embedded_fat/filesystem/
timestamp.rs

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1/// Things that impl this can tell you the current time.
2pub trait TimeSource {
3    /// Returns the current time
4    fn get_timestamp(&self) -> Timestamp;
5}
6
7/// Represents an instant in time, in the local time zone. TODO: Consider
8/// replacing this with POSIX time as a `u32`, which would save two bytes at
9/// the expense of some maths.
10#[cfg_attr(feature = "defmt-log", derive(defmt::Format))]
11#[derive(Copy, Clone, PartialOrd, Ord, PartialEq, Eq)]
12pub struct Timestamp {
13    /// Add 1970 to this file to get the calendar year
14    pub year_since_1970: u8,
15    /// Add one to this value to get the calendar month
16    pub zero_indexed_month: u8,
17    /// Add one to this value to get the calendar day
18    pub zero_indexed_day: u8,
19    /// The number of hours past midnight
20    pub hours: u8,
21    /// The number of minutes past the hour
22    pub minutes: u8,
23    /// The number of seconds past the minute
24    pub seconds: u8,
25}
26
27impl Timestamp {
28    /// Create a `Timestamp` from the 16-bit FAT date and time fields.
29    pub fn from_fat(date: u16, time: u16) -> Timestamp {
30        let year = 1980 + (date >> 9);
31        let month = ((date >> 5) & 0x000F) as u8;
32        let day = (date & 0x001F) as u8;
33        let hours = ((time >> 11) & 0x001F) as u8;
34        let minutes = ((time >> 5) & 0x0003F) as u8;
35        let seconds = ((time << 1) & 0x0003F) as u8;
36        // Volume labels have a zero for month/day, so tolerate that...
37        Timestamp {
38            year_since_1970: (year - 1970) as u8,
39            zero_indexed_month: if month == 0 { 0 } else { month - 1 },
40            zero_indexed_day: if day == 0 { 0 } else { day - 1 },
41            hours,
42            minutes,
43            seconds,
44        }
45    }
46
47    // TODO add tests for the method
48    /// Serialize a `Timestamp` to FAT format
49    pub fn serialize_to_fat(self) -> [u8; 4] {
50        let mut data = [0u8; 4];
51
52        let hours = (u16::from(self.hours) << 11) & 0xF800;
53        let minutes = (u16::from(self.minutes) << 5) & 0x07E0;
54        let seconds = (u16::from(self.seconds / 2)) & 0x001F;
55        data[..2].copy_from_slice(&(hours | minutes | seconds).to_le_bytes()[..]);
56
57        let year = if self.year_since_1970 < 10 {
58            0
59        } else {
60            (u16::from(self.year_since_1970 - 10) << 9) & 0xFE00
61        };
62        let month = (u16::from(self.zero_indexed_month + 1) << 5) & 0x01E0;
63        let day = u16::from(self.zero_indexed_day + 1) & 0x001F;
64        data[2..].copy_from_slice(&(year | month | day).to_le_bytes()[..]);
65        data
66    }
67
68    /// Create a `Timestamp` from year/month/day/hour/minute/second.
69    ///
70    /// Values should be given as you'd write then (i.e. 1980, 01, 01, 13, 30,
71    /// 05) is 1980-Jan-01, 1:30:05pm.
72    pub fn from_calendar(
73        year: u16,
74        month: u8,
75        day: u8,
76        hours: u8,
77        minutes: u8,
78        seconds: u8,
79    ) -> Result<Timestamp, &'static str> {
80        Ok(Timestamp {
81            year_since_1970: if (1970..=(1970 + 255)).contains(&year) {
82                (year - 1970) as u8
83            } else {
84                return Err("Bad year");
85            },
86            zero_indexed_month: if (1..=12).contains(&month) {
87                month - 1
88            } else {
89                return Err("Bad month");
90            },
91            zero_indexed_day: if (1..=31).contains(&day) {
92                day - 1
93            } else {
94                return Err("Bad day");
95            },
96            hours: if hours <= 23 {
97                hours
98            } else {
99                return Err("Bad hours");
100            },
101            minutes: if minutes <= 59 {
102                minutes
103            } else {
104                return Err("Bad minutes");
105            },
106            seconds: if seconds <= 59 {
107                seconds
108            } else {
109                return Err("Bad seconds");
110            },
111        })
112    }
113}
114
115impl core::fmt::Debug for Timestamp {
116    fn fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result {
117        write!(f, "Timestamp({})", self)
118    }
119}
120
121impl core::fmt::Display for Timestamp {
122    fn fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result {
123        write!(
124            f,
125            "{}-{:02}-{:02} {:02}:{:02}:{:02}",
126            u16::from(self.year_since_1970) + 1970,
127            self.zero_indexed_month + 1,
128            self.zero_indexed_day + 1,
129            self.hours,
130            self.minutes,
131            self.seconds
132        )
133    }
134}
embedded_fat/filesystem/timestamp.rs

embedded_fat/filesystem/
timestamp.rs
