name : \
66			(ep)->v.kid->v.kid->v.name)
67
68
69	greg	2.12	void
70	schorsch	2.16	fcompile( /* get definitions from a file */
71			char *fname
72			)
73	greg	1.1	{
74			FILE *fp;
75
76			if (fname == NULL)
77			fp = stdin;
78			else if ((fp = fopen(fname, "r")) == NULL) {
79			eputs(fname);
80			eputs(": cannot open\n");
81			quit(1);
82			}
83	greg	1.4	initfile(fp, fname, 0);
84	greg	1.1	while (nextc != EOF)
85	greg	1.13	getstatement();
86	greg	1.1	if (fname != NULL)
87			fclose(fp);
88			}
89
90
91	greg	2.12	void
92	schorsch	2.16	scompile( /* get definitions from a string */
93			char *str,
94			char *fn,
95			int ln
96			)
97	greg	1.1	{
98	greg	1.4	initstr(str, fn, ln);
99	greg	1.1	while (nextc != EOF)
100	greg	1.13	getstatement();
101	greg	1.1	}
102
103
104			double
105	schorsch	2.16	varvalue( /* return a variable's value */
106			char *vname
107			)
108	greg	1.1	{
109			return(dvalue(vname, dlookup(vname)));
110			}
111
112
113			double
114	schorsch	2.16	evariable( /* evaluate a variable */
115			EPNODE *ep
116			)
117	greg	1.1	{
118			register VARDEF *dp = ep->v.ln;
119
120			return(dvalue(dp->name, dp->def));
121			}
122
123
124	greg	2.12	void
125	schorsch	2.16	varset( /* set a variable's value */
126			char *vname,
127			int assign,
128			double val
129			)
130	greg	1.1	{
131	greg	1.13	char *qname;
132	greg	1.1	register EPNODE ep1, ep2;
133	greg	1.13	/* get qualified name */
134			qname = qualname(vname, 0);
135	greg	1.1	/* check for quick set */
136	greg	1.13	if ((ep1 = dlookup(qname)) != NULL && ep1->v.kid->type == SYM) {
137	greg	1.1	ep2 = ep1->v.kid->sibling;
138			if (ep2->type == NUM) {
139			ep2->v.num = val;
140	greg	1.8	ep1->type = assign;
141	greg	1.1	return;
142			}
143			}
144			/* hand build definition */
145			ep1 = newnode();
146	greg	1.8	ep1->type = assign;
147	greg	1.1	ep2 = newnode();
148			ep2->type = SYM;
149			ep2->v.name = savestr(vname);
150			addekid(ep1, ep2);
151			ep2 = newnode();
152			ep2->type = NUM;
153			ep2->v.num = val;
154			addekid(ep1, ep2);
155	greg	1.13	dremove(qname);
156			dpush(qname, ep1);
157	greg	1.1	}
158
159
160	greg	2.12	void
161	schorsch	2.16	dclear( /* delete variable definitions of name */
162			char *name
163			)
164	greg	1.1	{
165			register EPNODE *ep;
166
167	greg	1.8	while ((ep = dpop(name)) != NULL) {
168			if (ep->type == ':') {
169	greg	1.13	dpush(name, ep); /* don't clear constants */
170	greg	1.8	return;
171			}
172			epfree(ep);
173			}
174			}
175
176
177	greg	2.12	void
178	schorsch	2.16	dremove( /* delete all definitions of name */
179			char *name
180			)
181	greg	1.8	{
182			register EPNODE *ep;
183
184	greg	1.1	while ((ep = dpop(name)) != NULL)
185			epfree(ep);
186			}
187
188
189	greg	2.12	int
190	schorsch	2.16	vardefined( /* return non-zero if variable defined */
191			char *name
192			)
193	greg	1.1	{
194			register EPNODE *dp;
195
196			return((dp = dlookup(name)) != NULL && dp->v.kid->type == SYM);
197			}
198
199
200	greg	1.13	char *
201	schorsch	2.16	setcontext( /* set a new context path */
202			register char *ctx
203			)
204	greg	1.13	{
205			register char *cpp;
206
207			if (ctx == NULL)
208			return(context); /* just asking */
209	greg	2.6	while (*ctx == CNTXMARK)
210			ctx++; /* skip past marks */
211	greg	1.13	if (!*ctx) {
212	greg	2.6	context[0] = '\0'; /* empty means clear context */
213	greg	1.13	return(context);
214			}
215	greg	2.6	cpp = context; /* start context with mark */
216			*cpp++ = CNTXMARK;
217			do { /* carefully copy new context */
218	greg	2.11	if (cpp >= context+MAXCNTX)
219	greg	1.18	break; /* just copy what we can */
220	greg	1.13	if (isid(*ctx))
221			cpp++ = ctx++;
222			else {
223			*cpp++ = '_'; ctx++;
224			}
225			} while (*ctx);
226	greg	2.6	while (cpp[-1] == CNTXMARK) /* cannot end in context mark */
227			cpp--;
228	greg	1.13	*cpp = '\0';
229	greg	2.6	return(context);
230			}
231
232
233			char *
234	schorsch	2.16	pushcontext( /* push on another context */
235			char *ctx
236			)
237	greg	2.6	{
238	greg	2.11	char oldcontext[MAXCNTX+1];
239	greg	2.6	register int n;
240
241			strcpy(oldcontext, context); /* save old context */
242			setcontext(ctx); /* set new context */
243			n = strlen(context); /* tack on old */
244	greg	2.11	if (n+strlen(oldcontext) > MAXCNTX) {
245			strncpy(context+n, oldcontext, MAXCNTX-n);
246			context[MAXCNTX] = '\0';
247	greg	2.6	} else
248			strcpy(context+n, oldcontext);
249			return(context);
250			}
251
252
253			char *
254	schorsch	2.16	popcontext(void) /* pop off top context */
255	greg	2.6	{
256			register char cp1, cp2;
257
258			if (!context[0]) /* nothing left to pop */
259			return(context);
260			cp2 = context; /* find mark */
261			while (++cp2 && cp2 != CNTXMARK)
262			;
263			cp1 = context; /* copy tail to front */
264	schorsch	2.20	while ( (cp1++ = cp2++) )
265	greg	2.6	;
266	greg	1.13	return(context);
267			}
268
269
270			char *
271	schorsch	2.16	qualname( /* get qualified name */
272			register char *nam,
273			int lvl
274			)
275	greg	1.13	{
276	schorsch	2.17	static char nambuf[RMAXWORD+1];
277	greg	1.17	register char cp = nambuf, cpp;
278			/* check for explicit local */
279	greg	1.15	if (*nam == CNTXMARK)
280	greg	1.17	if (lvl > 0) /* only action is to refuse search */
281			return(NULL);
282			else
283			nam++;
284			else if (nam == nambuf) /* check for repeat call */
285			return(lvl > 0 ? NULL : nam);
286	greg	1.13	/* copy name to static buffer */
287			while (*nam) {
288	schorsch	2.17	if (cp >= nambuf+RMAXWORD)
289	greg	1.13	goto toolong;
290	greg	1.17	cp++ = nam++;
291	greg	1.13	}
292	greg	1.17	/* check for explicit global */
293			if (cp > nambuf && cp[-1] == CNTXMARK) {
294	greg	1.13	if (lvl > 0)
295	greg	1.17	return(NULL);
296			*--cp = '\0';
297			return(nambuf); /* already qualified */
298			}
299			cpp = context; /* else skip the requested levels */
300			while (lvl-- > 0) {
301			if (!*cpp)
302			return(NULL); /* return NULL if past global level */
303			while (++cpp && cpp != CNTXMARK)
304			;
305			}
306	greg	1.13	while (cpp) { / copy context to static buffer */
307	schorsch	2.17	if (cp >= nambuf+RMAXWORD)
308	greg	1.13	goto toolong;
309			cp++ = cpp++;
310			}
311	greg	1.18	toolong:
312	greg	1.13	*cp = '\0';
313			return(nambuf); /* return qualified name */
314			}
315
316
317	greg	2.12	int
318	schorsch	2.16	incontext( /* is qualified name in current context? */
319			register char *qn
320			)
321	greg	1.14	{
322	greg	2.9	if (!context[0]) /* global context accepts all */
323			return(1);
324	greg	1.14	while (qn && qn != CNTXMARK) /* find context mark */
325	greg	1.19	qn++;
326	greg	1.14	return(!strcmp(qn, context));
327			}
328
329
330	greg	2.12	void
331	schorsch	2.16	chanout( /* set output channels */
332			void (*cs)(int n, double v)
333			)
334	greg	1.1	{
335			register EPNODE *ep;
336
337			for (ep = outchan; ep != NULL; ep = ep->sibling)
338	greg	1.6	(*cs)(ep->v.kid->v.chan, evalue(ep->v.kid->sibling));
339	greg	1.1
340			}
341
342
343	greg	2.12	void
344	schorsch	2.16	dcleanup( /* clear definitions (0->vars,1->output,2->consts) */
345			int lvl
346			)
347	greg	1.1	{
348			register int i;
349			register VARDEF *vp;
350			register EPNODE *ep;
351	greg	1.14	/* if context is global, clear all */
352	greg	1.1	for (i = 0; i < NHASH; i++)
353			for (vp = hashtbl[i]; vp != NULL; vp = vp->next)
354	schorsch	2.19	if (incontext(vp->name)) {
355	greg	1.14	if (lvl >= 2)
356			dremove(vp->name);
357			else
358			dclear(vp->name);
359	schorsch	2.19	}
360	greg	1.12	if (lvl >= 1) {
361	greg	1.9	for (ep = outchan; ep != NULL; ep = ep->sibling)
362			epfree(ep);
363			outchan = NULL;
364			}
365	greg	1.1	}
366
367
368			EPNODE *
369	schorsch	2.16	dlookup( /* look up a definition */
370			char *name
371			)
372	greg	1.1	{
373			register VARDEF *vp;
374
375			if ((vp = varlookup(name)) == NULL)
376	greg	2.4	return(NULL);
377	greg	1.1	return(vp->def);
378			}
379
380
381			VARDEF *
382	schorsch	2.16	varlookup( /* look up a variable */
383			char *name
384			)
385	greg	1.1	{
386	greg	2.4	int lvl = 0;
387	greg	1.13	register char *qname;
388	greg	1.1	register VARDEF *vp;
389	greg	2.4	/* find most qualified match */
390	greg	1.13	while ((qname = qualname(name, lvl++)) != NULL)
391			for (vp = hashtbl[hash(qname)]; vp != NULL; vp = vp->next)
392			if (!strcmp(vp->name, qname))
393			return(vp);
394	greg	1.1	return(NULL);
395			}
396
397
398			VARDEF *
399	schorsch	2.16	varinsert( /* get a link to a variable */
400			char *name
401			)
402	greg	1.1	{
403			register VARDEF *vp;
404	greg	2.4	int hv;
405	greg	1.1
406	greg	1.13	if ((vp = varlookup(name)) != NULL) {
407			vp->nlinks++;
408			return(vp);
409			}
410	greg	2.3	vp = (VARDEF *)emalloc(sizeof(VARDEF));
411			vp->lib = liblookup(name);
412			if (vp->lib == NULL) /* if name not in library */
413	greg	1.16	name = qualname(name, 0); /* use fully qualified version */
414	greg	1.1	hv = hash(name);
415			vp->name = savestr(name);
416			vp->nlinks = 1;
417			vp->def = NULL;
418			vp->next = hashtbl[hv];
419			hashtbl[hv] = vp;
420			return(vp);
421			}
422	greg	2.2
423
424	greg	2.12	void
425	schorsch	2.16	libupdate( /* update library links */
426			char *fn
427			)
428	greg	2.2	{
429			register int i;
430			register VARDEF *vp;
431			/* if fn is NULL then relink all */
432			for (i = 0; i < NHASH; i++)
433			for (vp = hashtbl[i]; vp != NULL; vp = vp->next)
434			if (vp->lib != NULL \|\| fn == NULL \|\| !strcmp(fn, vp->name))
435			vp->lib = liblookup(vp->name);
436			}
437	greg	1.1
438
439	greg	2.12	void
440	schorsch	2.16	varfree( /* release link to variable */
441			register VARDEF *ln
442			)
443	greg	1.1	{
444			register VARDEF *vp;
445	greg	2.4	int hv;
446	greg	1.1
447			if (--ln->nlinks > 0)
448	greg	2.4	return; /* still active */
449	greg	1.1
450			hv = hash(ln->name);
451			vp = hashtbl[hv];
452			if (vp == ln)
453	greg	2.4	hashtbl[hv] = vp->next;
454	greg	1.1	else {
455	greg	2.4	while (vp->next != ln) /* must be in list */
456			vp = vp->next;
457			vp->next = ln->next;
458	greg	1.1	}
459			freestr(ln->name);
460			efree((char *)ln);
461			}
462
463
464			EPNODE *
465	schorsch	2.16	dfirst(void) /* return pointer to first definition */
466	greg	1.1	{
467			htndx = 0;
468			htpos = NULL;
469			ochpos = outchan;
470			return(dnext());
471			}
472
473
474			EPNODE *
475	schorsch	2.16	dnext(void) /* return pointer to next definition */
476	greg	1.1	{
477			register EPNODE *ep;
478	greg	1.19	register char *nm;
479	greg	1.1
480			while (htndx < NHASH) {
481	greg	2.4	if (htpos == NULL)
482			htpos = hashtbl[htndx++];
483			while (htpos != NULL) {
484			ep = htpos->def;
485	greg	1.19	nm = htpos->name;
486	greg	2.4	htpos = htpos->next;
487			if (ep != NULL && incontext(nm))
488			return(ep);
489			}
490	greg	1.1	}
491			if ((ep = ochpos) != NULL)
492	greg	2.4	ochpos = ep->sibling;
493	greg	1.1	return(ep);
494			}
495
496
497			EPNODE *
498	schorsch	2.16	dpop( /* pop a definition */
499			char *name
500			)
501	greg	1.1	{
502			register VARDEF *vp;
503			register EPNODE *dp;
504
505			if ((vp = varlookup(name)) == NULL \|\| vp->def == NULL)
506	greg	2.4	return(NULL);
507	greg	1.1	dp = vp->def;
508			vp->def = dp->sibling;
509			varfree(vp);
510			return(dp);
511			}
512
513
514	greg	2.12	void
515	schorsch	2.16	dpush( /* push on a definition */
516			char *nm,
517			register EPNODE *ep
518			)
519	greg	1.1	{
520			register VARDEF *vp;
521
522	greg	1.13	vp = varinsert(nm);
523	greg	1.1	ep->sibling = vp->def;
524			vp->def = ep;
525			}
526
527
528	greg	2.12	void
529	schorsch	2.16	addchan( /* add an output channel assignment */
530			EPNODE *sp
531			)
532	greg	1.1	{
533	greg	2.4	int ch = sp->v.kid->v.chan;
534	greg	1.1	register EPNODE ep, epl;
535
536			for (epl = NULL, ep = outchan; ep != NULL; epl = ep, ep = ep->sibling)
537			if (ep->v.kid->v.chan >= ch) {
538			if (epl != NULL)
539			epl->sibling = sp;
540			else
541			outchan = sp;
542			if (ep->v.kid->v.chan > ch)
543			sp->sibling = ep;
544			else {
545			sp->sibling = ep->sibling;
546			epfree(ep);
547			}
548			return;
549			}
550			if (epl != NULL)
551			epl->sibling = sp;
552			else
553			outchan = sp;
554			sp->sibling = NULL;
555
556			}
557
558
559	greg	2.12	void
560	schorsch	2.16	getstatement(void) /* get next statement */
561	greg	1.1	{
562			register EPNODE *ep;
563	greg	1.13	char *qname;
564	greg	1.16	register VARDEF *vdef;
565	greg	1.1
566			if (nextc == ';') { /* empty statement */
567			scan();
568			return;
569			}
570	greg	2.12	if (esupport&E_OUTCHAN &&
571			nextc == '$') { /* channel assignment */
572	greg	1.1	ep = getchan();
573			addchan(ep);
574	greg	2.12	} else { /* ordinary definition */
575	greg	1.1	ep = getdefn();
576	greg	1.13	qname = qualname(dname(ep), 0);
577	schorsch	2.19	if (esupport&E_REDEFW && (vdef = varlookup(qname)) != NULL) {
578	greg	2.7	if (vdef->def != NULL && epcmp(ep, vdef->def)) {
579	greg	1.16	wputs(qname);
580			if (vdef->def->type == ':')
581			wputs(": redefined constant expression\n");
582			else
583			wputs(": redefined\n");
584	greg	2.12	} else if (ep->v.kid->type == FUNC && vdef->lib != NULL) {
585	greg	1.16	wputs(qname);
586			wputs(": definition hides library function\n");
587			}
588	schorsch	2.19	}
589	greg	1.10	if (ep->type == ':')
590	greg	1.13	dremove(qname);
591	greg	1.10	else
592	greg	1.13	dclear(qname);
593			dpush(qname, ep);
594	greg	1.1	}
595			if (nextc != EOF) {
596			if (nextc != ';')
597			syntax("';' expected");
598			scan();
599			}
600			}
601
602
603			EPNODE *
604	schorsch	2.16	getdefn(void)
605			/* A -> SYM = E1 */
606			/* SYM : E1 */
607			/* FUNC(SYM,..) = E1 */
608			/* FUNC(SYM,..) : E1 */
609	greg	1.1	{
610			register EPNODE ep1, ep2;
611
612	greg	1.18	if (!isalpha(nextc) && nextc != CNTXMARK)
613	greg	1.1	syntax("illegal variable name");
614
615			ep1 = newnode();
616			ep1->type = SYM;
617			ep1->v.name = savestr(getname());
618
619	greg	2.12	if (esupport&E_FUNCTION && nextc == '(') {
620	greg	1.1	ep2 = newnode();
621			ep2->type = FUNC;
622			addekid(ep2, ep1);
623			ep1 = ep2;
624			do {
625			scan();
626			if (!isalpha(nextc))
627			syntax("illegal variable name");
628			ep2 = newnode();
629			ep2->type = SYM;
630			ep2->v.name = savestr(getname());
631			addekid(ep1, ep2);
632			} while (nextc == ',');
633			if (nextc != ')')
634			syntax("')' expected");
635			scan();
636			curfunc = ep1;
637	greg	2.10	}
638	greg	1.1
639	greg	1.8	if (nextc != '=' && nextc != ':')
640			syntax("'=' or ':' expected");
641	greg	1.1
642			ep2 = newnode();
643	greg	1.8	ep2->type = nextc;
644			scan();
645	greg	1.1	addekid(ep2, ep1);
646			addekid(ep2, getE1());
647
648	greg	2.12	if (ep1->type == SYM && ep1->sibling->type != NUM) {
649	greg	1.1	ep1 = newnode();
650			ep1->type = TICK;
651	greg	2.8	ep1->v.tick = 0;
652	greg	1.1	addekid(ep2, ep1);
653			ep1 = newnode();
654			ep1->type = NUM;
655			addekid(ep2, ep1);
656			}
657	greg	2.10	curfunc = NULL;
658	greg	1.1
659			return(ep2);
660			}
661
662
663			EPNODE *
664	schorsch	2.16	getchan(void) /* A -> $N = E1 */
665	greg	1.1	{
666			register EPNODE ep1, ep2;
667
668			if (nextc != '$')
669			syntax("missing '$'");
670			scan();
671
672			ep1 = newnode();
673			ep1->type = CHAN;
674			ep1->v.chan = getinum();
675
676			if (nextc != '=')
677			syntax("'=' expected");
678			scan();
679
680			ep2 = newnode();
681			ep2->type = '=';
682			addekid(ep2, ep1);
683			addekid(ep2, getE1());
684
685			return(ep2);
686			}
687
688
689
690			/*
691			* The following routines are for internal use only:
692			*/
693
694
695	schorsch	2.18	static double /* evaluate a variable */
696			dvalue(char name, EPNODE d)
697	greg	1.1	{
698			register EPNODE ep1, ep2;
699
700			if (d == NULL \|\| d->v.kid->type != SYM) {
701			eputs(name);
702			eputs(": undefined variable\n");
703			quit(1);
704			}
705			ep1 = d->v.kid->sibling; /* get expression */
706	greg	1.5	if (ep1->type == NUM)
707			return(ep1->v.num); /* return if number */
708	greg	1.1	ep2 = ep1->sibling; /* check time */
709	greg	2.12	if (eclock >= MAXCLOCK)
710			eclock = 1; /* wrap clock counter */
711			if (ep2->v.tick < MAXCLOCK &&
712	schorsch	2.20	(ep2->v.tick == 0) \| (ep2->v.tick != eclock)) {
713	greg	2.12	ep2->v.tick = d->type == ':' ? MAXCLOCK : eclock;
714	greg	1.1	ep2 = ep2->sibling;
715	greg	1.5	ep2->v.num = evalue(ep1); /* needs new value */
716	greg	1.1	} else
717	greg	1.5	ep2 = ep2->sibling; /* else reuse old value */
718	greg	1.1
719			return(ep2->v.num);
720			}