libkern/gen/OSAtomicOperations.c

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28
  29 #include <libkern/OSAtomic.h>
  30
  31 enum {
  32         false   = 0,
  33         true    = 1
  34 };
  35 #define NULL 0L
  36
  37
  38 /*
  39  * atomic operations
  40  *      these are _the_ atomic operations, currently cast atop CompareAndSwap,
  41  *      which is implemented in assembler.  if we are worried about the cost of
  42  *      this layering (we shouldn't be), then all this stuff could be
  43  *      implemented in assembler, as it is in MacOS8/9
  44  *      (derived from SuperMario/NativeLibs/IO/DriverServices/Synchronization.s,
  45  *      which I wrote for NuKernel in a previous life with a different last name...)
  46  *
  47  * native Boolean       CompareAndSwap(UInt32 oldValue, UInt32 newValue, UInt32 * oldValuePtr);
  48  *
  49  * We've since implemented a few more of these -- OSAddAtomic, OSDequeueAtomic,
  50  * OSEnqueueAtomic etc -- in assembler, either for speed or correctness.  See also the
  51  * commpage atomic operations, and the platform specific versions.
  52  * Like standards, there are a lot of atomic ops to choose from!
  53  */
  54
  55 #ifndef __ppc__
  56
  57 SInt32  OSAddAtomic(SInt32 amount, SInt32 * value)
  58 {
  59         SInt32  oldValue;
  60         SInt32  newValue;
  61
  62         do {
  63                 oldValue = *value;
  64                 newValue = oldValue + amount;
  65         } while (! OSCompareAndSwap((UInt32) oldValue, (UInt32) newValue, (UInt32 *) value));
  66
  67         return oldValue;
  68 }
  69
  70 SInt32  OSIncrementAtomic(SInt32 * value)
  71 {
  72         return OSAddAtomic(1, value);
  73 }
  74
  75 SInt32  OSDecrementAtomic(SInt32 * value)
  76 {
  77         return OSAddAtomic(-1, value);
  78 }
  79
  80 void *  OSDequeueAtomic(void ** inList, SInt32 inOffset)
  81 {
  82         void *  oldListHead;
  83         void *  newListHead;
  84
  85         do {
  86                 oldListHead = *inList;
  87                 if (oldListHead == NULL) {
  88                         break;
  89                 }
  90
  91                 newListHead = *(void **) (((char *) oldListHead) + inOffset);
  92         } while (! OSCompareAndSwap((UInt32)oldListHead,
  93                                         (UInt32)newListHead, (UInt32 *)inList));
  94
  95         return oldListHead;
  96 }
  97
  98 void    OSEnqueueAtomic(void ** inList, void * inNewLink, SInt32 inOffset)
  99 {
 100         void *  oldListHead;
 101         void *  newListHead = inNewLink;
 102         void ** newLinkNextPtr = (void **) (((char *) inNewLink) + inOffset);
 103
 104         do {
 105                 oldListHead = *inList;
 106                 *newLinkNextPtr = oldListHead;
 107         } while (! OSCompareAndSwap((UInt32)oldListHead, (UInt32)newListHead,
 108                                         (UInt32 *)inList));
 109 }
 110
 111 #endif  /* !__ppc__ */
 112
 113 static UInt32   OSBitwiseAtomic(UInt32 and_mask, UInt32 or_mask, UInt32 xor_mask, UInt32 * value)
 114 {
 115         UInt32  oldValue;
 116         UInt32  newValue;
 117
 118         do {
 119                 oldValue = *value;
 120                 newValue = ((oldValue & and_mask) | or_mask) ^ xor_mask;
 121         } while (! OSCompareAndSwap(oldValue, newValue, value));
 122
 123         return oldValue;
 124 }
 125
 126 UInt32  OSBitAndAtomic(UInt32 mask, UInt32 * value)
 127 {
 128         return OSBitwiseAtomic(mask, 0, 0, value);
 129 }
 130
 131 UInt32  OSBitOrAtomic(UInt32 mask, UInt32 * value)
 132 {
 133         return OSBitwiseAtomic((UInt32) -1, mask, 0, value);
 134 }
 135
 136 UInt32  OSBitXorAtomic(UInt32 mask, UInt32 * value)
 137 {
 138         return OSBitwiseAtomic((UInt32) -1, 0, mask, value);
 139 }
 140
 141 static Boolean OSCompareAndSwap8(UInt8 oldValue8, UInt8 newValue8, UInt8 * value8)
 142 {
 143         UInt32          mask        = 0x000000ff;
 144         UInt32          alignment   = ((UInt32) value8) & (sizeof(UInt32) - 1);
 145     UInt32      shiftValues = (24 << 24) | (16 << 16) | (8 << 8);
 146     int                 shift       = (UInt32) *(((UInt8 *) &shiftValues) + alignment);
 147         UInt32 *        value32     = (UInt32 *) (value8 - alignment);
 148     UInt32      oldValue;
 149     UInt32      newValue;
 150
 151     mask <<= shift;
 152
 153     oldValue = *value32;
 154     oldValue = (oldValue & ~mask) | (oldValue8 << shift);
 155     newValue = (oldValue & ~mask) | (newValue8 << shift);
 156
 157         return OSCompareAndSwap(oldValue, newValue, value32);
 158 }
 159
 160 static Boolean  OSTestAndSetClear(UInt32 bit, Boolean wantSet, UInt8 * startAddress)
 161 {
 162         UInt8           mask = 1;
 163         UInt8           oldValue;
 164         UInt8           wantValue;
 165
 166         startAddress += (bit / 8);
 167         mask <<= (7 - (bit % 8));
 168         wantValue = wantSet ? mask : 0;
 169
 170         do {
 171                 oldValue = *startAddress;
 172                 if ((oldValue & mask) == wantValue) {
 173                         break;
 174                 }
 175         } while (! OSCompareAndSwap8(oldValue, (oldValue & ~mask) | wantValue, startAddress));
 176
 177         return (oldValue & mask) == wantValue;
 178 }
 179
 180 Boolean OSTestAndSet(UInt32 bit, UInt8 * startAddress)
 181 {
 182         return OSTestAndSetClear(bit, true, startAddress);
 183 }
 184
 185 Boolean OSTestAndClear(UInt32 bit, UInt8 * startAddress)
 186 {
 187         return OSTestAndSetClear(bit, false, startAddress);
 188 }
 189
 190 /*
 191  * silly unaligned versions
 192  */
 193
 194 SInt8   OSIncrementAtomic8(SInt8 * value)
 195 {
 196         return OSAddAtomic8(1, value);
 197 }
 198
 199 SInt8   OSDecrementAtomic8(SInt8 * value)
 200 {
 201         return OSAddAtomic8(-1, value);
 202 }
 203
 204 SInt8   OSAddAtomic8(SInt32 amount, SInt8 * value)
 205 {
 206         SInt8   oldValue;
 207         SInt8   newValue;
 208
 209         do {
 210                 oldValue = *value;
 211                 newValue = oldValue + amount;
 212         } while (! OSCompareAndSwap8((UInt8) oldValue, (UInt8) newValue, (UInt8 *) value));
 213
 214         return oldValue;
 215 }
 216
 217 static UInt8    OSBitwiseAtomic8(UInt32 and_mask, UInt32 or_mask, UInt32 xor_mask, UInt8 * value)
 218 {
 219         UInt8   oldValue;
 220         UInt8   newValue;
 221
 222         do {
 223                 oldValue = *value;
 224                 newValue = ((oldValue & and_mask) | or_mask) ^ xor_mask;
 225         } while (! OSCompareAndSwap8(oldValue, newValue, value));
 226
 227         return oldValue;
 228 }
 229
 230 UInt8   OSBitAndAtomic8(UInt32 mask, UInt8 * value)
 231 {
 232         return OSBitwiseAtomic8(mask, 0, 0, value);
 233 }
 234
 235 UInt8   OSBitOrAtomic8(UInt32 mask, UInt8 * value)
 236 {
 237         return OSBitwiseAtomic8((UInt32) -1, mask, 0, value);
 238 }
 239
 240 UInt8   OSBitXorAtomic8(UInt32 mask, UInt8 * value)
 241 {
 242         return OSBitwiseAtomic8((UInt32) -1, 0, mask, value);
 243 }
 244
 245 static Boolean OSCompareAndSwap16(UInt16 oldValue16, UInt16 newValue16, UInt16 * value16)
 246 {
 247         UInt32          mask        = 0x0000ffff;
 248         UInt32          alignment   = ((UInt32) value16) & (sizeof(UInt32) - 1);
 249     UInt32      shiftValues = (16 << 24) | (16 << 16);
 250     UInt32              shift       = (UInt32) *(((UInt8 *) &shiftValues) + alignment);
 251         UInt32 *        value32     = (UInt32 *) (((UInt32) value16) - alignment);
 252     UInt32      oldValue;
 253     UInt32      newValue;
 254
 255     mask <<= shift;
 256
 257     oldValue = *value32;
 258     oldValue = (oldValue & ~mask) | (oldValue16 << shift);
 259     newValue = (oldValue & ~mask) | (newValue16 << shift);
 260
 261         return OSCompareAndSwap(oldValue, newValue, value32);
 262 }
 263
 264 SInt16  OSIncrementAtomic16(SInt16 * value)
 265 {
 266         return OSAddAtomic16(1, value);
 267 }
 268
 269 SInt16  OSDecrementAtomic16(SInt16 * value)
 270 {
 271         return OSAddAtomic16(-1, value);
 272 }
 273
 274 SInt16  OSAddAtomic16(SInt32 amount, SInt16 * value)
 275 {
 276         SInt16  oldValue;
 277         SInt16  newValue;
 278
 279         do {
 280                 oldValue = *value;
 281                 newValue = oldValue + amount;
 282         } while (! OSCompareAndSwap16((UInt16) oldValue, (UInt16) newValue, (UInt16 *) value));
 283
 284         return oldValue;
 285 }
 286
 287 static UInt16   OSBitwiseAtomic16(UInt32 and_mask, UInt32 or_mask, UInt32 xor_mask, UInt16 * value)
 288 {
 289         UInt16  oldValue;
 290         UInt16  newValue;
 291
 292         do {
 293                 oldValue = *value;
 294                 newValue = ((oldValue & and_mask) | or_mask) ^ xor_mask;
 295         } while (! OSCompareAndSwap16(oldValue, newValue, value));
 296
 297         return oldValue;
 298 }
 299
 300 UInt16  OSBitAndAtomic16(UInt32 mask, UInt16 * value)
 301 {
 302         return OSBitwiseAtomic16(mask, 0, 0, value);
 303 }
 304
 305 UInt16  OSBitOrAtomic16(UInt32 mask, UInt16 * value)
 306 {
 307         return OSBitwiseAtomic16((UInt32) -1, mask, 0, value);
 308 }
 309
 310 UInt16  OSBitXorAtomic16(UInt32 mask, UInt16 * value)
 311 {
 312         return OSBitwiseAtomic16((UInt32) -1, 0, mask, value);
 313 }
 314