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comparison src/audio/SDL_audiomem.c @ 0:74212992fb08

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Initial revision
author Sam Lantinga <slouken@lokigames.com>
date Thu, 26 Apr 2001 16:45:43 +0000
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children cf2af46e9e2a
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-1:000000000000 0:74212992fb08
1 /*
2 SDL - Simple DirectMedia Layer
3 Copyright (C) 1997, 1998, 1999, 2000, 2001 Sam Lantinga
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
20 slouken@devolution.com
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
32 #ifdef FORK_HACK
33 #include <sys/types.h>
34 #include <sys/ipc.h>
35 #include <sys/shm.h>
36 #include <stddef.h>
37 #else
38 #include <stdlib.h>
39 #endif
40
41 #include "SDL_audiomem.h"
42
43 /* Allocate memory that will be shared between threads (freed on exit) */
44 void *SDL_AllocAudioMem(int size)
45 {
46 void *chunk;
47
48 #ifdef FORK_HACK
49 int semid;
50
51 /* Create and get the address of a shared memory segment */
52 semid = shmget(IPC_PRIVATE, size, (IPC_CREAT|0600));
53 if ( semid < 0 ) {
54 return(NULL);
55 }
56 chunk = shmat(semid, NULL, 0);
57
58 /* Set the segment for deletion when it is detatched */
59 shmctl(semid, IPC_RMID, NULL); /* Delets semid if shmat() fails */
60 #else
61 chunk = malloc(size);
62 #endif
63 return((void *)chunk);
64 }
65
66 void SDL_FreeAudioMem(void *chunk)
67 {
68 #ifdef FORK_HACK
69 shmdt(chunk);
70 #else
71 free(chunk);
72 #endif
73 }