annotate src/audio/SDL_audiomem.c @ 1343:d5c4f8f6855e

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author Sam Lantinga <slouken@libsdl.org>
date Tue, 07 Feb 2006 17:46:19 +0000
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1 /*
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2 SDL - Simple DirectMedia Layer
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3 Copyright (C) 1997-2006 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 Lesser General Public
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7 License as published by the Free Software Foundation; either
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8 version 2.1 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 Lesser 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 Lesser General Public
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16 License along with this library; if not, write to the Free Software
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17 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 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 /* Functions to allocate audio buffer memory, shareable across threads
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24 (necessary because SDL audio emulates threads with fork()
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25 */
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26
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27 #ifdef FORK_HACK
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28 #include <sys/types.h>
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29 #include <sys/ipc.h>
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30 #include <sys/shm.h>
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31 #include <stddef.h>
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32 #endif
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33
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34 #include "SDL_stdlib.h"
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35 #include "SDL_audiomem.h"
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36
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37 /* Allocate memory that will be shared between threads (freed on exit) */
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38 void *SDL_AllocAudioMem(int size)
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39 {
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40 void *chunk;
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41
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42 #ifdef FORK_HACK
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43 int semid;
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44
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45 /* Create and get the address of a shared memory segment */
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46 semid = shmget(IPC_PRIVATE, size, (IPC_CREAT|0600));
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47 if ( semid < 0 ) {
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48 return(NULL);
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49 }
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50 chunk = shmat(semid, NULL, 0);
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51
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52 /* Set the segment for deletion when it is detatched */
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53 shmctl(semid, IPC_RMID, NULL); /* Delets semid if shmat() fails */
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54 #else
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55 chunk = SDL_malloc(size);
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56 #endif
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57 return((void *)chunk);
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58 }
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59
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60 void SDL_FreeAudioMem(void *chunk)
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61 {
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62 #ifdef FORK_HACK
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63 shmdt(chunk);
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64 #else
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65 SDL_free(chunk);
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66 #endif
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67 }