tai conversion functions overhaul.

 API change -> rc for 2.2.0.0
 Doc updated.

44 files changed, 220 insertions, 199 deletions

diff --git a/src/include/skalibs/tai.h b/src/include/skalibs/tai.h
index 8a3f777..e411ff0 100644
--- a/src/include/skalibs/tai.h
+++ b/src/include/skalibs/tai.h
@@ -24,28 +24,26 @@ struct tai_s
 #define TAI_INFINITE { .x = TAI_MAGIC + ((uint64)1 << 61) }
 
 #define tai_sec(t) ((t)->x)
-#define tai_u64(t, u) ((void)((t)->x = (u)))
+extern int tai_u64 (tai_t *, uint64) ;
 #define tai_unix(t, u) tai_u64(t, (TAI_MAGIC + (u)))
 #define tai_uint(t, u) tai_u64(t, (uint64)(u))
 
-extern int tai_relative_from_timeval (tai_t *, struct timeval const *) ;
-extern int tai_from_timeval (tai_t *, struct timeval const *) ;
-extern int timeval_from_tai_relative (struct timeval *, tai_t const *) ;
-extern int timeval_from_tai (struct timeval *, tai_t const *) ;
+extern int tai_now (tai_t *) ;
 
-extern int tai_relative_from_timespec (tai_t *, struct timespec const *) ;
-extern int tai_from_timespec (tai_t *, struct timespec const *) ;
-extern int timespec_from_tai_relative (struct timespec *, tai_t const *) ;
-extern int timespec_from_tai (struct timespec *, tai_t const *) ;
+#define tai_relative_from_time(t, u) ((t)->x = (uint64)(u), 1)
+#define tai_from_time(t, u) tai_unix(t, u)
+#define tai_from_time_sysclock(t, u) tai_from_sysclock(t, (uint64)(u) + TAI_MAGIC)
+extern int time_from_tai_relative (time_t *, tai_t const *) ;
+extern int time_from_tai (time_t *, tai_t const *) ;
+extern int time_sysclock_from_tai(time_t *, tai_t const *) ;
 
-extern int tai_now (tai_t *) ;
 extern int tai_from_sysclock (tai_t *, uint64) ;
 extern int sysclock_from_tai (uint64 *, tai_t const *) ;
 
 #define tai_approx(t) ((double)(tai_sec(t)))
 
-extern void tai_add (tai_t *, tai_t const *, tai_t const *) ;
-extern void tai_sub (tai_t *, tai_t const *, tai_t const *) ;
+extern int tai_add (tai_t *, tai_t const *, tai_t const *) ;
+extern int tai_sub (tai_t *, tai_t const *, tai_t const *) ;
 #define tai_less(t,u) (tai_sec(t) < tai_sec(u))
 
 #define TAI_PACK 8
@@ -78,16 +76,22 @@ extern tain_t const tain_nano500 ;
 
 extern int tain_relative_from_timeval (tain_t *, struct timeval const *) ;
 extern int tain_from_timeval (tain_t *, struct timeval const *) ;
+extern int tain_from_timeval_sysclock (tain_t *, struct timeval const *) ;
 extern int timeval_from_tain_relative (struct timeval *, tain_t const *) ;
 extern int timeval_from_tain (struct timeval *, tain_t const *) ;
+extern int timeval_sysclock_from_tain (struct timeval *, tain_t const *) ;
 
 extern int tain_relative_from_timespec (tain_t *, struct timespec const *) ;
 extern int tain_from_timespec (tain_t *, struct timespec const *) ;
+extern int tain_from_timespec_sysclock (tain_t *, struct timespec const *) ;
 extern int timespec_from_tain_relative (struct timespec *, tain_t const *) ;
 extern int timespec_from_tain (struct timespec *, tain_t const *) ;
+extern int timespec_sysclock_from_tain (struct timespec *, tain_t const *) ;
 
 extern int sysclock_get (tain_t *) ;
 extern int tain_sysclock (tain_t *) ;
+extern int tain_from_sysclock (tain_t *, tain_t const *) ;
+extern int sysclock_from_tain (tain_t *, tain_t const *) ;
 #define tain_sysclock_g() tain_sysclock(&STAMP)
 extern int tain_clockmon_init (tain_t *) ;
 extern int tain_clockmon (tain_t *, tain_t const *) ;
@@ -106,12 +110,11 @@ extern double tain_frac (tain_t const *) gccattr_pure ;
 extern int tain_from_millisecs (tain_t *, int) ;
 extern int tain_to_millisecs (tain_t const *) gccattr_pure ;
 
-extern void tain_add (tain_t *, tain_t const *, tain_t const *) ;
+extern int tain_add (tain_t *, tain_t const *, tain_t const *) ;
 #define tain_add_g(deadline, tto) tain_add(deadline, &STAMP, tto)
-extern void tain_addsec (tain_t *, tain_t const *, int) ;
+extern int tain_addsec (tain_t *, tain_t const *, int) ;
 #define tain_addsec_g(deadline, n) tain_addsec(deadline, &STAMP, n)
-extern void tain_sub (tain_t *, tain_t const *, tain_t const *) ;
-extern void tain_half (tain_t *, tain_t const *) ;
+extern int tain_sub (tain_t *, tain_t const *, tain_t const *) ;
 extern int tain_less (tain_t const *, tain_t const *) gccattr_pure ;
 #define tain_future(deadline) tain_less(&STAMP, (deadline))
 
@@ -129,7 +132,8 @@ extern unsigned int tain_scan (char const *, tain_t *) ;
 extern unsigned int tain_fmtfrac (char *, tain_t const *) ;
 
 #define tain_uint(a, u) tain_ulong(a, u)
-extern void tain_ulong (tain_t *, unsigned long) ;
+extern int tain_ulong (tain_t *, unsigned long) ;
+extern void tain_half (tain_t *, tain_t const *) ;
 
 #define TIMESTAMP (1 + (TAIN_PACK << 1))
 extern unsigned int timestamp_fmt (char *, tain_t const *) ;
diff --git a/src/libstddjb/sysclock_from_localtmn.c b/src/libstddjb/sysclock_from_localtmn.c
index 7b227d2..a0ee34b 100644
--- a/src/libstddjb/sysclock_from_localtmn.c
+++ b/src/libstddjb/sysclock_from_localtmn.c
@@ -5,9 +5,7 @@
 
 int sysclock_from_localtmn (tain_t *a, localtmn_t const *l)
 {
-  uint64 u ;
-  if (!sysclock_from_localtm(&u, &l->tm)) return 0 ;
-  tai_u64(&a->sec, u) ;
+  if (!sysclock_from_localtm(&a->sec.x, &l->tm)) return 0 ;
   a->nano = l->nano ;
   return 1 ;
 }
diff --git a/src/libstddjb/sysclock_from_tai.c b/src/libstddjb/sysclock_from_tai.c
index 3db2640..3814bf2 100644
--- a/src/libstddjb/sysclock_from_tai.c
+++ b/src/libstddjb/sysclock_from_tai.c
@@ -1,5 +1,6 @@
 /* ISC license. */
 
+#include <errno.h>
 #include <skalibs/config.h>
 #include <skalibs/tai.h>
 
@@ -7,6 +8,7 @@
 
 int sysclock_from_tai (uint64 *u, tai_t const *t)
 {
+  if (t->x < 10U) return (errno = EINVAL, 0) ;
   *u = t->x - 10U ;
   return 1 ;
 }
diff --git a/src/libstddjb/sysclock_from_tain.c b/src/libstddjb/sysclock_from_tain.c
new file mode 100644
index 0000000..8a2bd12
--- /dev/null
+++ b/src/libstddjb/sysclock_from_tain.c
@@ -0,0 +1,10 @@
+ /* ISC license. */
+
+#include <skalibs/tai.h>
+
+int sysclock_from_tain (tain_t *u, tain_t const *t)
+{
+  if (!sysclock_from_tai(&u->sec.x, &t->sec)) return 0 ;
+  u->nano = t->nano ;
+  return 1 ;
+}
diff --git a/src/libstddjb/sysclock_from_utc.c b/src/libstddjb/sysclock_from_utc.c
index 25f9205..49228a7 100644
--- a/src/libstddjb/sysclock_from_utc.c
+++ b/src/libstddjb/sysclock_from_utc.c
@@ -1,5 +1,6 @@
 /* ISC license. */
 
+#include <errno.h>
 #include <skalibs/config.h>
 #include <skalibs/uint64.h>
 #include <skalibs/djbtime.h>
@@ -12,6 +13,7 @@ int sysclock_from_utc (uint64 *u)
 {
   tai_t t ;
   if (!tai_from_utc(&t, *u)) return 0 ;
+  if (t.x < 10) return (errno = EINVAL, 0) ;
   *u = t.x - 10 ;
   return 1 ;
 }
diff --git a/src/libstddjb/tai_add.c b/src/libstddjb/tai_add.c
index 91af283..ad481ea 100644
--- a/src/libstddjb/tai_add.c
+++ b/src/libstddjb/tai_add.c
@@ -2,7 +2,7 @@
 
 #include <skalibs/tai.h>
 
-void tai_add (tai_t *t, tai_t const *u, tai_t const *v)
+int tai_add (tai_t *t, tai_t const *u, tai_t const *v)
 {
-  tai_u64(t, tai_sec(u) + tai_sec(v)) ;
+  return tai_u64(t, tai_sec(u) + tai_sec(v)) ;
 }
diff --git a/src/libstddjb/tai_from_ltm64.c b/src/libstddjb/tai_from_ltm64.c
index 12a7394..0ecb49a 100644
--- a/src/libstddjb/tai_from_ltm64.c
+++ b/src/libstddjb/tai_from_ltm64.c
@@ -9,7 +9,7 @@ int tai_from_ltm64 (tai_t *t, uint64 u)
 {
   switch (skalibs_tzisright())
   {
-    case 1 : tai_u64(t, u + 10U) ; return 1 ;
+    case 1 : return tai_u64(t, u + 10U) ;
     case 0 : return tai_from_utc(t, u) ;
     default : return 0 ;
   }
diff --git a/src/libstddjb/tai_from_sysclock.c b/src/libstddjb/tai_from_sysclock.c
index c2bb546..087f353 100644
--- a/src/libstddjb/tai_from_sysclock.c
+++ b/src/libstddjb/tai_from_sysclock.c
@@ -7,8 +7,7 @@
 
 int tai_from_sysclock (tai_t *t, uint64 u)
 {
-  tai_u64(t, u + 10U) ;
-  return 1 ;
+  return tai_u64(t, u + 10U) ;
 }
 
 #else
diff --git a/src/libstddjb/tai_from_timespec.c b/src/libstddjb/tai_from_timespec.c
deleted file mode 100644
index e9fbe3e..0000000
--- a/src/libstddjb/tai_from_timespec.c
+++ /dev/null
@@ -1,11 +0,0 @@
-/* ISC license. */
-
-#include <sys/types.h>
-#include <time.h>
-#include <skalibs/tai.h>
-
-int tai_from_timespec (tai_t *t, struct timespec const *ts)
-{
-  tai_unix(t, ts->tv_sec) ;
-  return 1 ;
-}
diff --git a/src/libstddjb/tai_from_timeval.c b/src/libstddjb/tai_from_timeval.c
deleted file mode 100644
index 41cf5a1..0000000
--- a/src/libstddjb/tai_from_timeval.c
+++ /dev/null
@@ -1,10 +0,0 @@
-/* ISC license. */
-
-#include <sys/time.h>
-#include <skalibs/tai.h>
-
-int tai_from_timeval (tai_t *t, struct timeval const *tv)
-{
-  tai_unix(t, tv->tv_sec) ;
-  return 1 ;
-}
diff --git a/src/libstddjb/tai_from_utc.c b/src/libstddjb/tai_from_utc.c
index ba9cea9..c5dc62d 100644
--- a/src/libstddjb/tai_from_utc.c
+++ b/src/libstddjb/tai_from_utc.c
@@ -8,7 +8,5 @@
 int tai_from_utc (tai_t *t, uint64 u)
 {
   if (leapsecs_add(&u, 0) < 0) return 0 ;
-  u += 10 ;
-  t->x = u ;
-  return 1 ;
+  return tai_u64(t, u + 10) ;
 }
diff --git a/src/libstddjb/tai_now.c b/src/libstddjb/tai_now.c
index a1847ab..aaf388a 100644
--- a/src/libstddjb/tai_now.c
+++ b/src/libstddjb/tai_now.c
@@ -3,11 +3,11 @@
 /* MT-unsafe */
 
 #include <time.h>
-#include <skalibs/uint64.h>
 #include <skalibs/tai.h>
 
 int tai_now (tai_t *t)
 {
-  register uint64 u = TAI_MAGIC + time(0) ;
-  return tai_from_sysclock(t, u) ;
+  register time_t u = time(0) ;
+  if (u == (time_t)-1) return 0 ;
+  return tai_from_time_sysclock(t, u) ;
 }
diff --git a/src/libstddjb/tai_relative_from_timespec.c b/src/libstddjb/tai_relative_from_timespec.c
deleted file mode 100644
index 34bb555..0000000
--- a/src/libstddjb/tai_relative_from_timespec.c
+++ /dev/null
@@ -1,11 +0,0 @@
-/* ISC license. */
-
-#include <sys/types.h>
-#include <time.h>
-#include <skalibs/tai.h>
-
-int tai_relative_from_timespec (tai_t *t, struct timespec const *ts)
-{
-  tai_u64(t, ts->tv_sec) ;
-  return 1 ;
-}
diff --git a/src/libstddjb/tai_relative_from_timeval.c b/src/libstddjb/tai_relative_from_timeval.c
deleted file mode 100644
index f685da7..0000000
--- a/src/libstddjb/tai_relative_from_timeval.c
+++ /dev/null
@@ -1,10 +0,0 @@
-/* ISC license. */
-
-#include <sys/time.h>
-#include <skalibs/tai.h>
-
-int tai_relative_from_timeval (tai_t *t, struct timeval const *tv)
-{
-  tai_u64(t, tv->tv_sec) ;
-  return 1 ;
-}
diff --git a/src/libstddjb/tai_sub.c b/src/libstddjb/tai_sub.c
index d0c879e..e0cda7a 100644
--- a/src/libstddjb/tai_sub.c
+++ b/src/libstddjb/tai_sub.c
@@ -2,7 +2,7 @@
 
 #include <skalibs/tai.h>
 
-void tai_sub (tai_t *t, tai_t const *u, tai_t const *v)
+int tai_sub (tai_t *t, tai_t const *u, tai_t const *v)
 {
-  tai_u64(t, tai_sec(u) - tai_sec(v)) ;
+  return tai_u64(t, tai_sec(u) - tai_sec(v)) ;
 }
diff --git a/src/libstddjb/tai_u64.c b/src/libstddjb/tai_u64.c
new file mode 100644
index 0000000..a26d907
--- /dev/null
+++ b/src/libstddjb/tai_u64.c
@@ -0,0 +1,12 @@
+/* ISC license. */
+
+#include <errno.h>
+#include <skalibs/uint64.h>
+#include <skalibs/tai.h>
+
+int tai_u64 (tai_t *t, uint64 u)
+{
+  if (u & ((uint64)1 << 63)) return (errno = EOVERFLOW, 0) ;
+  t->x = u ;
+  return 1 ;
+}
diff --git a/src/libstddjb/tain_add.c b/src/libstddjb/tain_add.c
index 6c6a237..aa6e705 100644
--- a/src/libstddjb/tain_add.c
+++ b/src/libstddjb/tain_add.c
@@ -2,13 +2,16 @@
 
 #include <skalibs/tai.h>
 
-void tain_add (tain_t *t, tain_t const *u, tain_t const *v)
+int tain_add (tain_t *t, tain_t const *u, tain_t const *v)
 {
-  tai_add(&t->sec, &u->sec, &v->sec) ;
-  t->nano = u->nano + v->nano ;
-  if (t->nano > 999999999U)
+  tain_t tt = *u ;
+  if (!tai_add(&tt.sec, &u->sec, &v->sec)) return 0 ;
+  tt.nano = u->nano + v->nano ;
+  if (tt.nano > 999999999U)
   {
-    t->nano -= 1000000000U ;
-    tai_u64(&t->sec, tai_sec(&t->sec)+1) ;
+    if (!tai_u64(&tt.sec, tai_sec(&tt.sec) + 1)) return 0 ;
+    tt.nano -= 1000000000U ;
   }
+  *t = tt ;
+  return 1 ;
 }
diff --git a/src/libstddjb/tain_addsec.c b/src/libstddjb/tain_addsec.c
index f4252a7..524ac20 100644
--- a/src/libstddjb/tain_addsec.c
+++ b/src/libstddjb/tain_addsec.c
@@ -2,19 +2,20 @@
 
 #include <skalibs/tai.h>
 
-void tain_addsec (tain_t *b, tain_t const *a, int c)
+int tain_addsec (tain_t *b, tain_t const *a, int c)
 {
-  b->nano = a->nano ;
   if (c >= 0)
   {
     tai_t t ;
-    tai_u64(&t, c) ;
-    tai_add(&b->sec, &a->sec, &t) ;
+    if (!tai_u64(&t, c)) return 0 ;
+    if (!tai_add(&b->sec, &a->sec, &t)) return 0 ;
   }
   else
   {
     tai_t t ;
-    tai_u64(&t, -c) ;
-    tai_sub(&b->sec, &a->sec, &t) ;
+    if (!tai_u64(&t, -c)) return 0 ;
+    if (!tai_sub(&b->sec, &a->sec, &t)) return 0 ;
   }
+  b->nano = a->nano ;
+  return 1 ;
 }
diff --git a/src/libstddjb/tain_from_ntp.c b/src/libstddjb/tain_from_ntp.c
index 6bf7697..5314a38 100644
--- a/src/libstddjb/tain_from_ntp.c
+++ b/src/libstddjb/tain_from_ntp.c
@@ -6,7 +6,7 @@
 
 int tain_from_ntp (tain_t *a, uint64 u)
 {
-  tai_t secs = { u >> 32 } ;
+  tai_t secs = { .x = u >> 32 } ;
   if (secs.x <= 0x7FFFFFFFUL) secs.x |= ((uint64)1 << 32) ;
   secs.x += TAI_MAGIC ;
   secs.x -= NTP_OFFSET ;
diff --git a/src/libstddjb/tain_from_sysclock.c b/src/libstddjb/tain_from_sysclock.c
new file mode 100644
index 0000000..468c248
--- /dev/null
+++ b/src/libstddjb/tain_from_sysclock.c
@@ -0,0 +1,10 @@
+/* ISC license. */
+
+#include <skalibs/tai.h>
+
+int tain_from_sysclock (tain_t *a, tain_t const *u)
+{
+  if (!tai_from_sysclock(&a->sec, u->sec.x)) return 0 ;
+  a->nano = u->nano ;
+  return 1 ;
+}
diff --git a/src/libstddjb/tain_from_timespec.c b/src/libstddjb/tain_from_timespec.c
index e862f46..e471b95 100644
--- a/src/libstddjb/tain_from_timespec.c
+++ b/src/libstddjb/tain_from_timespec.c
@@ -1,13 +1,11 @@
 /* ISC license. */
 
-#include <sys/types.h>
 #include <time.h>
-#include <errno.h>
 #include <skalibs/tai.h>
 
-int tain_from_timespec (tain_t *a, struct timespec const *ts)
+int tain_from_timespec (tain_t *t, struct timespec const *ts)
 {
-  if (!tai_from_timespec(tain_secp(a), ts)) return 0 ;
-  a->nano = ts->tv_nsec ;
+  if (!tai_from_time(&t->sec, ts->tv_sec)) return 0 ;
+  t->nano = ts->tv_nsec ;
   return 1 ;
 }
diff --git a/src/libstddjb/tain_from_timespec_sysclock.c b/src/libstddjb/tain_from_timespec_sysclock.c
new file mode 100644
index 0000000..b79cda8
--- /dev/null
+++ b/src/libstddjb/tain_from_timespec_sysclock.c
@@ -0,0 +1,11 @@
+/* ISC license. */
+
+#include <time.h>
+#include <skalibs/tai.h>
+
+int tain_from_timespec_sysclock (tain_t *t, struct timespec const *ts)
+{
+  if (!tai_from_time_sysclock(&t->sec, ts->tv_sec)) return 0 ;
+  t->nano = ts->tv_nsec ;
+  return 1 ;
+}
diff --git a/src/libstddjb/tain_from_timeval.c b/src/libstddjb/tain_from_timeval.c
index 9c74d13..0536070 100644
--- a/src/libstddjb/tain_from_timeval.c
+++ b/src/libstddjb/tain_from_timeval.c
@@ -1,12 +1,11 @@
 /* ISC license. */
 
 #include <sys/time.h>
-#include <errno.h>
 #include <skalibs/tai.h>
 
-int tain_from_timeval (tain_t *a, struct timeval const *tv)
+int tain_from_timeval (tain_t *t, struct timeval const *tv)
 {
-  if (!tai_from_timeval(tain_secp(a), tv)) return 0 ;
-  a->nano = 1000 * tv->tv_usec ;
+  if (!tai_from_time(&t->sec, tv->tv_sec)) return 0 ;
+  t->nano = 1000 * tv->tv_usec ;
   return 1 ;
 }
diff --git a/src/libstddjb/tain_from_timeval_sysclock.c b/src/libstddjb/tain_from_timeval_sysclock.c
new file mode 100644
index 0000000..625c4cd
--- /dev/null
+++ b/src/libstddjb/tain_from_timeval_sysclock.c
@@ -0,0 +1,11 @@
+/* ISC license. */
+
+#include <sys/time.h>
+#include <skalibs/tai.h>
+
+int tain_from_timeval_sysclock (tain_t *t, struct timeval const *tv)
+{
+  if (!tai_from_time_sysclock(&t->sec, tv->tv_sec)) return 0 ;
+  t->nano = 1000 * tv->tv_usec ;
+  return 1 ;
+}
diff --git a/src/libstddjb/tain_half.c b/src/libstddjb/tain_half.c
index a95072e..4b8f404 100644
--- a/src/libstddjb/tain_half.c
+++ b/src/libstddjb/tain_half.c
@@ -4,7 +4,7 @@
 
 void tain_half (tain_t *t, tain_t const *u)
 {
-  t->nano = u->nano>>1 ;
-  if (tai_sec(&u->sec) & 1) t->nano += 500000000U ;
-  tai_u64(&t->sec, tai_sec(&u->sec)>>1) ;
+  t->nano = u->nano >> 1 ;
+  if (u->sec.x & 1) t->nano += 500000000U ;
+  t->sec.x = u->sec.x >> 1 ;
 }
diff --git a/src/libstddjb/tain_relative_from_timespec.c b/src/libstddjb/tain_relative_from_timespec.c
index e25793e..5f492ff 100644
--- a/src/libstddjb/tain_relative_from_timespec.c
+++ b/src/libstddjb/tain_relative_from_timespec.c
@@ -1,13 +1,11 @@
 /* ISC license. */
 
-#include <sys/types.h>
 #include <time.h>
-#include <errno.h>
 #include <skalibs/tai.h>
 
 int tain_relative_from_timespec (tain_t *a, struct timespec const *ts)
 {
-  if (!tai_relative_from_timespec(tain_secp(a), ts)) return 0 ;
+  tai_relative_from_time(&a->sec, ts->tv_sec) ;
   a->nano = ts->tv_nsec ;
   return 1 ;
 }
diff --git a/src/libstddjb/tain_relative_from_timeval.c b/src/libstddjb/tain_relative_from_timeval.c
index 83aa1c3..eafb57a 100644
--- a/src/libstddjb/tain_relative_from_timeval.c
+++ b/src/libstddjb/tain_relative_from_timeval.c
@@ -1,12 +1,11 @@
 /* ISC license. */
 
 #include <sys/time.h>
-#include <errno.h>
 #include <skalibs/tai.h>
 
 int tain_relative_from_timeval (tain_t *a, struct timeval const *tv)
 {
-  if (!tai_relative_from_timeval(tain_secp(a), tv)) return 0 ;
+  tai_relative_from_time(&a->sec, tv->tv_sec) ;
   a->nano = 1000 * tv->tv_usec ;
   return 1 ;
 }
diff --git a/src/libstddjb/tain_sub.c b/src/libstddjb/tain_sub.c
index f7dd4eb..2921aa6 100644
--- a/src/libstddjb/tain_sub.c
+++ b/src/libstddjb/tain_sub.c
@@ -2,14 +2,16 @@
 
 #include <skalibs/tai.h>
 
-void tain_sub (tain_t *t, tain_t const *u, tain_t const *v)
+int tain_sub (tain_t *t, tain_t const *u, tain_t const *v)
 {
-  tain_t uu = *u ;
-  tai_sub(&t->sec, &uu.sec, &v->sec) ;
-  t->nano = uu.nano - v->nano ;
-  if (t->nano > uu.nano)
+  tain_t tt = *u ;
+  if (!tai_sub(&tt.sec, &u->sec, &v->sec)) return 0 ;
+  tt.nano = u->nano - v->nano ;
+  if (tt.nano > u->nano)
   {
-    t->nano += 1000000000U ;
-    tai_u64(&t->sec, tai_sec(&t->sec)-1) ;
+    if (!tai_u64(&tt.sec, tai_sec(&tt.sec) - 1)) return 0 ;
+    tt.nano += 1000000000U ;
   }
+  *t = tt ;
+  return 1 ;
 }
diff --git a/src/libstddjb/tain_sysclock.c b/src/libstddjb/tain_sysclock.c
index 7f54db6..3b98eb1 100644
--- a/src/libstddjb/tain_sysclock.c
+++ b/src/libstddjb/tain_sysclock.c
@@ -6,7 +6,5 @@ int tain_sysclock (tain_t *a)
 {
   tain_t aa ;
   if (!sysclock_get(&aa)) return 0 ;
-  if (!tai_from_sysclock(&a->sec, aa.sec.x)) return 0 ;
-  a->nano = aa.nano ;
-  return 1 ;
+  return tain_from_sysclock(a, &aa) ;
 }
diff --git a/src/libstddjb/tain_ulong.c b/src/libstddjb/tain_ulong.c
index 2ba730a..8eb890b 100644
--- a/src/libstddjb/tain_ulong.c
+++ b/src/libstddjb/tain_ulong.c
@@ -2,8 +2,9 @@
 
 #include <skalibs/tai.h>
 
-void tain_ulong (tain_t *t, unsigned long s)
+int tain_ulong (tain_t *t, unsigned long s)
 {
-  tai_u64(&t->sec, s) ;
+  if (!tai_u64(&t->sec, s)) return 0 ;
   t->nano = 0 ;
+  return 1 ;
 }
diff --git a/src/libstddjb/time_from_tai.c b/src/libstddjb/time_from_tai.c
new file mode 100644
index 0000000..e03b8c5
--- /dev/null
+++ b/src/libstddjb/time_from_tai.c
@@ -0,0 +1,17 @@
+ /* ISC license. */
+
+#include <sys/types.h>
+#include <errno.h>
+#include <skalibs/sysdeps.h>
+#include <skalibs/tai.h>
+
+int time_from_tai (time_t *u, tai_t const *t)
+{
+  register uint64 uu = t->x - TAI_MAGIC ;
+#if SKALIBS_SIZEOFTIME < 8
+  if ((uu >> 32) && (uu >> 32) != 0xffffffffUL)
+    return (errno = EOVERFLOW, 0) ;
+#endif
+  *u = (time_t)uu ;
+  return 1 ;
+}
diff --git a/src/libstddjb/time_from_tai_relative.c b/src/libstddjb/time_from_tai_relative.c
new file mode 100644
index 0000000..f5233fe
--- /dev/null
+++ b/src/libstddjb/time_from_tai_relative.c
@@ -0,0 +1,16 @@
+ /* ISC license. */
+
+#include <sys/types.h>
+#include <errno.h>
+#include <skalibs/sysdeps.h>
+#include <skalibs/tai.h>
+
+int time_from_tai_relative (time_t *u, tai_t const *t)
+{
+#if SKALIBS_SIZEOFTIME < 8
+  if ((t->x >> 32) && (t->x >> 32) != 0xffffffffUL)
+    return (errno = EOVERFLOW, 0) ;
+#endif
+  *u = (time_t)t->x ;
+  return 1 ;
+}
diff --git a/src/libstddjb/time_sysclock_from_tai.c b/src/libstddjb/time_sysclock_from_tai.c
new file mode 100644
index 0000000..c16dbe2
--- /dev/null
+++ b/src/libstddjb/time_sysclock_from_tai.c
@@ -0,0 +1,20 @@
+/* ISC license. */
+
+#include <sys/types.h>
+#include <errno.h>
+#include <skalibs/sysdeps.h>
+#include <skalibs/uint64.h>
+#include <skalibs/tai.h>
+
+int time_sysclock_from_tai (time_t *u, tai_t const *t)
+{
+  uint64 uu ;
+  if (!sysclock_from_tai(&uu, t)) return 0 ;
+  uu -= TAI_MAGIC ;
+#if SKALIBS_SIZEOFTIME < 8
+  if ((uu >> 32) && (uu >> 32) != 0xffffffffUL)
+    return (errno = EOVERFLOW, 0) ;
+#endif
+  *u = (time_t)uu ;
+  return 1 ;
+}
diff --git a/src/libstddjb/timespec_from_tai.c b/src/libstddjb/timespec_from_tai.c
deleted file mode 100644
index 7bb84d4..0000000
--- a/src/libstddjb/timespec_from_tai.c
+++ /dev/null
@@ -1,12 +0,0 @@
-/* ISC license. */
-
-#include <sys/types.h>
-#include <time.h>
-#include <skalibs/tai.h>
-
-int timespec_from_tai (struct timespec *ts, tai_t const *t)
-{
-  tai_t trel ;
-  tai_u64(&trel, tai_sec(t) - TAI_MAGIC) ;
-  return timespec_from_tai_relative(ts, &trel) ;
-}
diff --git a/src/libstddjb/timespec_from_tai_relative.c b/src/libstddjb/timespec_from_tai_relative.c
deleted file mode 100644
index 42f2e95..0000000
--- a/src/libstddjb/timespec_from_tai_relative.c
+++ /dev/null
@@ -1,19 +0,0 @@
-/* ISC license. */
-
-#include <sys/types.h>
-#include <time.h>
-#include <errno.h>
-#include <skalibs/sysdeps.h>
-#include <skalibs/uint64.h>
-#include <skalibs/tai.h>
-
-int timespec_from_tai_relative (struct timespec *ts, tai_t const *t)
-{
-  if (tai_sec(t) >= (uint64)1 << 63) return (errno = EINVAL, 0) ;
-#if SKALIBS_SIZEOFTIME < 8
-  if (tai_sec(t) > 0xffffffffU) return (errno = ERANGE, 0) ;
-#endif
-  ts->tv_sec = (time_t)tai_sec(t) ;
-  ts->tv_nsec = 0 ;
-  return 1 ;
-}
diff --git a/src/libstddjb/timespec_from_tain.c b/src/libstddjb/timespec_from_tain.c
index 5eb6e30..cd63547 100644
--- a/src/libstddjb/timespec_from_tain.c
+++ b/src/libstddjb/timespec_from_tain.c
@@ -1,14 +1,11 @@
 /* ISC license. */
 
-#include <sys/types.h>
 #include <time.h>
 #include <skalibs/tai.h>
 
-int timespec_from_tain (struct timespec *ts, tain_t const *a)
+int timespec_from_tain (struct timespec *ts, tain_t const *t)
 {
-  struct timespec tmp ;
-  if (!timespec_from_tai(&tmp, tain_secp(a))) return 0 ;
-  ts->tv_sec = tmp.tv_sec ;
-  ts->tv_nsec = a->nano ;
+  if (!time_from_tai(&ts->tv_sec, &t->sec)) return 0 ;
+  ts->tv_nsec = t->nano ;
   return 1 ;
 }
diff --git a/src/libstddjb/timespec_from_tain_relative.c b/src/libstddjb/timespec_from_tain_relative.c
index 32e7993..8ef34e8 100644
--- a/src/libstddjb/timespec_from_tain_relative.c
+++ b/src/libstddjb/timespec_from_tain_relative.c
@@ -1,14 +1,11 @@
 /* ISC license. */
 
-#include <sys/types.h>
 #include <time.h>
 #include <skalibs/tai.h>
 
-int timespec_from_tain_relative (struct timespec *ts, tain_t const *a)
+int timespec_from_tain_relative (struct timespec *ts, tain_t const *t)
 {
-  struct timespec tmp ;
-  if (!timespec_from_tai_relative(&tmp, tain_secp(a))) return 0 ;
-  ts->tv_sec = tmp.tv_sec ;
-  ts->tv_nsec = a->nano ;
+  if (!time_from_tai_relative(&ts->tv_sec, &t->sec)) return 0 ;
+  ts->tv_nsec = t->nano ;
   return 1 ;
 }
diff --git a/src/libstddjb/timespec_sysclock_from_tain.c b/src/libstddjb/timespec_sysclock_from_tain.c
new file mode 100644
index 0000000..5544511
--- /dev/null
+++ b/src/libstddjb/timespec_sysclock_from_tain.c
@@ -0,0 +1,11 @@
+/* ISC license. */
+
+#include <time.h>
+#include <skalibs/tai.h>
+
+int timespec_sysclock_from_tain (struct timespec *ts, tain_t const *t)
+{
+  if (!time_sysclock_from_tai(&ts->tv_sec, &t->sec)) return 0 ;
+  ts->tv_nsec = t->nano ;
+  return 1 ;
+}
diff --git a/src/libstddjb/timeval_from_tai.c b/src/libstddjb/timeval_from_tai.c
deleted file mode 100644
index d0c4777..0000000
--- a/src/libstddjb/timeval_from_tai.c
+++ /dev/null
@@ -1,11 +0,0 @@
-/* ISC license. */
-
-#include <sys/time.h>
-#include <skalibs/tai.h>
-
-int timeval_from_tai (struct timeval *tv, tai_t const *t)
-{
-  tai_t trel ;
-  tai_u64(&trel, tai_sec(t) - TAI_MAGIC) ;
-  return timeval_from_tai_relative(tv, &trel) ;
-}
diff --git a/src/libstddjb/timeval_from_tai_relative.c b/src/libstddjb/timeval_from_tai_relative.c
deleted file mode 100644
index 94bd3f7..0000000
--- a/src/libstddjb/timeval_from_tai_relative.c
+++ /dev/null
@@ -1,18 +0,0 @@
-/* ISC license. */
-
-#include <sys/time.h>
-#include <errno.h>
-#include <skalibs/sysdeps.h>
-#include <skalibs/uint64.h>
-#include <skalibs/tai.h>
-
-int timeval_from_tai_relative (struct timeval *tv, tai_t const *t)
-{
-  if (tai_sec(t) >= (uint64)1 << 63) return (errno = EINVAL, 0) ;
-#if SKALIBS_SIZEOFTIME < 8
-  if (tai_sec(t) > 0xffffffffU) return (errno = ERANGE, 0) ;
-#endif
-  tv->tv_sec = (time_t)tai_sec(t) ;
-  tv->tv_usec = 0 ;
-  return 1 ;
-}
diff --git a/src/libstddjb/timeval_from_tain.c b/src/libstddjb/timeval_from_tain.c
index c780af7..2b4d577 100644
--- a/src/libstddjb/timeval_from_tain.c
+++ b/src/libstddjb/timeval_from_tain.c
@@ -3,11 +3,9 @@
 #include <sys/time.h>
 #include <skalibs/tai.h>
 
-int timeval_from_tain (struct timeval *tv, tain_t const *a)
+int timeval_from_tain (struct timeval *tv, tain_t const *t)
 {
-  struct timeval tmp ;
-  if (!timeval_from_tai(&tmp, tain_secp(a))) return 0 ;
-  tv->tv_sec = tmp.tv_sec ;
-  tv->tv_usec = a->nano / 1000 ;
+  if (!time_from_tai(&tv->tv_sec, &t->sec)) return 0 ;
+  tv->tv_usec = (t->nano + 500) / 1000 ;
   return 1 ;
 }
diff --git a/src/libstddjb/timeval_from_tain_relative.c b/src/libstddjb/timeval_from_tain_relative.c
index 624293c..de775fd 100644
--- a/src/libstddjb/timeval_from_tain_relative.c
+++ b/src/libstddjb/timeval_from_tain_relative.c
@@ -3,11 +3,9 @@
 #include <sys/time.h>
 #include <skalibs/tai.h>
 
-int timeval_from_tain_relative (struct timeval *tv, tain_t const *a)
+int timeval_from_tain_relative (struct timeval *tv, tain_t const *t)
 {
-  struct timeval tmp ;
-  if (!timeval_from_tai_relative(&tmp, tain_secp(a))) return 0 ;
-  tv->tv_sec = tmp.tv_sec ;
-  tv->tv_usec = a->nano / 1000 ;
+  if (!time_from_tai_relative(&tv->tv_sec, &t->sec)) return 0 ;
+  tv->tv_usec = (t->nano + 500) / 1000 ;
   return 1 ;
 }
diff --git a/src/libstddjb/timeval_sysclock_from_tain.c b/src/libstddjb/timeval_sysclock_from_tain.c
new file mode 100644
index 0000000..c41b133
--- /dev/null
+++ b/src/libstddjb/timeval_sysclock_from_tain.c
@@ -0,0 +1,11 @@
+/* ISC license. */
+
+#include <sys/time.h>
+#include <skalibs/tai.h>
+
+int timeval_sysclock_from_tain (struct timeval *tv, tain_t const *t)
+{
+  if (!time_sysclock_from_tai(&tv->tv_sec, &t->sec)) return 0 ;
+  tv->tv_usec = (t->nano + 500) / 1000 ;
+  return 1 ;
+}
diff --git a/src/libstddjb/utc_from_tai.c b/src/libstddjb/utc_from_tai.c
index f4d247e..80d2763 100644
--- a/src/libstddjb/utc_from_tai.c
+++ b/src/libstddjb/utc_from_tai.c
@@ -1,5 +1,6 @@
 /* ISC license. */
 
+#include <errno.h>
 #include <skalibs/uint64.h>
 #include <skalibs/tai.h>
 #include <skalibs/djbtime.h>
@@ -8,6 +9,7 @@
 int utc_from_tai (uint64 *u, tai_t const *t)
 {
   uint64 tt = t->x - 10 ;
+  if (t->x < 10U) return (errno = EINVAL, 0) ;
   if (leapsecs_sub(&tt) < 0) return 0 ;
   *u = tt ;
   return 1 ;