645b5f8724
in addition to the pages, there's also changes to the mkfile to generate the index for the new section.
75 lines
1.5 KiB
Text
75 lines
1.5 KiB
Text
.TH SECONDS 9
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.SH NAME
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seconds, ticks, fastticks, HZ, MS2HZ, MS2TK, TK2MS, TK2SEC \- kernel times and time conversions
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.SH SYNOPSIS
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.ta \w'\fL#define 'u
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.B
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long seconds(void)
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.PP
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.B
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vlong fastticks(uvlong *hz)
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.PP
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.EX
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#define HZ ...
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#define MS2HZ (1000/HZ)
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#define TK2SEC(t) ((t)/HZ)
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#define TK2MS(t) ((t)*(1000/HZ))
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.EE
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.SH DESCRIPTION
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.I Seconds
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returns the system's idea of the current time as the number of seconds
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since the start of the epoch
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(00:00:00 GMT, January 1, 1970).
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.PP
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The
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.B ticks
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field of the
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.B Mach
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structure returns the number of system-dependent clock ticks on the
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given processor since system boot.
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On a multiprocessor,
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.B MACHP(0)
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is sometimes used to provide a reference time, since the tick value
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might vary slightly across processors.
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.PP
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.I Fastticks
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returns the number of ticks since boot as measured by the
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fastest clock provided by the platform.
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The frequency of the clock, in ticks per second,
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is returned through
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.IR hz ,
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unless it is nil.
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.PP
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The system clock frequencies are platform-dependent.
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Several symbolic constants and macro functions are defined by
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the file
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.B mem.h
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to convert between different time units:
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.TF TK2SEC(t)
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.PD
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.TP
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.B HZ
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The number of clock ticks per second.
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.TP
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.B MS2HZ
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Milliseconds per clock tick.
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.TP
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.BI TK2SEC( t )
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Convert
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.I t
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clock ticks to seconds (truncating not rounding).
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.TP
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.BI TK2MS( t )
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Convert
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.I t
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clock ticks to milliseconds.
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.SH SOURCE
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.B /sys/src/9/*/mem.h
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.br
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.B /sys/src/9/*/clock.c
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.br
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.B /sys/src/9/*/devarch.c
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.br
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.B /sys/src/9/*/timer.c
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.br
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.B /sys/src/9/port/tod.c
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