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varray(3m) MBA Library Functions varray(3m) NAME varray - A variable sized array. SYNOPSIS #include <mba/varray.h> int varray_init(struct varray *va, size_t membsize, struct allocator *al); int varray_deinit(struct varray *va); struct varray *varray_new(size_t membsize, struct allocator *al); void varray_del(void *va); void *varray_get(struct varray *va, unsigned int idx); int varray_index(struct varray *va, void *elem); void varray_release(struct varray *va, unsigned int from); void varray_iterate(void *va, iter_t *iter); void *varray_next(void *va, iter_t *iter); DESCRIPTION The varray(3m) module is a variable array that permits quick access to elements by index without allocating all the memory for the array when the array is created. Instead, memory is allocated as necessary in in- creasingly larger chunks (32 * membsize, 64 * membsize, 128 * membsize, upto 2^20 * membsize). init The varray_init function with initialize the varray va with no initial elements. The size of each element in the array will be membsize. The allocator al will be used to allocate memory to back the array. deinit The varray_deinit function deinitializes the varray va and re- leases any storage backing the array. new The varray_new function allocates storage for a new varray ob- ject and initializes with the varray_init function. del The varray_del function calls varray_deinit on the object va and then frees the va object itself. get The varray_get function returns a pointer to memory at index idx. The memory will be membsize bytes in size as specified in the varray_new function. The memory is initialized to 0 when the chunk backing it is allocated meaning the memory should ini- tially be 0. index The varray_index function returns the index of the element elem. If the element is not found -1 is returned and errno is set to EFAULT. release The varray_release function may release all memory chunks stor- ing elements from index from and higher. This function will only free memory chunks that constitute elements at the from index and above. If the from index is the first element of a chunk, that chunk will be freed as well. This function should only be used if it is understood that the range of elements being ac- cessed has been significantly reduced such that memory will not be frequently allocated and freed. iterate, next The varray_iterate and varray_next functions will enumerate over every element in the array that has ever been accessed with the varray_get function. However, adjacent elements in the same mem- ory chunk will also be returned by varray_next even if they those elements have never been accessed with varray_get. Simi- larly, there may be gaps in the full range that are not returned by varray_next because no element was accessed in a range neces- sary for the chunk of memory for that range to be allocated. The varray_iterate function initializes the iter object to point to the beginning of the array. The varray_next function returns each element in the array or NULL if all elements have been enu- merated. RETURNS init The varray_init function returns 0 on success or -1 for failure in which case errno will be set to an appropriate value. deinit The varray_deinit function returns 0 on success or -1 for fail- ure in which case errno will be set to an appropriate value. new The varray_new function returns the new varray object or a null pointer if an error occurred in which case errno will be set ap- propriately. get The varray_get function returns a pointer to the memory at index idx or a null pointer if an error occured in which case errno will be set appropriately. index The varray_index function returns the index of the element or -1 and sets errno to EFAULT to indicate the element is not in the array. next The varray_next function returns a pointer to the memory of the next element in the enumeration or a null pointer if there are no more elements to be enumerated. libmba-0.9.1 Apr 29, 2005 varray(3m)
NAME | SYNOPSIS | DESCRIPTION | RETURNS
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