tai64n.go

   1 /*
   2 goredo -- redo implementation on pure Go
   3 Copyright (C) 2020 Sergey Matveev <stargrave@stargrave.org>
   4
   5 This program is free software: you can redistribute it and/or modify
   6 it under the terms of the GNU General Public License as published by
   7 the Free Software Foundation, version 3 of the License.
   8
   9 This program is distributed in the hope that it will be useful,
  10 but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 GNU General Public License for more details.
  13
  14 You should have received a copy of the GNU General Public License
  15 along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16 */
  17
  18 package main
  19
  20 import (
  21         "bufio"
  22         "encoding/binary"
  23         "encoding/hex"
  24         "errors"
  25         "io"
  26         "strings"
  27         "time"
  28 )
  29
  30 const (
  31         TAI64NSize     = 12
  32         TAI64NBase     = 0x400000000000000a
  33         TAI64NLocalFmt = "2006-01-02 15:04:05.000000000"
  34 )
  35
  36 type TAI64N [TAI64NSize]byte
  37
  38 func tai64nNow(ts *TAI64N) {
  39         t := time.Now()
  40         binary.BigEndian.PutUint64(ts[:], uint64(TAI64NBase)+uint64(t.Unix()))
  41         binary.BigEndian.PutUint32(ts[8:], uint32(t.Nanosecond()))
  42 }
  43
  44 func tai64nLocal(dst io.StringWriter, src io.Reader) error {
  45         scanner := bufio.NewScanner(src)
  46         var err error
  47         var s string
  48         var sep int
  49         var ts []byte
  50         var secs int64
  51         var nano int64
  52         var t time.Time
  53         for {
  54                 if !scanner.Scan() {
  55                         if err = scanner.Err(); err != nil {
  56                                 return err
  57                         }
  58                         break
  59                 }
  60                 s = scanner.Text()
  61
  62                 if s[0] != '@' {
  63                         dst.WriteString(s + "\n")
  64                 }
  65                 sep = strings.IndexByte(s, byte(' '))
  66                 if sep == -1 {
  67                         dst.WriteString(s + "\n")
  68                 }
  69                 ts, err = hex.DecodeString(s[1:sep])
  70                 if err != nil {
  71                         return err
  72                 }
  73                 if len(ts) != TAI64NSize {
  74                         return errors.New("invalid ts length")
  75                 }
  76                 secs = int64(binary.BigEndian.Uint64(ts[:8]))
  77                 nano = int64(binary.BigEndian.Uint32(ts[8:]))
  78                 t = time.Unix(secs-TAI64NBase, nano)
  79                 dst.WriteString(t.Format(TAI64NLocalFmt) + s[sep:] + "\n")
  80         }
  81         return nil
  82 }