The function may be called by the names: m01cuc, nag_sort_chain_sort or nag_chain_sort.
m01cuc uses a variant of list merging, as described in Knuth (1973). It uses a local stack to avoid the need for a flag bit in each pointer.
Knuth D E (1973) The Art of Computer Programming (Volume 3) (2nd Edition) Addison–Wesley
1: – Pointer *Input/Output
On entry: the pointer to the pointer to the first structure of the linked list.
On exit: the pointer to which base points is updated to point to the first element of the ordered list.
2: – ptrdiff_tInput
On entry: the offset within the structure of the pointer field which points to the next element of the linked list.
Note: this field in the last element of the linked list must have the value NULL.
3: – function, supplied by the userExternal Function
m01cuc compares the data fields of two elements of the list. Its arguments are pointers to the structure, therefore, this function must allow for the offset of the data field in the structure (if it is not the first).
The function must return:
if the first data field is less than the second,
if the first data field is equal to the second,
if the first data field is greater than the second.
Too many elements in chain or chain in a loop. The linked list may have become corrupted.
8Parallelism and Performance
Background information to multithreading can be found in the Multithreading documentation.
m01cuc is not threaded in any implementation.
The time taken by m01cuc is approximately proportional to .
The example program declares a structure containing a data field, a pointer to the next record and an index field. It generates an array of such structures assigning random data to the data field. The index field is randomly assigned a unique value. The pointer to next record fields are assigned to create a linked list in the order of the index field. It sorts this linked list into ascending order according to the value of the data field.