嵌入式编程 中断 一题

Interrupts are an important part of embedded systems. Consequently, many compiler vendors offer an extension

to standard C to support interrupts. Typically, the keyword is _interrupt. The following routine(ISR), point out

the errors in the code.

_interrupt double compute_area(double radius)
{
    double area = PI * radius * radius;

    printf("\nArea = %f", area);

    return 0;
}

析：

1）ISR不能返回一个值
2）ISR不能传递参数
3）在许多处理器或编译器中，浮点一般都是不可重入的，此外，ISR应是短而有效率的，在ISR中做浮点去处是不明智的
4）printf()经常有重入和性能上的问题，所以一般不使用printf()