4.3BSD - /usr/src/ucb/lisp/franz/subbig.c

   1: #ifndef lint
   2: static char *rcsid =
   3:    "$Header: subbig.c,v 1.2 83/09/12 14:17:31 sklower Exp $";
   4: #endif
   5: 
   6: /*					-[Sat Jan 29 13:36:05 1983 by jkf]-
   7:  * 	subbig.c			$Locker:  $
   8:  * bignum subtraction
   9:  *
  10:  * (c) copyright 1982, Regents of the University of California
  11:  */
  12: 
  13: #include "global.h"
  14: 
  15: /*
  16:  * subbig -- subtract one bignum from another.
  17:  *
  18:  * What this does is it negates each coefficient of a copy of the bignum
  19:  * which is just pushed on the stack for convenience.  This may give rise
  20:  * to a bignum which is not in canonical form, but is nonetheless a repre
  21:  * sentation of a bignum.  Addbig then adds it to a bignum, and produces
  22:  * a result in canonical form.
  23:  */
  24: lispval
  25: subbig(pos,neg)
  26: lispval pos, neg;
  27: {
  28:     register lispval work;
  29:     lispval adbig();
  30:     register long *mysp = sp() - 2;
  31:     register long *ersatz = mysp;
  32:     Keepxs();
  33: 
  34:     for(work = neg; work!=0; work = work->s.CDR) {
  35:         stack((long)(mysp -= 2));
  36:         stack(-work->i);
  37:     }
  38:     mysp[3] = 0;
  39:     work = (adbig(pos,(lispval)ersatz));
  40:     Freexs();
  41:     return(work);
  42: }

Defined functions

Defined variables