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fastlock.h
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fastlock.h
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/*
* Copyright (C) 2001-2003 FhG Fokus
*
* This file is part of opensips, a free SIP server.
*
* opensips is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version
*
* opensips is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* History:
* --------
* 2002-02-05 created by andrei
* 2003-01-16 added PPC locking code contributed by Dinos Dorkofikis
* <kdor@intranet.gr>
* 2004-09-12 added MIPS locking for ISA>=2 (>r3000) (andrei)
* 2004-12-16 for now use the same locking code for sparc32 as for sparc64
* (it will work only if NOSMP is defined) (andrei)
*
* 2005-04-27 added alpha locking code (andrei)
* 2005-05-25 PPC locking code enabled for PPC64; added a lwsync to
* the tsl part and replaced the sync with a lwsync for the
* unlock part (andrei)
*/
/*!
* \file
* \brief Assembler routines for fast architecture dependend locking.
*
* Contains the assembler routines for the fast architecture dependend
* locking primitives used by the server. This routines are needed e.g.
* to protect shared data structures that are accessed from muliple processes.
* \todo replace this with the assembler routines provided by the linux kernel
*/
#ifndef fastlock_h
#define fastlock_h
#ifdef HAVE_SCHED_YIELD
#include <sched.h>
#else
#include <unistd.h>
/** Fake sched_yield if no unistd.h include is available */
#define sched_yield() sleep(0)
#endif
/*! The actual lock */
typedef volatile int fl_lock_t;
/*! Initialize a lock, zero is unlocked. */
#define init_lock( l ) (l)=0
/*! \brief
* Test and set a lock. Used by the get_lock function.
* \param lock the lock that should be set
* \return 1 if the lock is held by someone else, 0 otherwise
* \see get_lock
*/
inline static int tsl(fl_lock_t* lock)
{
int val;
#if defined(__CPU_i386) || defined(__CPU_x86_64)
#ifdef NOSMP
val=0;
asm volatile(
" btsl $0, %1 \n\t"
" adcl $0, %0 \n\t"
: "=q" (val), "=m" (*lock) : "0"(val) : "memory", "cc" /* "cc" */
);
#else
val=1;
asm volatile(
" xchg %1, %0" : "=q" (val), "=m" (*lock) : "0" (val) : "memory"
);
#endif /*NOSMP*/
#elif defined(__CPU_sparc64) || defined(__CPU_sparc)
asm volatile(
"ldstub [%1], %0 \n\t"
#ifndef NOSMP
"membar #StoreStore | #StoreLoad \n\t"
#endif
: "=r"(val) : "r"(lock):"memory"
);
#elif defined __CPU_arm
asm volatile(
"# here \n\t"
"swpb %0, %1, [%2] \n\t"
: "=&r" (val)
: "r"(1), "r" (lock) : "memory"
);
#elif defined(__CPU_ppc) || defined(__CPU_ppc64)
asm volatile(
"1: lwarx %0, 0, %2\n\t"
" cmpwi %0, 0\n\t"
" bne 0f\n\t"
" stwcx. %1, 0, %2\n\t"
" bne- 1b\n\t"
" lwsync\n\t" /* lwsync or isync, lwsync is faster
and should work, see
[ IBM Programming environments Manual, D.4.1.1]
*/
"0:\n\t"
: "=r" (val)
: "r"(1), "b" (lock) :
"memory", "cc"
);
#elif defined __CPU_mips2
long tmp;
tmp=1; /* just to kill a gcc 2.95 warning */
asm volatile(
".set noreorder\n\t"
"1: ll %1, %2 \n\t"
" li %0, 1 \n\t"
" sc %0, %2 \n\t"
" beqz %0, 1b \n\t"
" nop \n\t"
".set reorder\n\t"
: "=&r" (tmp), "=&r" (val), "=m" (*lock)
: "0" (tmp), "2" (*lock)
: "cc"
);
#elif defined __CPU_alpha
long tmp;
tmp=0;
/* lock low bit set to 1 when the lock is hold and to 0 otherwise */
asm volatile(
"1: ldl %0, %1 \n\t"
" blbs %0, 2f \n\t" /* optimization if locked */
" ldl_l %0, %1 \n\t"
" blbs %0, 2f \n\t"
" lda %2, 1 \n\t" /* or: or $31, 1, %2 ??? */
" stl_c %2, %1 \n\t"
" beq %2, 1b \n\t"
" mb \n\t"
"2: \n\t"
:"=&r" (val), "=m"(*lock), "=r"(tmp)
:"1"(*lock) /* warning on gcc 3.4: replace it with m or remove
it and use +m in the input line ? */
: "memory"
);
#else
#error "unknown architecture"
#endif
return val;
}
/*! \brief
* Set a lock.
* \param lock the lock that should be set
* \see tsl
*/
inline static void get_lock(fl_lock_t* lock)
{
#ifdef ADAPTIVE_WAIT
int i=ADAPTIVE_WAIT_LOOPS;
#endif
while(tsl(lock)){
#ifdef BUSY_WAIT
#elif defined ADAPTIVE_WAIT
if (i>0) i--;
else sched_yield();
#else
sched_yield();
#endif
}
}
/*! \brief
* Release a lock
* \param lock the lock that should be released
*/
inline static void release_lock(fl_lock_t* lock)
{
#if defined(__CPU_i386) || defined(__CPU_x86_64)
/* char val;
val=0; */
asm volatile(
" movb $0, (%0)" : /*no output*/ : "r"(lock): "memory"
/*" xchg %b0, %1" : "=q" (val), "=m" (*lock) : "0" (val) : "memory"*/
);
#elif defined(__CPU_sparc64) || defined(__CPU_sparc)
asm volatile(
#ifndef NOSMP
"membar #LoadStore | #StoreStore \n\t" /*is this really needed?*/
#endif
"stb %%g0, [%0] \n\t"
: /*no output*/
: "r" (lock)
: "memory"
);
#elif defined __CPU_arm
asm volatile(
" str %0, [%1] \n\r"
: /*no outputs*/
: "r"(0), "r"(lock)
: "memory"
);
#elif defined(__CPU_ppc) || defined(__CPU_ppc64)
asm volatile(
/* "sync\n\t" lwsync is faster and will work
* here too
* [IBM Programming Environments Manual, D.4.2.2]
*/
"lwsync\n\t"
"stw %0, 0(%1)\n\t"
: /* no output */
: "r"(0), "b" (lock)
: "memory"
);
*lock = 0;
#elif defined __CPU_mips2
asm volatile(
".set noreorder \n\t"
" sync \n\t"
" sw $0, %0 \n\t"
".set reorder \n\t"
: /*no output*/ : "m" (*lock) : "memory"
);
#elif defined __CPU_alpha
asm volatile(
" mb \n\t"
" stl $31, %0 \n\t"
: "=m"(*lock) :/* no input*/ : "memory" /* because of the mb */
);
#else
#error "unknown architecture"
#endif
}
#endif