get_ula_head

Source: hsio/get_ula_head.pro

 GET_ULA_HEAD
        Extract a ULA header block from the data. 
        called by ULA_STRUCT.
 Call:
        iget = get_ula_head(data, hds)

 Return Value:
        iget    int     1 if it was a valid 40-byte sfdu0 record, 3 if
                        32-byte sfdu0,  0 if not a valid record.

 Arguments:
        data    byte    input   The data from which the structure is to be
                                extracted
        hds     struct  output  The structure of type "ula_rh"  to return.

 History:
        Prototype: 22/1/91; SJT
        DHK block changes to integer*4: 22/1/91; SJT
        Incorporate new record definition: 22/7/91; SJT
        Change for 40 byte SFDU0: 30/3/92; SJT
        Make it return a structure even if convert fails: 21/11/94; SJT
        Drop support for the old 32-byte SFDU0, and make strings into
        strings: 25/11/99; SJT