Signature:

  SUBROUTINE h5aread_f(attr_id, memtype_id, buf, hdferr) 
    INTEGER(HID_T)  , INTENT(IN)    :: attr_id
    INTEGER(HID_T)  , INTENT(IN)    :: memtype_id
    TYPE(C_PTR)     , INTENT(INOUT) :: buf
    INTEGER         , INTENT(OUT)   :: hdferr

Inputs:

  attr_id     - Attribute identifier
  memtype_id  - Attribute datatype identifier  (in memory)

Outputs:

  buf         - Data buffer; may be a scalar or an array
  hdferr      - Returns 0 if successful and -1 if fails