User Guide

5-4 Ampex 1308911-02
Model No.
Running Head
DST API Overview libdd2 API Functions
dd2 Structure of type dst_dd2_pos_st for representing position in
standard DST (DD-2) format (see
dst_dd2_pos_st below).
dst600 Structure of type dst_600_pos_st for representing position in
DST600 format. (see
dst_600_pos_st below).
dis Structure of type dst_600_pos_st for representing position in DIS
format (see
dst_dis_pos_st below).
dst_pos_tok_t
This position token array defines sufficient elements to support standard DST, DST600, and
DIS tape drives. These include: tape cartridge volume ID, current tape drive type, absolute
double frame number (adfn), partition ID, file section number (fsn), logical data block number
(ldbn), cumulative data block number (cdbn), and timecode. The following caveats apply:
• Retrieving a token:
– If the drive is a DST or DIS, the token will contain
fsn/ldbn position
information. You cannot retrieve a token that contains DIS
timecode
information; you can create one, however, as described below.
– If the drive is a DST 600, the token will contain
cdbn position information.
• Creating a DIS token:
– To create a DIS token that contains
timecode position information, first use
dst_getpos() to retrieve a
DstPosDIS structure. Then, use dst_convpos() to
convert the structure to a token.
• Identifying a token:
– After a token is created, there is no way to identify what type of positioning
information it contains. The user is responsible for logging this information when
the token is created.
The token form of a position is always complete and contains within itself sufficient
information for conversion into a structure form of position.
#define DST_POS_TOK_SZ40
typedef u_char dst_pos_tok_t[DST_POS_TOK_SZ];
dst_dd2_pos_st
This structure type represents position in native DST (DD-2) format and may not be portable
across platforms.
typedef struct
{
u_int valid; /* Flag indicating which members are valid */