Structure of pages FPA page
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Structure of an BASE FPA page with a length of 2048 bytes
Figure 48: Structure of a FPA base page with a length of 2048 bytes
Meaning of the bytes
Byte Meaning
1-4 The address of the page is contained in the act-key
5 Starting from this byte there is an entry of 2 bytes for every page of the realm,
indicating the number of free bytes contained in the page.
This number is 0 for:
– the act-key-0 page, the act-key-N page
– FPA pages
– DBTT anchor pages
– DBTT pages
– CALC pages
as these pages are exclusively reserved for a particular pur pose and no further
data can be allocated to them by the Free Place Administration. The entry for
empty pages is 2028 bytes, which can actually be used, 20 bytes being res erved
for the page header.
Table 16:Meanings of the bytes of a FPA base page with a length of 2048 bytes
own act-key
page 0=0
page 1
page n
free
number
of free
bytes
in
. . .
1
5
7
9
2048
4
2
2
2