how to place two unsigned 16 bit values into a 32 bit unsigned value

Hi everyone,

I need to store an unsigned 16 bit number in the upper (MSB) and
another unsigned 16 bit number in the 16 LSB. Basically, I am trying
to store two unsigned 16 bit numbers into one unsigned 32 bit number.

So far, I have the following:

struct
{
unsigned int num1:16;
unsigned in num2:16;
} twoUnsigned16BitNums;

unsigned int num;

What I am having trouble with is to store the two 16 bit numbers into
the 32 bit number. I know one option is to use bit wise ANDs and ORs.
Any help on your part is greatly appreciated. Best Regards.

re: how to place two unsigned 16 bit values into a 32 bit unsigned value

pasamdivya@gmail.com wrote:It would seem that you're hesitant to use that option. May I ask, why?
Use a plus and a multiply.

V
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re: how to place two unsigned 16 bit values into a 32 bit unsigned value

On Nov 18, 9:22*pm, pasamdi...@gmail.com wrote:
That may or may work (then memcpy'ing the results); check your
compilers documentation.
That's the usual solution.
Is "number1 << 16 | number2" what you're looking for? (Just
make sure that 32 bit arithmetic is used here. If number1 is an
unsigned int, and int's are only 16 bits, you'll have to cast it
to unsigned long first.)

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re: how to place two unsigned 16 bit values into a 32 bit unsigned value

Depending on portability (compiler, processor, packing, etc) you may be able
to use a union. For VS on Intel

union

{

struct

{

unsigned a:16;

unsigned b:16;

} Half;

struct

{

unsigned ab:32;

} Whole;

} t;

t.Half.a = 0x1234;

t.Half.b = 0x5678;

t.Whole.ab is now 0x56781234


<pasamdivya@gmail.comwrote in message
news:89f27f84-c5aa-4af8-a4f8-89f2984432bd@s9g2000prg.googlegroups.com...

re: how to place two unsigned 16 bit values into a 32 bit unsigned value

On Nov 19, 9:24 am, "Bill Davy" <B...@XchelSys.co.ukwrote:Maybe. Trying to access it is undefined behavior, so there's no
way to tell.

--
James Kanze (GABI Software) email:james.kanze@gmail.com
Conseils en informatique orientée objet/
Beratung in objektorientierter Datenverarbeitung
9 place Sémard, 78210 St.-Cyr-l'École, France, +33 (0)1 30 23 00 34