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Annotation of 43BSD/contrib/cpm/src/ffc.c, revision 1.1

1.1     ! root        1: /*     ffc.c   1.4     83/05/13        */
        !             2: 
        !             3: /*
        !             4:  * If used on a vax (i.e., VAX is defined), this routine simply executes
        !             5:  * the VAX find-first-set instruction.
        !             6:  * Usage:
        !             7:  *     int startbit, field_lth, field, result;
        !             8:  *     result = ffc(startbit,field_lth,field);
        !             9:  *
        !            10:  * startbit is the bit number of the field to start the search,
        !            11:  *             the rightmost bit is number one.
        !            12:  * field_lth is the length of the field in bits.
        !            13:  * field is the actual field
        !            14:  * result is the resulting bit number,
        !            15:  *             e.g. the number of the first clear bit in the field.
        !            16:  * hs 10/29/82
        !            17:  */
        !            18: 
        !            19: ffc(start, len, field)
        !            20: 
        !            21: #ifndef VAX
        !            22:        register long field;
        !            23:        int start, len;
        !            24: {
        !            25:        register int i;
        !            26: 
        !            27:        for (i=start; i<len; i++) {
        !            28:                if ((field&1) == 0)
        !            29:                        break;
        !            30:                field >>= 1;
        !            31:        }
        !            32:        return (i);
        !            33: }
        !            34: #else
        !            35: 
        !            36:        int start, len, field;
        !            37: {
        !            38:        asm("ffc        4(ap),8(ap),12(ap),r0");
        !            39:        return;
        !            40: }
        !            41: #endif

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