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/*
* linux/arch/arm/lib/memset.S
*
* Copyright (C) 1995-2000 Russell King
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* ASM optimised string functions
*/
#include <asm/assembler.h>
.text
.align 5
.word 0
1: subs r2, r2, #4 @ 1 do we have enough
blt 5f @ 1 bytes to align with?
cmp r3, #2 @ 1
strltb r1, [r0], #1 @ 1
strleb r1, [r0], #1 @ 1
strb r1, [r0], #1 @ 1
add r2, r2, r3 @ 1 (r2 = r2 - (4 - r3))
/*
* The pointer is now aligned and the length is adjusted. Try doing the
* memset again.
*/
.globl memset
memset:
ands r3, r0, #3 @ 1 unaligned?
bne 1b @ 1
/*
* we know that the pointer in r0 is aligned to a word boundary.
*/
orr r1, r1, r1, lsl #8
orr r1, r1, r1, lsl #16
mov r3, r1
cmp r2, #16
blt 4f
#if ! CALGN(1)+0
/*
* 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, #64
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, #32
stmneia r0!, {r1, r3, ip, lr}
stmneia r0!, {r1, r3, ip, lr}
tst r2, #16
stmneia r0!, {r1, r3, ip, lr}
ldr lr, [sp], #4
#else
/*
* This version aligns the destination pointer in order to write
* whole cache lines at once.
*/
stmfd sp!, {r4-r7, lr}
mov r4, r1
mov r5, r1
mov r6, r1
mov r7, r1
mov ip, r1
mov lr, r1
cmp r2, #96
tstgt r0, #31
ble 3f
and ip, r0, #31
rsb ip, ip, #32
sub r2, r2, ip
movs ip, ip, lsl #(32 - 4)
stmcsia r0!, {r4, r5, r6, r7}
stmmiia r0!, {r4, r5}
tst ip, #(1 << 30)
mov ip, r1
strne r1, [r0], #4
3: subs r2, r2, #64
stmgeia r0!, {r1, r3-r7, ip, lr}
stmgeia r0!, {r1, r3-r7, ip, lr}
bgt 3b
ldmeqfd sp!, {r4-r7, pc}
tst r2, #32
stmneia r0!, {r1, r3-r7, ip, lr}
tst r2, #16
stmneia r0!, {r4-r7}
ldmfd sp!, {r4-r7, lr}
#endif
4: tst r2, #8
stmneia r0!, {r1, r3}
tst r2, #4
strne r1, [r0], #4
/*
* When we get here, we've got less than 4 bytes to zero. We
* may have an unaligned pointer as well.
*/
5: tst r2, #2
strneb r1, [r0], #1
strneb r1, [r0], #1
tst r2, #1
strneb r1, [r0], #1
mov pc, lr