printk and long long

printk and long long

[sting sting]

Hello,
I am trying to perfrom printk with a variable of type long long.
(loff_t is that type and it is long long , as can be seen in posix+types.h).
what is the format string for such a type ?
I had tried %lld" but it gace wrpng results.
regards,
sting

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Re: printk and long long

[wdebruij]

how about simply using a shift to output two regular longs, i.e.

printk("%ld%ld",loff_t >> (sizeof(long) * 8), loff_t << sizeof(long) * 8 >>
sizeof(long) * 8);

perhaps you could even place this ghastly code in a macro if you have to access
it often (so that you don't have to look at it :)?

I know it's not pretty, but at least the %ld is considered standard printf
functionality. I don't think %lld (even if it is implemented in some printf
derivates) can be considered portable.

Willem
Citeren sting sting <zstingx@hotmail.com>:

> Hello,
> I am trying to perfrom printk with a variable of type long long.
> (loff_t is that type and it is long long , as can be seen in
> posix+types.h).
> what is the format string for such a type ?
> I had tried %lld" but it gace wrpng results.
> regards,
> sting
> 
> _________________________________________________________________
> Protect your PC - get McAfee.com VirusScan Online 
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> 

Re: printk and long long

[Maciej Zenczykowski]

> how about simply using a shift to output two regular longs, i.e.
> 
> printk("%ld%ld",loff_t >> (sizeof(long) * 8), loff_t << sizeof(long) * 8 >>
> sizeof(long) * 8);

I'd venture to guess you'd also have to cast the above to long.

Cheers,
MaZe.

Re: printk and long long

[vda]

On Wednesday 11 February 2004 15:48, Maciej Zenczykowski wrote:
> > how about simply using a shift to output two regular longs, i.e.
> >
> > printk("%ld%ld",loff_t >> (sizeof(long) * 8), loff_t << sizeof(long) * 8
> > >> sizeof(long) * 8);
>
> I'd venture to guess you'd also have to cast the above to long.

Hey that will work only for %x, not %d.

BTW, man printf says:

The character L specifying that a following e, E, f, g, or G
conversion corresponds to a long double argument, or a following
d, i, o, u, x, or X conversion corresponds to a long long argument.
Note that long long is not specified in ANSI C and therefore
not portable to all architectures.
--
vda

Re: printk and long long

[Maciej Zenczykowski]

On Wed, 11 Feb 2004, vda wrote:

> The character L specifying that a following e, E, f, g, or G
> conversion corresponds to a long double argument, or a following
> d, i, o, u, x, or X conversion corresponds to a long long argument.
> Note that long long is not specified in ANSI C and therefore
> not portable to all architectures.

[ personally I'd say screw the un-portable architectures ;) ]
Long long is here to stay.
Besides if a linux architecture utilises long long in the kernel and 
doesn't support it in printf via %lld then it's horked.
printf/libc should be fixed instead.
Maybe that's the problem - the libc support fragment in the kernel tree is 
not up to date on that architecture - maybe the fixes should applied there 
instead - instead of trying to work around the problem, fix the cause.

Cheers,
MaZe.

Re: printk and long long

[H. Peter Anvin]

Followup to:  <Pine.LNX.4.44.0402111655170.17933-100000@gaia.cela.pl>
By author:    Maciej Zenczykowski <maze@cela.pl>
In newsgroup: linux.dev.kernel
>
> On Wed, 11 Feb 2004, vda wrote:
> 
> > The character L specifying that a following e, E, f, g, or G
> > conversion corresponds to a long double argument, or a following
> > d, i, o, u, x, or X conversion corresponds to a long long argument.
> > Note that long long is not specified in ANSI C and therefore
> > not portable to all architectures.
> 
> [ personally I'd say screw the un-portable architectures ;) ]
> Long long is here to stay.

long long is C99, so it's *definitely* here to say.  The conversion specifier
is "ll" not "L", however.

> Besides if a linux architecture utilises long long in the kernel and 
> doesn't support it in printf via %lld then it's horked.
> printf/libc should be fixed instead.
> Maybe that's the problem - the libc support fragment in the kernel tree is 
> not up to date on that architecture - maybe the fixes should applied there 
> instead - instead of trying to work around the problem, fix the cause.

Indeed.  Feel free to steal the code from klibc :)

	-hpa
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Re: printk and long long

[Måns Rullgård]

hpa@zytor.com (H. Peter Anvin) writes:

> Followup to:  <Pine.LNX.4.44.0402111655170.17933-100000@gaia.cela.pl>
> By author:    Maciej Zenczykowski <maze@cela.pl>
> In newsgroup: linux.dev.kernel
>>
>> On Wed, 11 Feb 2004, vda wrote:
>> 
>> > The character L specifying that a following e, E, f, g, or G
>> > conversion corresponds to a long double argument, or a following
>> > d, i, o, u, x, or X conversion corresponds to a long long argument.
>> > Note that long long is not specified in ANSI C and therefore
>> > not portable to all architectures.
>> 
>> [ personally I'd say screw the un-portable architectures ;) ]
>> Long long is here to stay.
>
> long long is C99, so it's *definitely* here to say.  The conversion specifier
> is "ll" not "L", however.

What is the proper way to deal with printing an int64_t when int64_t
can be either long or long long depending on machine?

-- 
Måns Rullgård
mru@kth.se

Re: printk and long long

[Chris Friesen]

Måns Rullgård wrote:

> What is the proper way to deal with printing an int64_t when int64_t
> can be either long or long long depending on machine?

Print it as long long, and even if there is an arch where that is 128 
bits it'll still work.

Chris


-- 
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Re: printk and long long

[Timothy Miller]

Chris Friesen wrote:
> Måns Rullgård wrote:
> 
>> What is the proper way to deal with printing an int64_t when int64_t
>> can be either long or long long depending on machine?
> 
> 
> Print it as long long, and even if there is an arch where that is 128 
> bits it'll still work.


In that case you'll want to cast it to (long long) before you pass it so 
as to be sure that "%lld" and the parameter are the same size.  Right?

Re: printk and long long

[Andreas Schwab]

mru@kth.se (Måns Rullgård) writes:

> What is the proper way to deal with printing an int64_t when int64_t
> can be either long or long long depending on machine?

PRId64 from <inttypes.h> (replace d with the desired format character).
This is for user space, not sure whether that is acceptable for kernel
code (<intttypes.h> is not one of the required headers for freestanding
implementations).

Andreas.

-- 
Andreas Schwab, SuSE Labs, schwab@suse.de
SuSE Linux AG, Maxfeldstraße 5, 90409 Nürnberg, Germany
Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
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Re: printk and long long

[Måns Rullgård]

Andreas Schwab <schwab@suse.de> writes:

> mru@kth.se (Måns Rullgård) writes:
>
>> What is the proper way to deal with printing an int64_t when int64_t
>> can be either long or long long depending on machine?
>
> PRId64 from <inttypes.h> (replace d with the desired format character).
> This is for user space, not sure whether that is acceptable for kernel
> code (<intttypes.h> is not one of the required headers for freestanding
> implementations).

That should work for userspace.  What standard specifies those?
What about kernel sources?

-- 
Måns Rullgård
mru@kth.se

Re: printk and long long

[H. Peter Anvin]

Followup to:  <yw1xn07pw6sy.fsf@kth.se>
By author:    mru@kth.se (=?iso-8859-1?q?M=E5ns_Rullg=E5rd?=)
In newsgroup: linux.dev.kernel
>
> Andreas Schwab <schwab@suse.de> writes:
> 
> > mru@kth.se (Måns Rullgård) writes:
> >
> >> What is the proper way to deal with printing an int64_t when int64_t
> >> can be either long or long long depending on machine?
> >
> > PRId64 from <inttypes.h> (replace d with the desired format character).
> > This is for user space, not sure whether that is acceptable for kernel
> > code (<intttypes.h> is not one of the required headers for freestanding
> > implementations).
> 
> That should work for userspace.  What standard specifies those?
> What about kernel sources?
> 

C99 defines those.

Another (frequently easier) way is to cast to (intmax_t) and use the %j size modifier:

	printf("foo = %jd\n", (intmax_t)foo);

	-hpa
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Just Say No to Morden * The Shadows were defeated -- Babylon 5 is renewed!!

Re: printk and long long

[Dick Streefland]

vda <vda@port.imtp.ilyichevsk.odessa.ua> wrote:
| Note that long long is not specified in ANSI C and therefore
| not portable to all architectures.

ANSI C corresponds to ISO-C90, which is 14 years old now. The current
C standard is ISO-C99, which specifies "ll" as the length modifier for
"long long" integer arguments.

-- 
Dick Streefland                      ////                      Altium BV
dick.streefland@altium.nl           (@ @)          http://www.altium.com
--------------------------------oOO--(_)--OOo---------------------------

Re: printk and long long

[Måns Rullgård]

wdebruij@dds.nl writes:

> how about simply using a shift to output two regular longs, i.e.
>
> printk("%ld%ld",loff_t >> (sizeof(long) * 8), loff_t << sizeof(long) * 8 >>
> sizeof(long) * 8);

And how do you plan to make sense of the printed value?

-- 
Måns Rullgård
mru@kth.se

Re: printk and long long

[wdebruij]

Quoting Måns Rullgård <mru@kth.se>:

> 
> And how do you plan to make sense of the printed value?
> 

perhaps I was a bit quick with replying. As others have pointed out, you should
specify the precision to be able to glue the two parts together. Ideally, this
should be done using a "%.8lx%.8lx", since the length of the variable in hex is
static. Unfortunately, it seems %ld is requested, in which case "%ld*(2^32)+%ld"
works (for humans), but is obviously not great.

I guess you'll need a number of extra tests (if lower 32bits > 1 billion ..) and
specific printk statements if the output should be shown as a correct 10-base
number. 

I don't know, it depends on the specific use-case, really. If at all possible, I
would stick to the hex-representation.

Re: printk and long long

[Richard B. Johnson]

On Wed, 11 Feb 2004 wdebruij@dds.nl wrote:

> how about simply using a shift to output two regular longs, i.e.
>
> printk("%ld%ld",loff_t >> (sizeof(long) * 8), loff_t << sizeof(long) * 8 >>
> sizeof(long) * 8);
>
> perhaps you could even place this ghastly code in a macro if you have to access
> it often (so that you don't have to look at it :)?
>
> I know it's not pretty, but at least the %ld is considered standard printf
> functionality. I don't think %lld (even if it is implemented in some printf
> derivates) can be considered portable.
>
> Willem
> Citeren sting sting <zstingx@hotmail.com>:
>
> > Hello,
> > I am trying to perfrom printk with a variable of type long long.
> > (loff_t is that type and it is long long , as can be seen in
> > posix+types.h).
> > what is the format string for such a type ?
> > I had tried %lld" but it gace wrpng results.
> > regards,
> > sting

This is probably portable. I could do it much simpler in
assembly but it wouldn't be portable.

Printing both unsigned long long and signed long long.




#include <stdio.h>

unsigned long long tester0 = 12345678901234567890ULL;
unsigned long long tester1 = 0xffffffffffffffff;


char *ulltoa(char *buf, unsigned long long val)
{
    char tmp[0x20];
    char *cp = tmp;
    char *rp = buf;
    do {
            *cp++ = (char) (val%10ULL) + '0';
            val /= 10ULL;
       } while (val);
    do {
           *buf++ = *(--cp);
       } while (cp != tmp);
    *buf = 0x00;
    return rp;
}

char *lltoa(char *buf, long long val)
{
   char *cp = buf;
   if(val < 0) {
        *cp++ = (char) '-';
        val = ~val + 1LL;
   }
   (void) ulltoa(cp, (unsigned long)val);
   return buf;
}

int main()
{
    char buf[0x100];

    printf("%llu\n", 0ULL);
    printf("%llu\n", tester0);
    printf("%llu\n", tester1);
    printf("%s\n", ulltoa(buf, 0ULL));
    printf("%s\n", ulltoa(buf, tester0));
    printf("%s\n", ulltoa(buf, tester1));
    printf("%s\n", lltoa(buf, tester1));

    return 0;
}



Cheers,
Dick Johnson
Penguin : Linux version 2.4.24 on an i686 machine (797.90 BogoMips).
            Note 96.31% of all statistics are fiction.

Re: printk and long long

[Peter Chubb]

>>>>> "Richard" == Richard B Johnson <root@chaos.analogic.com> writes:

Richard> On Wed, 11 Feb 2004 wdebruij@dds.nl wrote:
>> how about simply using a shift to output two regular longs, i.e.
>> 
>> printk("%ld%ld",loff_t >> (sizeof(long) * 8), loff_t <<
>> sizeof(long) * 8 >> sizeof(long) * 8);

Why bother?  printk already handles 64-bit types just fine.

Do
	loff_t x;
	printk("%lld\n" (long long)x)

You need the cast, because on 64-bit architectures, loff_t is long not
long long.

Peter c

Re: printk and long long

[Bart Hartgers]

On 11 Feb, Maciej Zenczykowski wrote:
>> how about simply using a shift to output two regular longs, i.e.
>> 
>> printk("%ld%ld",loff_t >> (sizeof(long) * 8), loff_t << sizeof(long) * 8 >>
>> sizeof(long) * 8);
> 
> I'd venture to guess you'd also have to cast the above to long.
> 
> Cheers,
> MaZe.

And use %lx%lx ?

> 
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Re: printk and long long

[YOSHIFUJI Hideaki / 吉藤英明]

In article <20040211135456.B33ED2BD4@etpmod.phys.tue.nl> (at Wed, 11 Feb 2004 14:54:56 +0100 (CET)), Bart Hartgers <bart@etpmod.phys.tue.nl> says:

> On 11 Feb, Maciej Zenczykowski wrote:
> >> how about simply using a shift to output two regular longs, i.e.
> >> 
> >> printk("%ld%ld",loff_t >> (sizeof(long) * 8), loff_t << sizeof(long) * 8 >>
> >> sizeof(long) * 8);
> > 
> > I'd venture to guess you'd also have to cast the above to long.
:
> And use %lx%lx ?

%08lx%08lx

--yoshfuji

Re: printk and long long

[Andreas Schwab]

Bart Hartgers <bart@etpmod.phys.tue.nl> writes:

> On 11 Feb, Maciej Zenczykowski wrote:
>>> how about simply using a shift to output two regular longs, i.e.
>>> 
>>> printk("%ld%ld",loff_t >> (sizeof(long) * 8), loff_t << sizeof(long) * 8 >>
>>> sizeof(long) * 8);
>> 
>> I'd venture to guess you'd also have to cast the above to long.
>> 
>> Cheers,
>> MaZe.
>
> And use %lx%lx ?

Rather %lx%0lx.

Andreas.

-- 
Andreas Schwab, SuSE Labs, schwab@suse.de
SuSE Linux AG, Maxfeldstraße 5, 90409 Nürnberg, Germany
Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."