ALSA depends on types struct timespec and struct timeval . Its global.h header therefore appropriately does this: /* for timeval and timespec */ #include ... ... <看更多>

Structure defined by POSIX.1b to be like a timeval. */. struct timespec {. time_t tv_sec; /* seconds */. long tv_nsec; /* and nanoseconds */. };. ... <看更多>

據我的了解, preprocessor如#ifdef, 頂多是把"已經寫在header裡面的某些東西"不compile ... 有個struct叫做timeval, 我看資料他定義在sys/time.h裡面, ... ... <看更多>