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Annotation of 43BSDReno/pgrm/lisp/franz/tahoe/exarith.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * exarith(mul1,mul2,add,hi,lo)
        !             3:  *
        !             4:  * (hi,lo) gets 64 bit product + sum of mul1*mul2+add;
        !             5:  * routine returns non-zero if product is bigger than 30 bits
        !             6:  *
        !             7:  * Copyright (c) 1982, Regents, University of California
        !             8:  *
        !             9:  * stolen from 68k by P. S. Housel 04/29/86, with minor mods
        !            10:  *     (replaced call to emul with asm("emul..."))
        !            11:  */
        !            12: 
        !            13: struct vl
        !            14:        {long high;
        !            15:        long low;
        !            16:        };
        !            17: 
        !            18: long exarith(mul1,mul2,add,hi,lo)
        !            19: long *hi, *lo;
        !            20: register long add;
        !            21: {
        !            22:        register long rlo;
        !            23:        struct vl work;
        !            24: 
        !            25:             asm("      emul    4(fp),8(fp),r12,-60(fp)");
        !            26: 
        !            27:            add = work.high;
        !            28:            add <<= 2;
        !            29:            if((rlo = work.low) < 0) add += 2;
        !            30:            if(rlo & 0x40000000) add += 1;
        !            31:            *lo = rlo &0x3fffffff;
        !            32:            (*hi = add);
        !            33:            if((add==0) || (add!=-1)) return(add);
        !            34:            *lo = rlo;
        !            35:            return(0);
        !            36: }

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