annotate src/audio/SDL_audiomem.c @ 344:7a69392b8599

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author Sam Lantinga <slouken@libsdl.org>
date Sat, 13 Apr 2002 15:43:15 +0000
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children b8d311d90021
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1 /*
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2 SDL - Simple DirectMedia Layer
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3 Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002 Sam Lantinga
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4
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5 This library is free software; you can redistribute it and/or
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6 modify it under the terms of the GNU Library General Public
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7 License as published by the Free Software Foundation; either
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8 version 2 of the License, or (at your option) any later version.
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9
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10 This library is distributed in the hope that it will be useful,
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11 but WITHOUT ANY WARRANTY; without even the implied warranty of
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12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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13 Library General Public License for more details.
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14
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15 You should have received a copy of the GNU Library General Public
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16 License along with this library; if not, write to the Free
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17 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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18
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19 Sam Lantinga
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20 slouken@libsdl.org
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21 */
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22
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23 #ifdef SAVE_RCSID
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24 static char rcsid =
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25 "@(#) $Id$";
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26 #endif
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27
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28 /* Functions to allocate audio buffer memory, shareable across threads
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29 (necessary because SDL audio emulates threads with fork()
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30 */
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31
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32 #include <stdlib.h>
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33 #ifdef FORK_HACK
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34 #include <sys/types.h>
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35 #include <sys/ipc.h>
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36 #include <sys/shm.h>
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37 #include <stddef.h>
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38 #endif
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39
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40 #include "SDL_audiomem.h"
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41
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42 /* Allocate memory that will be shared between threads (freed on exit) */
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43 void *SDL_AllocAudioMem(int size)
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44 {
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45 void *chunk;
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46
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47 #ifdef FORK_HACK
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48 int semid;
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49
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50 /* Create and get the address of a shared memory segment */
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51 semid = shmget(IPC_PRIVATE, size, (IPC_CREAT|0600));
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52 if ( semid < 0 ) {
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53 return(NULL);
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54 }
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55 chunk = shmat(semid, NULL, 0);
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56
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57 /* Set the segment for deletion when it is detatched */
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58 shmctl(semid, IPC_RMID, NULL); /* Delets semid if shmat() fails */
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59 #else
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60 chunk = malloc(size);
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61 #endif
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62 return((void *)chunk);
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63 }
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64
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65 void SDL_FreeAudioMem(void *chunk)
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66 {
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67 #ifdef FORK_HACK
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68 shmdt(chunk);
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69 #else
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70 free(chunk);
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71 #endif
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72 }