Am 07.07.2019 um 02:55 schrieb Ralf Quint:
On 7/6/2019 12:21 PM, Florian Klaempfl wrote:
Am 05.07.2019 um 13:53 schrieb Ralf Quint:
Shouldn't a PACKED Record guarantee that values are aligned at the byte
level?
It does in TP, but the ISO says only that it shall be economised.
Well, the ISO is probably what has done most of the damage to Pascal.
AFAIK, the ISO doesn't not actually specify any "packed record" per
se, but there is an explicit PACK and UNPACK procedures to more
economically store sets and arrays (and possibly records, I would have
to look up the ISO text to be certain). For example this would be
something to create bit fields, pretty much the only feature of C that
I sometimes miss in (Free)Pascal.
You mean like this?
=== code begin ===
struct Test
{
uint8_t field1;
uint16_t bfield1 : 1;
uint16_t bfield2 : 1;
uint16_t bfield3 : 3;
uint16_t bfield4 : 5;
uint16_t bfield5 : 1;
uint16_t field2;
};
=== code end ===
=== code begin ===
type
TTest = bitpacked record
field1: UInt8;
bfield1: 0..1;
bfield2: 0..1;
bfield3: 0..7;
bfield4: 0..31;
bfield5: 0..1;
pad: UInt8; // needed due to bitpacked
field2: UInt16;
end;
=== code end ===
The size of both records is 6. :)
Regards,
Sven
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