Function op_sdata_by_sdata

methods/svec/src/pg_gp/SparseData.c:1015–1122

* Addition, Scalar Product, Division between SparseData arrays * * There are a few factors to consider: * - The dimension of the left and right arguments must be the same * - We employ an algorithm that does the computation on the compressed contents * which creates a new SparseData array *------------------------------------------------------------------------------ */

 *------------------------------------------------------------------------------
 */
SparseData op_sdata_by_sdata(enum operation_t operation,
					   SparseData left, SparseData right)
{
	SparseData sdata = makeSparseData();

	/*
	 * Loop over the contents of the left array, operating on elements
	 * of the right array and append a new value to the sdata when a
	 * new unique value is generated.
	 *
	 * We will manage two cursors, one for each of left and right arrays
	 */
	char *liptr=left->index->data;
	char *riptr=right->index->data;
	int left_run_length, right_run_length;
	char *new_value,*last_new_value;
	int tot_run_length=-1;
	left_run_length = compword_to_int8(liptr);
	right_run_length = compword_to_int8(riptr);
	int left_lst=0,right_lst=0;
	int left_nxt=left_run_length,right_nxt=right_run_length;
	int nextpos = Min(left_nxt,right_nxt),lastpos=0;
	int i=0,j=0;
	size_t width = size_of_type(left->type_of_data);

	check_sdata_dimensions(left,right);

	new_value      = (char *)palloc(width);
	last_new_value = (char *)palloc(width);

	while (1)
	{
		switch (operation)
		{
			case subtract:
				accum_sdata_result(new_value,left,i,-,right,j)
				break;
			case add:
			default:
				accum_sdata_result(new_value,left,i,+,right,j)
				break;
			case multiply:
				accum_sdata_result(new_value,left,i,*,right,j)
				break;
			case divide:
				accum_sdata_result(new_value,left,i,/,right,j)
				break;
		}
		/*
		 * Potentially add a new run, depending on whether this is a
		 * different value from the previous calculation. It may be
		 * that this calculation has produced an identical value to
		 * the previous, in which case we store it up, waiting for a
		 * new value to happen.
		 */
		if (tot_run_length==-1)
		{
			memcpy(last_new_value,new_value,width);