forked from len0rd/rockbox
Port of Duke Nukem 3D
This ports Fabien Sanglard's Chocolate Duke to run on a version of SDL for Rockbox. Change-Id: I8f2c4c78af19de10c1633ed7bb7a997b43256dd9
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994 changed files with 336924 additions and 15 deletions
215
apps/plugins/sdl/src/thread/os2/SDL_syscond.c
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apps/plugins/sdl/src/thread/os2/SDL_syscond.c
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/*
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SDL - Simple DirectMedia Layer
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Copyright (C) 1997-2012 Sam Lantinga
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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Sam Lantinga
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slouken@libsdl.org
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*/
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#include "SDL_config.h"
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/* An implementation of condition variables using semaphores and mutexes */
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/*
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This implementation borrows heavily from the BeOS condition variable
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implementation, written by Christopher Tate and Owen Smith. Thanks!
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*/
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#include "SDL_thread.h"
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struct SDL_cond
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{
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SDL_mutex *lock;
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int waiting;
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int signals;
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SDL_sem *wait_sem;
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SDL_sem *wait_done;
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};
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/* Create a condition variable */
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DECLSPEC SDL_cond * SDLCALL SDL_CreateCond(void)
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{
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SDL_cond *cond;
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cond = (SDL_cond *) SDL_malloc(sizeof(SDL_cond));
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if ( cond ) {
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cond->lock = SDL_CreateMutex();
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cond->wait_sem = SDL_CreateSemaphore(0);
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cond->wait_done = SDL_CreateSemaphore(0);
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cond->waiting = cond->signals = 0;
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if ( ! cond->lock || ! cond->wait_sem || ! cond->wait_done ) {
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SDL_DestroyCond(cond);
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cond = NULL;
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}
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} else {
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SDL_OutOfMemory();
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}
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return(cond);
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}
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/* Destroy a condition variable */
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DECLSPEC void SDLCALL SDL_DestroyCond(SDL_cond *cond)
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{
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if ( cond ) {
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if ( cond->wait_sem ) {
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SDL_DestroySemaphore(cond->wait_sem);
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}
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if ( cond->wait_done ) {
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SDL_DestroySemaphore(cond->wait_done);
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}
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if ( cond->lock ) {
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SDL_DestroyMutex(cond->lock);
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}
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SDL_free(cond);
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}
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}
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/* Restart one of the threads that are waiting on the condition variable */
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DECLSPEC int SDLCALL SDL_CondSignal(SDL_cond *cond)
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{
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if ( ! cond ) {
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SDL_SetError("Passed a NULL condition variable");
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return -1;
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}
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/* If there are waiting threads not already signalled, then
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signal the condition and wait for the thread to respond.
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*/
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SDL_LockMutex(cond->lock);
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if ( cond->waiting > cond->signals ) {
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++cond->signals;
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SDL_SemPost(cond->wait_sem);
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SDL_UnlockMutex(cond->lock);
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SDL_SemWait(cond->wait_done);
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} else {
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SDL_UnlockMutex(cond->lock);
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}
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return 0;
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}
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/* Restart all threads that are waiting on the condition variable */
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DECLSPEC int SDLCALL SDL_CondBroadcast(SDL_cond *cond)
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{
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if ( ! cond ) {
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SDL_SetError("Passed a NULL condition variable");
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return -1;
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}
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/* If there are waiting threads not already signalled, then
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signal the condition and wait for the thread to respond.
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*/
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SDL_LockMutex(cond->lock);
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if ( cond->waiting > cond->signals ) {
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int i, num_waiting;
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num_waiting = (cond->waiting - cond->signals);
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cond->signals = cond->waiting;
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for ( i=0; i<num_waiting; ++i ) {
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SDL_SemPost(cond->wait_sem);
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}
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/* Now all released threads are blocked here, waiting for us.
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Collect them all (and win fabulous prizes!) :-)
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*/
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SDL_UnlockMutex(cond->lock);
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for ( i=0; i<num_waiting; ++i ) {
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SDL_SemWait(cond->wait_done);
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}
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} else {
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SDL_UnlockMutex(cond->lock);
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}
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return 0;
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}
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/* Wait on the condition variable for at most 'ms' milliseconds.
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The mutex must be locked before entering this function!
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The mutex is unlocked during the wait, and locked again after the wait.
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Typical use:
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Thread A:
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SDL_LockMutex(lock);
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while ( ! condition ) {
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SDL_CondWait(cond);
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}
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SDL_UnlockMutex(lock);
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Thread B:
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SDL_LockMutex(lock);
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...
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condition = true;
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...
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SDL_UnlockMutex(lock);
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*/
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DECLSPEC int SDLCALL SDL_CondWaitTimeout(SDL_cond *cond, SDL_mutex *mutex, Uint32 ms)
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{
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int retval;
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if ( ! cond ) {
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SDL_SetError("Passed a NULL condition variable");
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return -1;
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}
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/* Obtain the protection mutex, and increment the number of waiters.
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This allows the signal mechanism to only perform a signal if there
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are waiting threads.
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*/
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SDL_LockMutex(cond->lock);
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++cond->waiting;
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SDL_UnlockMutex(cond->lock);
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/* Unlock the mutex, as is required by condition variable semantics */
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SDL_UnlockMutex(mutex);
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/* Wait for a signal */
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if ( ms == SDL_MUTEX_MAXWAIT ) {
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retval = SDL_SemWait(cond->wait_sem);
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} else {
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retval = SDL_SemWaitTimeout(cond->wait_sem, ms);
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}
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/* Let the signaler know we have completed the wait, otherwise
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the signaler can race ahead and get the condition semaphore
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if we are stopped between the mutex unlock and semaphore wait,
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giving a deadlock. See the following URL for details:
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http://www-classic.be.com/aboutbe/benewsletter/volume_III/Issue40.html
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*/
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SDL_LockMutex(cond->lock);
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if ( cond->signals > 0 ) {
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/* If we timed out, we need to eat a condition signal */
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if ( retval > 0 ) {
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SDL_SemWait(cond->wait_sem);
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}
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/* We always notify the signal thread that we are done */
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SDL_SemPost(cond->wait_done);
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/* Signal handshake complete */
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--cond->signals;
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}
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--cond->waiting;
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SDL_UnlockMutex(cond->lock);
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/* Lock the mutex, as is required by condition variable semantics */
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SDL_LockMutex(mutex);
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return retval;
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}
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/* Wait on the condition variable forever */
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DECLSPEC int SDLCALL SDL_CondWait(SDL_cond *cond, SDL_mutex *mutex)
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{
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return SDL_CondWaitTimeout(cond, mutex, SDL_MUTEX_MAXWAIT);
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}
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