seminix 0.1.60

seminix 内核标准库
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

#![allow(static_mut_refs)]

use alloc::sync::Arc;

use crate::{
    irq::irqflags::irqs_disabled,
    println,
    sync::seqlock::SeqCount,
    time::{
        NSEC_PER_SEC,
        clocksource::{clocks_calc_max_nsecs, clocks_calc_mult_shift},
        hrtimer::{Hrtimer, HrtimerRestart, hrtimer_start},
    },
};

#[derive(Clone, Copy)]
struct ClockReadData {
    epoch_ns: u64,
    epoch_cyc: u64,
    sched_clock_mask: u64,
    read_sched_clock: fn() -> u64,
    mult: u32,
    shift: u32,
}

impl ClockReadData {
    const fn new() -> Self {
        Self {
            epoch_ns: 0,
            epoch_cyc: 0,
            sched_clock_mask: 0xff,
            read_sched_clock: dummy_read,
            mult: 1,
            shift: 1,
        }
    }
}

#[repr(align(64))]
struct ClockData {
    seq: SeqCount,
    read_data: [ClockReadData; 2],
    wrap_kt: u64,
    rate: usize,
    actual_read_sched_clock: fn() -> u64,
}

static mut CD: ClockData = ClockData {
    seq: SeqCount::new(),
    read_data: [ClockReadData::new(); 2],
    wrap_kt: 1,
    rate: 1,
    actual_read_sched_clock: dummy_read,
};

#[inline(always)]
fn dummy_read() -> u64 {
    0
}

#[inline(always)]
fn cyc_to_ns(cyc: u64, mult: u32, shift: u32) -> u64 {
    (cyc * u64::from(mult)) >> shift
}

fn update_clock_read_data(rd: &ClockReadData) {
    unsafe {
        CD.read_data[1] = *rd;

        CD.seq.write_seqcount_latch();
        CD.read_data[0] = *rd;
        CD.seq.write_seqcount_latch();
    }
}

fn update_sched_clock() {
    unsafe {
        let mut rd = CD.read_data[0];

        let cyc = (CD.actual_read_sched_clock)();
        let ns =
            rd.epoch_ns + cyc_to_ns((cyc - rd.epoch_cyc) & rd.sched_clock_mask, rd.mult, rd.shift);

        rd.epoch_ns = ns;
        rd.epoch_cyc = cyc;

        update_clock_read_data(&rd);
    }
}

pub(crate) fn sched_clock_register(read: fn() -> u64, mask: u64, rate: usize) {
    unsafe {
        assert!(irqs_disabled());

        let mut new_mult = 0;
        let mut new_shift = 0;
        clocks_calc_mult_shift(
            &mut new_mult,
            &mut new_shift,
            rate as u32,
            NSEC_PER_SEC as u32,
            3600,
        );

        CD.rate = rate;

        let mut max_cyc = 0;
        let wrap = clocks_calc_max_nsecs(new_mult, new_shift, 0, mask, &mut max_cyc);
        CD.wrap_kt = wrap;

        let mut rd = CD.read_data[0];

        let new_epoch = read();
        let cyc = (CD.actual_read_sched_clock)();
        let ns =
            rd.epoch_ns + cyc_to_ns((cyc - rd.epoch_cyc) & rd.sched_clock_mask, rd.mult, rd.shift);
        CD.actual_read_sched_clock = read;

        rd.read_sched_clock = read;
        rd.sched_clock_mask = mask;
        rd.mult = new_mult;
        rd.shift = new_shift;
        rd.epoch_cyc = new_epoch;
        rd.epoch_ns = ns;

        update_clock_read_data(&rd);

        let mut r_unit = ' ';
        let mut r = rate;
        if r >= 4000000 {
            r /= 1000000;
            r_unit = 'M';
        } else if r >= 1000 {
            r /= 1000;
            r_unit = 'k';
        }

        let res = cyc_to_ns(1, new_mult, new_shift);
        println!(
            "sched_clock: {} bits at {}{}Hz, resolution {}ns, wraps every {}ns",
            mask.count_ones(),
            r,
            r_unit,
            res,
            wrap
        );
    }
}

pub(crate) fn sched_clock_init() {
    update_sched_clock();

    let timer = Arc::new(Hrtimer::create(super::hrtimer::HrtimerMode::Rel, sched_clock_poll, None));
    unsafe {
        assert!(hrtimer_start(&timer, CD.wrap_kt));
    }
}

fn sched_clock_poll(timer: &Hrtimer) -> HrtimerRestart {
    update_sched_clock();
    unsafe {
        timer.forward_now(CD.wrap_kt);
    }
    HrtimerRestart::Restart
}

pub(crate) fn sched_clock() -> u64 {
    unsafe {
        loop {
            let seq = CD.seq.read_seqcount();
            let rd = CD.read_data[seq as usize & 1];
            let cyc = ((rd.read_sched_clock)() - rd.epoch_cyc) & rd.sched_clock_mask;
            let res = rd.epoch_ns + cyc_to_ns(cyc, rd.mult, rd.shift);
            if !CD.seq.read_seqcount_retry(seq) {
                return res;
            }
        }
    }
}