* configure (have_sys_time): New variable.

Added check for setitimer/getitimer which also
checks for <sys/time.h>.

* signal.c (sig_init): Register itimer-real, itimer-virtual,
itimer-prof variables and getitimer and setitimer functions.
(tv_to_usec): New static function.
(getitimer_wrap, setitimer_wrap): New functions.

* signal.h (getitimer_wrap, setitimer_wrap): Declared.

* txr.1: Documented itimers.

1 files changed, 37 insertions, 0 deletions

diff --git a/txr.1 b/txr.1
index 176d665c..2f9efc99 100644
--- a/txr.1
+++ b/txr.1
@@ -14608,6 +14608,43 @@ It is a wrapper for the POSIX kill function.
 
 If the <signal> argument is omitted, it defaults to the same value as sig-term.
 
+.SH UNIX ITIMERS
+
+Itimers can be used in combination with signal handling to execute asynchronous
+actions. Itimers deliver one-time or periodic signals. For more information,
+consult the POSIX specification.
+
+.SS Variables itimer-real, itimer-virtual and itimer-prof
+
+.TP
+Description:
+
+These variables correspond to the POSIX constants ITIMER_REAL, ITIMER_VIRTUAL
+and ITIMER_PROF. Thir values are suitable as the <timer> argument of
+the getitimer and setitimer functions.
+
+.SS Functions getitimer and setitimer
+
+.TP
+Syntax:
+
+  (getitimer <timer>)
+  (setitimer <timer> <interval> <value>)
+
+.TP
+Description
+
+The getitimer function returns the current value of the specified timer,
+which must be itimer-real, itimer-virtual or itimer-prof.
+
+The current value consists of a list of two integer values, which
+represents microseconds. The first value is the timer interval,
+and the second value is the timer's current value.
+
+The setitimer function also retrieves the specified timer, exactly
+as getitimer. In addition, it stores a new value in the timer,
+which is given by the two arguments, expressed in microseconds.
+
 .SH UNIX SYSLOG
 
 On platforms where a Unix-like syslog API is available, TXR exports this