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memset.S revision 1.1 
      1 /*	$NetBSD: memset.S,v 1.1 2014/09/03 19:34:25 matt Exp $ */
      2 
      3 /*-
      4  * Copyright (c) 2014 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Matt Thomas of 3am Software Foundry.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 #include <machine/asm.h>
     33 
     34 
     35 #if defined(LIBC_SCCS) && !defined(lint)
     36 __RCSID("$NetBSD: memset.S,v 1.1 2014/09/03 19:34:25 matt Exp $")
     37 #endif /* LIBC_SCCS && !lint */
     38 
     39 /*----------------------------------------------------------------------*/
     40 /*
     41      void bzero(void *b r3, size_t len r4);
     42      void * memset(void *b r3, int c r4, size_t len r5);
     43 */
     44 /*----------------------------------------------------------------------*/
     45 
     46 
     47 #ifdef _BZERO
     48 #define r_fill	r0
     49 ENTRY(bzero)
     50 #else
     51 #define r_fill	r4
     52 ENTRY(memset)
     53 #endif
     54 #ifdef _BZERO
     55 		l.ori	r5, r4, 0
     56 		l.or	r4, r0, r0
     57 #else
     58 		l.or	r11, r3, r0		/* move start to return value */
     59 #endif
     60 		l.sfeqi	r5, 0			/* anything to do? */
     61 		l.bf	.Lret			/*   no, just return */
     62 		l.nop
     63 
     64 		l.sfgeui r5, 7			/* small buffer? */
     65 		l.add	r5, r5, r3		/* r5 is end pointer */
     66 		l.bnf	.Lbyte_fill		/*   yes.  just byte fill */
     67 		l.nop
     68 
     69 #ifndef _BZERO
     70 		// Let's see the fill type
     71 		l.sfeqi	r4, 0			/* filling with 0? */
     72 		l.bf	.Lalignment_check	/* don't to replicate */
     73 		l.nop
     74 		l.extbz	r4, r4			/* truncate to 8 bits */
     75 		l.slli	r13, r4, 8		/* shift left 8 bits */
     76 		l.or	r4, r4, r13		/* merge the two bytes */
     77 		l.slli	r13, r4, 16		/* shift left 16 bits */
     78 		l.or	r4, r4, r13		/* merge the two halves */
     79 
     80 .Lalignment_check:
     81 #endif
     82 		l.andi	r13, r3, 3		/* get low bits of start */
     83 		l.sfeqi	r13, 0			/* word aligned? */
     84 		l.bf	.Lword_fill		/*   yes, start setting */
     85 		l.nop
     86 
     87 		l.add	r5, r5, r13		/* increase length */
     88 		l.sub	r3, r3, r13		/* mask word aligned */
     89 		l.slli	r13, r13, 3		/* bytes to bits */
     90 		l.addi	r15, r13, -8		/* minus one byte */
     91 
     92 		l.lwz	r6, 0(r3)		/* get first word */
     93 		l.movhi	r7, 0xff00		/* 0xff000000 */
     94 		l.sra	r7, r7, r13		/* shift right align bytes */
     95 		l.and	r6, r6, r7		/* clear bytes to be filled */
     96 #ifndef _BZERO
     97 		l.srl	r7, r_fill, r13		/* clear bytes to preserve */
     98 		l.or	r6, r6, r7		/* merge existing with new */
     99 #endif
    100 		l.sw	0(r3), r6		/* store first word */
    101 		l.addi	r3, r3, 4		/* advance to next word */
    102 		l.addi	r5, r5, -4		/* one less word to do */
    103 
    104 .Lword_aligned:
    105 		l.srli	r6, r5, 2		/* clear low two bits of len */
    106 		l.srli	r6, r6, 2		/* ... */
    107 		l.sfgeu	r3, r6			/* any more full words? */
    108 		l.bf	.Lend_fill		/* no, handle the last bytes */
    109 		l.nop
    110 
    111 .Lword_fill:
    112 		l.sw	0(r3), r_fill		/* store a word */
    113 		l.addi	r3, r3, 4		/* advance */
    114 		l.sfgeu	r3, r6			/* any more full words? */
    115 		l.bnf	.Lword_fill		/*   yes, fill next word */
    116 		l.nop
    117 		l.j	.Lend_fill		/* fill any leftover bytes */
    118 		l.nop
    119 
    120 .Lbyte_fill:
    121 		l.sb	0(r3), r_fill		/* store a byte */
    122 		l.addi	r3, r3, 1		/* advance */
    123 .Lend_fill:
    124 		l.sfeq	r3, r5			/* at the end? */
    125 		l.bnf	.Lbyte_fill		/*   no, fill next byte */
    126 		l.nop
    127 
    128 .Lret:
    129 		l.jr	lr			/* return */
    130 		l.nop
    131 #ifdef _BZERO
    132 END(bzero)
    133 #else
    134 END(memset)
    135 #endif
    136