sdl-ios-xcode: src/atomic/SDL

annotate src/atomic/SDL_atomic.c @ 5217:b0797947dd1c

You don't need to copy the pixels into the streaming texture's pixel data. This behavior is defined specifically to optimize the UpdateTexture path.

author	Sam Lantinga <slouken@libsdl.org>
date	Sun, 06 Feb 2011 20:56:21 -0800
parents	dceec93471e7
children	b530ef003506

rev	line source
5003 3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	1 /*
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	2 SDL - Simple DirectMedia Layer
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	3 Copyright (C) 1997-2010 Sam Lantinga
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	4
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	5 This library is free software; you can redistribute it and/or
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	6 modify it under the terms of the GNU Lesser General Public
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	7 License as published by the Free Software Foundation; either
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	8 version 2.1 of the License, or (at your option) any later version.
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	9
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	10 This library is distributed in the hope that it will be useful,
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	11 but WITHOUT ANY WARRANTY; without even the implied warranty of
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	13 Lesser General Public License for more details.
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	14
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	15 You should have received a copy of the GNU Lesser General Public
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	16 License along with this library; if not, write to the Free Software
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	17 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	18
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	19 Sam Lantinga
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	20 slouken@libsdl.org
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	21 */
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	22 #include "SDL_stdinc.h"
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	23
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	24 #include "SDL_atomic.h"
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	25
5004 0c72ae7b7cb2 Added native atomic operations for Windows, Mac OS X, and gcc compiler intrinsics. Sam Lantinga <slouken@libsdl.org> parents: 5003 diff changeset	26 /* Note that we undefine the atomic operations here, in case they are
0c72ae7b7cb2 Added native atomic operations for Windows, Mac OS X, and gcc compiler intrinsics. Sam Lantinga <slouken@libsdl.org> parents: 5003 diff changeset	27 defined as compiler intrinsics while building SDL but the library user
0c72ae7b7cb2 Added native atomic operations for Windows, Mac OS X, and gcc compiler intrinsics. Sam Lantinga <slouken@libsdl.org> parents: 5003 diff changeset	28 doesn't have that compiler. That way we always have a working set of
0c72ae7b7cb2 Added native atomic operations for Windows, Mac OS X, and gcc compiler intrinsics. Sam Lantinga <slouken@libsdl.org> parents: 5003 diff changeset	29 atomic operations built into the library.
0c72ae7b7cb2 Added native atomic operations for Windows, Mac OS X, and gcc compiler intrinsics. Sam Lantinga <slouken@libsdl.org> parents: 5003 diff changeset	30 */
0c72ae7b7cb2 Added native atomic operations for Windows, Mac OS X, and gcc compiler intrinsics. Sam Lantinga <slouken@libsdl.org> parents: 5003 diff changeset	31
5003 3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	32 /*
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	33 If any of the operations are not provided then we must emulate some
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	34 of them. That means we need a nice implementation of spin locks
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	35 that avoids the "one big lock" problem. We use a vector of spin
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	36 locks and pick which one to use based on the address of the operand
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	37 of the function.
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	38
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	39 To generate the index of the lock we first shift by 3 bits to get
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	40 rid on the zero bits that result from 32 and 64 bit allignment of
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	41 data. We then mask off all but 5 bits and use those 5 bits as an
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	42 index into the table.
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	43
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	44 Picking the lock this way insures that accesses to the same data at
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	45 the same time will go to the same lock. OTOH, accesses to different
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	46 data have only a 1/32 chance of hitting the same lock. That should
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	47 pretty much eliminate the chances of several atomic operations on
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	48 different data from waiting on the same "big lock". If it isn't
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	49 then the table of locks can be expanded to a new size so long as
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	50 the new size is a power of two.
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	51
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	52 Contributed by Bob Pendleton, bob@pendleton.com
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	53 */
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	54
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	55 static SDL_SpinLock locks[32];
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	56
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	57 static __inline__ void
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	58 enterLock(void *a)
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	59 {
5004 0c72ae7b7cb2 Added native atomic operations for Windows, Mac OS X, and gcc compiler intrinsics. Sam Lantinga <slouken@libsdl.org> parents: 5003 diff changeset	60 uintptr_t index = ((((uintptr_t)a) >> 3) & 0x1f);
5003 3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	61
5004 0c72ae7b7cb2 Added native atomic operations for Windows, Mac OS X, and gcc compiler intrinsics. Sam Lantinga <slouken@libsdl.org> parents: 5003 diff changeset	62 SDL_AtomicLock(&locks[index]);
5003 3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	63 }
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	64
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	65 static __inline__ void
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	66 leaveLock(void *a)
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	67 {
5004 0c72ae7b7cb2 Added native atomic operations for Windows, Mac OS X, and gcc compiler intrinsics. Sam Lantinga <slouken@libsdl.org> parents: 5003 diff changeset	68 uintptr_t index = ((((uintptr_t)a) >> 3) & 0x1f);
5003 3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	69
5004 0c72ae7b7cb2 Added native atomic operations for Windows, Mac OS X, and gcc compiler intrinsics. Sam Lantinga <slouken@libsdl.org> parents: 5003 diff changeset	70 SDL_AtomicUnlock(&locks[index]);
5003 3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	71 }
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	72
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	73 SDL_bool
5097 dceec93471e7 Improvements based on feedback from Anthony Williams Sam Lantinga <slouken@libsdl.org> parents: 5004 diff changeset	74 SDL_AtomicCAS_(SDL_atomic_t *a, int oldval, int newval)
5003 3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	75 {
5004 0c72ae7b7cb2 Added native atomic operations for Windows, Mac OS X, and gcc compiler intrinsics. Sam Lantinga <slouken@libsdl.org> parents: 5003 diff changeset	76 SDL_bool retval = SDL_FALSE;
5003 3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	77
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	78 enterLock(a);
5004 0c72ae7b7cb2 Added native atomic operations for Windows, Mac OS X, and gcc compiler intrinsics. Sam Lantinga <slouken@libsdl.org> parents: 5003 diff changeset	79 if (a->value == oldval) {
5003 3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	80 a->value = newval;
5004 0c72ae7b7cb2 Added native atomic operations for Windows, Mac OS X, and gcc compiler intrinsics. Sam Lantinga <slouken@libsdl.org> parents: 5003 diff changeset	81 retval = SDL_TRUE;
5003 3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	82 }
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	83 leaveLock(a);
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	84
5004 0c72ae7b7cb2 Added native atomic operations for Windows, Mac OS X, and gcc compiler intrinsics. Sam Lantinga <slouken@libsdl.org> parents: 5003 diff changeset	85 return retval;
5003 3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	86 }
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	87
5097 dceec93471e7 Improvements based on feedback from Anthony Williams Sam Lantinga <slouken@libsdl.org> parents: 5004 diff changeset	88 SDL_bool
dceec93471e7 Improvements based on feedback from Anthony Williams Sam Lantinga <slouken@libsdl.org> parents: 5004 diff changeset	89 SDL_AtomicCASPtr_(void *a, void oldval, void *newval)
5003 3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	90 {
5004 0c72ae7b7cb2 Added native atomic operations for Windows, Mac OS X, and gcc compiler intrinsics. Sam Lantinga <slouken@libsdl.org> parents: 5003 diff changeset	91 SDL_bool retval = SDL_FALSE;
5003 3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	92
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	93 enterLock(a);
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	94 if (*a == oldval) {
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	95 *a = newval;
5004 0c72ae7b7cb2 Added native atomic operations for Windows, Mac OS X, and gcc compiler intrinsics. Sam Lantinga <slouken@libsdl.org> parents: 5003 diff changeset	96 retval = SDL_TRUE;
5003 3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	97 }
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	98 leaveLock(a);
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	99
5004 0c72ae7b7cb2 Added native atomic operations for Windows, Mac OS X, and gcc compiler intrinsics. Sam Lantinga <slouken@libsdl.org> parents: 5003 diff changeset	100 return retval;
5003 3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	101 }
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	102
3a95a2b93eb3 Updated the atomic API for better use cases Sam Lantinga <slouken@libsdl.org> parents: diff changeset	103 /* vi: set ts=4 sw=4 expandtab: */

Mercurial > sdl-ios-xcode

annotate src/atomic/SDL_atomic.c @ 5217:b0797947dd1c