98 lines
3.2 KiB
ArmAsm
98 lines
3.2 KiB
ArmAsm
/***************************************************************************
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* __________ __ ___.
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* Open \______ \ ____ ____ | | _\_ |__ _______ ___
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* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
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* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
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* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
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* \/ \/ \/ \/ \/
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* $Id$
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*
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* Copyright (C) 2006 by Thom Johansen
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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* KIND, either express or implied.
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*
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****************************************************************************/
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#include "config.h"
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.section .icode,"ax",%progbits
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.align 2
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/* The following code is based on code found in Linux kernel version 2.6.15.3
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* linux/arch/arm/lib/memset.S
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*
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* Copyright (C) 1995-2000 Russell King
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*/
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/* This code will align a pointer for memset, if needed */
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1: cmp r2, #4 @ 1 do we have enough
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blt 5f @ 1 bytes to align with?
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cmp r3, #2 @ 1
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strgtb r1, [r0, #-1]! @ 1
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strgeb r1, [r0, #-1]! @ 1
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strb r1, [r0, #-1]! @ 1
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sub r2, r2, r3 @ 1 r2 = r2 - r3
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b 2f
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.global memset
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.type memset,%function
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memset:
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add r0, r0, r2 @ we'll write backwards in memory
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ands r3, r0, #3 @ 1 unaligned?
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bne 1b @ 1
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2:
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/*
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* we know that the pointer in r0 is aligned to a word boundary.
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*/
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orr r1, r1, r1, lsl #8
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orr r1, r1, r1, lsl #16
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mov r3, r1
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cmp r2, #16
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blt 5f
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/*
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* We need an extra register for this loop - save the return address and
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* use the LR
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*/
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str lr, [sp, #-4]!
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mov ip, r1
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mov lr, r1
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3: subs r2, r2, #64
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stmgedb r0!, {r1, r3, ip, lr} @ 64 bytes at a time.
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stmgedb r0!, {r1, r3, ip, lr}
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stmgedb r0!, {r1, r3, ip, lr}
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stmgedb r0!, {r1, r3, ip, lr}
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bgt 3b
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ldrpc cond=eq @ Now <64 bytes to go.
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/*
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* No need to correct the count; we're only testing bits from now on
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*/
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tst r2, #32
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stmnedb r0!, {r1, r3, ip, lr}
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stmnedb r0!, {r1, r3, ip, lr}
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tst r2, #16
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stmnedb r0!, {r1, r3, ip, lr}
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ldr lr, [sp], #4
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5: tst r2, #8
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stmnedb r0!, {r1, r3}
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tst r2, #4
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strne r1, [r0, #-4]!
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/*
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* When we get here, we've got less than 4 bytes to zero. We
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* may have an unaligned pointer as well.
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*/
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6: tst r2, #2
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strneb r1, [r0, #-1]!
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strneb r1, [r0, #-1]!
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tst r2, #1
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strneb r1, [r0, #-1]!
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bx lr
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.end:
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.size memset,.end-memset
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