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