glib/gatomic.c

   1 /*
   2  * Copyright © 2011 Ryan Lortie
   3  *
   4  * This library is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU Lesser General Public License as
   6  * published by the Free Software Foundation; either version 2 of the
   7  * licence, or (at your option) any later version.
   8  *
   9  * This library is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * Lesser General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Lesser General Public
  15  * License along with this library; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
  17  * USA.
  18  *
  19  * Author: Ryan Lortie <desrt@desrt.ca>
  20  */
  21
  22 #include "config.h"
  23
  24 #include "gatomic.h"
  25
  26 /**
  27  * SECTION:atomic_operations
  28  * @title: Atomic Operations
  29  * @short_description: basic atomic integer and pointer operations
  30  * @see_also: #GMutex
  31  *
  32  * The following is a collection of compiler macros to provide atomic
  33  * access to integer and pointer-sized values.
  34  *
  35  * The macros that have 'int' in the name will operate on pointers to
  36  * #gint and #guint.  The macros with 'pointer' in the name will operate
  37  * on pointers to any pointer-sized value, including #gsize.  There is
  38  * no support for 64bit operations on platforms with 32bit pointers
  39  * because it is not generally possible to perform these operations
  40  * atomically.
  41  *
  42  * The get, set and exchange operations for integers and pointers
  43  * nominally operate on #gint and #gpointer, respectively.  Of the
  44  * arithmetic operations, the 'add' operation operates on (and returns)
  45  * signed integer values (#gint and #gssize) and the 'and', 'or', and
  46  * 'xor' operations operate on (and return) unsigned integer values
  47  * (#guint and #gsize).
  48  *
  49  * All of the operations act as a full compiler and (where appropriate)
  50  * hardware memory barrier.  Acquire and release or producer and
  51  * consumer barrier semantics are not available through this API.
  52  *
  53  * It is very important that all accesses to a particular integer or
  54  * pointer be performed using only this API and that different sizes of
  55  * operation are not mixed or used on overlapping memory regions.  Never
  56  * read or assign directly from or to a value -- always use this API.
  57  *
  58  * For simple reference counting purposes you should use
  59  * g_atomic_int_inc() and g_atomic_int_dec_and_test().  Other uses that
  60  * fall outside of simple reference counting patterns are prone to
  61  * subtle bugs and occasionally undefined behaviour.  It is also worth
  62  * noting that since all of these operations require global
  63  * synchronisation of the entire machine, they can be quite slow.  In
  64  * the case of performing multiple atomic operations it can often be
  65  * faster to simply acquire a mutex lock around the critical area,
  66  * perform the operations normally and then release the lock.
  67  **/
  68
  69 /**
  70  * G_ATOMIC_LOCK_FREE:
  71  *
  72  * This macro is defined if the atomic operations of GLib are
  73  * implemented using real hardware atomic operations.  This means that
  74  * the GLib atomic API can be used between processes and safely mixed
  75  * with other (hardware) atomic APIs.
  76  *
  77  * If this macro is not defined, the atomic operations may be
  78  * emulated using a mutex.  In that case, the GLib atomic operations are
  79  * only atomic relative to themselves and within a single process.
  80  **/
  81
  82 /* NOTE CAREFULLY:
  83  *
  84  * This file is the lowest-level part of GLib.
  85  *
  86  * Other lowlevel parts of GLib (threads, slice allocator, g_malloc,
  87  * messages, etc) call into these functions and macros to get work done.
  88  *
  89  * As such, these functions can not call back into any part of GLib
  90  * without risking recursion.
  91  */
  92
  93 #ifdef G_ATOMIC_LOCK_FREE
  94
  95 /* if G_ATOMIC_LOCK_FREE was defined by ./configure then we MUST
  96  * implement the atomic operations in a lock-free manner.
  97  */
  98
  99 #if defined (__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4)
 100 /**
 101  * g_atomic_int_get:
 102  * @atomic: a pointer to a #gint or #guint
 103  *
 104  * Gets the current value of @atomic.
 105  *
 106  * This call acts as a full compiler and hardware
 107  * memory barrier (before the get).
 108  *
 109  * Returns: the value of the integer
 110  *
 111  * Since: 2.4
 112  **/
 113 gint
 114 (g_atomic_int_get) (const volatile gint *atomic)
 115 {
 116   return g_atomic_int_get (atomic);
 117 }
 118
 119 /**
 120  * g_atomic_int_set:
 121  * @atomic: a pointer to a #gint or #guint
 122  * @newval: a new value to store
 123  *
 124  * Sets the value of @atomic to @newval.
 125  *
 126  * This call acts as a full compiler and hardware
 127  * memory barrier (after the set).
 128  *
 129  * Since: 2.4
 130  */
 131 void
 132 (g_atomic_int_set) (volatile gint *atomic,
 133                     gint           newval)
 134 {
 135   g_atomic_int_set (atomic, newval);
 136 }
 137
 138 /**
 139  * g_atomic_int_inc:
 140  * @atomic: a pointer to a #gint or #guint
 141  *
 142  * Increments the value of @atomic by 1.
 143  *
 144  * Think of this operation as an atomic version of
 145  * <literal>{ *@atomic += 1; }</literal>
 146  *
 147  * This call acts as a full compiler and hardware memory barrier.
 148  *
 149  * Since: 2.4
 150  **/
 151 void
 152 (g_atomic_int_inc) (volatile gint *atomic)
 153 {
 154   g_atomic_int_inc (atomic);
 155 }
 156
 157 /**
 158  * g_atomic_int_dec_and_test:
 159  * @atomic: a pointer to a #gint or #guint
 160  *
 161  * Decrements the value of @atomic by 1.
 162  *
 163  * Think of this operation as an atomic version of
 164  * <literal>{ *@atomic -= 1; return (*@atomic == 0); }</literal>
 165  *
 166  * This call acts as a full compiler and hardware memory barrier.
 167  *
 168  * Returns: %TRUE if the resultant value is zero
 169  *
 170  * Since: 2.4
 171  **/
 172 gboolean
 173 (g_atomic_int_dec_and_test) (volatile gint *atomic)
 174 {
 175   return g_atomic_int_dec_and_test (atomic);
 176 }
 177
 178 /**
 179  * g_atomic_int_compare_and_exchange:
 180  * @atomic: a pointer to a #gint or #guint
 181  * @oldval: the value to compare with
 182  * @newval: the value to conditionally replace with
 183  *
 184  * Compares @atomic to @oldval and, if equal, sets it to @newval.
 185  * If @atomic was not equal to @oldval then no change occurs.
 186  *
 187  * This compare and exchange is done atomically.
 188  *
 189  * Think of this operation as an atomic version of
 190  * <literal>{ if (*@atomic == @oldval) { *@atomic = @newval; return TRUE; } else return FALSE; }</literal>
 191  *
 192  * This call acts as a full compiler and hardware memory barrier.
 193  *
 194  * Returns: %TRUE if the exchange took place
 195  *
 196  * Since: 2.4
 197  **/
 198 gboolean
 199 (g_atomic_int_compare_and_exchange) (volatile gint *atomic,
 200                                      gint           oldval,
 201                                      gint           newval)
 202 {
 203   return g_atomic_int_compare_and_exchange (atomic, oldval, newval);
 204 }
 205
 206 /**
 207  * g_atomic_int_add:
 208  * @atomic: a pointer to a #gint or #guint
 209  * @val: the value to add
 210  *
 211  * Atomically adds @val to the value of @atomic.
 212  *
 213  * Think of this operation as an atomic version of
 214  * <literal>{ tmp = *atomic; *@atomic += @val; return tmp; }</literal>
 215  *
 216  * This call acts as a full compiler and hardware memory barrier.
 217  *
 218  * Before version 2.30, this function did not return a value
 219  * (but g_atomic_int_exchange_and_add() did, and had the same meaning).
 220  *
 221  * Returns: the value of @atomic before the add, signed
 222  *
 223  * Since: 2.4
 224  **/
 225 gint
 226 (g_atomic_int_add) (volatile gint *atomic,
 227                     gint           val)
 228 {
 229   return g_atomic_int_add (atomic, val);
 230 }
 231
 232 /**
 233  * g_atomic_int_and:
 234  * @atomic: a pointer to a #gint or #guint
 235  * @val: the value to 'and'
 236  *
 237  * Performs an atomic bitwise 'and' of the value of @atomic and @val,
 238  * storing the result back in @atomic.
 239  *
 240  * This call acts as a full compiler and hardware memory barrier.
 241  *
 242  * Think of this operation as an atomic version of
 243  * <literal>{ tmp = *atomic; *@atomic &= @val; return tmp; }</literal>
 244  *
 245  * Returns: the value of @atomic before the operation, unsigned
 246  *
 247  * Since: 2.30
 248  **/
 249 guint
 250 (g_atomic_int_and) (volatile guint *atomic,
 251                     guint           val)
 252 {
 253   return g_atomic_int_and (atomic, val);
 254 }
 255
 256 /**
 257  * g_atomic_int_or:
 258  * @atomic: a pointer to a #gint or #guint
 259  * @val: the value to 'or'
 260  *
 261  * Performs an atomic bitwise 'or' of the value of @atomic and @val,
 262  * storing the result back in @atomic.
 263  *
 264  * Think of this operation as an atomic version of
 265  * <literal>{ tmp = *atomic; *@atomic |= @val; return tmp; }</literal>
 266  *
 267  * This call acts as a full compiler and hardware memory barrier.
 268  *
 269  * Returns: the value of @atomic before the operation, unsigned
 270  *
 271  * Since: 2.30
 272  **/
 273 guint
 274 (g_atomic_int_or) (volatile guint *atomic,
 275                    guint           val)
 276 {
 277   return g_atomic_int_or (atomic, val);
 278 }
 279
 280 /**
 281  * g_atomic_int_xor:
 282  * @atomic: a pointer to a #gint or #guint
 283  * @val: the value to 'xor'
 284  *
 285  * Performs an atomic bitwise 'xor' of the value of @atomic and @val,
 286  * storing the result back in @atomic.
 287  *
 288  * Think of this operation as an atomic version of
 289  * <literal>{ tmp = *atomic; *@atomic ^= @val; return tmp; }</literal>
 290  *
 291  * This call acts as a full compiler and hardware memory barrier.
 292  *
 293  * Returns: the value of @atomic before the operation, unsigned
 294  *
 295  * Since: 2.30
 296  **/
 297 guint
 298 (g_atomic_int_xor) (volatile guint *atomic,
 299                     guint           val)
 300 {
 301   return g_atomic_int_xor (atomic, val);
 302 }
 303
 304
 305 /**
 306  * g_atomic_pointer_get:
 307  * @atomic: a pointer to a #gpointer-sized value
 308  *
 309  * Gets the current value of @atomic.
 310  *
 311  * This call acts as a full compiler and hardware
 312  * memory barrier (before the get).
 313  *
 314  * Returns: the value of the pointer
 315  *
 316  * Since: 2.4
 317  **/
 318 gpointer
 319 (g_atomic_pointer_get) (const volatile void *atomic)
 320 {
 321   return g_atomic_pointer_get ((const volatile gpointer *) atomic);
 322 }
 323
 324 /**
 325  * g_atomic_pointer_set:
 326  * @atomic: a pointer to a #gpointer-sized value
 327  * @newval: a new value to store
 328  *
 329  * Sets the value of @atomic to @newval.
 330  *
 331  * This call acts as a full compiler and hardware
 332  * memory barrier (after the set).
 333  *
 334  * Since: 2.4
 335  **/
 336 void
 337 (g_atomic_pointer_set) (volatile void *atomic,
 338                         gpointer       newval)
 339 {
 340   g_atomic_pointer_set ((volatile gpointer *) atomic, newval);
 341 }
 342
 343 /**
 344  * g_atomic_pointer_compare_and_exchange:
 345  * @atomic: a pointer to a #gpointer-sized value
 346  * @oldval: the value to compare with
 347  * @newval: the value to conditionally replace with
 348  *
 349  * Compares @atomic to @oldval and, if equal, sets it to @newval.
 350  * If @atomic was not equal to @oldval then no change occurs.
 351  *
 352  * This compare and exchange is done atomically.
 353  *
 354  * Think of this operation as an atomic version of
 355  * <literal>{ if (*@atomic == @oldval) { *@atomic = @newval; return TRUE; } else return FALSE; }</literal>
 356  *
 357  * This call acts as a full compiler and hardware memory barrier.
 358  *
 359  * Returns: %TRUE if the exchange took place
 360  *
 361  * Since: 2.4
 362  **/
 363 gboolean
 364 (g_atomic_pointer_compare_and_exchange) (volatile void *atomic,
 365                                          gpointer       oldval,
 366                                          gpointer       newval)
 367 {
 368   return g_atomic_pointer_compare_and_exchange ((volatile gpointer *) atomic,
 369                                                 oldval, newval);
 370 }
 371
 372 /**
 373  * g_atomic_pointer_add:
 374  * @atomic: a pointer to a #gpointer-sized value
 375  * @val: the value to add
 376  *
 377  * Atomically adds @val to the value of @atomic.
 378  *
 379  * Think of this operation as an atomic version of
 380  * <literal>{ tmp = *atomic; *@atomic += @val; return tmp; }</literal>
 381  *
 382  * This call acts as a full compiler and hardware memory barrier.
 383  *
 384  * Returns: the value of @atomic before the add, signed
 385  *
 386  * Since: 2.30
 387  **/
 388 gssize
 389 (g_atomic_pointer_add) (volatile void *atomic,
 390                         gssize         val)
 391 {
 392   return g_atomic_pointer_add ((volatile gpointer *) atomic, val);
 393 }
 394
 395 /**
 396  * g_atomic_pointer_and:
 397  * @atomic: a pointer to a #gpointer-sized value
 398  * @val: the value to 'and'
 399  *
 400  * Performs an atomic bitwise 'and' of the value of @atomic and @val,
 401  * storing the result back in @atomic.
 402  *
 403  * Think of this operation as an atomic version of
 404  * <literal>{ tmp = *atomic; *@atomic &= @val; return tmp; }</literal>
 405  *
 406  * This call acts as a full compiler and hardware memory barrier.
 407  *
 408  * Returns: the value of @atomic before the operation, unsigned
 409  *
 410  * Since: 2.30
 411  **/
 412 gsize
 413 (g_atomic_pointer_and) (volatile void *atomic,
 414                         gsize          val)
 415 {
 416   return g_atomic_pointer_and ((volatile gpointer *) atomic, val);
 417 }
 418
 419 /**
 420  * g_atomic_pointer_or:
 421  * @atomic: a pointer to a #gpointer-sized value
 422  * @val: the value to 'or'
 423  *
 424  * Performs an atomic bitwise 'or' of the value of @atomic and @val,
 425  * storing the result back in @atomic.
 426  *
 427  * Think of this operation as an atomic version of
 428  * <literal>{ tmp = *atomic; *@atomic |= @val; return tmp; }</literal>
 429  *
 430  * This call acts as a full compiler and hardware memory barrier.
 431  *
 432  * Returns: the value of @atomic before the operation, unsigned
 433  *
 434  * Since: 2.30
 435  **/
 436 gsize
 437 (g_atomic_pointer_or) (volatile void *atomic,
 438                        gsize          val)
 439 {
 440   return g_atomic_pointer_or ((volatile gpointer *) atomic, val);
 441 }
 442
 443 /**
 444  * g_atomic_pointer_xor:
 445  * @atomic: a pointer to a #gpointer-sized value
 446  * @val: the value to 'xor'
 447  *
 448  * Performs an atomic bitwise 'xor' of the value of @atomic and @val,
 449  * storing the result back in @atomic.
 450  *
 451  * Think of this operation as an atomic version of
 452  * <literal>{ tmp = *atomic; *@atomic ^= @val; return tmp; }</literal>
 453  *
 454  * This call acts as a full compiler and hardware memory barrier.
 455  *
 456  * Returns: the value of @atomic before the operation, unsigned
 457  *
 458  * Since: 2.30
 459  **/
 460 gsize
 461 (g_atomic_pointer_xor) (volatile void *atomic,
 462                         gsize          val)
 463 {
 464   return g_atomic_pointer_xor ((volatile gpointer *) atomic, val);
 465 }
 466
 467 #elif defined (G_PLATFORM_WIN32)
 468
 469 #include <windows.h>
 470 #if !defined(_M_AMD64) && !defined (_M_IA64) && !defined(_M_X64)
 471 #define InterlockedAnd _InterlockedAnd
 472 #define InterlockedOr _InterlockedOr
 473 #define InterlockedXor _InterlockedXor
 474 #endif
 475
 476 /*
 477  * http://msdn.microsoft.com/en-us/library/ms684122(v=vs.85).aspx
 478  */
 479 gint
 480 (g_atomic_int_get) (const volatile gint *atomic)
 481 {
 482   MemoryBarrier ();
 483   return *atomic;
 484 }
 485
 486 void
 487 (g_atomic_int_set) (volatile gint *atomic,
 488                     gint           newval)
 489 {
 490   *atomic = newval;
 491   MemoryBarrier ();
 492 }
 493
 494 void
 495 (g_atomic_int_inc) (volatile gint *atomic)
 496 {
 497   InterlockedIncrement (atomic);
 498 }
 499
 500 gboolean
 501 (g_atomic_int_dec_and_test) (volatile gint *atomic)
 502 {
 503   return InterlockedDecrement (atomic) == 0;
 504 }
 505
 506 gboolean
 507 (g_atomic_int_compare_and_exchange) (volatile gint *atomic,
 508                                      gint           oldval,
 509                                      gint           newval)
 510 {
 511   return InterlockedCompareExchange (atomic, newval, oldval) == oldval;
 512 }
 513
 514 gint
 515 (g_atomic_int_add) (volatile gint *atomic,
 516                     gint           val)
 517 {
 518   return InterlockedExchangeAdd (atomic, val);
 519 }
 520
 521 guint
 522 (g_atomic_int_and) (volatile guint *atomic,
 523                     guint           val)
 524 {
 525   return InterlockedAnd (atomic, val);
 526 }
 527
 528 guint
 529 (g_atomic_int_or) (volatile guint *atomic,
 530                    guint           val)
 531 {
 532   return InterlockedOr (atomic, val);
 533 }
 534
 535 guint
 536 (g_atomic_int_xor) (volatile guint *atomic,
 537                     guint           val)
 538 {
 539   return InterlockedXor (atomic, val);
 540 }
 541
 542
 543 gpointer
 544 (g_atomic_pointer_get) (const volatile void *atomic)
 545 {
 546   const volatile gpointer *ptr = atomic;
 547
 548   MemoryBarrier ();
 549   return *ptr;
 550 }
 551
 552 void
 553 (g_atomic_pointer_set) (volatile void *atomic,
 554                         gpointer       newval)
 555 {
 556   volatile gpointer *ptr = atomic;
 557
 558   *ptr = newval;
 559   MemoryBarrier ();
 560 }
 561
 562 gboolean
 563 (g_atomic_pointer_compare_and_exchange) (volatile void *atomic,
 564                                          gpointer       oldval,
 565                                          gpointer       newval)
 566 {
 567   return InterlockedCompareExchangePointer (atomic, newval, oldval) == oldval;
 568 }
 569
 570 gssize
 571 (g_atomic_pointer_add) (volatile void *atomic,
 572                         gssize         val)
 573 {
 574 #if GLIB_SIZEOF_VOID_P == 8
 575   return InterlockedExchangeAdd64 (atomic, val);
 576 #else
 577   return InterlockedExchangeAdd (atomic, val);
 578 #endif
 579 }
 580
 581 gsize
 582 (g_atomic_pointer_and) (volatile void *atomic,
 583                         gsize          val)
 584 {
 585 #if GLIB_SIZEOF_VOID_P == 8
 586   return InterlockedAnd64 (atomic, val);
 587 #else
 588   return InterlockedAnd (atomic, val);
 589 #endif
 590 }
 591
 592 gsize
 593 (g_atomic_pointer_or) (volatile void *atomic,
 594                        gsize          val)
 595 {
 596 #if GLIB_SIZEOF_VOID_P == 8
 597   return InterlockedOr64 (atomic, val);
 598 #else
 599   return InterlockedOr (atomic, val);
 600 #endif
 601 }
 602
 603 gsize
 604 (g_atomic_pointer_xor) (volatile void *atomic,
 605                         gsize          val)
 606 {
 607 #if GLIB_SIZEOF_VOID_P == 8
 608   return InterlockedXor64 (atomic, val);
 609 #else
 610   return InterlockedXor (atomic, val);
 611 #endif
 612 }
 613 #else
 614
 615 /* This error occurs when ./configure decided that we should be capable
 616  * of lock-free atomics but we find at compile-time that we are not.
 617  */
 618 #error G_ATOMIC_LOCK_FREE defined, but incapable of lock-free atomics.
 619
 620 #endif /* defined (__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4) */
 621
 622 #else /* G_ATOMIC_LOCK_FREE */
 623
 624 /* We are not permitted to call into any GLib functions from here, so we
 625  * can not use GMutex.
 626  *
 627  * Fortunately, we already take care of the Windows case above, and all
 628  * non-Windows platforms on which glib runs have pthreads.  Use those.
 629  */
 630 #include <pthread.h>
 631
 632 static pthread_mutex_t g_atomic_lock = PTHREAD_MUTEX_INITIALIZER;
 633
 634 gint
 635 (g_atomic_int_get) (volatile gint *atomic)
 636 {
 637   gint value;
 638
 639   pthread_mutex_lock (&g_atomic_lock);
 640   value = *atomic;
 641   pthread_mutex_unlock (&g_atomic_lock);
 642
 643   return value;
 644 }
 645
 646 void
 647 (g_atomic_int_set) (volatile gint *atomic,
 648                     gint           value)
 649 {
 650   pthread_mutex_lock (&g_atomic_lock);
 651   *atomic = value;
 652   pthread_mutex_unlock (&g_atomic_lock);
 653 }
 654
 655 void
 656 (g_atomic_int_inc) (volatile gint *atomic)
 657 {
 658   pthread_mutex_lock (&g_atomic_lock);
 659   (*atomic)++;
 660   pthread_mutex_unlock (&g_atomic_lock);
 661 }
 662
 663 gboolean
 664 (g_atomic_int_dec_and_test) (volatile gint *atomic)
 665 {
 666   gboolean is_zero;
 667
 668   pthread_mutex_lock (&g_atomic_lock);
 669   is_zero = --(*atomic) == 0;
 670   pthread_mutex_unlock (&g_atomic_lock);
 671
 672   return is_zero;
 673 }
 674
 675 gboolean
 676 (g_atomic_int_compare_and_exchange) (volatile gint *atomic,
 677                                      gint           oldval,
 678                                      gint           newval)
 679 {
 680   gboolean success;
 681
 682   pthread_mutex_lock (&g_atomic_lock);
 683
 684   if ((success = (*atomic == oldval)))
 685     *atomic = newval;
 686
 687   pthread_mutex_unlock (&g_atomic_lock);
 688
 689   return success;
 690 }
 691
 692 gint
 693 (g_atomic_int_add) (volatile gint *atomic,
 694                     gint           val)
 695 {
 696   gint oldval;
 697
 698   pthread_mutex_lock (&g_atomic_lock);
 699   oldval = *atomic;
 700   *atomic = oldval + val;
 701   pthread_mutex_unlock (&g_atomic_lock);
 702
 703   return oldval;
 704 }
 705
 706 guint
 707 (g_atomic_int_and) (volatile guint *atomic,
 708                     guint           val)
 709 {
 710   guint oldval;
 711
 712   pthread_mutex_lock (&g_atomic_lock);
 713   oldval = *atomic;
 714   *atomic = oldval & val;
 715   pthread_mutex_unlock (&g_atomic_lock);
 716
 717   return oldval;
 718 }
 719
 720 guint
 721 (g_atomic_int_or) (volatile guint *atomic,
 722                    guint           val)
 723 {
 724   guint oldval;
 725
 726   pthread_mutex_lock (&g_atomic_lock);
 727   oldval = *atomic;
 728   *atomic = oldval | val;
 729   pthread_mutex_unlock (&g_atomic_lock);
 730
 731   return oldval;
 732 }
 733
 734 guint
 735 (g_atomic_int_xor) (volatile guint *atomic,
 736                     guint           val)
 737 {
 738   guint oldval;
 739
 740   pthread_mutex_lock (&g_atomic_lock);
 741   oldval = *atomic;
 742   *atomic = oldval ^ val;
 743   pthread_mutex_unlock (&g_atomic_lock);
 744
 745   return oldval;
 746 }
 747
 748
 749 gpointer
 750 (g_atomic_pointer_get) (volatile void *atomic)
 751 {
 752   volatile gpointer *ptr = atomic;
 753   gpointer value;
 754
 755   pthread_mutex_lock (&g_atomic_lock);
 756   value = *ptr;
 757   pthread_mutex_unlock (&g_atomic_lock);
 758
 759   return value;
 760 }
 761
 762 void
 763 (g_atomic_pointer_set) (volatile void *atomic,
 764                         gpointer       newval)
 765 {
 766   volatile gpointer *ptr = atomic;
 767
 768   pthread_mutex_lock (&g_atomic_lock);
 769   *ptr = newval;
 770   pthread_mutex_unlock (&g_atomic_lock);
 771 }
 772
 773 gboolean
 774 (g_atomic_pointer_compare_and_exchange) (volatile void *atomic,
 775                                          gpointer       oldval,
 776                                          gpointer       newval)
 777 {
 778   volatile gpointer *ptr = atomic;
 779   gboolean success;
 780
 781   pthread_mutex_lock (&g_atomic_lock);
 782
 783   if ((success = (*ptr == oldval)))
 784     *ptr = newval;
 785
 786   pthread_mutex_unlock (&g_atomic_lock);
 787
 788   return success;
 789 }
 790
 791 gssize
 792 (g_atomic_pointer_add) (volatile void *atomic,
 793                         gssize         val)
 794 {
 795   volatile gssize *ptr = atomic;
 796   gssize oldval;
 797
 798   pthread_mutex_lock (&g_atomic_lock);
 799   oldval = *ptr;
 800   *ptr = oldval + val;
 801   pthread_mutex_unlock (&g_atomic_lock);
 802
 803   return oldval;
 804 }
 805
 806 gsize
 807 (g_atomic_pointer_and) (volatile void *atomic,
 808                         gsize          val)
 809 {
 810   volatile gsize *ptr = atomic;
 811   gsize oldval;
 812
 813   pthread_mutex_lock (&g_atomic_lock);
 814   oldval = *ptr;
 815   *ptr = oldval & val;
 816   pthread_mutex_unlock (&g_atomic_lock);
 817
 818   return oldval;
 819 }
 820
 821 gsize
 822 (g_atomic_pointer_or) (volatile void *atomic,
 823                        gsize          val)
 824 {
 825   volatile gsize *ptr = atomic;
 826   gsize oldval;
 827
 828   pthread_mutex_lock (&g_atomic_lock);
 829   oldval = *ptr;
 830   *ptr = oldval | val;
 831   pthread_mutex_unlock (&g_atomic_lock);
 832
 833   return oldval;
 834 }
 835
 836 gsize
 837 (g_atomic_pointer_xor) (volatile void *atomic,
 838                         gsize          val)
 839 {
 840   volatile gsize *ptr = atomic;
 841   gsize oldval;
 842
 843   pthread_mutex_lock (&g_atomic_lock);
 844   oldval = *ptr;
 845   *ptr = oldval ^ val;
 846   pthread_mutex_unlock (&g_atomic_lock);
 847
 848   return oldval;
 849 }
 850
 851 #endif
 852
 853 /**
 854  * g_atomic_int_exchange_and_add:
 855  * @atomic: a pointer to a #gint
 856  * @val: the value to add
 857  *
 858  * This function existed before g_atomic_int_add() returned the prior
 859  * value of the integer (which it now does).  It is retained only for
 860  * compatibility reasons.  Don't use this function in new code.
 861  *
 862  * Returns: the value of @atomic before the add, signed
 863  * Since: 2.4
 864  * Deprecated: 2.30: Use g_atomic_int_add() instead.
 865  **/
 866 gint
 867 g_atomic_int_exchange_and_add (volatile gint *atomic,
 868                                gint           val)
 869 {
 870   return (g_atomic_int_add) (atomic, val);
 871 }