shm: introduce shmp_index

[lttng-ust.git] / libringbuffer / shm.h

diff --git a/libringbuffer/shm.h b/libringbuffer/shm.h
index da466df734c0f7b9a51ad54f3c41fbaf70fe5cb5..f5cc8e69a2b7a62faf9f614dec2489f99ccee96d 100644 (file)
--- a/libringbuffer/shm.h
+++ b/libringbuffer/shm.h
@@ -19,28 +19,32 @@
  * both the index and offset with known boundaries.
  */
 static inline
-char *_shmp(struct shm_object_table *table, struct shm_ref *ref)
+char *_shmp_offset(struct shm_object_table *table, struct shm_ref *ref,
+                  size_t offset)
 {
        struct shm_object *obj;
-       size_t index, offset;
+       size_t index, ref_offset;
 
        index = (size_t) ref->index;
        if (unlikely(index >= table->allocated_len))
                return NULL;
        obj = &table->objects[index];
-       offset = (size_t) ref->offset;
-       if (unlikely(offset >= obj->memory_map_size))
+       ref_offset = (size_t) ref->offset;
+       ref_offset += offset;
+       if (unlikely(ref_offset >= obj->memory_map_size))
                return NULL;
-       return &obj->memory_map[offset];
+       return &obj->memory_map[ref_offset];
 }
 
-#define shmp(handle, ref)                                              \
+#define shmp_index(handle, ref, offset)                                        \
        ({                                                              \
                __typeof__((ref)._type) ____ptr_ret;                    \
-               ____ptr_ret = (__typeof__(____ptr_ret)) _shmp((handle)->table, &(ref)._ref);    \
+               ____ptr_ret = (__typeof__(____ptr_ret)) _shmp_offset((handle)->table, &(ref)._ref, ((offset) * sizeof(*____ptr_ret)));  \
                ____ptr_ret;                                            \
        })
 
+#define shmp(handle, ref)      shmp_index(handle, ref, 0)
+
 static inline
 void _set_shmp(struct shm_ref *ref, struct shm_ref src)
 {