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// Copyright (c) 2012-2016 Eli Janssen
// Use of this source code is governed by an MIT-style
// license that can be found in the LICENSE file.
package main
import (
"bufio"
"bytes"
"flag"
"fmt"
"go/format"
"html/template"
"log"
"net/http"
"os"
"path"
"strconv"
"strings"
"time"
)
const tplText = `
// Copyright (c) 2012-2016 Eli Janssen
// Use of this source code is governed by an MIT-style
// license that can be found in the LICENSE file.
// THIS FILE IS AUTOGENERATED. DO NOT EDIT!
package {{.Pkg}}
// https://hpiers.obspm.fr/iers/bul/bulc/Leap_Second.dat
// http://www.stjarnhimlen.se/comp/time.html
var tia64nDifferences = []struct {
// TAI time
ttime int64
// TAI-UTC offset
offset int64
// unix UTC time
utime int64
}{
{{- range .Entries}}
{{"{"}}0x{{.Tts|printf "%x"}}, {{.Drift}}, {{.Ts}}{{"}"}}, // {{.TsD}}
{{- end}}
}
var tia64nSize = len(tia64nDifferences)
`
type srcFile struct {
Pkg string
Entries []entry
}
type entry struct {
Ts int64
TsD string
Drift int64
Tts int64
}
const datURL = "https://hpiers.obspm.fr/iers/bul/bulc/Leap_Second.dat"
func main() {
var output, pkg string
flag.StringVar(&output, "output", "", "output file")
flag.StringVar(&pkg, "pkg", "", "package name")
flag.Parse()
if output == "" {
log.Fatal("Output option is required")
}
if pkg == "" {
log.Fatal("Package option is required")
}
var br *bufio.Reader
resp, err := http.Get(datURL)
if err != nil {
log.Fatalf("Error fetching '%s': %s", datURL, err)
}
defer resp.Body.Close()
br = bufio.NewReader(resp.Body)
fmt.Printf("Generating '%s' based on '%s'\n", path.Base(output), datURL)
t, err := template.New("fileTemplate").Parse(strings.TrimLeft(tplText, "\n"))
if err != nil {
log.Fatal(err)
}
entries := make([]entry, 0)
for {
line, err := br.ReadString('\n')
if err != nil {
break
}
line = strings.TrimSpace(line)
if line == "" || strings.HasPrefix(line, ";") || strings.HasPrefix(line, "#") {
continue
}
parts := strings.Fields(line)
// parse date of leap second
t, err := time.Parse("2-1-2006", strings.Join(parts[1:4], "-"))
if err != nil {
fmt.Println(err)
continue
}
if t.Before(time.Date(1972, 1, 1, 0, 0, 0, 0, time.UTC)) {
continue
}
// parse TAI-UTC(s)
s, err := strconv.ParseFloat(parts[4], 32)
if err != nil {
fmt.Println(err)
continue
}
// just truncate the float to int
unixT := t.Unix()
taiT := (2 << 61) + unixT + int64(s)
e := entry{unixT, t.Format(time.RFC3339), int64(s), taiT}
entries = append(entries, e)
}
bufr := &bytes.Buffer{}
srcfile := &srcFile{pkg, entries}
err = t.Execute(bufr, srcfile)
if err != nil {
log.Fatal(err)
}
outBytes, err := format.Source(bufr.Bytes())
if err != nil {
log.Fatal(err)
}
err = os.WriteFile(output, outBytes, 0644)
if err != nil {
log.Fatal(err)
}
}
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