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Linux Cross Reference
JACK/jack/shm.h 

** Warning: Cannot open xref database.

  1 #ifndef __jack_shm_h__
  2 #define __jack_shm_h__
  3 
  4 #include <limits.h>
  5 #include <sys/types.h>
  6 #include <jack/types.h>
  7 
  8 #define MAX_SHM_ID 256 /* likely use is more like 16 per jackd */
  9 
 10 #ifdef USE_POSIX_SHM
 11 typedef shm_name_t jack_shm_id_t;
 12 #else
 13 typedef int jack_shm_id_t;
 14 #endif /* !USE_POSIX_SHM */
 15 
 16 typedef int16_t jack_shm_registry_index_t;
 17 
 18 /** 
 19  * A structure holding information about shared memory
 20  * allocated by JACK. this version persists across
 21  * invocations of JACK, and can be used by multiple
 22  * JACK servers. It contains no pointers and is valid
 23  * across address spaces.
 24  */
 25 typedef struct _jack_shm_registry {
 26     pid_t                     allocator; /* PID that created shm segment */
 27     jack_shmsize_t            size;      /* needed for POSIX unattach */
 28     jack_shm_registry_index_t index;     /* offset into the registry */
 29     jack_shm_id_t             id;        /* API specific, see above */
 30 } jack_shm_registry_t;
 31 
 32 /** 
 33  * a structure holding information about shared memory
 34  * allocated by JACK. this version is valid only
 35  * for a given address space. It contains a pointer
 36  * indicating where the shared memory has been
 37  * attached to the address space.
 38  */
 39 typedef struct _jack_shm_info {
 40     jack_shm_registry_index_t index;       /* offset into the registry */
 41     char*                     attached_at; /* address where attached */
 42 } jack_shm_info_t;
 43 
 44 /* utility functions used only within JACK */
 45 
 46 extern void jack_shm_copy_from_registry (jack_shm_info_t*, 
 47                                          jack_shm_registry_index_t);
 48 extern void jack_shm_copy_to_registry (jack_shm_info_t*,
 49                                        jack_shm_registry_index_t*);
 50 extern void jack_release_shm_info (jack_shm_registry_index_t);
 51 
 52 static inline char* jack_shm_addr (jack_shm_info_t* si) {
 53         return si->attached_at;
 54 }
 55 
 56 /* here beginneth the API */
 57 
 58 extern int  jack_initialize_shm ();
 59 extern void jack_cleanup_shm ();
 60 
 61 extern int  jack_shmalloc (const char *shm_name, jack_shmsize_t size, jack_shm_info_t* result);
 62 extern void jack_release_shm (jack_shm_info_t*);
 63 extern void jack_destroy_shm (jack_shm_info_t*);
 64 extern int  jack_attach_shm (jack_shm_info_t*);
 65 extern int  jack_resize_shm (jack_shm_info_t*, jack_shmsize_t size);
 66 
 67 #endif /* __jack_shm_h__ */
 68
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