root/trunk/libffado/src/libutil/Atomic.h

/*
 * Copyright (C) 2005-2008 by Pieter Palmers
 *
 * This file is part of FFADO
 * FFADO = Free Firewire (pro-)audio drivers for linux
 *
 * FFADO is based upon FreeBoB
 *
 * This program 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) version 3 of the License.
 *
 * This program 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, see <http://www.gnu.org/licenses/>.
 *
 */

/*
 * Copied from the jackd/jackdmp sources
 * function names changed in order to avoid naming problems when using this in
 * a jackd backend.
 */

/* Original license:
 *
 *  Copyright (C) 2004-2006 Grame
 *
 *  This program 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) version 3 of the License.
 *
 *  This program 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., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */

#ifndef __FFADOATOMIC__
#define __FFADOATOMIC__

#include <stdint.h>

#if defined(__APPLE__)

#if defined(__ppc__)

static inline int CAS(register uint32_t value, register uint32_t newvalue, register volatile void* addr)
{
    register int result;
    asm volatile (
        "# CAS                    \n"
        "    lwarx    r0, 0, %1    \n"         // creates a reservation on addr
        "    cmpw    r0, %2        \n"            //  test value at addr
        "    bne-    1f          \n"
        "    sync                \n"         //  synchronize instructions
        "    stwcx.    %3, 0, %1    \n"         //  if the reservation is not altered
        //  stores the new value at addr
        "    bne-    1f          \n"
        "   li      %0, 1       \n"
        "    b        2f          \n"
        "1:                     \n"
        "   li      %0, 0       \n"
        "2:                     \n"
        : "=r" (result)
        : "r" (addr), "r" (value), "r" (newvalue)
        : "r0"
        );
    return result;
}

#endif

#if defined(__i386__) || defined(__x86_64__)

#ifdef __SMP__
#    define LOCK "lock ; "
#else
#    define LOCK ""
#endif

static inline char CAS(volatile uint32_t value, uint32_t newvalue, volatile void* addr)
{
    register char ret;
    __asm__ __volatile__ (
        "# CAS \n\t"
        LOCK "cmpxchg %2, (%1) \n\t"
        "sete %0               \n\t"
        : "=a" (ret)
        : "c" (addr), "d" (newvalue), "a" (value)
        );
    return ret;
}

#endif

#endif

#ifdef __linux__

#ifdef __PPC__

static inline int CAS(register uint32_t value, register uint32_t newvalue, register volatile void* addr)
{
    register int result;
    register uint32_t tmp;
    asm volatile (
        "# CAS                    \n"
        "    lwarx    %4, 0, %1    \n"         // creates a reservation on addr
        "    cmpw    %4, %2        \n"        //  test value at addr
        "    bne-    1f          \n"
        "    sync                \n"         //  synchronize instructions
        "    stwcx.    %3, 0, %1    \n"         //  if the reservation is not altered
        //  stores the new value at addr
        "    bne-    1f          \n"
        "   li      %0, 1       \n"
        "    b        2f          \n"
        "1:                     \n"
        "   li      %0, 0       \n"
        "2:                     \n"
        : "=r" (result)
        : "r" (addr), "r" (value), "r" (newvalue), "r" (tmp)
        );
    return result;
}

#endif

#if defined(__i386__) || defined(__x86_64__)

#ifdef __SMP__
#    define LOCK "lock ; "
#else
#    define LOCK ""
#endif

static inline char CAS(volatile uint32_t value, uint32_t newvalue, volatile void* addr)
{
    register char ret;
    __asm__ __volatile__ (
        "# CAS \n\t"
        LOCK "cmpxchg %2, (%1) \n\t"
        "sete %0               \n\t"
        : "=a" (ret)
        : "c" (addr), "d" (newvalue), "a" (value)
        );
    return ret;
}

#endif

#endif

static inline long INC_ATOMIC(volatile int32_t* val)
{
    int32_t actual;
    do {
        actual = *val;
    } while (!CAS(actual, actual + 1, val));
    return actual;
}

static inline long DEC_ATOMIC(volatile int32_t* val)
{
    int32_t actual;
    do {
        actual = *val;
    } while (!CAS(actual, actual - 1, val));
    return actual;
}

static inline long ADD_ATOMIC(volatile int32_t* val, int32_t addval)
{
    int32_t actual;
    do {
        actual = *val;
    } while (!CAS(actual, actual + addval, val));
    return actual;
}

static inline long SUBSTRACT_ATOMIC(volatile int32_t* val, int32_t addval)
{
    int32_t actual;
    do {
        actual = *val;
    } while (!CAS(actual, actual - addval, val));
    return actual;
}

static inline long ZERO_ATOMIC(volatile int32_t* val)
{
    int32_t actual;
    do {
        actual = *val;
    } while (!CAS(actual, 0, val));
    return actual;
}

#endif // __FFADO_ATOMIC__