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Annotation of 43BSD/ucb/lisp/franz/68k/exarith.c, revision 1.1.1.1

1.1       root        1: /* Copyright (c) 1982, Regents, University of California */
                      2: struct vl      { long high; long low; };
                      3: 
                      4: /*
                      5:  * $Header $
                      6:  * exarith(mul1,mul2,add,hi,lo)
                      7:  *
                      8:  * (hi,lo) gets 64 bit product + sum of mul1*mul2+add;
                      9:  * routine returns non-zero if product is bigger than 30 bits
                     10:  */
                     11: 
                     12: long exarith(mul1,mul2,add,hi,lo)
                     13: long *hi, *lo;
                     14: register long add;
                     15: {
                     16:        struct vl work;
                     17:        register long rlo;
                     18: 
                     19:            emul(mul1,mul2,add,&work);
                     20:            add = work.high;
                     21:            add <<= 2;
                     22:            if((rlo = work.low) < 0) add += 2;
                     23:            if(rlo & 0x40000000) add += 1;
                     24:            *lo = rlo &0x3fffffff;
                     25:            (*hi = add);
                     26:            if((add==0) || (add!=-1)) return(add);
                     27:            *lo = rlo;
                     28:            return(0);
                     29: }

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