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Language Extensions
3.3.2 long long
The ARM compiler supports 64-bit integer types through the type specifiers long long
and unsigned long long. They behave analogously to long and unsigned long with
respect to the usual arithmetic conversions. __int64 is a synonym for long long.
Integer constants can have:
• an ll suffix to force the type of the constant to long long, if it fits, or to unsigned
long long if it does not fit
• a ull or llu suffix to force the type of the constant to unsigned long long.
Format specifiers for printf() and scanf() can include ll to specify that the following
conversion applies to a long long argument, as7 in %lld or %llu.
Also, a plain integer constant is of type long long or unsigned long long if its value is
large enough. There is a warning message from the compiler indicating the change. For
example, in strict 1990 ISO Standard C 2147483648 has type unsigned long. In ARM
C and C++ it has the type long long. One consequence of this is the value of an
expression such as:
2147483648 > –1
This expression evaluates to 0 in strict C and C++, and to 1 in ARM C and C++.
The long long types are accommodated in the usual arithmetic conversions.
See also
• __int64 on page 4-10.
3.3.3 restrict
The restrict keyword is a C99 feature. It enables you to convey a declaration of intent
to the compiler that different pointers and function parameter arrays do not point to
overlapping regions of memory at runtime. This enables the compiler to perform
optimizations that can otherwise be prevented because of possible aliasing.
Usage
The keywords __restrict and __restrict__ are supported as synonyms for restrict and
are always available.
You can specify --restrict to allow the use of the restrict keyword in C90 or C++.
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