Converting Turbo database to Windows Pascal
lazarus / 16-Databases

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lmcmillan · 2024-01-25 16:52

I am dealing with a Turbo database that has real variables in it. 
They are 6 bytes long.  In Windows Pascal, a real is 8 bytes long, and
a single and/or shortreal is 4 bytes long.  I dont see any variable
type in Windows Pascal that is 6 bytes long.  Short of converting all
of the Turbo databases to a different format, is there any way around
this -- to create a "dummy" 6-type "real" variable in Windows Pascal?

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alpine · 2024-01-25 17:06

Try with the Real48 type from the System unit. There are overloaded
assignment operators.

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lmcmillan · 2024-01-25 22:25

Thanks very much.  That looks promising.  I downloaded several online
user manuals.  Not a single one of them mentions Real48.  Where would
I find source material for that and potentially other useful things
like that?

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KodeZwerg · 2024-01-25 22:33

Quote from: lmcmillan on January 25, 2024, 11:25:40 pmWhere would I
find source material for that...In the documentation, a small
reference about types you find here and there is the Real48 type.

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Thaddy · 2024-01-26 05:48

The real48utils unit comes with freepascal (in the rtl-extra package)
and is targeted at manipulating 48 bit real values. It is installed by
default.
It is included in the standard distribution.
The real48 type itself is declared in the system unit , though. And
that is usually enough to read and write TP data structures.
https://www.freepascal.org/docs-html/rtl/system/real48.html

So to summarize, if you want to load and store old school 48 bit
reals, simply use real48 as type, but if you want to manipulate 48 bit
real values, add the real48utils unit to the uses clause.

Note it is also important to have the right packing settings for
structures with 48 bit real values, which depends on the age of the TP
data: it can be either 1 or 2, not anything else.

I usually have TP3 and TP5.5 installed in Dosbox, which are free, to
check my old programs and data against FPC.