asm statement syntax 1 asm 1 __asm 1 __asm__ 2? volatile 3 ( 4 code_format_string 4.1+ : 4.1? 4.1 output 4.1 input 4.1 clobbers 4.1.1 ) input: 1+ , 1 constraint ( C_expression ) output: 1+ , 1 constraint ( C_expression )