Mercurial > sdl-ios-xcode
annotate src/thread/amigaos/SDL_syssem.c @ 968:4675910b0b7b
Date: Mon, 11 Oct 2004 15:17:27 +0300 (EEST)
From: Hannu Savolainen
Subject: Re: SDL uses obsolete OSS features
I did some work on getting OSS to work better with SDL. There have been
some problems with select which should be fixed now.
I'm having some problems in understanding what is the purpose of the
DSP_WaitAudio() routine. I added a return to the very beginning of this
routine and commendted out the define for USE_BLOCKING_WRITES. At least
lbreakout2 seems to work as well as earlier. The latencies are the same.
An ordinary blocking write does exactly the same thing than DSP_WaitAudio
does. So I would recommend using the USE_BLOCKING_WRITES approach and
removing everything from the DSP_WaitAudio routine. Also enabling
USE_BLOCKING_WRITES makes it possible to simplify DSP_PlayAudio() because
you don't need to handle the partial writes (the do-while loop).
Attached is a patch against SDL-1.2.7. After these changes SDL will use
OSS as it's designed to be used (make it as simple as possible). This code
should work with all OSS implementations because it uses only the very
fundamental features that have been there since the jurassic times.
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Fri, 12 Nov 2004 21:39:04 +0000 |
| parents | b8d311d90021 |
| children | c9b51268668f |
| rev | line source |
|---|---|
| 0 | 1 /* |
| 2 SDL - Simple DirectMedia Layer | |
|
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3 Copyright (C) 1997-2004 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 |