error: ‘asm’ undeclared (first use in this function)

Question

I am getting the following error during compilation:

error: ‘asm’ undeclared (first use in this function)
 EXCHANGE( s, *(a) );
 ^

in a header

Answer 1

asm is a gcc extension, Hence you can not used with flags like std=c99 or ansi

More details at https://gcc.gnu.org/onlinedocs/gcc/C-Extensions.html#C-Extensions