On 30/09/2011 08:05, Gunther Nikl wrote:
Ian Lance Taylor schrieb:
Gunther Nikl<gnikl@xxxxxxxxxxxxxxxxxxxxx> writes:
Is there a special requirement about the value of the limits
macros for fastest minimum-width integers? Eg. would it be legal
to use the limits of a a "signed char" if int_fast8_t is defined
in terms of an int? Or is it required to use the proper limit of
int?
I don't understand what you mean. Can you show us some example code
that you are uncertain about?
Here is an example for int_fast8_t:
typedef signed char int_fast8_t;
#define INT_FAST8_MIN INT8_MIN
#define INT_FAST8_MAX INT8_MAX
Now if int_fast8_t uses "int" as underlying type like this:
typedef int int_fast8_t;
which value is its MIN/MAX macros supposed to have? Is it
allowed to use the same "char" limits as above or do I need
to use
#define INT_FAST8_MIN INT32_MIN
#define INT_FAST8_MAX INT32_MAX
You mean "#define INT_FAST8_MIN INT_MIN" in this case - you would only
use "INT32_MIN" if you had "typedef int32_t int_fast8_t". If you are
going to write your own <stdint.h>, try to be accurate - otherwise
you'll end up with something that looks standard and portable, but is
not quite correct and will cause problems if it is reused on other
platforms.
I believe it is standard practice that INT_FAST8_MIN and similar limits
match those of the underlying type, even though it would be legal to
make it smaller. Similarly with INT_LEAST8_MIN. That seems to be the
case on the various compilers I have lying around.
in that case?
So this is not about user code but an implementation question.
Thank you,
Gunther Nikl
