72 lines
2.0 KiB
C++
Executable File
72 lines
2.0 KiB
C++
Executable File
/*
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* \brief Atomic Userland operations for Microblaze
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* \author Norman Feske
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* \date 2009-10-02
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*/
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/*
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* Copyright (C) 2009-2013 Genode Labs GmbH
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*
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* This file is part of the Genode OS framework, which is distributed
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* under the terms of the GNU General Public License version 2.
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*/
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#ifndef _INCLUDE__CPU__ATOMIC_H_
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#define _INCLUDE__CPU__ATOMIC_H_
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#include <kernel/syscalls.h>
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namespace Genode {
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extern void* const _atomic_cmpxchg;
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/**
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* Executes compare and exchange as atomic operation
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*
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* This function compares the value at dest with cmp_val.
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* If both values are equal, dest is set to new_val. If
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* both values are different, the value at dest remains
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* unchanged.
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*
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* \return 1 if the value was successfully changed to new_val,
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* 0 if cmp_val and the value at dest differ.
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*/
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inline int cmpxchg(volatile int *dest,
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unsigned int cmp_val,
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unsigned int new_val)
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{
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int result = 0;
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unsigned int r15_buf = 0;
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/**
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* r27-r30 are arguments/return-values
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* for _atomic_cmpxchg in r31 kernel denotes if
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* interrupt has occured while executing atomic code
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*/
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asm volatile ("lwi r30, %[dest] \n"
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"lwi r29, %[cmp_val] \n"
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"lwi r28, %[new_val] \n"
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"lwi r27, %[dest_val] \n"
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"or r31, r0, r0 \n"
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"swi r15, %[r15_buf] \n"
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"bralid r15, _atomic_cmpxchg \n"
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"or r0, r0, r0 \n"
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"lwi r15, %[r15_buf] \n"
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"swi r28, %[result] "
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:
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[result] "=m" (result),
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[r15_buf] "+m" (r15_buf),
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[dest] "+m" (dest),
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[cmp_val] "+m" (cmp_val),
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[new_val] "+m" (new_val),
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[dest_val] "+m" (*dest)
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:: "r31", "r30", "r29", "r28", "r27", "memory");
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return result;
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}
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}
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#endif /* _INCLUDE__CPU__ATOMIC_H_ */
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