spinlock.s

著名的 helix realplayer 基于手机 symbian 系统的 播放器全套源代码

// ***** BEGIN LICENSE BLOCK *****  
// Source last modified: $Id: spinlock.s,v 1.1 2003/08/03 21:55:06 dcollins Exp $
//   
// Portions Copyright (c) 1995-2003 RealNetworks, Inc. All Rights Reserved.  
//       
// The contents of this file, and the files included with this file, 
// are subject to the current version of the RealNetworks Public 
// Source License (the "RPSL") available at 
// http://www.helixcommunity.org/content/rpsl unless you have licensed 
// the file under the current version of the RealNetworks Community 
// Source License (the "RCSL") available at 
// http://www.helixcommunity.org/content/rcsl, in which case the RCSL 
// will apply. You may also obtain the license terms directly from 
// RealNetworks.  You may not use this file except in compliance with 
// the RPSL or, if you have a valid RCSL with RealNetworks applicable 
// to this file, the RCSL.  Please see the applicable RPSL or RCSL for 
// the rights, obligations and limitations governing use of the 
// contents of the file. 
//   
// This file is part of the Helix DNA Technology. RealNetworks is the 
// developer of the Original Code and owns the copyrights in the 
// portions it created. 
//   
// This file, and the files included with this file, is distributed 
// and made available on an 'AS IS' basis, WITHOUT WARRANTY OF ANY 
// KIND, EITHER EXPRESS OR IMPLIED, AND REALNETWORKS HEREBY DISCLAIMS 
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// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, QUIET 
// ENJOYMENT OR NON-INFRINGEMENT. 
//  
// Technology Compatibility Kit Test Suite(s) Location:  
//    http://www.helixcommunity.org/content/tck  
//  
// Contributor(s):  
//   
// ***** END LICENSE BLOCK ***** */  


//////////////////////////////////////////////////////////////////////
//
// spinlock.s
//      Implements a test-and-set operator, for use with a spinlock.
//      implemented in IA64 (Itanium) assembly.
//
// Implementation Notes:
//      A work-in-progress....
//
//////////////////////////////////////////////////////////////////////

  
//////////////////////////////////////////////////////////////////////
// Misc. Assembler Directives
//////////////////////////////////////////////////////////////////////

        .radix  C       // C-style numeric constants
        .section .text = "ax", "progbits" // read-only object code


//////////////////////////////////////////////////////////////////////
//
// _HXMutexSetBit
//      atomic test-and-set operator
//
// Interface:
//   extern "C" int _HXMutexSetBit(HX_MUTEX pLock);
//
// Inputs:
//   Paramaters:
//     in0 :  HX_MUTEX pLock  - pointer to mutex (integer) to modify
//
// Outputs:
//   Atomically modifies memory at *pLock:
//     *pLock = 1
//
//   Return value:
//     r8 : UINT32 - previous value of *pLock
//                   If zero, the lock attempt was successful
//
//////////////////////////////////////////////////////////////////////
	.proc   _HXMutexSetBit
	.global _HXMutexSetBit
_HXMutexSetBit:
        alloc           loc0 = ar.pfs, 1, 1, 0, 0 //one input, one local
	mov		r8 = 1;;                //x = 1
	xchg4		r8 = [in0], r8;;        //swap *pLock and x
	br.ret.dptk.few	rp;;                    //return previous *pLock value
        .endp   _HXMutexSetBit



//////////////////////////////////////////////////////////////////////
//
// _HXMutexClearBit
//      atomic bit clear operator
//
// Interface:
//   extern "C" void _HXMutexClearBit(HX_MUTEX pLock);
//
// Inputs:
//   Paramaters:
//     in0 :  HX_MUTEX pLock  - pointer to mutex (integer) to modify
//
// Outputs:
//   Atomically modifies memory at *pLock:
//     *pLock = 0
//
//   Return value:
//     none
//
//////////////////////////////////////////////////////////////////////
//
// Implementation notes:
// We cannot safely just set the lock to zero with an assignment, the
// use of the st4.rel release semantics is necessary to enforce correct
// memory ordering.
//
//////////////////////////////////////////////////////////////////////
        .proc   _HXMutexClearBit
        .global _HXMutexClearBit
_HXMutexClearBit:
        alloc           loc0 = ar.pfs, 1, 1, 0, 0 //one input, one local
        st4.rel         [in0] = r0;;            //atomically set to zero
	br.ret.dptk.few	rp;;                    //return
        .endp   _HXMutexClearBit