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Annotation of sys/lib/libkern/arch/mips64/bcopy.S, Revision 1.1

1.1     ! nbrk        1: /*     $OpenBSD: bcopy.S,v 1.4 2004/10/08 14:42:09 pefo Exp $  */
        !             2: /*-
        !             3:  * Copyright (c) 1991, 1993
        !             4:  *      The Regents of the University of California.  All rights reserved.
        !             5:  *
        !             6:  * This code is derived from software contributed to Berkeley by
        !             7:  * Ralph Campbell.
        !             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: #include "DEFS.h"
        !            35:
        !            36:
        !            37: /*
        !            38:  * memcpy(to, from, len)
        !            39:  * {ov}bcopy(from, to, len)
        !            40:  */
        !            41: LEAF(memcpy, 0)
        !            42:        .set    noreorder
        !            43:        move    v0, a0                  # swap from and to
        !            44:        move    a0, a1
        !            45:        move    a1, v0
        !            46: ALEAF(bcopy)
        !            47: ALEAF(ovbcopy)
        !            48:        .set    noreorder
        !            49:        PTR_ADDU t0, a0, a2             # t0 = end of s1 region
        !            50:        sltu    t1, a1, t0
        !            51:        sltu    t2, a0, a1
        !            52:        and     t1, t1, t2              # t1 = true if from < to < (from+len)
        !            53:        beq     t1, zero, forward       # non overlapping, do forward copy
        !            54:        slt     t2, a2, 12              # check for small copy
        !            55:
        !            56:        ble     a2, zero, 2f
        !            57:        PTR_ADDU t1, a1, a2             # t1 = end of to region
        !            58: 1:
        !            59:        lb      v1, -1(t0)              # copy bytes backwards,
        !            60:        PTR_SUBU t0, t0, 1              #   doesnt happen often so do slow way
        !            61:        PTR_SUBU t1, t1, 1
        !            62:        bne     t0, a0, 1b
        !            63:        sb      v1, 0(t1)
        !            64: 2:
        !            65:        j       ra
        !            66:        nop
        !            67: forward:
        !            68:        bne     t2, zero, smallcpy      # do a small bcopy
        !            69:        xor     v1, a0, a1              # compare low two bits of addresses
        !            70:        and     v1, v1, 3
        !            71:        PTR_SUBU a3, zero, a1           # compute # bytes to word align address
        !            72:        beq     v1, zero, aligned       # addresses can be word aligned
        !            73:        and     a3, a3, 3
        !            74:
        !            75:        beq     a3, zero, 1f
        !            76:        PTR_SUBU a2, a2, a3             # subtract from remaining count
        !            77:        LWHI    v1, 0(a0)               # get next 4 bytes (unaligned)
        !            78:        LWLO    v1, 3(a0)
        !            79:        PTR_ADDU a0, a0, a3
        !            80:        SWHI    v1, 0(a1)               # store 1, 2, or 3 bytes to align a1
        !            81:        PTR_ADDU a1, a1, a3
        !            82: 1:
        !            83:        and     v1, a2, 3               # compute number of words left
        !            84:        PTR_SUBU a3, a2, v1
        !            85:        move    a2, v1
        !            86:        PTR_ADDU a3, a3, a0             # compute ending address
        !            87: 2:
        !            88:        LWHI    v1, 0(a0)               # copy words a0 unaligned, a1 aligned
        !            89:        LWLO    v1, 3(a0)
        !            90:        PTR_ADDU a0, a0, 4
        !            91:        sw      v1, 0(a1)
        !            92:        PTR_ADDU a1, a1, 4
        !            93:        bne     a0, a3, 2b
        !            94:        nop                             # We have to do this mmu-bug.
        !            95:        b       smallcpy
        !            96:        nop
        !            97: aligned:
        !            98:        beq     a3, zero, 1f
        !            99:        PTR_SUBU a2, a2, a3             # subtract from remaining count
        !           100:        LWHI    v1, 0(a0)               # copy 1, 2, or 3 bytes to align
        !           101:        PTR_ADDU a0, a0, a3
        !           102:        SWHI    v1, 0(a1)
        !           103:        PTR_ADDU a1, a1, a3
        !           104: 1:
        !           105:        and     v1, a2, 3               # compute number of whole words left
        !           106:        PTR_SUBU a3, a2, v1
        !           107:        move    a2, v1
        !           108:        PTR_ADDU a3, a3, a0             # compute ending address
        !           109: 2:
        !           110:        lw      v1, 0(a0)               # copy words
        !           111:        PTR_ADDU a0, a0, 4
        !           112:        sw      v1, 0(a1)
        !           113:        bne     a0, a3, 2b
        !           114:        PTR_ADDU a1, a1, 4
        !           115: smallcpy:
        !           116:        ble     a2, zero, 2f
        !           117:        PTR_ADDU a3, a2, a0             # compute ending address
        !           118: 1:
        !           119:        lbu     v1, 0(a0)               # copy bytes
        !           120:        PTR_ADDU a0, a0, 1
        !           121:        sb      v1, 0(a1)
        !           122:        bne     a0, a3, 1b
        !           123:        PTR_ADDU a1, a1, 1      # MMU BUG ? can not do -1(a1) at 0x80000000!!
        !           124: 2:
        !           125:        j       ra
        !           126:        nop
        !           127: END(memcpy)