=head2 GCC ATTRIBUTES

=over 4

=item ecb_attribute ((attrs...))

A simple wrapper that expands to C<__attribute__((attrs))> on GCC, and
to nothing on other compilers, so the effect is that only GCC sees these.

=item ecb_noinline

=item ecb_noreturn

=item ecb_unused

=item ecb_const

=item ecb_pure

=item ecb_hot

=item ecb_cold

=item ecb_artificial

=back

=head2 OPTIMISATION HINTS

=over 4

=item bool ecb_is_constant(expr)

=item bool ecb_expect(expr,value)

=item bool ecb_unlikely(bool)

=item bool ecb_likely(bool)

=item bool ecb_assume(cond)

=item bool ecb_unreachable()

=item bool ecb_prefetch(addr,rw,locality)

=back

=head2 BIT FIDDLING / BITSTUFFS

bool ecb_big_endian ();
bool ecb_little_endian ();
int ecb_ctz32 (uint32_t x);
int ecb_popcount32 (uint32_t x);
uint32_t ecb_bswap32 (uint32_t x);
uint32_t ecb_bswap16 (uint32_t x);
uint32_t ecb_rotr32 (uint32_t x, unsigned int count);
uint32_t ecb_rotl32 (uint32_t x, unsigned int count);

=head2 ARITHMETIC

x = ecb_mod (m, n)

=head2 UTILITY

ecb_array_length (name)