libkern/gen/OSAtomicOperations.c

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22
  23 #include <libkern/OSAtomic.h>
  24
  25 enum {
  26         false   = 0,
  27         true    = 1
  28 };
  29 #define NULL 0L
  30
  31
  32 /*
  33  * atomic operations
  34  *      these are _the_ atomic operations, currently cast atop CompareAndSwap,
  35  *      which is implemented in assembler.  if we are worried about the cost of
  36  *      this layering (we shouldn't be), then all this stuff could be
  37  *      implemented in assembler, as it is in MacOS8/9
  38  *      (derived from SuperMario/NativeLibs/IO/DriverServices/Synchronization.s,
  39  *      which I wrote for NuKernel in a previous life with a different last name...)
  40  *
  41  * native Boolean       CompareAndSwap(UInt32 oldValue, UInt32 newValue, UInt32 * oldValuePtr);
  42  */
  43
  44 #ifndef __ppc__
  45
  46 SInt32  OSAddAtomic(SInt32 amount, SInt32 * value)
  47 {
  48         SInt32  oldValue;
  49         SInt32  newValue;
  50
  51         do {
  52                 oldValue = *value;
  53                 newValue = oldValue + amount;
  54         } while (! OSCompareAndSwap((UInt32) oldValue, (UInt32) newValue, (UInt32 *) value));
  55
  56         return oldValue;
  57 }
  58
  59 SInt32  OSIncrementAtomic(SInt32 * value)
  60 {
  61         return OSAddAtomic(1, value);
  62 }
  63
  64 SInt32  OSDecrementAtomic(SInt32 * value)
  65 {
  66         return OSAddAtomic(-1, value);
  67 }
  68
  69 #endif  /* !__ppc__ */
  70
  71 static UInt32   OSBitwiseAtomic(UInt32 and_mask, UInt32 or_mask, UInt32 xor_mask, UInt32 * value)
  72 {
  73         UInt32  oldValue;
  74         UInt32  newValue;
  75
  76         do {
  77                 oldValue = *value;
  78                 newValue = ((oldValue & and_mask) | or_mask) ^ xor_mask;
  79         } while (! OSCompareAndSwap(oldValue, newValue, value));
  80
  81         return oldValue;
  82 }
  83
  84 UInt32  OSBitAndAtomic(UInt32 mask, UInt32 * value)
  85 {
  86         return OSBitwiseAtomic(mask, 0, 0, value);
  87 }
  88
  89 UInt32  OSBitOrAtomic(UInt32 mask, UInt32 * value)
  90 {
  91         return OSBitwiseAtomic((UInt32) -1, mask, 0, value);
  92 }
  93
  94 UInt32  OSBitXorAtomic(UInt32 mask, UInt32 * value)
  95 {
  96         return OSBitwiseAtomic((UInt32) -1, 0, mask, value);
  97 }
  98
  99 static Boolean OSCompareAndSwap8(UInt8 oldValue8, UInt8 newValue8, UInt8 * value8)
 100 {
 101         UInt32          mask        = 0x000000ff;
 102         UInt32          alignment   = ((UInt32) value8) & (sizeof(UInt32) - 1);
 103     UInt32      shiftValues = (24 << 24) | (16 << 16) | (8 << 8);
 104     int                 shift       = (UInt32) *(((UInt8 *) &shiftValues) + alignment);
 105         UInt32 *        value32     = (UInt32 *) (value8 - alignment);
 106     UInt32      oldValue;
 107     UInt32      newValue;
 108
 109     mask <<= shift;
 110
 111     oldValue = *value32;
 112     oldValue = (oldValue & ~mask) | (oldValue8 << shift);
 113     newValue = (oldValue & ~mask) | (newValue8 << shift);
 114
 115         return OSCompareAndSwap(oldValue, newValue, value32);
 116 }
 117
 118 static Boolean  OSTestAndSetClear(UInt32 bit, Boolean wantSet, UInt8 * startAddress)
 119 {
 120         UInt8           mask = 1;
 121         UInt8           oldValue;
 122         UInt8           wantValue;
 123
 124         startAddress += (bit / 8);
 125         mask <<= (7 - (bit % 8));
 126         wantValue = wantSet ? mask : 0;
 127
 128         do {
 129                 oldValue = *startAddress;
 130                 if ((oldValue & mask) == wantValue) {
 131                         break;
 132                 }
 133         } while (! OSCompareAndSwap8(oldValue, (oldValue & ~mask) | wantValue, startAddress));
 134
 135         return (oldValue & mask) == wantValue;
 136 }
 137
 138 Boolean OSTestAndSet(UInt32 bit, UInt8 * startAddress)
 139 {
 140         return OSTestAndSetClear(bit, true, startAddress);
 141 }
 142
 143 Boolean OSTestAndClear(UInt32 bit, UInt8 * startAddress)
 144 {
 145         return OSTestAndSetClear(bit, false, startAddress);
 146 }
 147
 148 void *  OSDequeueAtomic(void ** inList, SInt32 inOffset)
 149 {
 150         void *  oldListHead;
 151         void *  newListHead;
 152
 153         do {
 154                 oldListHead = *inList;
 155                 if (oldListHead == NULL) {
 156                         break;
 157                 }
 158
 159                 newListHead = *(void **) (((char *) oldListHead) + inOffset);
 160         } while (! OSCompareAndSwap((UInt32)oldListHead,
 161                                         (UInt32)newListHead, (UInt32 *)inList));
 162
 163         return oldListHead;
 164 }
 165
 166 void    OSEnqueueAtomic(void ** inList, void * inNewLink, SInt32 inOffset)
 167 {
 168         void *  oldListHead;
 169         void *  newListHead = inNewLink;
 170         void ** newLinkNextPtr = (void **) (((char *) inNewLink) + inOffset);
 171
 172         do {
 173                 oldListHead = *inList;
 174                 *newLinkNextPtr = oldListHead;
 175         } while (! OSCompareAndSwap((UInt32)oldListHead, (UInt32)newListHead,
 176                                         (UInt32 *)inList));
 177 }
 178
 179 /*
 180  * silly unaligned versions
 181  */
 182
 183 SInt8   OSIncrementAtomic8(SInt8 * value)
 184 {
 185         return OSAddAtomic8(1, value);
 186 }
 187
 188 SInt8   OSDecrementAtomic8(SInt8 * value)
 189 {
 190         return OSAddAtomic8(-1, value);
 191 }
 192
 193 SInt8   OSAddAtomic8(SInt32 amount, SInt8 * value)
 194 {
 195         SInt8   oldValue;
 196         SInt8   newValue;
 197
 198         do {
 199                 oldValue = *value;
 200                 newValue = oldValue + amount;
 201         } while (! OSCompareAndSwap8((UInt8) oldValue, (UInt8) newValue, (UInt8 *) value));
 202
 203         return oldValue;
 204 }
 205
 206 static UInt8    OSBitwiseAtomic8(UInt32 and_mask, UInt32 or_mask, UInt32 xor_mask, UInt8 * value)
 207 {
 208         UInt8   oldValue;
 209         UInt8   newValue;
 210
 211         do {
 212                 oldValue = *value;
 213                 newValue = ((oldValue & and_mask) | or_mask) ^ xor_mask;
 214         } while (! OSCompareAndSwap8(oldValue, newValue, value));
 215
 216         return oldValue;
 217 }
 218
 219 UInt8   OSBitAndAtomic8(UInt32 mask, UInt8 * value)
 220 {
 221         return OSBitwiseAtomic8(mask, 0, 0, value);
 222 }
 223
 224 UInt8   OSBitOrAtomic8(UInt32 mask, UInt8 * value)
 225 {
 226         return OSBitwiseAtomic8((UInt32) -1, mask, 0, value);
 227 }
 228
 229 UInt8   OSBitXorAtomic8(UInt32 mask, UInt8 * value)
 230 {
 231         return OSBitwiseAtomic8((UInt32) -1, 0, mask, value);
 232 }
 233
 234 static Boolean OSCompareAndSwap16(UInt16 oldValue16, UInt16 newValue16, UInt16 * value16)
 235 {
 236         UInt32          mask        = 0x0000ffff;
 237         UInt32          alignment   = ((UInt32) value16) & (sizeof(UInt32) - 1);
 238     UInt32      shiftValues = (16 << 24) | (16 << 16);
 239     UInt32              shift       = (UInt32) *(((UInt8 *) &shiftValues) + alignment);
 240         UInt32 *        value32     = (UInt32 *) (((UInt32) value16) - alignment);
 241     UInt32      oldValue;
 242     UInt32      newValue;
 243
 244     mask <<= shift;
 245
 246     oldValue = *value32;
 247     oldValue = (oldValue & ~mask) | (oldValue16 << shift);
 248     newValue = (oldValue & ~mask) | (newValue16 << shift);
 249
 250         return OSCompareAndSwap(oldValue, newValue, value32);
 251 }
 252
 253 SInt16  OSIncrementAtomic16(SInt16 * value)
 254 {
 255         return OSAddAtomic16(1, value);
 256 }
 257
 258 SInt16  OSDecrementAtomic16(SInt16 * value)
 259 {
 260         return OSAddAtomic16(-1, value);
 261 }
 262
 263 SInt16  OSAddAtomic16(SInt32 amount, SInt16 * value)
 264 {
 265         SInt16  oldValue;
 266         SInt16  newValue;
 267
 268         do {
 269                 oldValue = *value;
 270                 newValue = oldValue + amount;
 271         } while (! OSCompareAndSwap16((UInt16) oldValue, (UInt16) newValue, (UInt16 *) value));
 272
 273         return oldValue;
 274 }
 275
 276 static UInt16   OSBitwiseAtomic16(UInt32 and_mask, UInt32 or_mask, UInt32 xor_mask, UInt16 * value)
 277 {
 278         UInt16  oldValue;
 279         UInt16  newValue;
 280
 281         do {
 282                 oldValue = *value;
 283                 newValue = ((oldValue & and_mask) | or_mask) ^ xor_mask;
 284         } while (! OSCompareAndSwap16(oldValue, newValue, value));
 285
 286         return oldValue;
 287 }
 288
 289 UInt16  OSBitAndAtomic16(UInt32 mask, UInt16 * value)
 290 {
 291         return OSBitwiseAtomic16(mask, 0, 0, value);
 292 }
 293
 294 UInt16  OSBitOrAtomic16(UInt32 mask, UInt16 * value)
 295 {
 296         return OSBitwiseAtomic16((UInt32) -1, mask, 0, value);
 297 }
 298
 299 UInt16  OSBitXorAtomic16(UInt32 mask, UInt16 * value)
 300 {
 301         return OSBitwiseAtomic16((UInt32) -1, 0, mask, value);
 302 }
 303