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Diffstat (limited to 'doc/lispref/os.texi')
| -rw-r--r-- | doc/lispref/os.texi | 48 |
1 files changed, 22 insertions, 26 deletions
diff --git a/doc/lispref/os.texi b/doc/lispref/os.texi index e604d92e690..6431ac8bead 100644 --- a/doc/lispref/os.texi +++ b/doc/lispref/os.texi @@ -1166,7 +1166,9 @@ The value may be a floating point number. zone. @cindex epoch - Most of these functions represent time as a list of either three + Most of these functions represent time as a list of either four +integers, @code{(@var{sec-high} @var{sec-low} @var{microsec} +@var{picosec})}, or of three integers, @code{(@var{sec-high} @var{sec-low} @var{microsec})}, or of two integers, @code{(@var{sec-high} @var{sec-low})}. The integers @var{sec-high} and @var{sec-low} give the high and low bits of an @@ -1181,12 +1183,15 @@ is the number of seconds from the @dfn{epoch} (0:00 January 1, 1970 UTC) to the specified time. The third list element @var{microsec}, if present, gives the number of microseconds from the start of that second to the specified time. +Similarly, the fourth list element @var{picosec}, if present, gives +the number of picoseconds from the start of that microsecond to the +specified time. The return value of @code{current-time} represents time using three -integers, while the timestamps in the return value of -@code{file-attributes} use two integers (@pxref{Definition of +integers, as do the timestamps in the return value of +@code{file-attributes} (@pxref{Definition of file-attributes}). In function arguments, e.g.@: the @var{time-value} -argument to @code{current-time-string}, both two- and three-integer +argument to @code{current-time-string}, two-, three-, and four-integer lists are accepted. You can convert times from the list representation into standard human-readable strings using @code{current-time}, or to other forms using the @code{decode-time} @@ -1216,9 +1221,12 @@ The argument @var{time-value}, if given, specifies a time to format @end defun @defun current-time -This function returns the current time, represented as a list of three -integers @code{(@var{sec-high} @var{sec-low} @var{microsec})}. On -systems with only one-second time resolutions, @var{microsec} is 0. +This function returns the current time, represented as a list of four +integers @code{(@var{sec-high} @var{sec-low} @var{microsec} @var{picosec})}. +These integers have trailing zeros on systems that return time with +lower resolutions. On all current machines @var{picosec} is a +multiple of 1000, but this may change as higher-resolution clocks +become available. @end defun @defun float-time &optional time-value @@ -1259,7 +1267,7 @@ time zone. @node Time Conversion @section Time Conversion - These functions convert time values (lists of two or three integers, + These functions convert time values (lists of two to four integers, as explained in the previous section) into calendrical information and vice versa. @@ -1410,8 +1418,6 @@ This stands for a newline. This stands for the nanoseconds (000000000-999999999). To ask for fewer digits, use @samp{%3N} for milliseconds, @samp{%6N} for microseconds, etc. Any excess digits are discarded, without rounding. -Currently Emacs time stamps are at best microsecond resolution so the -last three digits generated by plain @samp{%N} are always zero. @item %p This stands for @samp{AM} or @samp{PM}, as appropriate. @item %r @@ -1563,18 +1569,9 @@ When called interactively, it prints the uptime in the echo area. @defun get-internal-run-time This function returns the processor run time used by Emacs as a list -of three integers: @code{(@var{high} @var{low} @var{microsec})}. The -integers @var{high} and @var{low} combine to give the number of -seconds, which is -@ifnottex -@var{high} * 2**16 + @var{low}. -@end ifnottex -@tex -$high*2^{16}+low$. -@end tex - -The third element, @var{microsec}, gives the microseconds (or 0 for -systems that return time with the resolution of only one second). +of four integers: @code{(@var{high} @var{low} @var{microsec} +@var{picosec})}, using the same format as @code{current-time} +(@pxref{Time of Day}). Note that the time returned by this function excludes the time Emacs was not using the processor, and if the Emacs process has several @@ -1817,10 +1814,9 @@ set up to repeat will subsequently run another time, one by one. @defun current-idle-time If Emacs is idle, this function returns the length of time Emacs has -been idle, as a list of three integers: @code{(@var{sec-high} -@var{sec-low} @var{microsec})}, where @var{high} and @var{low} are the -high and low bits for the number of seconds and @var{microsec} is the -additional number of microseconds (@pxref{Time of Day}). +been idle, as a list of four integers: @code{(@var{sec-high} +@var{sec-low} @var{microsec} @var{picosec})}, using the same format as +@code{current-time} (@pxref{Time of Day}). When Emacs is not idle, @code{current-idle-time} returns @code{nil}. This is a convenient way to test whether Emacs is idle. |