This changes the buildlink3.mk files to use an include guard for the
recursive include. The use of BUILDLINK_DEPTH, BUILDLINK_DEPENDS,
BUILDLINK_PACKAGES and BUILDLINK_ORDER is handled by a single new
variable BUILDLINK_TREE. Each buildlink3.mk file adds a pair of
enter/exit marker, which can be used to reconstruct the tree and
to determine first level includes. Avoiding := for large variables
(BUILDLINK_ORDER) speeds up parse time as += has linear complexity.
The include guard reduces system time by avoiding reading files over and
over again. For complex packages this reduces both %user and %sys time to
half of the former time.
and manipulating dates and times.
libtai supports two time scales: (1) TAI64, covering a few hundred
billion years with 1-second precision; (2) TAI64NA, covering the
same period with 1-attosecond precision. Both scales are defined
in terms of TAI, the current international real time standard.
libtai provides an internal format for TAI64, struct tai, designed
for fast time manipulations. The tai_pack() and tai_unpack() routines
convert between struct tai and a portable 8-byte TAI64 storage
format. libtai provides similar internal and external formats for
TAI64NA.
This version of libtai requires a UNIX system with gettimeofday().
It will be easy to port to other operating systems with compilers
supporting 64-bit arithmetic.
