Mercurial > sdl-ios-xcode
annotate src/thread/amigaos/SDL_syssem.c @ 765:4c2ba6161939
Editors Note: The original patch was modified to use SDL_Delay() instead of
nanosleep because nanosleep may not be portable to all systems
using SDL with the ALSA backend. This may be a moot point with
the switch to blocking writes anyway...
Date: Sat, 27 Dec 2003 21:47:36 +0100
From: Michel Daenzer
To: Debian Bug Tracking System
Subject: [SDL] Bug#225252: [PATCH] ALSA fixes
Package: libsdl1.2debian-all
Version: 1.2.6-2
Severity: normal
Tags: patch
For SDL 1.2.6, the ALSA backend was changed to call snd_pcm_open() with
SND_PCM_NONBLOCK. That's a good idea per se, however, it causes high CPU
usage, interrupted sound and stuttering in some games here. Taking a nanosleep
whenever snd_pcm_writei() returns -EAGAIN fixes this, but I think it's more
efficient to use blocking mode for the actual sound playback. Feedback from the
SDL and ALSA lists appreciated.
The patch also fixes the default ALSA device to be used.
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Sun, 04 Jan 2004 15:40:50 +0000 |
| parents | f6ffac90895c |
| children | b8d311d90021 |
| rev | line source |
|---|---|
| 0 | 1 /* |
| 2 SDL - Simple DirectMedia Layer | |
|
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3 Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002 Sam Lantinga |
| 0 | 4 |
| 5 This library is free software; you can redistribute it and/or | |
| 6 modify it under the terms of the GNU Library General Public | |
| 7 License as published by the Free Software Foundation; either | |
| 8 version 2 of the License, or (at your option) any later version. | |
| 9 | |
| 10 This library is distributed in the hope that it will be useful, | |
| 11 but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
| 13 Library General Public License for more details. | |
| 14 | |
| 15 You should have received a copy of the GNU Library General Public | |
| 16 License along with this library; if not, write to the Free | |
| 17 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
| 18 | |
| 19 Sam Lantinga | |
|
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20 slouken@libsdl.org |
| 0 | 21 */ |
| 22 | |
| 23 #ifdef SAVE_RCSID | |
| 24 static char rcsid = | |
| 25 "@(#) $Id$"; | |
| 26 #endif | |
| 27 | |
|
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28 /* An implementation of semaphores using mutexes and condition variables */ |
| 0 | 29 |
| 30 #include "SDL_error.h" | |
| 31 #include "SDL_thread.h" | |
| 32 #include "SDL_systhread_c.h" | |
| 33 | |
| 34 | |
| 35 struct SDL_semaphore | |
| 36 { | |
| 37 struct SignalSemaphore Sem; | |
|
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38 Uint32 count; |
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39 Uint32 waiters_count; |
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40 SDL_mutex *count_lock; |
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41 SDL_cond *count_nonzero; |
| 0 | 42 }; |
| 43 | |
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44 #undef D |
| 0 | 45 |
| 46 #define D(x) | |
| 47 | |
| 48 SDL_sem *SDL_CreateSemaphore(Uint32 initial_value) | |
| 49 { | |
| 50 SDL_sem *sem; | |
| 51 | |
| 52 sem = (SDL_sem *)malloc(sizeof(*sem)); | |
|
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53 |
| 0 | 54 if ( ! sem ) { |
| 55 SDL_OutOfMemory(); | |
| 56 return(0); | |
| 57 } | |
| 58 | |
| 59 D(bug("Creating semaphore %lx...\n",sem)); | |
| 60 | |
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61 memset(sem,0,sizeof(*sem)); |
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62 |
| 0 | 63 InitSemaphore(&sem->Sem); |
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64 |
| 0 | 65 return(sem); |
| 66 } | |
| 67 | |
| 68 void SDL_DestroySemaphore(SDL_sem *sem) | |
| 69 { | |
| 70 D(bug("Destroying semaphore %lx...\n",sem)); | |
| 71 | |
| 72 if ( sem ) { | |
| 73 // Condizioni per liberare i task in attesa? | |
| 74 free(sem); | |
| 75 } | |
| 76 } | |
| 77 | |
| 78 int SDL_SemTryWait(SDL_sem *sem) | |
| 79 { | |
| 80 if ( ! sem ) { | |
| 81 SDL_SetError("Passed a NULL semaphore"); | |
| 82 return -1; | |
| 83 } | |
| 84 | |
| 85 D(bug("TryWait semaphore...%lx\n",sem)); | |
| 86 | |
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87 ObtainSemaphore(&sem->Sem); |
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88 // ReleaseSemaphore(&sem->Sem); |
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89 |
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90 return 1; |
| 0 | 91 } |
| 92 | |
| 93 int SDL_SemWaitTimeout(SDL_sem *sem, Uint32 timeout) | |
| 94 { | |
| 95 int retval; | |
| 96 | |
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97 |
| 0 | 98 if ( ! sem ) { |
| 99 SDL_SetError("Passed a NULL semaphore"); | |
| 100 return -1; | |
| 101 } | |
| 102 | |
| 103 D(bug("WaitTimeout (%ld) semaphore...%lx\n",timeout,sem)); | |
| 104 | |
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105 /* A timeout of 0 is an easy case */ |
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106 if ( timeout == 0 ) { |
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107 return SDL_SemTryWait(sem); |
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108 } |
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109 /* |
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110 SDL_LockMutex(sem->count_lock); |
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111 ++sem->waiters_count; |
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112 retval = 0; |
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113 while ( (sem->count == 0) && (retval != SDL_MUTEX_TIMEDOUT) ) { |
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114 retval = SDL_CondWaitTimeout(sem->count_nonzero, |
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115 sem->count_lock, timeout); |
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116 } |
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117 --sem->waiters_count; |
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118 --sem->count; |
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119 SDL_UnlockMutex(sem->count_lock); |
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120 */ |
| 0 | 121 if(!(retval=AttemptSemaphore(&sem->Sem))) |
| 122 { | |
| 123 SDL_Delay(timeout); | |
| 124 retval=AttemptSemaphore(&sem->Sem); | |
| 125 } | |
| 126 | |
| 127 if(retval==TRUE) | |
| 128 { | |
| 129 // ReleaseSemaphore(&sem->Sem); | |
| 130 retval=1; | |
| 131 } | |
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132 |
| 0 | 133 return retval; |
| 134 } | |
| 135 | |
| 136 int SDL_SemWait(SDL_sem *sem) | |
| 137 { | |
| 138 ObtainSemaphore(&sem->Sem); | |
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139 return 0; |
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140 // return SDL_SemWaitTimeout(sem, SDL_MUTEX_MAXWAIT); |
| 0 | 141 } |
| 142 | |
| 143 Uint32 SDL_SemValue(SDL_sem *sem) | |
| 144 { | |
| 145 Uint32 value; | |
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146 |
| 0 | 147 value = 0; |
| 148 if ( sem ) { | |
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149 #ifdef STORMC4_WOS |
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150 value = sem->Sem.ssppc_SS.ss_NestCount; |
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151 #else |
| 0 | 152 value = sem->Sem.ss_NestCount; |
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153 #endif |
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154 // SDL_UnlockMutex(sem->count_lock); |
| 0 | 155 } |
| 156 return value; | |
| 157 } | |
| 158 | |
| 159 int SDL_SemPost(SDL_sem *sem) | |
| 160 { | |
| 161 if ( ! sem ) { | |
| 162 SDL_SetError("Passed a NULL semaphore"); | |
| 163 return -1; | |
| 164 } | |
| 165 D(bug("SemPost semaphore...%lx\n",sem)); | |
| 166 | |
| 167 ReleaseSemaphore(&sem->Sem); | |
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168 #if 0 |
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169 SDL_LockMutex(sem->count_lock); |
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170 if ( sem->waiters_count > 0 ) { |
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171 SDL_CondSignal(sem->count_nonzero); |
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172 } |
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173 ++sem->count; |
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174 SDL_UnlockMutex(sem->count_lock); |
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175 #endif |
| 0 | 176 return 0; |
| 177 } | |
| 178 |