| 1 | #ifndef _LIBRINGBUFFER_SHM_H |
| 2 | #define _LIBRINGBUFFER_SHM_H |
| 3 | |
| 4 | /* |
| 5 | * libringbuffer/shm.h |
| 6 | * |
| 7 | * Copyright 2011 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 8 | * |
| 9 | * Dual LGPL v2.1/GPL v2 license. |
| 10 | */ |
| 11 | |
| 12 | #include <stdint.h> |
| 13 | #include "ust/core.h" |
| 14 | |
| 15 | #define SHM_MAGIC 0x54335433 |
| 16 | #define SHM_MAJOR 0 |
| 17 | #define SHM_MINOR 1 |
| 18 | |
| 19 | /* |
| 20 | * Defining a max shm offset, for debugging purposes. |
| 21 | */ |
| 22 | #if (CAA_BITS_PER_LONG == 32) |
| 23 | /* Define the maximum shared memory size to 128MB on 32-bit machines */ |
| 24 | #define MAX_SHM_SIZE 134217728 |
| 25 | #else |
| 26 | /* Define the maximum shared memory size to 8GB on 64-bit machines */ |
| 27 | #define MAX_SHM_SIZE 8589934592 |
| 28 | #endif |
| 29 | |
| 30 | #define DECLARE_SHMP(type, name) type *****name |
| 31 | |
| 32 | struct shm_header { |
| 33 | uint32_t magic; |
| 34 | uint8_t major; |
| 35 | uint8_t minor; |
| 36 | uint8_t bits_per_long; |
| 37 | size_t shm_size, shm_allocated; |
| 38 | |
| 39 | DECLARE_SHMP(struct channel, chan); |
| 40 | }; |
| 41 | |
| 42 | #define shmp(shm_offset) \ |
| 43 | ((__typeof__(****(shm_offset))) (((char *) &(shm_offset)) + (ptrdiff_t) (shm_offset))) |
| 44 | |
| 45 | #define _shmp_abs(a) ((a < 0) ? -(a) : (a)) |
| 46 | |
| 47 | static inline |
| 48 | void _set_shmp(ptrdiff_t *shm_offset, void *ptr) |
| 49 | { |
| 50 | *shm_offset = (((char *) ptr) - ((char *) shm_offset)); |
| 51 | assert(_shmp_abs(*shm_offset) < MAX_SHM_SIZE); |
| 52 | } |
| 53 | |
| 54 | #define set_shmp(shm_offset, ptr) \ |
| 55 | _set_shmp((ptrdiff_t *) ****(shm_offset), ptr) |
| 56 | |
| 57 | /* Shared memory is already zeroed by shmget */ |
| 58 | /* *NOT* multithread-safe (should be protected by mutex) */ |
| 59 | static inline |
| 60 | void *zalloc_shm(struct shm_header *shm_header, size_t len) |
| 61 | { |
| 62 | void *ret; |
| 63 | |
| 64 | if (shm_header->shm_size - shm_header->shm_allocated < len) |
| 65 | return NULL; |
| 66 | ret = (char *) shm_header + shm_header->shm_allocated; |
| 67 | shm_header->shm_allocated += len; |
| 68 | return ret; |
| 69 | } |
| 70 | |
| 71 | #endif /* _LIBRINGBUFFER_SHM_H */ |