On Thu, 6 Dec 2007, Christoph Mallon wrote:
Kip Macy wrote:
On Dec 6, 2007 2:25 AM, Bruce Evans <[EMAIL PROTECTED]> wrote:
On Thu, 6 Dec 2007, Kip Macy wrote:
kmacy 2007-12-06 04:00:59 UTC
FreeBSD src repository
Modified files:
sys/sys param.h
Log:
Respect the fact that the value a may be constant so cast to const
uint8_t *
Revision Changes Path
1.318 +2 -2 src/sys/sys/param.h
The correct fix is to back out 1.317. If not, at least spell `unsigned
char' correctly and fix the other new style bug (a line longer than
80 characters from adding `const'). Using uint8_t is only a style bug
since POSIX probably requires unsigned char to be the same as uint8_t.
If unsigned char is larger than uint8_t, then revs.1.317-318 give
undefined behaviour (aliasing bugs) and clearly broken behaviour (wrong
divisor NBBY). These bugs are easy to avoid by using the correct
spelling.
I'm inclined to do whatever you say so long as my code works without a
substantial rewrite.
Couldn't you just use a cast in your own code.
Code newer than 1994 should probably use bitstring(3). 4.4BSD put
bitstring.h in src/include 1994, and FreeBSD repo-copied bitstring.h to
src/sys/sys in 2003.
However, can you please point me at where it says
uint8_t is not style(9) compliant?
I think, he means that uint8_t is not necessarily the same type as unsigned
char. In fact according to the C99 standard the type uint8_t does not
necessarily exist (section 7.18.1.1).
Right.
I checked that POSIX.1.2001 explicitly requires uint8_t and other
fixed-width types to exist (mainly because POSIX finally got around
to Standardizing 20-year old mistakes in network APIs -- (in_addr_t
is uint32_t, etc.)), and that when uint8_t exists, C99 implicitly
requires unsigned char to have the same representation as unsigned
char (because unsigned char is the smallest non-bitfield type, and
uint8_t is as small as possible -- both must be 8 bits with no padding).
The remaining details are subtler -- does having the same representation
require the types to be the same in this case though it doesn't in
general, or is having the same representation enough for the special
features of unsigned char to apply to uint8_t?
Bruce
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