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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 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@devolution.com
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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 #ifdef FORK_HACK
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33 #include <sys/types.h>
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34 #include <sys/ipc.h>
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35 #include <sys/shm.h>
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36 #include <stddef.h>
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37 #else
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38 #include <stdlib.h>
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39 #endif
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40
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41 #include "SDL_audiomem.h"
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42
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43 /* Allocate memory that will be shared between threads (freed on exit) */
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44 void *SDL_AllocAudioMem(int size)
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45 {
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46 void *chunk;
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47
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48 #ifdef FORK_HACK
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49 int semid;
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50
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51 /* Create and get the address of a shared memory segment */
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52 semid = shmget(IPC_PRIVATE, size, (IPC_CREAT|0600));
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53 if ( semid < 0 ) {
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54 return(NULL);
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55 }
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56 chunk = shmat(semid, NULL, 0);
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57
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58 /* Set the segment for deletion when it is detatched */
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59 shmctl(semid, IPC_RMID, NULL); /* Delets semid if shmat() fails */
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60 #else
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61 chunk = malloc(size);
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62 #endif
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63 return((void *)chunk);
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64 }
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65
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66 void SDL_FreeAudioMem(void *chunk)
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67 {
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68 #ifdef FORK_HACK
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69 shmdt(chunk);
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70 #else
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71 free(chunk);
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72 #endif
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73 }
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