/*
* Copyright (c) 2012 Apple Computer, Inc. All rights reserved.
*
* @APPLE_OSREFERENCE_LICENSE_HEADER_START@
*
* This file contains Original Code and/or Modifications of Original Code
* as defined in and that are subject to the Apple Public Source License
* Version 2.0 (the 'License'). You may not use this file except in
* compliance with the License. The rights granted to you under the License
* may not be used to create, or enable the creation or redistribution of,
* unlawful or unlicensed copies of an Apple operating system, or to
* circumvent, violate, or enable the circumvention or violation of, any
* terms of an Apple operating system software license agreement.
*
* Please obtain a copy of the License at
* http://www.opensource.apple.com/apsl/ and read it before using this file.
*
* The Original Code and all software distributed under the License are
* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
* Please see the License for the specific language governing rights and
* limitations under the License.
*
* @APPLE_OSREFERENCE_LICENSE_HEADER_END@
*
* This file implements the following functions for the arm64 architecture:
*
* void bzero(void *buffer, size_t length) * void *memset(void *buffer, int value, size_t length) * The first two zero-fill a buffer. The third fills the buffer with the low
* byte of its second argument.
*/
#include "asm.h"
.globl _bzero
.globl ___bzero
.globl _memset
.globl _secure_memset
/*****************************************************************************
* bzero entrypoint *
*****************************************************************************/
.text
.align 4
_bzero:
___bzero:
PUSH_FRAME
mov x2, x1
eor x1, x1, x1
mov x3, x0
cmp x2, #128
b.cc L_memsetSmall
/*****************************************************************************
* Large buffer zero engine *
*****************************************************************************/
L_bzeroLarge:
// Write the first 64 bytes of the buffer without regard to alignment, then
// advance x3 to point to a cacheline-aligned location within the buffer, and
// decrement the length accordingly.
stp x1, x1, [x0]
stp x1, x1, [x0, #16]
stp x1, x1, [x0, #32]
stp x1, x1, [x0, #48]
add x3, x0, #64
and x3, x3, #-64
add x2, x2, x0 // end of buffer
add x4, x3, #64 // end of first cacheline to zero
subs x2, x2, x4 // if the end of the buffer comes first, jump
b.ls 1f // directly to the cleanup pass.
0: dc zva, x3 // zero cacheline
add x3, x3, #64 // increment pointer
subs x2, x2, #64 // decrement length
b.hi 0b
1: add x3, x3, x2 // back up pointer to (end of buffer) - 64.
stp x1, x1, [x3] // and store 64 bytes to reach end of buffer.
stp x1, x1, [x3, #16]
stp x1, x1, [x3, #32]
stp x1, x1, [x3, #48]
POP_FRAME
ret
/*****************************************************************************
* memset entrypoint *
*****************************************************************************/
.align 4
/*
* It is important that secure_memset remains defined in assembly to avoid
* compiler optimizations.
*/
_secure_memset:
_memset:
PUSH_FRAME
and x1, x1, #0xff
orr x3, xzr,#0x0101010101010101
mul x1, x1, x3
mov x3, x0
cmp x2, #64
b.cc L_memsetSmall
/*****************************************************************************
* Large buffer store engine *
*****************************************************************************/
L_memsetLarge:
// Write the first 64 bytes of the buffer without regard to alignment, then
// advance x3 to point to an aligned location within the buffer, and
// decrement the length accordingly.
stp x1, x1, [x0]
add x3, x0, #16
and x3, x3, #-16
add x2, x2, x0 // end of buffer
add x4, x3, #64 // end of first aligned 64-byte store
subs x2, x2, x4 // if the end of the buffer comes first, jump
b.ls 1f // directly to the cleanup store.
0: stnp x1, x1, [x3]
stnp x1, x1, [x3, #16]
stnp x1, x1, [x3, #32]
stnp x1, x1, [x3, #48]
add x3, x3, #64
subs x2, x2, #64
b.hi 0b
1: add x3, x3, x2 // back up pointer to (end of buffer) - 64.
stp x1, x1, [x3]
stp x1, x1, [x3, #16]
stp x1, x1, [x3, #32]
stp x1, x1, [x3, #48]
POP_FRAME
ret
/*****************************************************************************
* Small buffer store engine *
*****************************************************************************/
0: str x1, [x3],#8
L_memsetSmall:
subs x2, x2, #8
b.cs 0b
adds x2, x2, #8
b.eq 2f
1: strb w1, [x3],#1
subs x2, x2, #1
b.ne 1b
2: POP_FRAME
ret