124 lines
4.1 KiB
ArmAsm
124 lines
4.1 KiB
ArmAsm
/* unaligned.S - utility routines to perform unaligned reads/writes */
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/*
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* Copyright (c) 2011-2014 Wind River Systems, Inc.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1) Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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*
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* 2) Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* 3) Neither the name of Wind River Systems nor the names of its contributors
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* may be used to endorse or promote products derived from this software without
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* specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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DESCRIPTION
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This module contains utilities to perform unaligned reads/writes from/to a
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32-bit quantity. Some memory subsystems to not support the IA-32 byte
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enable lines, and thus accessing an unaligned 32-bit quantity is
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performed byte-by-byte.
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*/
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#define _ASMLANGUAGE
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#ifdef CONFIG_UNALIGNED_WRITE_UNSUPPORTED
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#include <arch/x86/asm.h>
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/* exports (internal APIs) */
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GTEXT(_Unaligned32Write)
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GTEXT(_Unaligned32Read)
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/**
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*
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* @brief Perform an unaligned 32-bit write operation
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*
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* This function is used during the interrupt and exception stub code
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* synthesis step when writing out the 32-bit relative jmp/branch
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* offsets.
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*
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* Generally, the 32-bit offsets are located at an odd memory address. For
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* target hardware that don't fully (or properly) decode the byte enable
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* lines from the IA-32 processor, this function shall be utilized to write out
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* the data byte-by-byte.
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*
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* The BSP specific configuration option CONFIG_UNALIGNED_WRITE_UNSUPPORTED
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* shall be defined when the kernel is built for target hardware that cannot
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* support unaligned double word (32-bit) write operations.
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*
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* C function prototype:
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*
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* void _Unaligned32Write
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* (
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* unsigned int * ptr,
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* unsigned int val
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* );
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*/
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SECTION_FUNC(TEXT, _Unaligned32Write)
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movl 0x4(%esp), %edx /* fetch ptr argument */
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movl 0x8(%esp), %eax /* fetch val argument */
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movb %al, (%edx)
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movb %ah, 1(%edx)
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shrl $0x10, %eax
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movb %al, 2(%edx)
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movb %ah, 3(%edx)
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ret
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/**
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*
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* @brief Perform an unaligned 32-bit read operation
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*
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* This function is used during the interrupt and exception stub code
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* synthesis step when reading the 32-bit relative jmp/branch
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* offsets.
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*
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* Generally, the 32-bit offsets are located at an odd memory address. For
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* target hardware that don't fully (or properly) decode the byte enable
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* lines from the IA-32 processor, this function shall be utilized to read
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* the data byte-by-byte.
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*
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* The BSP specific configuration option CONFIG_UNALIGNED_WRITE_UNSUPPORTED
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* shall be defined when the kernel is built for target hardware that cannot
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* support unaligned double word (32-bit) write operations.
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*
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* C function prototype:
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*
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* unsigned int _Unaligned32Read
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* (
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* unsigned int * ptr
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* );
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*/
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SECTION_FUNC(TEXT, _Unaligned32Read)
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movl 0x4(%esp), %edx /* fetch ptr argument */
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movb 3(%edx), %ah
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movb 2(%edx), %al
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shll $0x10, %eax
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movb 1(%edx), %ah
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movb (%edx), %al
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ret
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#endif /* CONFIG_UNALIGNED_WRITE_UNSUPPORTED */
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