126 lines
2.8 KiB
ArmAsm
126 lines
2.8 KiB
ArmAsm
/*
|
|
* linux/arch/arm/lib/memzero.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.
|
|
*/
|
|
#include <linux/linkage.h>
|
|
#include <asm/assembler.h>
|
|
|
|
.text
|
|
.align 5
|
|
.word 0
|
|
/*
|
|
* Align the pointer in r0. r3 contains the number of bytes that we are
|
|
* mis-aligned by, and r1 is the number of bytes. If r1 < 4, then we
|
|
* don't bother; we use byte stores instead.
|
|
*/
|
|
1: subs r1, r1, #4 @ 1 do we have enough
|
|
blt 5f @ 1 bytes to align with?
|
|
cmp r3, #2 @ 1
|
|
strltb r2, [r0], #1 @ 1
|
|
strleb r2, [r0], #1 @ 1
|
|
strb r2, [r0], #1 @ 1
|
|
add r1, r1, r3 @ 1 (r1 = r1 - (4 - r3))
|
|
/*
|
|
* The pointer is now aligned and the length is adjusted. Try doing the
|
|
* memzero again.
|
|
*/
|
|
|
|
ENTRY(__memzero)
|
|
mov r2, #0 @ 1
|
|
ands r3, r0, #3 @ 1 unaligned?
|
|
bne 1b @ 1
|
|
/*
|
|
* r3 = 0, and we know that the pointer in r0 is aligned to a word boundary.
|
|
*/
|
|
cmp r1, #16 @ 1 we can skip this chunk if we
|
|
blt 4f @ 1 have < 16 bytes
|
|
|
|
#if ! CALGN(1)+0
|
|
|
|
/*
|
|
* We need an extra register for this loop - save the return address and
|
|
* use the LR
|
|
*/
|
|
str lr, [sp, #-4]! @ 1
|
|
mov ip, r2 @ 1
|
|
mov lr, r2 @ 1
|
|
|
|
3: subs r1, r1, #64 @ 1 write 32 bytes out per loop
|
|
stmgeia r0!, {r2, r3, ip, lr} @ 4
|
|
stmgeia r0!, {r2, r3, ip, lr} @ 4
|
|
stmgeia r0!, {r2, r3, ip, lr} @ 4
|
|
stmgeia r0!, {r2, r3, ip, lr} @ 4
|
|
bgt 3b @ 1
|
|
ldmeqfd sp!, {pc} @ 1/2 quick exit
|
|
/*
|
|
* No need to correct the count; we're only testing bits from now on
|
|
*/
|
|
tst r1, #32 @ 1
|
|
stmneia r0!, {r2, r3, ip, lr} @ 4
|
|
stmneia r0!, {r2, r3, ip, lr} @ 4
|
|
tst r1, #16 @ 1 16 bytes or more?
|
|
stmneia r0!, {r2, r3, ip, lr} @ 4
|
|
ldr lr, [sp], #4 @ 1
|
|
|
|
#else
|
|
|
|
/*
|
|
* This version aligns the destination pointer in order to write
|
|
* whole cache lines at once.
|
|
*/
|
|
|
|
stmfd sp!, {r4-r7, lr}
|
|
mov r4, r2
|
|
mov r5, r2
|
|
mov r6, r2
|
|
mov r7, r2
|
|
mov ip, r2
|
|
mov lr, r2
|
|
|
|
cmp r1, #96
|
|
andgts ip, r0, #31
|
|
ble 3f
|
|
|
|
rsb ip, ip, #32
|
|
sub r1, r1, ip
|
|
movs ip, ip, lsl #(32 - 4)
|
|
stmcsia r0!, {r4, r5, r6, r7}
|
|
stmmiia r0!, {r4, r5}
|
|
movs ip, ip, lsl #2
|
|
strcs r2, [r0], #4
|
|
|
|
3: subs r1, r1, #64
|
|
stmgeia r0!, {r2-r7, ip, lr}
|
|
stmgeia r0!, {r2-r7, ip, lr}
|
|
bgt 3b
|
|
ldmeqfd sp!, {r4-r7, pc}
|
|
|
|
tst r1, #32
|
|
stmneia r0!, {r2-r7, ip, lr}
|
|
tst r1, #16
|
|
stmneia r0!, {r4-r7}
|
|
ldmfd sp!, {r4-r7, lr}
|
|
|
|
#endif
|
|
|
|
4: tst r1, #8 @ 1 8 bytes or more?
|
|
stmneia r0!, {r2, r3} @ 2
|
|
tst r1, #4 @ 1 4 bytes or more?
|
|
strne r2, [r0], #4 @ 1
|
|
/*
|
|
* When we get here, we've got less than 4 bytes to zero. We
|
|
* may have an unaligned pointer as well.
|
|
*/
|
|
5: tst r1, #2 @ 1 2 bytes or more?
|
|
strneb r2, [r0], #1 @ 1
|
|
strneb r2, [r0], #1 @ 1
|
|
tst r1, #1 @ 1 a byte left over
|
|
strneb r2, [r0], #1 @ 1
|
|
mov pc, lr @ 1
|
|
ENDPROC(__memzero)
|