SDL_audiomem.c
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/*
SDL - Simple DirectMedia Layer
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Copyright (C) 1997-2006 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 Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 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,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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Sam Lantinga
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slouken@libsdl.org
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*/
/* Functions to allocate audio buffer memory, shareable across threads
(necessary because SDL audio emulates threads with fork()
*/
#ifdef FORK_HACK
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <stddef.h>
#endif
#include "SDL_audiomem.h"
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#include "SDL_stdlib.h"
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/* Allocate memory that will be shared between threads (freed on exit) */
void *SDL_AllocAudioMem(int size)
{
void *chunk;
#ifdef FORK_HACK
int semid;
/* Create and get the address of a shared memory segment */
semid = shmget(IPC_PRIVATE, size, (IPC_CREAT|0600));
if ( semid < 0 ) {
return(NULL);
}
chunk = shmat(semid, NULL, 0);
/* Set the segment for deletion when it is detatched */
shmctl(semid, IPC_RMID, NULL); /* Delets semid if shmat() fails */
#else
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chunk = SDL_malloc(size);
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#endif
return((void *)chunk);
}
void SDL_FreeAudioMem(void *chunk)
{
#ifdef FORK_HACK
shmdt(chunk);
#else
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SDL_free(chunk);
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#endif
}