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#ifndef __jack_shm_h__
#define __jack_shm_h__
#include <limits.h>
#include <sys/types.h>
#include <jack/types.h>
#define MAX_SERVERS 8 /* maximum concurrent servers */
#define MAX_SHM_ID 256 /* generally about 16 per server */
#define JACK_SERVER_NAME_SIZE 256 /* maximum length of server name */
#define JACK_SHM_MAGIC 0x4a41434b /* shm magic number: "JACK" */
#define JACK_SHM_NULL_INDEX -1 /* NULL SHM index */
#define JACK_SHM_REGISTRY_INDEX -2 /* pseudo SHM index for registry */
/* On Mac OS X, SHM_NAME_MAX is the maximum length of a shared memory
* segment name (instead of NAME_MAX or PATH_MAX as defined by the
* standard).
*/
#ifdef USE_POSIX_SHM
#ifndef SHM_NAME_MAX
#define SHM_NAME_MAX NAME_MAX
#endif
typedef char shm_name_t[SHM_NAME_MAX];
typedef shm_name_t jack_shm_id_t;
#else /* System V SHM */
typedef int jack_shm_id_t;
#endif /* SHM type */
/* shared memory type */
typedef enum {
shm_POSIX = 1, /* POSIX shared memory */
shm_SYSV = 2 /* System V shared memory */
} jack_shmtype_t;
typedef int16_t jack_shm_registry_index_t;
/**
* A structure holding information about shared memory allocated by
* JACK. this persists across invocations of JACK, and can be used by
* multiple JACK servers. It contains no pointers and is valid across
* address spaces.
*
* The registry consists of two parts: a header including an array of
* server names, followed by an array of segment registry entries.
*/
typedef struct _jack_shm_server {
pid_t pid; /* process ID */
char name[JACK_SERVER_NAME_SIZE];
} jack_shm_server_t;
typedef struct _jack_shm_header {
uint32_t magic; /* magic number */
uint16_t protocol; /* JACK protocol version */
jack_shmtype_t type; /* shm type */
jack_shmsize_t size; /* total registry segment size */
jack_shmsize_t hdr_len; /* size of header */
jack_shmsize_t entry_len; /* size of registry entry */
jack_shm_server_t server[MAX_SERVERS]; /* current server array */
} jack_shm_header_t;
typedef struct _jack_shm_registry {
jack_shm_registry_index_t index; /* offset into the registry */
pid_t allocator; /* PID that created shm segment */
jack_shmsize_t size; /* for POSIX unattach */
jack_shm_id_t id; /* API specific, see above */
} jack_shm_registry_t;
#define JACK_SHM_REGISTRY_SIZE (sizeof (jack_shm_header_t) \
+ sizeof (jack_shm_registry_t) * MAX_SHM_ID)
/**
* a structure holding information about shared memory
* allocated by JACK. this version is valid only
* for a given address space. It contains a pointer
* indicating where the shared memory has been
* attached to the address space.
*/
typedef struct _jack_shm_info {
jack_shm_registry_index_t index; /* offset into the registry */
void *attached_at; /* address where attached */
} jack_shm_info_t;
/* utility functions used only within JACK */
extern void jack_shm_copy_from_registry (jack_shm_info_t*,
jack_shm_registry_index_t);
extern void jack_shm_copy_to_registry (jack_shm_info_t*,
jack_shm_registry_index_t*);
extern void jack_release_shm_info (jack_shm_registry_index_t);
static inline char* jack_shm_addr (jack_shm_info_t* si) {
return si->attached_at;
}
/* here beginneth the API */
extern int jack_register_server (const char *server_name, int new_registry);
extern void jack_unregister_server (const char *server_name);
extern int jack_initialize_shm (const char *server_name);
extern int jack_cleanup_shm (void);
extern int jack_shmalloc (jack_shmsize_t size, jack_shm_info_t* result);
extern void jack_release_shm (jack_shm_info_t*);
extern void jack_destroy_shm (jack_shm_info_t*);
extern int jack_attach_shm (jack_shm_info_t*);
extern int jack_resize_shm (jack_shm_info_t*, jack_shmsize_t size);
#endif /* __jack_shm_h__ */
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