mirror of https://bitbucket.org/ausocean/av.git
97 lines
2.2 KiB
Go
97 lines
2.2 KiB
Go
/*
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NAME
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op.go
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DESCRIPTION
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op.go provides functionality for editing and reading bytes slices
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directly in order to insert/read timestamp and gps data in psi.
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AUTHOR
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Saxon Milton <saxon@ausocean.org>
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LICENSE
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op.go is Copyright (C) 2018 the Australian Ocean Lab (AusOcean)
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It is free software: you can redistribute it and/or modify them
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under the terms of the GNU General Public License as published by the
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Free Software Foundation, either version 3 of the License, or (at your
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option) any later version.
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It is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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You should have received a copy of the GNU General Public License
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along with revid in gpl.txt. If not, see http://www.gnu.org/licenses.
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*/
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package psi
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import (
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"encoding/binary"
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"errors"
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)
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func TimeBytes(time uint64) (s []byte) {
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s = make([]byte, timeDataSize)
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binary.BigEndian.PutUint64(s[:], time)
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return s
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}
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func chkTime(d []byte) error {
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if d[timeTagIndx] != timeDescTag {
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return errors.New("PSI does not contain a time descriptor, cannot update")
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}
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return nil
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}
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func chkGps(d []byte) error {
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if d[gpsTagIndx] != gpsDescTag {
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return errors.New("PSI does not contain a gps descriptor, cannot update")
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}
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return nil
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}
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// Updatetime
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func UpdateTime(d []byte, t int) error {
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err := chkTime(d)
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if err != nil {
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return err
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}
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ts := TimeBytes(uint64(t))
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for i := range d[timeDataIndx : timeDataIndx+timeDataSize] {
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d[i+timeDataIndx] = ts[i]
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}
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return nil
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}
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func TimeOf(d []byte) (t uint64, err error) {
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err = chkTime(d)
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if err != nil {
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return 0, err
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}
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for i := range d[timeDataIndx : timeDataIndx+timeDataSize] {
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t |= uint64(d[i+timeDataIndx]) << uint(56-i*timeDataSize)
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}
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return t, nil
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}
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func GpsStrBytes(l string) (out []byte) {
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out = make([]byte, gpsDataSize)
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copy(out, []byte(l))
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return
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}
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func UpdateGps(d []byte, s string) error {
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// First check if there is a GPS descriptor
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err := chkGps(d)
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if err != nil {
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return err
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}
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gb := GpsStrBytes(s)
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for i := range d[gpsDataIndx : gpsDataIndx+gpsDataSize] {
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d[i+gpsDataIndx] = gb[i]
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}
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return nil
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}
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