usr/src/lib/libc/vax/gen/udiv.s

/*      udiv.s  4.1     83/06/27        */

/*
 * udiv - unsigned division for vax-11
 *
 * arguments: dividend, divisor.
 * result: quotient.
 * uses r0-r2
 *
 * If 1 < divisor <= 2147483647, zero-extend the dividend
 * to 64 bits and let ediv do the work.  If the divisor is 1,
 * ediv will overflow if bit 31 of the dividend is on, so
 * just return the dividend unchanged.  If the divisor is 0,
 * do the ediv also, so it will generate the proper exception.
 * All other values of the divisor have bit 31 on: in this case
 * the quotient must be 0 if divisor > dividend, and 1 otherwise,
 * provided that the comparison is made as unsigned.
 */

#include "DEFS.h"

ENTRY(udiv)
        movl    4(ap),r0        /* dividend */
        movl    8(ap),r2        /* divisor */
        jeql    1f              /* if divisor=0, force exception */
        cmpl    r2,$1           /* if divisor <= 1 (signed), */
        jleq    2f              /*  no division is necessary */
1:
        clrl    r1              /* zero-extend the dividend */
        ediv    r2,r0,r0,r2     /* divide.  q->r0, r->r2 (discarded) */
        ret
2:
        jeql    1f              /* if divisor=1, return dividend */
        cmpl    r0,r2           /* unsigned comparison between */
        jgequ   2f              /*  dividend and divisor */
        clrl    r0              /* dividend < divisor, return 0 */
        ret
2:
        movl    $1,r0           /* dividend >= divisor, return 1 */
1:
        ret