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    SubjectRe: Problems (a bug?) with UINT_MAX from kernel.h
    Richard Purdie wrote:
    > The kernel uses UINT_MAX defined from kernel.h in a variety of places.
    > While looking at the behaviour of the LZO code, I noticed it seemed to
    > think an int was 8 bytes large on my 32 bit i386 machine. It isn't but
    > why did it think that?
    > kernel.h says:
    > #define INT_MAX ((int)(~0U>>1))
    > #define INT_MIN (-INT_MAX - 1)
    > #define UINT_MAX (~0U)
    > #define LONG_MAX ((long)(~0UL>>1))
    > #define LONG_MIN (-LONG_MAX - 1)
    > #define ULONG_MAX (~0UL)
    > #define LLONG_MAX ((long long)(~0ULL>>1))
    > #define LLONG_MIN (-LLONG_MAX - 1)
    > #define ULLONG_MAX (~0ULL)
    > If I try to compile the code fragment below, I see the error:
    > #define UINT_MAX (~0U)
    > #if (0xffffffffffffffff == UINT_MAX)
    > #error argh
    > #endif
    > I've tested this on several systems with a variety of gcc versions with
    > the same result. I've tried various other ways of testing this all with
    > the same conclusion, UINT_MAX is wrong.

    C99 states that all arithmetic in the preprocessor is done in
    (u)intmax_t, regardless of prefixes or suffixes.

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      Last update: 2007-06-05 20:39    [W:0.032 / U:10.512 seconds]
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