src/audio/SDL_audiomem.c
author Sam Lantinga <slouken@libsdl.org>
Fri, 14 Dec 2001 12:30:25 +0000
changeset 249 e3d0d44f6f2e
parent 1 cf2af46e9e2a
child 252 e8157fcb3114
permissions -rw-r--r--
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/*
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    SDL - Simple DirectMedia Layer
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    Copyright (C) 1997, 1998, 1999, 2000, 2001  Sam Lantinga
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    This library is free software; you can redistribute it and/or
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    modify it under the terms of the GNU Library General Public
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    License as published by the Free Software Foundation; either
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    version 2 of the License, or (at your option) any later version.
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    This library is distributed in the hope that it will be useful,
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    but WITHOUT ANY WARRANTY; without even the implied warranty of
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    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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    Library General Public License for more details.
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    You should have received a copy of the GNU Library General Public
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    License along with this library; if not, write to the Free
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    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
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    Sam Lantinga
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    slouken@devolution.com
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*/
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#ifdef SAVE_RCSID
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static char rcsid =
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 "@(#) $Id$";
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#endif
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/* Functions to allocate audio buffer memory, shareable across threads
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	(necessary because SDL audio emulates threads with fork()
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 */
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#include <stdlib.h>
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#ifdef FORK_HACK
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#include <sys/types.h>
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#include <sys/ipc.h>
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#include <sys/shm.h>
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#include <stddef.h>
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#endif
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#include "SDL_audiomem.h"
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/* Allocate memory that will be shared between threads (freed on exit) */
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void *SDL_AllocAudioMem(int size)
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{
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	void *chunk;
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#ifdef FORK_HACK
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	int   semid;
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	/* Create and get the address of a shared memory segment */
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	semid = shmget(IPC_PRIVATE, size, (IPC_CREAT|0600));
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	if ( semid < 0 ) {
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		return(NULL);
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	}
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	chunk = shmat(semid, NULL, 0);
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	/* Set the segment for deletion when it is detatched */
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	shmctl(semid, IPC_RMID, NULL);	/* Delets semid if shmat() fails */
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#else
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	chunk = malloc(size);
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#endif
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	return((void *)chunk);
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}
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void SDL_FreeAudioMem(void *chunk)
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{
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#ifdef FORK_HACK
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	shmdt(chunk);
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#else
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	free(chunk);
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#endif
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}