Function ArrayGetOffset

src/backend/utils/adt/arrayutils.c:31–44

* Convert subscript list into linear element number (from 0) * * We assume caller has already range-checked the dimensions and subscripts, * so no overflow is possible. */

 * so no overflow is possible.
 */
int
ArrayGetOffset(int n, const int *dim, const int *lb, const int *indx)
{
	int			i,
				scale = 1,
				offset = 0;

	for (i = n - 1; i >= 0; i--)
	{
		offset += (indx[i] - lb[i]) * scale;
		scale *= dim[i];
	}
	return offset;
}

/*
 * Same, but subscripts are assumed 0-based, and use a scale array