141 lines
2.4 KiB
Groff
141 lines
2.4 KiB
Groff
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.TH taia 3
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.SH NAME
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taia \- manipulate times with 1-attosecond precision
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.SH SYNTAX
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.B #include <taia.h>
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double \fBtaia_approx\fP(&\fIt\fR);
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.br
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double \fBtaia_frac\fP(&\fIt\fR);
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.br
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void \fBtaia_tai\fP(&\fIt\fR,&\fIsec\fR);
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int \fBtaia_less\fP(&\fIa\fR,&\fIb\fR);
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.br
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void \fBtaia_add\fP(&\fIt\fR,&\fIa\fR,&\fIb\fR);
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.br
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void \fBtaia_sub\fP(&\fIt\fR,&\fIa\fR,&\fIb\fR);
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.br
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void \fBtaia_half\fP(&\fIt\fR,&\fIa\fR);
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unsigned int \fBtaia_fmtfrac\fP(\fIs\fR,&\fIt\fR);
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struct taia \fIt\fR;
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.br
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struct taia \fIa\fR;
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.br
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struct taia \fIb\fR;
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.br
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struct tai \fIsec\fR;
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.br
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char *\fIs\fR;
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.SH DESCRIPTION
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A
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.B struct taia
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stores an integer between 0 inclusive and 2^64x10^18 exclusive.
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The format of
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.B struct taia
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is designed to speed up common operations;
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applications should not look inside
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.B struct taia\fR.
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A
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.B struct taia
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variable is commonly used to store
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a TAI64NA label.
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Each TAI64NA label refers to one attosecond of real time;
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see
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.B http://pobox.com/~djb/proto/tai64.txt
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for more information.
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The integer in the
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.B struct taia
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is 10^18 times the second count,
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plus 10^9 times the nanosecond count,
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plus the attosecond count.
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A
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.B struct taia
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variable may also be used to store
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the numerical difference between two TAI64NA labels.
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.SH ARITHMETIC
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.B taia_approx
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returns a double-precision approximation to
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.IR t /10^18.
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The result of
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.B taia_approx
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is always nonnegative.
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.B taia_tai
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places into
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.I sec
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the integer part of
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.IR t /10^18.
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.B taia_frac
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returns a double-precision approximation to
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the fraction part of
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.IR t /10^18.
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The result of
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.B taia_frac
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is always nonnegative.
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.B taia_less
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returns 1 if
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.I a
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is smaller than
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.IR b ,
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0 otherwise.
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.B taia_add
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adds
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.I a
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and
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.I b
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modulo 2^64x10^18
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and puts the result into
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.IR t .
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The inputs and outputs may overlap.
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.B taia_sub
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subtracts
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.I b
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from
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.I a
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modulo 2^64x10^18
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and puts the result into
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.IR t .
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The inputs and outputs may overlap.
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.B taia_half
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divides
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.I a
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by 2, rounding down,
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and puts the result into
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.IR t .
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The input and output may overlap.
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.SH "FORMATTING"
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.B taia_fmtfrac
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prints the remainder of
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.IR t /10^18,
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padded to exactly 18 digits,
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into the character buffer
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.IR s ,
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without a terminating NUL.
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It returns 18, the number of characters written.
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.I s
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may be zero;
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then
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.B taia_fmtfrac
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returns 18 without printing anything.
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The macro
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.B TAIA_FMTFRAC
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is defined as 19;
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this is enough space for the output of
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.B taia_fmtfrac
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and a terminating NUL.
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.SH "SEE ALSO"
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taia_now(3),
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taia_pack(3),
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tai(3)
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