Do we have atomic uint32 type in C?

Question

sig_atomic_t is a typedef of int. But I am curious do we have an atomic type which is matched to uint32_t ?

Answer 1

C11 defines following typedefs to atomic types in <stdatomic.h>:

atomic_bool
atomic_char
atomic_schar
atomic_uchar
atomic_short
atomic_ushort
atomic_int
atomic_uint
atomic_long
atomic_ulong
atomic_llong
atomic_ullong
atomic_char16_t
atomic_char32_t
atomic_wchar_t
atomic_int_least8_t
atomic_uint_least8_t
atomic_int_least16_t
atomic_uint_least16_t
atomic_int_least32_t
atomic_uint_least32_t
atomic_int_least64_t
atomic_uint_least64_t
atomic_int_fast8_t
atomic_uint_fast8_t
atomic_int_fast16_t
atomic_uint_fast16_t
atomic_int_fast32_t
atomic_uint_fast32_t
atomic_int_fast64_t
atomic_uint_fast64_t
atomic_intptr_t
atomic_uintptr_t
atomic_size_t
atomic_ptrdiff_t
atomic_intmax_t
atomic_uintmax_t

There is no atomic_uint32_t, so your options are:

• You can use _Atomic(uint32_t) directly.
• You can use one of existing alternative types (atomic_uint_least32_t, atomic_uint_fast32_t or even atomic_char32_t) if this fits your purpose (probably it doesn't).
• You can assume atomic_uint is 32-bit and use it as a replacement. This should be actually one of the most portable ways as most OS (*BSDs, Linux, Windows) assume int is a 32-bit type.