binex 0.5.2

BINEX encoder and decoder for real-time GNSS
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280

//! Epoch encoding & decoding
use crate::{Error, utils::Utils};
use hifitime::prelude::{Epoch, TimeScale, Unit};

/// BINEX Time Resolution
#[derive(Debug, Copy, Clone, PartialEq)]
pub enum TimeResolution {
    /// One Byte Second = 250ms resolution on [Epoch]s
    QuarterSecond = 0,
    /// 4 Byte Minutes and 2 byte millisecond
    MilliSecond = 1,
}

impl TimeResolution {
    pub fn encoding_size(&self) -> usize {
        match self {
            Self::MilliSecond => 6,
            Self::QuarterSecond => 5,
        }
    }
}

/// [Epoch] decoding attempt from buffered content.
/// If buffer does not contain enough data (5 bytes needed), this returns [Error::NotEnoughBytes].
pub fn decode_epoch(
    big_endian: bool,
    time_res: TimeResolution,
    buf: &[u8],
    ts: TimeScale,
) -> Result<Epoch, Error> {
    if buf.len() < time_res.encoding_size() {
        return Err(Error::NotEnoughBytes);
    }

    let min = Utils::decode_u32(big_endian, buf)?;

    match time_res {
        TimeResolution::QuarterSecond => {
            let qsec = buf[4];
            Ok(Epoch::from_duration(
                (min as f64) * Unit::Minute + (qsec as f64 / 4.0) * Unit::Second,
                ts,
            ))
        },
        TimeResolution::MilliSecond => {
            let ms = Utils::decode_u16(big_endian, &buf[4..])?;
            Ok(Epoch::from_duration(
                (min as f64) * Unit::Minute + (ms as f64) * Unit::Millisecond,
                ts,
            ))
        },
    }
}

/// [Epoch] encoding method.
/// If buffer is too small (needs 5 bytes), this returns [Error::NotEnoughBytes].
/// This is the exact [decode_epoch] mirror operation.
pub fn encode_epoch(
    t: Epoch,
    time_res: TimeResolution,
    big_endian: bool,
    buf: &mut [u8],
) -> Result<usize, Error> {
    let size = time_res.encoding_size();
    if buf.len() < size {
        return Err(Error::NotEnoughBytes);
    }

    let dt_s = t.duration.to_seconds();
    let total_mins = (dt_s / 60.0).round() as u32;
    let bytes = total_mins.to_be_bytes();

    if big_endian {
        buf[0] = bytes[0];
        buf[1] = bytes[1];
        buf[2] = bytes[2];
        buf[3] = bytes[3];
    } else {
        buf[0] = bytes[3];
        buf[1] = bytes[2];
        buf[2] = bytes[1];
        buf[3] = bytes[0];
    }

    match time_res {
        TimeResolution::MilliSecond => {
            let total_msec = (dt_s - (total_mins as f64) * 60.0) * 1.0E3;
            let bytes = ((total_msec as u16).min(59999)).to_be_bytes();

            if big_endian {
                buf[4] = bytes[0];
                buf[5] = bytes[1];
            } else {
                buf[4] = bytes[1];
                buf[5] = bytes[0];
            }
        },
        TimeResolution::QuarterSecond => {
            let total_qsec = (dt_s - (total_mins as f64) * 60.0) / 0.25;
            buf[4] = total_qsec as u8 & 0x7f; // 0xf0-0xff are excluded
        },
    }

    Ok(size)
}

/// GPST [Epoch] decoding attempt from buffered content.
pub(crate) fn decode_gpst_epoch(
    big_endian: bool,
    time_res: TimeResolution,
    buf: &[u8],
) -> Result<Epoch, Error> {
    decode_epoch(big_endian, time_res, buf, TimeScale::GPST)
}

// /// GST [Epoch] decoding attempt from buffered content.
// pub(crate) fn decode_gst_epoch(
//     big_endian: bool,
//     time_res: TimeResolution,
//     buf: &[u8],
// ) -> Result<Epoch, Error> {
//     decode_epoch(big_endian, time_res, buf, TimeScale::GST)
// }

// /// BDT [Epoch] decoding attempt from buffered content.
// pub(crate) fn decode_bdt_epoch(
//     big_endian: bool,
//     time_res: TimeResolution,
//     buf: &[u8],
// ) -> Result<Epoch, Error> {
//     decode_epoch(big_endian, time_res, buf, TimeScale::BDT)
// }

#[cfg(test)]
mod test {
    use super::*;

    #[test]
    fn epoch_fail() {
        let buf = [0];
        assert!(decode_gpst_epoch(true, TimeResolution::QuarterSecond, &buf).is_err());
        let buf = [0, 0, 0];
        assert!(decode_gpst_epoch(true, TimeResolution::QuarterSecond, &buf).is_err());
        let buf = [0, 0, 0, 0];
        assert!(decode_gpst_epoch(true, TimeResolution::MilliSecond, &buf).is_err());
    }

    #[test]
    fn gpst_qsec_sub_minute() {
        let big_endian = true;

        let mut buf = [0, 0, 0, 0, 0];
        let t = Epoch::from_gpst_seconds(10.0);
        let _ = encode_epoch(t, TimeResolution::QuarterSecond, big_endian, &mut buf).unwrap();
        assert_eq!(buf, [0, 0, 0, 0, 40]);

        let decoded = decode_epoch(
            big_endian,
            TimeResolution::QuarterSecond,
            &buf,
            TimeScale::GPST,
        )
        .unwrap();

        assert_eq!(decoded, t);

        let mut buf = [0, 0, 0, 0, 0];
        let t = Epoch::from_gpst_seconds(0.75);
        let _ = encode_epoch(t, TimeResolution::QuarterSecond, big_endian, &mut buf).unwrap();
        assert_eq!(buf, [0, 0, 0, 0, 3]);

        let decoded = decode_epoch(
            big_endian,
            TimeResolution::QuarterSecond,
            &buf,
            TimeScale::GPST,
        )
        .unwrap();

        assert_eq!(decoded, t);

        let mut buf = [0, 0, 0, 0, 0];
        let t = Epoch::from_gpst_seconds(10.75);
        let _ = encode_epoch(t, TimeResolution::QuarterSecond, big_endian, &mut buf).unwrap();
        assert_eq!(buf, [0, 0, 0, 0, 43]);

        let decoded = decode_epoch(
            big_endian,
            TimeResolution::QuarterSecond,
            &buf,
            TimeScale::GPST,
        )
        .unwrap();

        assert_eq!(decoded, t);
    }

    #[test]
    fn gpst_qsec_epoch_decoding() {
        for (buf, big_endian, gpst_epoch) in [
            ([0, 0, 0, 1, 0], true, Epoch::from_gpst_seconds(60.0)),
            ([0, 0, 0, 5, 0], true, Epoch::from_gpst_seconds(300.0)),
            (
                [0, 0, 1, 1, 1],
                true,
                Epoch::from_gpst_seconds(2.0_f64.powf(8.0) * 60.0 + 60.0 + 0.25),
            ),
            (
                [0, 0, 1, 1, 2],
                true,
                Epoch::from_gpst_seconds(2.0_f64.powf(8.0) * 60.0 + 60.0 + 0.5),
            ),
            (
                [0, 0, 1, 1, 0],
                true,
                Epoch::from_gpst_seconds(2.0_f64.powf(8.0) * 60.0 + 60.0),
            ),
            (
                [1, 1, 1, 0, 0],
                true,
                Epoch::from_gpst_seconds(
                    (2.0_f64.powf(24.0) + 2.0_f64.powf(16.0) + 2.0_f64.powf(8.0)) * 60.0,
                ),
            ),
        ] {
            let epoch = decode_gpst_epoch(big_endian, TimeResolution::QuarterSecond, &buf);
            assert!(epoch.is_ok(), "to parse valid gpst_epoch");
            let epoch = epoch.unwrap();
            assert_eq!(epoch, gpst_epoch);

            // test mirror op
            let mut test = [0, 0, 0, 0, 0];
            let _ =
                encode_epoch(epoch, TimeResolution::QuarterSecond, big_endian, &mut test).unwrap();
            assert_eq!(test, buf, "encode_epoch failed for {}", epoch);
        }
    }

    #[test]
    fn gpst_msec() {
        let mut buf = [0, 0, 0, 0, 0, 0];
        let t = Epoch::from_gpst_seconds(60.0);
        encode_epoch(t, TimeResolution::MilliSecond, true, &mut buf).unwrap();
        assert_eq!(buf, [0, 0, 0, 1, 0, 0]);

        let parsed = decode_gpst_epoch(true, TimeResolution::MilliSecond, &buf).unwrap();
        assert_eq!(parsed, t);

        let mut buf = [0, 0, 0, 0, 0, 0];
        let t = Epoch::from_gpst_seconds(61.0);
        encode_epoch(t, TimeResolution::MilliSecond, true, &mut buf).unwrap();
        assert_eq!(buf, [0, 0, 0, 1, 0x3, 0xe8]);

        let parsed = decode_gpst_epoch(true, TimeResolution::MilliSecond, &buf).unwrap();
        assert_eq!(parsed, t);

        let mut buf = [0, 0, 0, 0, 0, 0];
        let t = Epoch::from_gpst_seconds(1.1);
        encode_epoch(t, TimeResolution::MilliSecond, true, &mut buf).unwrap();
        assert_eq!(buf, [0, 0, 0, 0, 4, 76]);

        let parsed = decode_gpst_epoch(true, TimeResolution::MilliSecond, &buf).unwrap();
        assert_eq!(parsed, t);

        let mut buf = [0, 0, 0, 0, 0, 0];
        let t = Epoch::from_gpst_seconds(71.0);
        encode_epoch(t, TimeResolution::MilliSecond, true, &mut buf).unwrap();
        assert_eq!(buf, [0, 0, 0, 1, 0x2a, 0xf8]);

        let parsed = decode_gpst_epoch(true, TimeResolution::MilliSecond, &buf).unwrap();
        assert_eq!(parsed, t);

        let mut buf = [0, 0, 0, 0, 0, 0];
        let t = Epoch::from_gpst_seconds(60.100);
        encode_epoch(t, TimeResolution::MilliSecond, true, &mut buf).unwrap();

        let parsed = decode_gpst_epoch(true, TimeResolution::MilliSecond, &buf).unwrap();
        assert_eq!(parsed, t);
    }
}