Mercurial > sdl-ios-xcode
view src/thread/generic/SDL_syscond.c @ 1257:448a9a64537b
[PATCH] SDL_GetVideoMode() does not find best mode, part 2
Following commit 1.51, I come accross a problem when SDL must choose between
several video modes that could suit the one asked.
If I ask 320x240 with this list:
768x480 768x240 640x400 640x200 384x480 384x240 320x400 320x200
The smallest selectables modes are 384x240 and 320x400. And SDL choose the later
in this list, but 384x240 is more suitable. So I added a check to compare
the pixel count (surface) of modes, and select the one which has the smallest
pixel count.
In my example, 384x240 has 92160 pixels, and 320x400 has 128000 pixels. So now
SDL will choose 384x240 for the asked 320x240 mode.
author | Patrice Mandin <patmandin@gmail.com> |
---|---|
date | Thu, 19 Jan 2006 21:28:52 +0000 |
parents | b8d311d90021 |
children | c9b51268668f |
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/* SDL - Simple DirectMedia Layer Copyright (C) 1997-2004 Sam Lantinga This library is free software; you can redistribute it and/or modify it under the terms of the GNU Library General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public License for more details. You should have received a copy of the GNU Library General Public License along with this library; if not, write to the Free Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA Sam Lantinga slouken@libsdl.org */ #ifdef SAVE_RCSID static char rcsid = "@(#) $Id$"; #endif /* An implementation of condition variables using semaphores and mutexes */ /* This implementation borrows heavily from the BeOS condition variable implementation, written by Christopher Tate and Owen Smith. Thanks! */ #include <stdio.h> #include <stdlib.h> #include "SDL_error.h" #include "SDL_thread.h" struct SDL_cond { SDL_mutex *lock; int waiting; int signals; SDL_sem *wait_sem; SDL_sem *wait_done; }; /* Create a condition variable */ SDL_cond * SDL_CreateCond(void) { SDL_cond *cond; cond = (SDL_cond *) malloc(sizeof(SDL_cond)); if ( cond ) { cond->lock = SDL_CreateMutex(); cond->wait_sem = SDL_CreateSemaphore(0); cond->wait_done = SDL_CreateSemaphore(0); cond->waiting = cond->signals = 0; if ( ! cond->lock || ! cond->wait_sem || ! cond->wait_done ) { SDL_DestroyCond(cond); cond = NULL; } } else { SDL_OutOfMemory(); } return(cond); } /* Destroy a condition variable */ void SDL_DestroyCond(SDL_cond *cond) { if ( cond ) { if ( cond->wait_sem ) { SDL_DestroySemaphore(cond->wait_sem); } if ( cond->wait_done ) { SDL_DestroySemaphore(cond->wait_done); } if ( cond->lock ) { SDL_DestroyMutex(cond->lock); } free(cond); } } /* Restart one of the threads that are waiting on the condition variable */ int SDL_CondSignal(SDL_cond *cond) { if ( ! cond ) { SDL_SetError("Passed a NULL condition variable"); return -1; } /* If there are waiting threads not already signalled, then signal the condition and wait for the thread to respond. */ SDL_LockMutex(cond->lock); if ( cond->waiting > cond->signals ) { ++cond->signals; SDL_SemPost(cond->wait_sem); SDL_UnlockMutex(cond->lock); SDL_SemWait(cond->wait_done); } else { SDL_UnlockMutex(cond->lock); } return 0; } /* Restart all threads that are waiting on the condition variable */ int SDL_CondBroadcast(SDL_cond *cond) { if ( ! cond ) { SDL_SetError("Passed a NULL condition variable"); return -1; } /* If there are waiting threads not already signalled, then signal the condition and wait for the thread to respond. */ SDL_LockMutex(cond->lock); if ( cond->waiting > cond->signals ) { int i, num_waiting; num_waiting = (cond->waiting - cond->signals); cond->signals = cond->waiting; for ( i=0; i<num_waiting; ++i ) { SDL_SemPost(cond->wait_sem); } /* Now all released threads are blocked here, waiting for us. Collect them all (and win fabulous prizes!) :-) */ SDL_UnlockMutex(cond->lock); for ( i=0; i<num_waiting; ++i ) { SDL_SemWait(cond->wait_done); } } else { SDL_UnlockMutex(cond->lock); } return 0; } /* Wait on the condition variable for at most 'ms' milliseconds. The mutex must be locked before entering this function! The mutex is unlocked during the wait, and locked again after the wait. Typical use: Thread A: SDL_LockMutex(lock); while ( ! condition ) { SDL_CondWait(cond); } SDL_UnlockMutex(lock); Thread B: SDL_LockMutex(lock); ... condition = true; ... SDL_UnlockMutex(lock); */ int SDL_CondWaitTimeout(SDL_cond *cond, SDL_mutex *mutex, Uint32 ms) { int retval; if ( ! cond ) { SDL_SetError("Passed a NULL condition variable"); return -1; } /* Obtain the protection mutex, and increment the number of waiters. This allows the signal mechanism to only perform a signal if there are waiting threads. */ SDL_LockMutex(cond->lock); ++cond->waiting; SDL_UnlockMutex(cond->lock); /* Unlock the mutex, as is required by condition variable semantics */ SDL_UnlockMutex(mutex); /* Wait for a signal */ if ( ms == SDL_MUTEX_MAXWAIT ) { retval = SDL_SemWait(cond->wait_sem); } else { retval = SDL_SemWaitTimeout(cond->wait_sem, ms); } /* Let the signaler know we have completed the wait, otherwise the signaler can race ahead and get the condition semaphore if we are stopped between the mutex unlock and semaphore wait, giving a deadlock. See the following URL for details: http://www-classic.be.com/aboutbe/benewsletter/volume_III/Issue40.html */ SDL_LockMutex(cond->lock); if ( cond->signals > 0 ) { /* If we timed out, we need to eat a condition signal */ if ( retval > 0 ) { SDL_SemWait(cond->wait_sem); } /* We always notify the signal thread that we are done */ SDL_SemPost(cond->wait_done); /* Signal handshake complete */ --cond->signals; } --cond->waiting; SDL_UnlockMutex(cond->lock); /* Lock the mutex, as is required by condition variable semantics */ SDL_LockMutex(mutex); return retval; } /* Wait on the condition variable forever */ int SDL_CondWait(SDL_cond *cond, SDL_mutex *mutex) { return SDL_CondWaitTimeout(cond, mutex, SDL_MUTEX_MAXWAIT); }