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Annotation of 43BSD/lib/libc/vax/gen/urem.s, revision 1.1.1.1

1.1       root        1: #ifdef LIBC_SCCS
                      2:        .asciz  "@(#)urem.s     5.2 (Berkeley) 3/9/86"
                      3: #endif LIBC_SCCS
                      4: 
                      5: /*
                      6:  * urem - unsigned remainder for vax-11
                      7:  *
                      8:  * arguments: dividend, divisor
                      9:  * result: remainder
                     10:  * uses r0-r2
                     11:  *
                     12:  * if 1 < divisor <= 2147483647, zero-extend the dividend
                     13:  * to 64 bits and let ediv do the work.  If the divisor is 1,
                     14:  * ediv will overflow if bit 31 of the dividend is on, so
                     15:  * just return 0.  If the divisor is 0, do the ediv also,
                     16:  * so it will generate the proper exception.  All other values
                     17:  * of the divisor have bit 31 on: in this case the remainder
                     18:  * must be the dividend if divisor > dividend, and the dividend
                     19:  * minus the divisor otherwise.  The comparison must be unsigned.
                     20:  */
                     21: #include "DEFS.h"
                     22: 
                     23: ASENTRY(urem, 0)
                     24:        movl    4(ap),r0        /* dividend */
                     25:        movl    8(ap),r2        /* divisor */
                     26:        jeql    1f              /* if divisor=0, force exception */
                     27:        cmpl    r2,$1           /* if divisor <= 1 (signed), */
                     28:        jleq    2f              /*  no division is necessary */
                     29: 1:
                     30:        clrl    r1              /* zero-extend the dividend */
                     31:        ediv    r2,r0,r2,r0     /* divide.  q->r2 (discarded), r->r0 */
                     32:        ret
                     33: 2:
                     34:        jneq    1f              /* if divisor=1, return 0 */
                     35:        clrl    r0              /*  (because doing the divide will overflow */
                     36:        ret                     /*  if the dividend has its high bit on) */
                     37: 1:
                     38:        cmpl    r0,r2           /* if dividend < divisor (unsigned) */
                     39:        jlssu   1f              /*  remainder is dividend */
                     40:        subl2   r2,r0           /*  else remainder is dividend - divisor */
                     41: 1:
                     42:        ret
                     43: 
                     44: /*
                     45:  * aurem - unsigned remainder for vax-11
                     46:  *
                     47:  * arguments: *dividend, divisor
                     48:  * result: remainder in r0 and *dividend
                     49:  * uses r0-r2
                     50:  */
                     51: #include "DEFS.h"
                     52: 
                     53: ASENTRY(aurem, 0)
                     54:        movl    *4(ap),r0       /* dividend */
                     55:        movl    8(ap),r2        /* divisor */
                     56:        jeql    1f              /* if divisor=0, force exception */
                     57:        cmpl    r2,$1           /* if divisor <= 1 (signed), */
                     58:        jleq    2f              /*  no division is necessary */
                     59: 1:
                     60:        clrl    r1              /* zero-extend the dividend */
                     61:        ediv    r2,r0,r2,r0     /* divide.  q->r2 (discarded), r->r0 */
                     62:        movl    r0,*4(ap)       /* save result */
                     63:        ret
                     64: 2:
                     65:        jneq    1f              /* if divisor=1, return 0 */
                     66:        clrl    r0              /*  (because doing the divide will overflow */
                     67:        clrl    *4(ap)          /*  if the dividend has its high bit on) */
                     68:        ret     
                     69: 1:
                     70:        cmpl    r0,r2           /* if dividend < divisor (unsigned) */
                     71:        jlssu   1f              /*  remainder is dividend */
                     72:        subl2   r2,r0           /*  else remainder is dividend - divisor */
                     73: 1:
                     74:        movl    r0,*4(ap)       /* save result */
                     75:        ret

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