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Annotation of sys/arch/powerpc/powerpc/bcopy.c, Revision 1.1

1.1     ! nbrk        1: /*     $OpenBSD: bcopy.c,v 1.5 2003/10/15 02:43:09 drahn Exp $ */
        !             2: /*-
        !             3:  * Copyright (c) 1990 The Regents of the University of California.
        !             4:  * All rights reserved.
        !             5:  *
        !             6:  * This code is derived from software contributed to Berkeley by
        !             7:  * Chris Torek.
        !             8:  *
        !             9:  * Redistribution and use in source and binary forms, with or without
        !            10:  * modification, are permitted provided that the following conditions
        !            11:  * are met:
        !            12:  * 1. Redistributions of source code must retain the above copyright
        !            13:  *    notice, this list of conditions and the following disclaimer.
        !            14:  * 2. Redistributions in binary form must reproduce the above copyright
        !            15:  *    notice, this list of conditions and the following disclaimer in the
        !            16:  *    documentation and/or other materials provided with the distribution.
        !            17:  * 3. Neither the name of the University nor the names of its contributors
        !            18:  *    may be used to endorse or promote products derived from this software
        !            19:  *    without specific prior written permission.
        !            20:  *
        !            21:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
        !            22:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
        !            23:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
        !            24:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
        !            25:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
        !            26:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
        !            27:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
        !            28:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
        !            29:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
        !            30:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
        !            31:  * SUCH DAMAGE.
        !            32:  */
        !            33:
        !            34: #if defined(LIBC_SCCS) && !defined(lint)
        !            35: /*static char *sccsid = "from: @(#)bcopy.c     5.11 (Berkeley) 6/21/91";*/
        !            36: static char *rcsid = "$Id: bcopy.c,v 1.5 2003/10/15 02:43:09 drahn Exp $";
        !            37: #endif /* LIBC_SCCS and not lint */
        !            38:
        !            39: #include <sys/cdefs.h>
        !            40: /*
        !            41: #include <string.h>
        !            42: */
        !            43: #include <sys/types.h>
        !            44: #include <sys/systm.h>
        !            45:
        !            46: /*
        !            47:  * sizeof(word) MUST BE A POWER OF TWO
        !            48:  * SO THAT wmask BELOW IS ALL ONES
        !            49:  */
        !            50: typedef        int word;               /* "word" used for optimal copy speed */
        !            51:
        !            52: #define        wsize   sizeof(word)
        !            53: #define        wmask   (wsize - 1)
        !            54:
        !            55: /*
        !            56:  * Copy a block of memory, handling overlap.
        !            57:  * This is the routine that actually implements
        !            58:  * (the portable versions of) bcopy, memcpy, and memmove.
        !            59:  */
        !            60: #ifdef MEMCOPY
        !            61: void *
        !            62: memcpy(void *dst0, const void *src0, size_t length)
        !            63: #else
        !            64: #ifdef MEMMOVE
        !            65: void *
        !            66: memmove(void *dst0, const void *src0, size_t length)
        !            67: #else
        !            68: void
        !            69: bcopy(const void *src0, void *dst0, size_t length)
        !            70: #endif
        !            71: #endif
        !            72: {
        !            73:        char *dst = dst0;
        !            74:        const char *src = src0;
        !            75:        size_t t;
        !            76:
        !            77:        if (length == 0 || dst == src)          /* nothing to do */
        !            78:                goto done;
        !            79:
        !            80:        /*
        !            81:         * Macros: loop-t-times; and loop-t-times, t>0
        !            82:         */
        !            83: #define        TLOOP(s) if (t) TLOOP1(s)
        !            84: #define        TLOOP1(s) do { s; } while (--t)
        !            85:
        !            86:        if ((unsigned long)dst < (unsigned long)src) {
        !            87:                /*
        !            88:                 * Copy forward.
        !            89:                 */
        !            90:                t = (int)src;   /* only need low bits */
        !            91:                if ((t | (int)dst) & wmask) {
        !            92:                        /*
        !            93:                         * Try to align operands.  This cannot be done
        !            94:                         * unless the low bits match.
        !            95:                         */
        !            96:                        if ((t ^ (int)dst) & wmask || length < wsize)
        !            97:                                t = length;
        !            98:                        else
        !            99:                                t = wsize - (t & wmask);
        !           100:                        length -= t;
        !           101:                        TLOOP1(*dst++ = *src++);
        !           102:                }
        !           103:                /*
        !           104:                 * Copy whole words, then mop up any trailing bytes.
        !           105:                 */
        !           106:                t = length / wsize;
        !           107:                TLOOP(*(word *)dst = *(word *)src; src += wsize; dst += wsize);
        !           108:                t = length & wmask;
        !           109:                TLOOP(*dst++ = *src++);
        !           110:        } else {
        !           111:                /*
        !           112:                 * Copy backwards.  Otherwise essentially the same.
        !           113:                 * Alignment works as before, except that it takes
        !           114:                 * (t&wmask) bytes to align, not wsize-(t&wmask).
        !           115:                 */
        !           116:                src += length;
        !           117:                dst += length;
        !           118:                t = (int)src;
        !           119:                if ((t | (int)dst) & wmask) {
        !           120:                        if ((t ^ (int)dst) & wmask || length <= wsize)
        !           121:                                t = length;
        !           122:                        else
        !           123:                                t &= wmask;
        !           124:                        length -= t;
        !           125:                        TLOOP1(*--dst = *--src);
        !           126:                }
        !           127:                t = length / wsize;
        !           128:                TLOOP(src -= wsize; dst -= wsize; *(word *)dst = *(word *)src);
        !           129:                t = length & wmask;
        !           130:                TLOOP(*--dst = *--src);
        !           131:        }
        !           132: done:
        !           133: #if defined(MEMCOPY) || defined(MEMMOVE)
        !           134:        return (dst0);
        !           135: #else
        !           136:        return;
        !           137: #endif
        !           138: }