BSD 3 development

[unix-history] / usr / src / cmd / pi / lab.c

/* Copyright (c) 1979 Regents of the University of California */
#
/*
* pi - Pascal interpreter code translator
*
* Charles Haley, Bill Joy UCB
* Version 1.2 November 1978
*/

#include "whoami"
#include "0.h"
#include "tree.h"
#include "opcode.h"

/*
* Label enters the definitions
* of the label declaration part
* into the namelist.
*/
label(r, l)
       int *r, l;
{
#ifndef PI0
       register *ll;
       register struct nl *p, *lp;

       lp = NIL;
#else
       send(REVLAB, r);
#endif
       line = l;
#ifndef PI1
       if (parts & (CPRT|TPRT|VPRT))
               error("Label declarations must precede const, type and var declarations");
       if (parts & LPRT)
               error("All labels must be declared in one label part");
       parts |= LPRT;
#endif
#ifndef PI0
       for (ll = r; ll != NIL; ll = ll[2]) {
               l = getlab();
               p = enter(defnl(ll[1], LABEL, 0, l));
               /*
                * Get the label for the eventual target
                */
               p->value[1] = getlab();
               p->chain = lp;
               p->nl_flags |= (NFORWD|NMOD);
               p->value[NL_GOLEV] = NOTYET;
               p->entloc = l;
               lp = p;
               /*
                * This operator is between
                * the bodies of two procedures
                * and provides a target for
                * gotos for this label via TRA.
                */
               putlab(l);
               put2(O_GOTO | cbn<<9, p->value[1]);
       }
       gotos[cbn] = lp;
#       ifdef PTREE
           {
               pPointer        Labels = LabelDCopy( r );

               pDEF( PorFHeader[ nesting ] ).PorFLabels = Labels;
           }
#       endif
#endif
}

#ifndef PI0
/*
* Gotoop is called when
* we get a statement "goto label"
* and generates the needed tra.
*/
gotoop(s)
       char *s;
{
       register struct nl *p;

       gocnt++;
       p = lookup(s);
       if (p == NIL)
               return (NIL);
       put2(O_TRA4, p->entloc);
       if (bn == cbn)
               if (p->nl_flags & NFORWD) {
                       if (p->value[NL_GOLEV] == NOTYET) {
                               p->value[NL_GOLEV] = level;
                               p->value[NL_GOLINE] = line;
                       }
               } else
                       if (p->value[NL_GOLEV] == DEAD) {
                               recovered();
                               error("Goto %s is into a structured statement", p->symbol);
                       }
}

/*
* Labeled is called when a label
* definition is encountered, and
* marks that it has been found and
* patches the associated GOTO generated
* by gotoop.
*/
labeled(s)
       char *s;
{
       register struct nl *p;

       p = lookup(s);
       if (p == NIL)
               return (NIL);
       if (bn != cbn) {
               error("Label %s not defined in correct block", s);
               return;
       }
       if ((p->nl_flags & NFORWD) == 0) {
               error("Label %s redefined", s);
               return;
       }
       p->nl_flags &= ~NFORWD;
       patch4(p->entloc);
       if (p->value[NL_GOLEV] != NOTYET)
               if (p->value[NL_GOLEV] < level) {
                       recovered();
                       error("Goto %s from line %d is into a structured statement", s, p->value[NL_GOLINE]);
               }
       p->value[NL_GOLEV] = level;
}
#endif