On Fri, Sep 3, 2021 at 8:02 AM LacaK via fpc-pascal < fpc-pascal@lists.freepascal.org> wrote:
> Can we say that in Pascal the result of: > E1 shl E2 > is of same type as E1 ? > (so if E1 is LongWord then result is LongWord also?) > > What if there is an expression on left side: > (E1*x) shl E2 > Will E1*x promote to 64 bits (on 64 bit target)? > See documentation on automatic type conversion (the remarks section below table 3.3): https://www.freepascal.org/docs-html/ref/refsu4.html#x26-26004r3 While this doesn't explicitly mention shift behaviour, it implies that E1 and (E1*x) will be promoted to native sized integer if smaller. For the first example, if E1 is a longword on a 32 bit machine, the result should also be a longword. Personal note: I find the naming of ordinal types confusing. Is shortint smaller than smallint, or smallint shorter than shortint? In FPC a word is 2 bytes in size, however on the hardware side a word refers to "the natural unit of data used by a particular processor design" ( https://en.wikipedia.org/wiki/Word_(computer_architecture)). I prefer to use the type aliases with explicit mention of size, such as int16, uint8 etc. I assume the flip side of this is when trying to write portable code that uses the most efficient size available on a target.
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