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Annotation of 43BSDReno/lib/libc/vax/string/memmove.s, revision 1.1.1.1

1.1       root        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 are permitted
                      6:  * provided that: (1) source distributions retain this entire copyright
                      7:  * notice and comment, and (2) distributions including binaries display
                      8:  * the following acknowledgement:  ``This product includes software
                      9:  * developed by the University of California, Berkeley and its contributors''
                     10:  * in the documentation or other materials provided with the distribution
                     11:  * and in all advertising materials mentioning features or use of this
                     12:  * software. Neither the name of the University nor the names of its
                     13:  * contributors may be used to endorse or promote products derived
                     14:  * from this software without specific prior written permission.
                     15:  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
                     16:  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
                     17:  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
                     18:  */
                     19: 
                     20: #if defined(LIBC_SCCS) && !defined(lint)
                     21:        .asciz "@(#)memmove.s   5.1 (Berkeley) 5/15/90"
                     22: #endif /* LIBC_SCCS and not lint */
                     23: 
                     24: /*
                     25:  * void *memmove(dst, src, size)
                     26:  * returns dst
                     27:  *
                     28:  * This optimises the usual case (count < 65536) at the expense
                     29:  * of some extra memory references and branches when count >= 65536.
                     30:  */
                     31: 
                     32: #include "DEFS.h"
                     33: 
                     34: ENTRY(memmove, 0)
                     35:        movzwl  $65535,r0       /* r0 = 64K (needed below) */
                     36:        movq    8(ap),r1        /* r1 = src, r2 = length */
                     37:        movl    4(ap),r3        /* r3 = dst */
                     38:        cmpl    r1,r3
                     39:        bgtru   1f              /* normal forward case */
                     40:        beql    2f              /* equal, nothing to do */
                     41:        addl2   r2,r1           /* overlaps iff src<dst but src+len>dst */
                     42:        cmpl    r1,r3
                     43:        bgtru   4f              /* overlapping, must move backwards */
                     44:        subl2   r2,r1
                     45: 
                     46: 1:     /* move forward */
                     47:        cmpl    r2,r0
                     48:        bgtru   3f              /* stupid movc3 limitation */
                     49:        movc3   r2,(r1),(r3)    /* move it all */
                     50: 2:
                     51:        movl    4(ap),r0        /* return original dst */
                     52:        ret
                     53: 3:
                     54:        subl2   r0,12(ap)       /* adjust length by 64K */
                     55:        movc3   r0,(r1),(r3)    /* move 64K */
                     56:        movl    12(ap),r2
                     57:        decw    r0              /* from 0 to 65535 */
                     58:        brb     1b              /* retry */
                     59: 
                     60: 4:     /* move backward */
                     61:        addl2   r2,r3
                     62: 5:
                     63:        cmpl    r2,r0
                     64:        bgtru   6f              /* stupid movc3 limitation */
                     65:        subl2   r2,r1
                     66:        subl2   r2,r3
                     67:        movc3   r2,(r1),(r3)    /* move it all */
                     68:        movl    4(ap),r0        /* return original dst */
                     69:        ret
                     70: 6:
                     71:        subl2   r0,12(ap)       /* adjust length by 64K */
                     72:        subl2   r0,r1
                     73:        subl2   r0,r3
                     74:        movc3   r0,(r1),(r3)    /* move 64K */
                     75:        movl    12(ap),r2
                     76:        decw    r0
                     77:        subl2   r0,r1
                     78:        subl2   r0,r3
                     79:        brb     5b

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