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//
// atomic.h
//
// Atomic operations
//
// Copyright (C) 2002 Michael Ringgaard. All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
// 
// 1. Redistributions of source code must retain the above copyright 
//    notice, this list of conditions and the following disclaimer.  
// 2. Redistributions in binary form must reproduce the above copyright
//    notice, this list of conditions and the following disclaimer in the
//    documentation and/or other materials provided with the distribution.  
// 3. Neither the name of the project nor the names of its contributors
//    may be used to endorse or promote products derived from this software
//    without specific prior written permission. 
// 
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
// OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
// HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
// LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
// OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 
// SUCH DAMAGE.
// 

#if _MSC_VER > 1000
#pragma once
#endif

#ifndef ATOMIC_H
#define ATOMIC_H

#ifdef  __cplusplus
extern "C" {
#endif

// On uniprocessors, the 'lock' prefixes are not necessary (and expensive). 
// Since sanos does not (yet) support SMP the 'lock' prefix is disabled for now.

#pragma warning(disable: 4035) // Disables warnings reporting missing return statement

__inline int atomic_add(int *dest, int value) {
  __asm {
    mov edx, dest;
    mov eax, value;
    mov ecx, eax;
    /*lock*/ xadd dword ptr [edx], eax;
    add eax, ecx;
  }
}

__inline int atomic_increment(int *dest) {
  __asm {
    mov edx, dest;
    mov eax, 1;
    /*lock*/ xadd dword ptr [edx], eax;
    inc eax;
  }
}

__inline int atomic_decrement(int *dest) {
  __asm {
    mov edx, dest;
    mov eax, -1;
    /*lock*/ xadd dword ptr [edx], eax;
    dec eax;
  }
}

__inline int atomic_exchange(int *dest, int value) {
  __asm {
    mov eax, value;
    mov ecx, dest;
    xchg eax, dword ptr [ecx];
  }
}

__inline int atomic_compare_and_exchange(int *dest, int exchange, int comperand) {
  __asm {
    mov edx, dest
    mov ecx, exchange
    mov eax, comperand
    /*lock*/ cmpxchg dword ptr [edx], ecx
  }
}

#pragma warning(default: 4035)

#ifdef  __cplusplus
}
#endif

#endif