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// Copyright (c) 2012-2015 Ugorji Nwoke. All rights reserved.
// Use of this source code is governed by a MIT license found in the LICENSE file.
package codec
import (
"fmt"
"reflect"
"time"
)
var (
timeDigits = [...]byte{'0', '1', '2', '3', '4', '5', '6', '7', '8', '9'}
timeExtEncFn = func(rv reflect.Value) (bs []byte, err error) {
defer panicToErr(&err)
bs = timeExt{}.WriteExt(rv.Interface())
return
}
timeExtDecFn = func(rv reflect.Value, bs []byte) (err error) {
defer panicToErr(&err)
timeExt{}.ReadExt(rv.Interface(), bs)
return
}
)
type timeExt struct{}
func (x timeExt) WriteExt(v interface{}) (bs []byte) {
switch v2 := v.(type) {
case time.Time:
bs = encodeTime(v2)
case *time.Time:
bs = encodeTime(*v2)
default:
panic(fmt.Errorf("unsupported format for time conversion: expecting time.Time; got %T", v2))
}
return
}
func (x timeExt) ReadExt(v interface{}, bs []byte) {
tt, err := decodeTime(bs)
if err != nil {
panic(err)
}
*(v.(*time.Time)) = tt
}
func (x timeExt) ConvertExt(v interface{}) interface{} {
return x.WriteExt(v)
}
func (x timeExt) UpdateExt(v interface{}, src interface{}) {
x.ReadExt(v, src.([]byte))
}
// EncodeTime encodes a time.Time as a []byte, including
// information on the instant in time and UTC offset.
//
// Format Description
//
// A timestamp is composed of 3 components:
//
// - secs: signed integer representing seconds since unix epoch
// - nsces: unsigned integer representing fractional seconds as a
// nanosecond offset within secs, in the range 0 <= nsecs < 1e9
// - tz: signed integer representing timezone offset in minutes east of UTC,
// and a dst (daylight savings time) flag
//
// When encoding a timestamp, the first byte is the descriptor, which
// defines which components are encoded and how many bytes are used to
// encode secs and nsecs components. *If secs/nsecs is 0 or tz is UTC, it
// is not encoded in the byte array explicitly*.
//
// Descriptor 8 bits are of the form `A B C DDD EE`:
// A: Is secs component encoded? 1 = true
// B: Is nsecs component encoded? 1 = true
// C: Is tz component encoded? 1 = true
// DDD: Number of extra bytes for secs (range 0-7).
// If A = 1, secs encoded in DDD+1 bytes.
// If A = 0, secs is not encoded, and is assumed to be 0.
// If A = 1, then we need at least 1 byte to encode secs.
// DDD says the number of extra bytes beyond that 1.
// E.g. if DDD=0, then secs is represented in 1 byte.
// if DDD=2, then secs is represented in 3 bytes.
// EE: Number of extra bytes for nsecs (range 0-3).
// If B = 1, nsecs encoded in EE+1 bytes (similar to secs/DDD above)
//
// Following the descriptor bytes, subsequent bytes are:
//
// secs component encoded in `DDD + 1` bytes (if A == 1)
// nsecs component encoded in `EE + 1` bytes (if B == 1)
// tz component encoded in 2 bytes (if C == 1)
//
// secs and nsecs components are integers encoded in a BigEndian
// 2-complement encoding format.
//
// tz component is encoded as 2 bytes (16 bits). Most significant bit 15 to
// Least significant bit 0 are described below:
//
// Timezone offset has a range of -12:00 to +14:00 (ie -720 to +840 minutes).
// Bit 15 = have\_dst: set to 1 if we set the dst flag.
// Bit 14 = dst\_on: set to 1 if dst is in effect at the time, or 0 if not.
// Bits 13..0 = timezone offset in minutes. It is a signed integer in Big Endian format.
//
func encodeTime(t time.Time) []byte {
//t := rv.Interface().(time.Time)
tsecs, tnsecs := t.Unix(), t.Nanosecond()
var (
bd byte
btmp [8]byte
bs [16]byte
i int = 1
)
l := t.Location()
if l == time.UTC {
l = nil
}
if tsecs != 0 {
bd = bd | 0x80
bigen.PutUint64(btmp[:], uint64(tsecs))
f := pruneSignExt(btmp[:], tsecs >= 0)
bd = bd | (byte(7-f) << 2)
copy(bs[i:], btmp[f:])
i = i + (8 - f)
}
if tnsecs != 0 {
bd = bd | 0x40
bigen.PutUint32(btmp[:4], uint32(tnsecs))
f := pruneSignExt(btmp[:4], true)
bd = bd | byte(3-f)
copy(bs[i:], btmp[f:4])
i = i + (4 - f)
}
if l != nil {
bd = bd | 0x20
// Note that Go Libs do not give access to dst flag.
_, zoneOffset := t.Zone()
//zoneName, zoneOffset := t.Zone()
zoneOffset /= 60
z := uint16(zoneOffset)
bigen.PutUint16(btmp[:2], z)
// clear dst flags
bs[i] = btmp[0] & 0x3f
bs[i+1] = btmp[1]
i = i + 2
}
bs[0] = bd
return bs[0:i]
}
// DecodeTime decodes a []byte into a time.Time.
func decodeTime(bs []byte) (tt time.Time, err error) {
bd := bs[0]
var (
tsec int64
tnsec uint32
tz uint16
i byte = 1
i2 byte
n byte
)
if bd&(1<<7) != 0 {
var btmp [8]byte
n = ((bd >> 2) & 0x7) + 1
i2 = i + n
copy(btmp[8-n:], bs[i:i2])
//if first bit of bs[i] is set, then fill btmp[0..8-n] with 0xff (ie sign extend it)
if bs[i]&(1<<7) != 0 {
copy(btmp[0:8-n], bsAll0xff)
//for j,k := byte(0), 8-n; j < k; j++ { btmp[j] = 0xff }
}
i = i2
tsec = int64(bigen.Uint64(btmp[:]))
}
if bd&(1<<6) != 0 {
var btmp [4]byte
n = (bd & 0x3) + 1
i2 = i + n
copy(btmp[4-n:], bs[i:i2])
i = i2
tnsec = bigen.Uint32(btmp[:])
}
if bd&(1<<5) == 0 {
tt = time.Unix(tsec, int64(tnsec)).UTC()
return
}
// In stdlib time.Parse, when a date is parsed without a zone name, it uses "" as zone name.
// However, we need name here, so it can be shown when time is printed.
// Zone name is in form: UTC-08:00.
// Note that Go Libs do not give access to dst flag, so we ignore dst bits
i2 = i + 2
tz = bigen.Uint16(bs[i:i2])
i = i2
// sign extend sign bit into top 2 MSB (which were dst bits):
if tz&(1<<13) == 0 { // positive
tz = tz & 0x3fff //clear 2 MSBs: dst bits
} else { // negative
tz = tz | 0xc000 //set 2 MSBs: dst bits
//tzname[3] = '-' (TODO: verify. this works here)
}
tzint := int16(tz)
if tzint == 0 {
tt = time.Unix(tsec, int64(tnsec)).UTC()
} else {
// For Go Time, do not use a descriptive timezone.
// It's unnecessary, and makes it harder to do a reflect.DeepEqual.
// The Offset already tells what the offset should be, if not on UTC and unknown zone name.
// var zoneName = timeLocUTCName(tzint)
tt = time.Unix(tsec, int64(tnsec)).In(time.FixedZone("", int(tzint)*60))
}
return
}
func timeLocUTCName(tzint int16) string {
if tzint == 0 {
return "UTC"
}
var tzname = []byte("UTC+00:00")
//tzname := fmt.Sprintf("UTC%s%02d:%02d", tzsign, tz/60, tz%60) //perf issue using Sprintf. inline below.
//tzhr, tzmin := tz/60, tz%60 //faster if u convert to int first
var tzhr, tzmin int16
if tzint < 0 {
tzname[3] = '-' // (TODO: verify. this works here)
tzhr, tzmin = -tzint/60, (-tzint)%60
} else {
tzhr, tzmin = tzint/60, tzint%60
}
tzname[4] = timeDigits[tzhr/10]
tzname[5] = timeDigits[tzhr%10]
tzname[7] = timeDigits[tzmin/10]
tzname[8] = timeDigits[tzmin%10]
return string(tzname)
//return time.FixedZone(string(tzname), int(tzint)*60)
}
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