a/sys/vax/urem.s

#       urem.s  5.1     82/07/15
#
#       urem - unsigned remainder for vax-11
#
#       arguments: dividend, divisor
#       result: remainder
#       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 0.  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 remainder
#       must be the dividend if divisor > dividend, and the dividend
#       minus the divisor otherwise.  The comparison must be unsigned.
#
        .text
        .align  1
        .globl  urem
urem:   .word   0x0000
        movl    4(ap),r0        # Dividend
        movl    8(ap),r2        # Divisor
        jeql    div             # If divisor=0, force exception
        cmpl    r2,$1           # If divisor <= 1 (signed),
        jleq    nodiv           #  no division is necessary
div:    clrl    r1              # Zero-extend the dividend
        ediv    r2,r0,r2,r0     # Divide.  q->r2 (discarded), r->r0
        ret
nodiv:  jneq    nzero           # If divisor=1, return 0
        clrl    r0              #  (because doing the divide will overflow
        ret                     #  if the dividend has its high bit on)
nzero:  cmpl    r0,r2           # If dividend < divisor (unsigned)
        jlssu   retn            #  remainder is dividend
        subl2   r2,r0           #  else remainder is dividend - divisor
retn:   ret