implement monotonic clock on unix platforms

extra/monotonic-clock/monotonic-clock.factor

@@ -1,7 +1,12 @@
 ! Copyright (C) 2009 Doug Coleman.
 ! See http://factorcode.org/license.txt for BSD license.
-USING: system ;
+USING: combinators system vocabs.loader ;
 IN: monotonic-clock
 
 HOOK: monotonic-count os ( -- n )
 
+{
+    { [ os unix? ] [ "monotonic-clock.unix" ] }
+    { [ os windows? ] [ "monotonic-clock.windows" ] }
+    { [ os macosx? ] [ "monotonic-clock.unix.macosx" ] }
+} cond require

extra/monotonic-clock/unix/linux/linux.factor

@@ -1,4 +0,0 @@
-! Copyright (C) 2009 Doug Coleman.
-! See http://factorcode.org/license.txt for BSD license.
-USING: ;
-IN: monotonic-clock.unix.linux

extra/monotonic-clock/unix/linux/tags.txt

@@ -1 +0,0 @@
-unportable

extra/monotonic-clock/unix/unix.factor

@@ -0,0 +1,22 @@
+! Copyright (C) 2009 Doug Coleman.
+! See http://factorcode.org/license.txt for BSD license.
+USING: alien.c-types alien.syntax calendar.unix classes.struct
+kernel monotonic-clock system unix unix.time unix.types ;
+IN: monotonic-clock.unix
+
+LIBRARY: librt
+
+FUNCTION: int clock_settime ( clockid_t clock_id, timespec* tp ) ;
+FUNCTION: int clock_gettime ( clockid_t clock_id, timespec* tp ) ;
+FUNCTION: int clock_getres ( clockid_t clock_id, timespec* res ) ;
+
+CONSTANT: CLOCK_REALTIME 0
+CONSTANT: CLOCK_MONOTONIC 1
+CONSTANT: CLOCK_PROCESS_CPUTIME_ID 2
+CONSTANT: CLOCK_THREAD_CPUTIME_ID 3
+
+CONSTANT: TIMER_ABSTIME 1
+
+M: unix monotonic-count
+    CLOCK_MONOTONIC timespec <struct> [ clock_gettime io-error ] keep
+    timespec>nanoseconds ;