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/*======================================================================
Cs <- SCADDSCON(C,A)
Sub-CAD data structure construct.
Inputs
C : A partial cad.
A : The ancestor of C.
n : The highest level to allow the CAD to go.
Outputs
Cs: A sub-CAD data structure representing the input cad.
Note: The sub-cad data structure:
(c,L,a,i,S) SC_REP 1 SC_PAR 2 SC_INX 3 SC_CDTV 4
c : A cell in C which represents c.
a : The ancestor of c (NIL if c is the root cell)
i : The index of c in its stack.
L : If c has children then a list of its children (each element being
a sub-cad cell structure). If c has no children, then its truth
value.
This is a recursive data structure, so trying to 'OWRITE' it, for
example, would be bad.
======================================================================*/
#include "qepcad.h"
#include "coarsecad.h"
Word SCADDSCON(Word C, Word A, Word n)
{
Word c,a,i,Cs,X,L;
Step1: /* Construct a preliminary version of Cs, with all but the child
list filled in. */
c = C;
a = A;
if (A == NIL)
i = 0;
else
i = LAST(LELTI(C,INDX));
if (n == 0) {
Cs = LIST4(c,a,i,CATV(C));
goto Return; }
else
Cs = LIST4(c,a,i,NIL);
Step2: /* Fill in the child list, using the list handle for Cs for
recursive calls to SCADDSCON. */
X = LELTI(C,CHILD);
if (X == NIL)
L = LELTI(C,TRUTH);
else {
X = CINV(X);
L = NIL;
while (X != NIL) {
L = COMP(SCADDSCON(FIRST(X),Cs,n-1),L);
X = RED(X); } }
Step3: /* Set the SC_CDTV element to L as constructed in Step2. */
SLELTI(Cs,SC_CDTV,L);
Return: /* Prepare to return. */
return (Cs);
}
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