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Annotation of sys/lib/libkern/arch/mips64/bzero.S, Revision 1.1.1.1

1.1       nbrk        1: /*     $OpenBSD: bzero.S,v 1.6 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:
                     35: #include "DEFS.h"
                     36:
                     37: /*
                     38:  * bzero(void *p, size_t len)
                     39:  */
                     40: LEAF(bzero, 0)
                     41: ALEAF(blkclr)
                     42:        .set    noreorder
                     43: #ifdef _STANDALONE
                     44:        blt     a1, 12, smallclr        # small amount to clear?
                     45:        PTR_SUBU a3, zero, a0           # compute # bytes to word align address
                     46:        and     a3, a3, 3
                     47:        beq     a3, zero, 1f            # skip if word aligned
                     48:        PTR_SUBU a1, a1, a3             # subtract from remaining count
                     49:        SWHI    zero, 0(a0)             # clear 1, 2, or 3 bytes to align
                     50:        PTR_ADDU a0, a0, a3
                     51: 1:
                     52:        and     v0, a1, 3               # compute number of words left
                     53:        PTR_SUBU a3, a1, v0
                     54:        move    a1, v0
                     55:        PTR_ADDU a3, a3, a0             # compute ending address
                     56: 2:
                     57:        PTR_ADDU a0, a0, 4              # clear words
                     58:        bne     a0, a3, 2b              #  unrolling loop does not help
                     59:        sw      zero, -4(a0)            #  since we are limited by memory speed
                     60: #else
                     61:        blt     a1, 24, smallclr        # small amount to clear?
                     62:        PTR_SUBU a3, zero, a0           # compute # bytes to word align address
                     63:        and     a3, a3, 7
                     64:        beq     a3, zero, 1f            # skip if word aligned
                     65:        PTR_SUBU a1, a1, a3             # subtract from remaining count
                     66:        SDHI    zero, 0(a0)             # clear 1, 2, or 3 bytes to align
                     67:        PTR_ADDU a0, a0, a3
                     68: 1:
                     69:        and     v0, a1, 7               # compute number of words left
                     70:        PTR_SUBU a3, a1, v0
                     71:        move    a1, v0
                     72:        PTR_ADDU a3, a3, a0             # compute ending address
                     73: 2:
                     74:        PTR_ADDU a0, a0, 8              # clear words
                     75:        bne     a0, a3, 2b              #  unrolling loop does not help
                     76:        sd      zero, -8(a0)            #  since we are limited by memory speed
                     77: #endif
                     78: smallclr:
                     79:        ble     a1, zero, 2f
                     80:        PTR_ADDU a3, a1, a0             # compute ending address
                     81: 1:
                     82:        PTR_ADDU a0, a0, 1              # clear bytes
                     83:        bne     a0, a3, 1b
                     84:        sb      zero, -1(a0)
                     85: 2:
                     86:        j       ra
                     87:        nop
                     88: END(bzero)