110 lines
3.5 KiB
C
110 lines
3.5 KiB
C
/*
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* Copyright (c) 2000, 2001, 2002, 2003, 2004, 2005, 2008, 2009
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* The President and Fellows of Harvard College.
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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
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY AND CONTRIBUTORS ``AS IS'' AND
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* 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 UNIVERSITY OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#ifndef _SPL_H_
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#define _SPL_H_
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#include <cdefs.h>
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/* Inlining support - for making sure an out-of-line copy gets built */
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#ifndef SPL_INLINE
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#define SPL_INLINE INLINE
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#endif
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/*
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* Machine-independent interface to interrupt enable/disable.
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*
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* "spl" stands for "set priority level", and was originally the name of
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* a VAX assembler instruction.
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*
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* The idea is that one can block less important interrupts while
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* processing them, but still allow more urgent interrupts to interrupt
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* that processing.
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*
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* Ordinarily there would be a whole bunch of defined interrupt
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* priority levels and functions for setting them - spltty(),
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* splbio(), etc., etc. But we don't support interrupt priorities in
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* OS/161, so there are only three:
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*
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* spl0() sets IPL to 0, enabling all interrupts.
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* splhigh() sets IPL to the highest value, disabling all interrupts.
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* splx(s) sets IPL to S, enabling whatever state S represents.
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*
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* All three return the old interrupt state. Thus, these are commonly used
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* as follows:
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*
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* int s = splhigh();
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* [ code ]
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* splx(s);
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*
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* Note that these functions only affect interrupts on the current
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* processor.
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*/
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SPL_INLINE int spl0(void);
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SPL_INLINE int splhigh(void);
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int splx(int);
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/*
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* Integer interrupt priority levels.
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*/
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#define IPL_NONE 0
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#define IPL_HIGH 1
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/*
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* Lower-level functions for explicitly raising and lowering
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* particular interrupt levels. These are used by splx() and by the
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* spinlock code.
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*
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* A previous setting of OLDIPL is cancelled and replaced with NEWIPL.
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*
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* For splraise, NEWIPL > OLDIPL, and for spllower, NEWIPL < OLDIPL.
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*/
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void splraise(int oldipl, int newipl);
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void spllower(int oldipl, int newipl);
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////////////////////////////////////////////////////////////
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SPL_INLINE
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int
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spl0(void)
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{
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return splx(IPL_NONE);
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}
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SPL_INLINE
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int
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splhigh(void)
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{
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return splx(IPL_HIGH);
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}
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#endif /* _SPL_H_ */
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