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61 lines
2.2 KiB
C
61 lines
2.2 KiB
C
#ifndef TAI_H
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#define TAI_H
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/* Times with 1 second precision */
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#include "uint64.h"
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/* A struct tai value is an integer between 0 inclusive and 2^64
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* exclusive. The format of struct tai is designed to speed up common
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* operations; applications should not look inside struct tai.
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*
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* A struct tai variable is commonly used to store a TAI64 label. Each
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* TAI64 label refers to one second of real time. TAI64 labels span a
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* range of hundreds of billions of years.
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*
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* A struct tai variable may also be used to store the numerical
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* difference between two TAI64 labels.
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* See http://cr.yp.to/libtai/tai64.html */
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typedef struct tai {
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uint64 x;
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} tai64;
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#define tai_unix(t,u) ((void) ((t)->x = 4611686018427387914ULL + (uint64) (u)))
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/* tai_now puts the current time into t. More precisely: tai_now puts
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* into t its best guess as to the TAI64 label for the 1-second interval
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* that contains the current time.
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*
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* This implementation of tai_now assumes that the time_t returned from
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* the time function represents the number of TAI seconds since
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* 1970-01-01 00:00:10 TAI. This matches the convention used by the
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* Olson tz library in ``right'' mode. */
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extern void tai_now(struct tai *);
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/* tai_approx returns a double-precision approximation to t. The result
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* of tai_approx is always nonnegative. */
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#define tai_approx(t) ((double) ((t)->x))
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/* tai_add adds a to b modulo 2^64 and puts the result into t. The
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* inputs and output may overlap. */
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extern void tai_add(struct tai *,const struct tai *,const struct tai *);
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/* tai_sub subtracts b from a modulo 2^64 and puts the result into t.
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* The inputs and output may overlap. */
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extern void tai_sub(struct tai *,const struct tai *,const struct tai *);
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/* tai_less returns 1 if a is less than b, 0 otherwise. */
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#define tai_less(t,u) ((t)->x < (u)->x)
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#define TAI_PACK 8
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/* tai_pack converts a TAI64 label from internal format in t to external
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* TAI64 format in buf. */
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extern void tai_pack(char *,const struct tai *);
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/* tai_unpack converts a TAI64 label from external TAI64 format in buf
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* to internal format in t. */
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extern void tai_unpack(const char *,struct tai *);
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extern void tai_uint(struct tai *,unsigned int);
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#endif
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