一、基础题 (每题4分)

1. 描述C语言内嵌汇编中, __asm__ __volatile__ 这一句的 __volatile__ 的作用是？当修饰变量时volatile什么含义?

__volatile__ 表示编译器不要优化代码，后面的指令 保留原样， volatile 是它的别名。-One, the basic topic (4 point per question)

1. Describe the inline assembler, C __asm__ __volatile__ __volatile__ role is it?When modified variable volatile what meaning?

__volatile__　said don t optimize code, the compiler behind instructions to keep the same,　volatile　is its alias.