cdsa/cdsa_utilities/threading_internal.h

   1 /*
   2  * Copyright (c) 2000-2001 Apple Computer, Inc. All Rights Reserved.
   3  *
   4  * The contents of this file constitute Original Code as defined in and are
   5  * subject to the Apple Public Source License Version 1.2 (the 'License').
   6  * You may not use this file except in compliance with the License. Please obtain
   7  * a copy of the License at http://www.apple.com/publicsource and read it before
   8  * using this file.
   9  *
  10  * This Original Code and all software distributed under the License are
  11  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESS
  12  * OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, INCLUDING WITHOUT
  13  * LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
  14  * PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. Please see the License for the
  15  * specific language governing rights and limitations under the License.
  16  */
  17
  18
  19 //
  20 // threading_internal - internal support classes and functions for threading implementation
  21 //
  22 #ifndef _H_THREADING_INTERNAL
  23 #define _H_THREADING_INTERNAL
  24
  25 #include <Security/utilities.h>
  26
  27
  28 namespace Security {
  29
  30
  31 //
  32 // Architecture-specific atomic operation primitives.
  33 // AtomicWord is an integer type that works with these;
  34 // we'll assume that a pointer fits into it (using reinterpret_cast).
  35 //
  36 #if TARGET_CPU_PPC
  37
  38 #define _HAVE_ATOMIC_OPERATIONS
  39
  40 typedef unsigned int AtomicWord;
  41
  42 inline AtomicWord atomicLoad(AtomicWord &atom)
  43 {
  44     AtomicWord result;
  45     asm volatile (
  46         "0:     lwarx %0,0,%1 \n"
  47         "       stwcx. %0,0,%1 \n"
  48         "       bne- 0b"
  49         : "=&r"(result)
  50         : "b"(&atom)
  51         : "cc"
  52     );
  53     return result;
  54 }
  55
  56 inline AtomicWord atomicStore(AtomicWord &atom, AtomicWord newValue, AtomicWord oldValue)
  57 {
  58     register bool result;
  59     asm volatile (
  60         "0:     lwarx %0,0,%1 \n"               // load and reserve -> %0
  61         "       cmpw %0,%3 \n"          // compare to old
  62         "       bne 1f \n"                              // fail if not equal
  63         "       stwcx. %2,0,%1 \n"      // store and check
  64         "       bne 0b \n"                              // retry if contended
  65         "1:     "
  66         : "=&r"(result)
  67         : "b"(&atom), "r"(newValue), "r"(oldValue)
  68         : "cc"
  69     );
  70     return result;
  71 }
  72
  73 inline AtomicWord atomicOffset(AtomicWord &atom, int offset)
  74 {
  75     AtomicWord result;
  76     asm volatile (
  77         "0:     lwarx %0,0,%1 \n"
  78         "       add %0,%0,%2 \n"
  79         "       stwcx. %0,0,%1 \n"
  80         "       bne- 0b"
  81         : "=&r"(result)
  82         : "b"(&atom), "r"(offset)
  83         : "cc"
  84     );
  85     return result;
  86 }
  87
  88 inline AtomicWord atomicIncrement(AtomicWord &atom)
  89 { return atomicOffset(atom, +1); }
  90
  91 inline AtomicWord atomicDecrement(AtomicWord &atom)
  92 { return atomicOffset(atom, -1); }
  93
  94 #endif //TARGET_CPU_PPC
  95
  96 } // end namespace Security
  97
  98 #endif //_H_THREADING_INTERNAL