/*
* linux/arch/arm/lib/clear_user.S
*
* Copyright (C) 1995, 1996,1997,1998 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
/* Prototype: int __clear_user(void *addr, size_t sz)
* Purpose : clear some user memory
* Params : addr - user memory address to clear
* : sz - number of bytes to clear
* Returns : number of bytes NOT cleared
*/
ENTRY(__clear_user)
stmfd sp!, {r1, lr}
mov r2, #0
cmp r1, #4
blt 2f
ands ip, r0, #3
beq 1f
cmp ip, #2
USER( strbt r2, [r0], #1)
USER( strlebt r2, [r0], #1)
USER( strltbt r2, [r0], #1)
rsb ip, ip, #4
sub r1, r1, ip @ 7 6 5 4 3 2 1
1: subs r1, r1, #8 @ -1 -2 -3 -4 -5 -6 -7
USER( strplt r2, [r0], #4)
USER( strplt r2, [r0], #4)
bpl 1b
adds r1, r1, #4 @ 3 2 1 0 -1 -2 -3
USER( strplt r2, [r0], #4)
2: tst r1, #2 @ 1x 1x 0x 0x 1x 1x 0x
USER( strnebt r2, [r0], #1)
USER( strnebt r2, [r0], #1)
tst r1, #1 @ x1 x0 x1 x0 x1 x0 x1
USER( strnebt r2, [r0], #1)
mov r0, #0
ldmfd sp!, {r1, pc}
.section .fixup,"ax"
.align 0
9001: ldmfd sp!, {r0, pc}
.previous
