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Annotation of sys/lib/libkern/arch/amd64/bcopy.S, Revision 1.1.1.1

1.1       nbrk        1: /*-
                      2:  * Copyright (c) 1990 The Regents of the University of California.
                      3:  * All rights reserved.
                      4:  *
                      5:  * This code is derived from locore.s.
                      6:  *
                      7:  * Redistribution and use in source and binary forms, with or without
                      8:  * modification, are permitted provided that the following conditions
                      9:  * are met:
                     10:  * 1. Redistributions of source code must retain the above copyright
                     11:  *    notice, this list of conditions and the following disclaimer.
                     12:  * 2. Redistributions in binary form must reproduce the above copyright
                     13:  *    notice, this list of conditions and the following disclaimer in the
                     14:  *    documentation and/or other materials provided with the distribution.
                     15:  * 3. All advertising materials mentioning features or use of this software
                     16:  *    must display the following acknowledgement:
                     17:  *     This product includes software developed by the University of
                     18:  *     California, Berkeley and its contributors.
                     19:  * 4. Neither the name of the University nor the names of its contributors
                     20:  *    may be used to endorse or promote products derived from this software
                     21:  *    without specific prior written permission.
                     22:  *
                     23:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
                     24:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
                     25:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
                     26:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
                     27:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
                     28:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
                     29:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
                     30:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
                     31:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
                     32:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
                     33:  * SUCH DAMAGE.
                     34:  */
                     35:
                     36: #include <machine/asm.h>
                     37:
                     38: #if defined(LIBC_SCCS)
                     39:        RCSID("$NetBSD: bcopy.S,v 1.1 2001/06/19 00:22:45 fvdl Exp $")
                     40: #endif
                     41:
                     42:        /*
                     43:         * (ov)bcopy (src,dst,cnt)
                     44:         *  ws@tools.de     (Wolfgang Solfrank, TooLs GmbH) +49-228-985800
                     45:         */
                     46:
                     47: #ifdef MEMCOPY
                     48: ENTRY(memcpy)
                     49: #else
                     50: #ifdef MEMMOVE
                     51: ENTRY(memmove)
                     52: #else
                     53: #ifdef OVBCOPY
                     54: ENTRY(ovbcopy)
                     55: #else
                     56: ENTRY(bcopy)
                     57: #endif
                     58: #endif
                     59: #endif
                     60: #if defined(MEMCOPY) || defined(MEMMOVE)
                     61:        movq    %rdi,%r11       /* save dest */
                     62: #else
                     63:        xchgq   %rdi,%rsi
                     64: #endif
                     65:        movq    %rdx,%rcx
                     66:        movq    %rdi,%rax
                     67:        subq    %rsi,%rax
                     68:        cmpq    %rcx,%rax       /* overlapping? */
                     69:        jb      1f
                     70:        cld                     /* nope, copy forwards. */
                     71:        shrq    $3,%rcx         /* copy by words */
                     72:        rep
                     73:        movsq
                     74:        movq    %rdx,%rcx
                     75:        andq    $7,%rcx         /* any bytes left? */
                     76:        rep
                     77:        movsb
                     78: #if defined(MEMCOPY) || defined(MEMMOVE)
                     79:        movq    %r11,%rax
                     80: #endif
                     81:        ret
                     82: 1:
                     83:        addq    %rcx,%rdi       /* copy backwards. */
                     84:        addq    %rcx,%rsi
                     85:        std
                     86:        andq    $7,%rcx         /* any fractional bytes? */
                     87:        decq    %rdi
                     88:        decq    %rsi
                     89:        rep
                     90:        movsb
                     91:        movq    %rdx,%rcx       /* copy remainder by words */
                     92:        shrq    $3,%rcx
                     93:        subq    $7,%rsi
                     94:        subq    $7,%rdi
                     95:        rep
                     96:        movsq
                     97: #if defined(MEMCOPY) || defined(MEMMOVE)
                     98:        movq    %r11,%rax
                     99: #endif
                    100:        cld
                    101:        ret