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| -rw-r--r-- | manual/examples/timeval_subtract.c | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/manual/examples/timeval_subtract.c b/manual/examples/timeval_subtract.c new file mode 100644 index 0000000000..683322ffeb --- /dev/null +++ b/manual/examples/timeval_subtract.c @@ -0,0 +1,28 @@ +/* Subtract the `struct timeval' values X and Y, + storing the result in RESULT. + Return 1 if the difference is negative, otherwise 0. */ + +int +timeval_subtract (result, x, y) + struct timeval *result, *x, *y; +{ + /* Perform the carry for the later subtraction by updating @var{y}. */ + if (x->tv_usec < y->tv_usec) { + int nsec = (y->tv_usec - x->tv_usec) / 1000000 + 1; + y->tv_usec -= 1000000 * nsec; + y->tv_sec += nsec; + } + if (x->tv_usec - y->tv_usec > 1000000) { + int nsec = (x->tv_usec - y->tv_usec) / 1000000; + y->tv_usec += 1000000 * nsec; + y->tv_sec -= nsec; + } + + /* Compute the time remaining to wait. + @code{tv_usec} is certainly positive. */ + result->tv_sec = x->tv_sec - y->tv_sec; + result->tv_usec = x->tv_usec - y->tv_usec; + + /* Return 1 if result is negative. */ + return x->tv_sec < y->tv_sec; +} |