### 8.170 `MCLOCK8` — Time function (64-bit)

Description:
  Returns the number of clock ticks since the start of the process, based on the function `clock(3)` in the C standard library.

  Warning: this intrinsic does not increase the range of the timing values over that returned by `clock(3)`. On a system with a 32-bit `clock(3)`, `MCLOCK8` will return a 32-bit value, even though it is converted to a 64-bit `INTEGER(8)` value. That means overflows of the 32-bit value can still occur. Therefore, the values returned by this intrinsic might be or become negative or numerically less than previous values during a single run of the compiled program.

Standard:
  GNU extension
Class:
  Function
Syntax:
  `RESULT = MCLOCK8()`
Return value:
  The return value is a scalar of type `INTEGER(8)`, equal to the number of clock ticks since the start of the process, or `-1` if the system does not support `clock(3)`.
See also:
  CTIME, GMTIME, LTIME, MCLOCK, TIME8