c - 中断对上下文的干扰有多大？如何恢复它？

Question

§5.1.2.3.5

5 When the processing of the abstract machine is interrupted byreceipt of a signal, the values of objects that are neither lock-freeatomic objects nor of type volatile sig_atomic_t are not specified,as is the state of the floating-point environment. The value of anyobject modified by the handler that is neither a lock-free atomicobject nor of type volatile sig_atomic_t becomes indeterminate whenthe handler exits, as does the state of the floating-point environmentif it is modified by the handler and not restored to its originalstate.

(强调我的)

我认为这意味着，在硬件/软件中断的情况下，如果中断处理程序执行任何浮点计算(例如在其本地堆栈变量上)，则被中断的进程将处于不一致的状态，并且必须重新启动任何浮点计算。正在进行的浮点计算。 是这样吗？这意味着什么？如何“恢复上下文”？

Answer 1

“浮点环境”是指浮点异常和舍入模式的设置，由 fesetround() 等函数修改。

您可以使用fegetenv()保存当前浮点环境，并使用fesetenv()恢复它。如果您安装了执行浮点运算的信号处理程序，那么它应该执行此操作(例如，这确保它不会更改其中断的代码当前引发的浮点异常集)。