src/code/early-time.lisp

   1 ;;;; Time-related constants that are needed before unix.lisp / win32.lisp
   2 ;;;; can be built.
   3
   4 ;;;; This software is part of the SBCL system. See the README file for
   5 ;;;; more information.
   6 ;;;;
   7 ;;;; This software is derived from the CMU CL system, which was
   8 ;;;; written at Carnegie Mellon University and released into the
   9 ;;;; public domain. The software is in the public domain and is
  10 ;;;; provided with absolutely no warranty. See the COPYING and CREDITS
  11 ;;;; files for more information.
  12
  13 (in-package "SB-IMPL")
  14
  15 (defconstant internal-time-units-per-second
  16   #+64-bit 1000000 ; microseconds
  17   ;; 1 week in milliseconds is: (* 1000 60 60 24 7) = 604800000 which is
  18   ;; a 30-bit number, but there are only 29 bits in a positive fixnum.
  19   ;; It is left as an exercise to change the 32-bit code to use hundredths
  20   ;; instead of thousands of a second. The upside of so doing is that
  21   ;; GET-INTERNAL-REAL-TIME would be able to express more range without consing.
  22   ;; The downside is of course decreased resolution.
  23   #-64-bit 1000    ; milliseconds
  24   "The number of internal time units that fit into a second. See
  25 GET-INTERNAL-REAL-TIME and GET-INTERNAL-RUN-TIME.")
  26
  27 (defconstant unix-to-universal-time 2208988800)