minix/common/lib/libc/arch/arm/string/memset_naive.S
Lionel Sambuc 84d9c625bf Synchronize on NetBSD-CVS (2013/12/1 12:00:00 UTC)
- Fix for possible unset uid/gid in toproto
 - Fix for default mtree style
 - Update libelf
 - Importing libexecinfo
 - Resynchronize GCC, mpc, gmp, mpfr
 - build.sh: Replace params with show-params.
     This has been done as the make target has been renamed in the same
     way, while a new target named params has been added. This new
     target generates a file containing all the parameters, instead of
     printing it on the console.
 - Update test48 with new etc/services (Fix by Ben Gras <ben@minix3.org)
     get getservbyport() out of the inner loop

Change-Id: Ie6ad5226fa2621ff9f0dee8782ea48f9443d2091
2014-07-28 17:05:06 +02:00

86 lines
3.5 KiB
ArmAsm

/*-
* Copyright (c) 2013 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Matt Thomas of 3am Software Foundry.
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``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 FOUNDATION OR CONTRIBUTORS
* 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>
RCSID("$NetBSD: memset_naive.S,v 1.1 2013/01/08 20:15:00 matt Exp $")
/*
* This isn't quite as simple/short as it could be but the truly trivial
* memset was an order of magnitude slower than this.
*/
ENTRY(memset)
/* LINTSTUB: void *memset(void *, int, size_t) */
mov ip, r0 /* need to preserve r0 */
cmp r2, #10 /* 10 bytes or less? */
ble .Lbyte_by_byte /* yes, bytewise is faster */
ands r3, r1, #0xff /* we are dealing with bytes */
orrne r3, r3, r3, lsl #8 /* move value into 2nd byte lane */
orrne r3, r3, r3, lsl #16 /* move value into all byte lanes */
mov r1, r2 /* move count */
ands r2, ip, #7 /* are we dword aligned? */
beq 1f /* yes we are */
rsb r2, r2, #8 /* how many bytes until aligned? */
sub r1, r1, r2 /* subtract from count */
tst ip, #1 /* halfword aligned? */
strneb r3, [ip], #1 /* nope, write a byte */
tst ip, #2 /* word aligned? */
strneh r3, [ip], #2 /* nope, write a halfword */
tst ip, #4 /* dword aligned? */
strne r3, [ip], #4 /* nope, write a word */
/*
* At this point, we are dword aligned.
*/
1: mov r2, r3 /* duplicate fill value */
2: subs r1, r1, #16 /* can we write 16 bytes? */
stmgeia ip!, {r2,r3} /* yes, write the first 8 of them */
stmgeia ip!, {r2,r3} /* yes, write the second 8 of them */
bgt 2b /* more left to fill */
RETc(eq) /* no, return */
/*
* Our count went negative but the bits below 16 haven't changed.
* So we are effectively testing modulo 16.
*/
tst r1, #8 /* can we write at least 8 bytes? */
stmneia ip!, {r2,r3} /* so do it */
tst r1, #4 /* can we write at least 4 bytes? */
strne r3, [ip], #4 /* so do it */
tst r1, #2 /* can we write at least 2 bytes? */
strneh r3, [ip], #2 /* so do it */
tst r1, #1 /* can we write 1 bytes? */
strneb r3, [ip], #1 /* so do it */
RET /* return */
.Lbyte_by_byte:
subs r2, r2, #1 /* can we write a byte? */
RETc(lt) /* no, return */
strb r3, [ip], #1 /* write a byte */
b .Lbyte_by_byte /* do next byte */
END(memset)