rockbox/firmware/target/arm/memset16-arm.S

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/***************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
* $Id$
*
* Copyright (C) 2006 by Thom Johansen
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
****************************************************************************/
#include "config.h"
.section .icode,"ax",%progbits
.align 2
/* The following code is based on code from the Linux kernel version 2.6.15.3,
* linux/arch/arm/lib/memset.S
*
* Copyright (C) 1995-2000 Russell King
*/
.global memset16
.type memset16,%function
memset16:
tst r0, #2 @ unaligned?
cmpne r2, #0
strneh r1, [r0], #2 @ store one halfword to align
subne r2, r2, #1
/*
* we know that the pointer in r0 is aligned to a word boundary.
*/
orr r1, r1, r1, lsl #16
mov r3, r1
cmp r2, #8
blt 4f
/*
* We need an extra register for this loop - save the return address and
* use the LR
*/
str lr, [sp, #-4]!
mov ip, r1
mov lr, r1
2: subs r2, r2, #32
stmgeia r0!, {r1, r3, ip, lr} @ 64 bytes at a time.
stmgeia r0!, {r1, r3, ip, lr}
stmgeia r0!, {r1, r3, ip, lr}
stmgeia r0!, {r1, r3, ip, lr}
bgt 2b
ldmeqfd sp!, {pc} @ Now <64 bytes to go.
/*
* No need to correct the count; we're only testing bits from now on
*/
tst r2, #16
stmneia r0!, {r1, r3, ip, lr}
stmneia r0!, {r1, r3, ip, lr}
tst r2, #8
stmneia r0!, {r1, r3, ip, lr}
ldr lr, [sp], #4
4: tst r2, #4
stmneia r0!, {r1, r3}
tst r2, #2
strne r1, [r0], #4
tst r2, #1
strneh r1, [r0], #2
bx lr
.end:
.size memset16,.end-memset16