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Re: 64 bit assignment on a 32 bit platform
- From: Andrew Haley <aph-gcc at littlepinkcloud dot COM>
- To: kum <a dot kumaresh at gmail dot com>
- Cc: gcc-help at gcc dot gnu dot org
- Date: Mon, 29 Oct 2007 10:15:09 +0000
- Subject: Re: 64 bit assignment on a 32 bit platform
- References: <302c6e640710290307u3750341p8c5acaaaa3fe0323@mail.gmail.com>
kum writes:
> Hi,
>
> UINT64 a64; // UINT64 has been typedefed as long long unsigned int
> UINT32 a32, b32;
> a32 = x; // some value
> b32 = y; // some value
>
> a64 = a32 * b32;
> a64 += a32 + b32;
>
> Is it necessary to type-cast both a32 and b32 to yield correct 64 bit
> results? Without casting, I find that addition (even if the result
> overflows) works while the multiplication does not. Is there a
> compiler option to make this work without casting? I am using gcc
> 4.1.1 on an xscale platform.
You have to cast at leat one of the operands in a binary operation to
get the widening to anything wider than int.
Andrew.