Mercurial > sdl-ios-xcode
annotate src/audio/SDL_audiomem.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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Updated copyright information for 2004 (Happy New Year!)
Sam Lantinga <slouken@libsdl.org>
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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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Updated the source with the correct e-mail address
Sam Lantinga <slouken@libsdl.org>
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20 slouken@libsdl.org |
| 0 | 21 */ |
| 22 | |
| 23 #ifdef SAVE_RCSID | |
| 24 static char rcsid = | |
| 25 "@(#) $Id$"; | |
| 26 #endif | |
| 27 | |
| 28 /* Functions to allocate audio buffer memory, shareable across threads | |
| 29 (necessary because SDL audio emulates threads with fork() | |
| 30 */ | |
| 31 | |
|
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Changes since SDL 1.2.0 release
Sam Lantinga <slouken@lokigames.com>
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32 #include <stdlib.h> |
| 0 | 33 #ifdef FORK_HACK |
| 34 #include <sys/types.h> | |
| 35 #include <sys/ipc.h> | |
| 36 #include <sys/shm.h> | |
| 37 #include <stddef.h> | |
| 38 #endif | |
| 39 | |
| 40 #include "SDL_audiomem.h" | |
| 41 | |
| 42 /* Allocate memory that will be shared between threads (freed on exit) */ | |
| 43 void *SDL_AllocAudioMem(int size) | |
| 44 { | |
| 45 void *chunk; | |
| 46 | |
| 47 #ifdef FORK_HACK | |
| 48 int semid; | |
| 49 | |
| 50 /* Create and get the address of a shared memory segment */ | |
| 51 semid = shmget(IPC_PRIVATE, size, (IPC_CREAT|0600)); | |
| 52 if ( semid < 0 ) { | |
| 53 return(NULL); | |
| 54 } | |
| 55 chunk = shmat(semid, NULL, 0); | |
| 56 | |
| 57 /* Set the segment for deletion when it is detatched */ | |
| 58 shmctl(semid, IPC_RMID, NULL); /* Delets semid if shmat() fails */ | |
| 59 #else | |
| 60 chunk = malloc(size); | |
| 61 #endif | |
| 62 return((void *)chunk); | |
| 63 } | |
| 64 | |
| 65 void SDL_FreeAudioMem(void *chunk) | |
| 66 { | |
| 67 #ifdef FORK_HACK | |
| 68 shmdt(chunk); | |
| 69 #else | |
| 70 free(chunk); | |
| 71 #endif | |
| 72 } |