sysdeps/vax/memmove.s

   1 /*-
   2  * Copyright (c) 1990 The Regents of the University of California.
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 4. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  */
  29
  30 #if defined(LIBC_SCCS) && !defined(lint)
  31         .asciz "@(#)memmove.s   5.1 (Berkeley) 5/15/90"
  32 #endif /* LIBC_SCCS and not lint */
  33
  34 /*
  35  * void *memmove(dst, src, size)
  36  * returns dst
  37  *
  38  * This optimises the usual case (count < 65536) at the expense
  39  * of some extra memory references and branches when count >= 65536.
  40  */
  41
  42 #include "DEFS.h"
  43
  44 ENTRY(memmove, 0)
  45         movzwl  $65535,r0       /* r0 = 64K (needed below) */
  46         movq    8(ap),r1        /* r1 = src, r2 = length */
  47         movl    4(ap),r3        /* r3 = dst */
  48         cmpl    r1,r3
  49         bgtru   1f              /* normal forward case */
  50         beql    2f              /* equal, nothing to do */
  51         addl2   r2,r1           /* overlaps iff src<dst but src+len>dst */
  52         cmpl    r1,r3
  53         bgtru   4f              /* overlapping, must move backwards */
  54         subl2   r2,r1
  55
  56 1:      /* move forward */
  57         cmpl    r2,r0
  58         bgtru   3f              /* stupid movc3 limitation */
  59         movc3   r2,(r1),(r3)    /* move it all */
  60 2:
  61         movl    4(ap),r0        /* return original dst */
  62         ret
  63 3:
  64         subl2   r0,12(ap)       /* adjust length by 64K */
  65         movc3   r0,(r1),(r3)    /* move 64K */
  66         movl    12(ap),r2
  67         decw    r0              /* from 0 to 65535 */
  68         brb     1b              /* retry */
  69
  70 4:      /* move backward */
  71         addl2   r2,r3
  72 5:
  73         cmpl    r2,r0
  74         bgtru   6f              /* stupid movc3 limitation */
  75         subl2   r2,r1
  76         subl2   r2,r3
  77         movc3   r2,(r1),(r3)    /* move it all */
  78         movl    4(ap),r0        /* return original dst */
  79         ret
  80 6:
  81         subl2   r0,12(ap)       /* adjust length by 64K */
  82         subl2   r0,r1
  83         subl2   r0,r3
  84         movc3   r0,(r1),(r3)    /* move 64K */
  85         movl    12(ap),r2
  86         decw    r0
  87         subl2   r0,r1
  88         subl2   r0,r3
  89         brb     5b