Enscribe Programmer's Guide

Figure 36 Header for Bit-Map Block
common-block-header
Offset
(Decimal)
0
28
32
28
Length
in
Bytes
4 stib-eerf-fo-rebmun
block size - 32
bit-map
The fields in Figure 36 are defined as:
common-block-header
is the 28-byte common block header shown in Figure 31.
number-of-free-bits
indicates how many bits in this bit-map identify blocks that are free (empty) in a key-sequenced
or queue file. For relative files, it indicates how many bits identify blocks that are not full.
bit-map
is an array of bits describing availability of index or data blocks. For a key-sequenced or queue
file, each bit tells whether the corresponding block is free (0) or in use (1). For a relative file,
each bit tells whether there is room for at least one more record in the corresponding block.
An empty bit-map has 8 * (block-size - 32) free bits.
With a 1024-byte block, for example, the map has 7872 available bits.
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