On 03/29/2016 06:13 PM, Marco van de Voort wrote:
In our previous episode, Graeme Geldenhuys said:
Just curious. What is the history behind the Cardinal data type. As per
the FPC documentation, it is always mapped to the LongWord type. I
presume it is the same in Delphi.
Cardinal is the Wirthian designation for the default unsigned integer,
just like "integer" is for signed.
The Delphi side of things is more convoluted because pre-int64 Delphis had
31-bits Cardinals.
Even more so, Delphi 1 was 16-bit and its Cardinal type was 16-bit (i.e.
equal to the "Word" type) With Delphi 2 (the first 32-bit Delphi),
Cardinal became 32-bit (31-bit, actually, as Marco said).
So, back then it was a CPU-specific unsigned integer type (just like
"Integer" is the signed version).
Note that even though FPC now also supports 16-bit x86 CPUs, Cardinal is
still 32-bit unsigned there. Even though this is not Delphi 1
compatible, changing Cardinal to 16-bit does more harm that good. Many
FPC demos, such as fpctris and samegame now run unmodified on
i8086-msdos. If we changed the Cardinal type to 16-bit, they would break
and require changes in order to work. And most 16-bit code that is
likely to be ported to FPC is coming from Turbo Pascal, which didn't
have Cardinal (only "Word", which is always 16-bit), so we don't really
follow the convention that Cardinal is a platform specific type. So, in
FPC it is fixed to 32-bit unsigned on all platforms and in all compiler
modes.
Nikolay
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