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/*
 *  (c) Copyright 1986 HEWLETT-PACKARD COMPANY
 *
 *  To anyone who acknowledges that this file is provided "AS IS"
 *  without any express or implied warranty:
 *      permission to use, copy, modify, and distribute this file
 *  for any purpose is hereby granted without fee, provided that
 *  the above copyright notice and this notice appears in all
 *  copies, and that the name of Hewlett-Packard Company not be
 *  used in advertising or publicity pertaining to distribution
 *  of the software without specific, written prior permission.
 *  Hewlett-Packard Company makes no representations about the
 *  suitability of this software for any purpose.
 */

/* SPECTRUM_ID: @(#)memset.s    37.4     86/08/25 */
/*
 * memset(s, c, n)
 *
 * Sets first n chars in memory area s to value of character c.
 * Returns s.
 */
#ifndef _NAMESPACE_CLEAN
#define NOSECDEF   /* prevent _memset from being defined as entry */
#endif

#include "DEFS.h"

#define TO      arg0
#define FILLCHAR arg1
#define COUNT   arg2
#define TMP     r31

ENTRY(memset)
        comb,<= COUNT,r0,msexit /* return if count not positive */
        copy    TO,ret0         /* return value is start of copy */
        comibf,<,n      5,COUNT,msbyteloop /* be straightforward */

        dep     FILLCHAR,23,8,FILLCHAR  /* dup low byte  */
        dep     FILLCHAR,15,16,FILLCHAR /* into high bytes */

        add             TO,COUNT,TMP    /* TMP points just past fill area */
        stbys,m         FILLCHAR,0(TO)  /* fill out first word */
        /*
         * If we're pointing to high-order byte, no fill will happen,
         * but permissions will be checked.  We don't want this (we
         * might be pointing at the beginning of a protected region),
         * so we branch around stbys if neither low bits are set.
         */
        bb,<,n          TMP,31,filend   /* if low bit is set, stbys */
        bb,>=,n         TMP,30,endfil   /* if next lowest bit isn't set */
                                        /*  (and lowest isn't, either) */
                                        /*  do not stbys */
filend:
        stbys,m,e       FILLCHAR,0(TMP) /* fill out the last */
endfil:
        addi            4, TO, TO
        sub             TMP,TO,COUNT    /* will now divide by 4 */
        comb,=,n        COUNT,r0,msexit /* If count is zero ret. */

        extru,<>        COUNT,31,4,r1
        b               msquadloop
        depi            0,31,4,COUNT    /* will now divide by 16 */


mswordloop:
        addib,<>        -4,r1,mswordloop
        stws,ma         FILLCHAR,4(TO)

        comb,=,n        COUNT,r0,msexit /* If count is zero ret. */

msquadloop:
        stws,ma         FILLCHAR,4(TO)
        stws,ma         FILLCHAR,4(TO)
        stws,ma         FILLCHAR,4(TO)
        addib,<>        -16,COUNT,msquadloop
        stws,ma         FILLCHAR,4(TO)
        b,n             msexit

msbyteloop:
        addib,<>        -1,COUNT,msbyteloop
        stbs,ma         FILLCHAR,1(TO)

msexit:
EXIT(memset)