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