/*      $NetBSD: memset.S,v 1.7 2011/01/17 07:07:36 matt Exp $ */

/*-
 * Copyright (C) 2003   Matt Thomas <matt@3am-software.com>
 * Copyright (C) 2001   Martin J. Laubach <mjl@NetBSD.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
/*----------------------------------------------------------------------*/

#include <machine/asm.h>

/*----------------------------------------------------------------------*/
/*
     void bzero(void *b r3, size_t len r4);
     void *memset(void *b r3, int c r4, size_t len r5);
*/
/*----------------------------------------------------------------------*/

#define r_dst   %r4
#define r_len   %r5
#define r_tmp   %r6
#define r_val   %r0

ENTRY(bzero)
                li      r_val, 0                /* Value to fill with */
                mr      r_len, %r4
                b       cb_memset

ENTRY(memset)
                mr      r_val, %r4              /* Value to fill with */

cb_memset:
                cmplwi  r_len, 0                /* is the length 0? */
                beqlr-                          /*    nothing to do */
                mr      r_dst, %r3
                /*
                 * r3=start, r4=dstptr, r5=length, r0=fill-val
                 */
                cmplwi  r_len, 6                /* more than 6 bytes? */
                bgt     complex_fill            /*    do it the complex way */
                subi    r_dst, r_dst, 1         /* presubtract for stbu */
simple_fill:    mtctr   r_len                   /* set CTR */
1:              stbu    r_val, 1(r_dst)         /* update memory */
                bdnz+   1b                      /*    until CTR is 0 */
                blr                             /* return */

complex_fill:
                rlwimi  r_val, r_val, 8, 16, 23 /* word extend fill value */
                rlwimi  r_val, r_val, 16, 0, 15
                andi.   r_tmp, r_dst, 0x03
                beq+    word_fill               /* already aligned to word? */
                andi.   r_tmp, r_dst, 0x01
                beq     half_fill               /* aligned to halfword? */
                stb     r_val, 0(r_dst)
                addi    r_dst, r_dst, 1
                subi    r_len, r_len, 1         /* subtract byte */
                andi.   r_tmp, r_dst, 0x02
                beq     word_fill               /* aligned to word? */
half_fill:
                sth     r_val, 0(r_dst)
                addi    r_dst, r_dst, 2
                subi    r_len, r_len, 2         /* subtract halfword */

word_fill:
                cmplwi  r_len, 4                /* we have more than 4 bytes? */
                blt-    trailing_bytes          /* no?  finish writing */
                srwi    r_tmp, r_len, 2         /* get word count */
                mtctr   r_tmp
                subi    r_dst, r_dst, 4
1:              stwu    r_val, 4(r_dst)
                bdnz+   1b

trailing_bytes:
                andi.   r_len, r_len, 0x03      /* how much left? */
                beqlr+                          /* nothing? return */
                addi    r_dst, r_dst, 3
                b       simple_fill