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

#![allow(unused)]

use core::ops::{Bound, Range, RangeBounds};

use embedded_storage::nor_flash::{ErrorType, NorFlash, NorFlashError, NorFlashErrorKind, ReadNorFlash};
#[cfg(feature = "nightly")]
use embedded_storage_async::nor_flash::{NorFlash as AsyncNorFlash, ReadNorFlash as AsyncReadNorFlash};

pub struct MemFlash<const SIZE: usize, const ERASE_SIZE: usize, const WRITE_SIZE: usize> {
    pub mem: [u8; SIZE],
}

#[derive(Debug)]
pub struct MemFlashError;

impl<const SIZE: usize, const ERASE_SIZE: usize, const WRITE_SIZE: usize> MemFlash<SIZE, ERASE_SIZE, WRITE_SIZE> {
    pub const fn new(fill: u8) -> Self {
        Self { mem: [fill; SIZE] }
    }

    fn read(&mut self, offset: u32, bytes: &mut [u8]) -> Result<(), MemFlashError> {
        let len = bytes.len();
        bytes.copy_from_slice(&self.mem[offset as usize..offset as usize + len]);
        Ok(())
    }

    fn write(&mut self, offset: u32, bytes: &[u8]) -> Result<(), MemFlashError> {
        let offset = offset as usize;
        assert!(bytes.len() % WRITE_SIZE == 0);
        assert!(offset % WRITE_SIZE == 0);
        assert!(offset + bytes.len() <= SIZE);

        for ((offset, mem_byte), new_byte) in self.mem.iter_mut().enumerate().skip(offset).take(bytes.len()).zip(bytes) {
            assert_eq!(0xFF, *mem_byte, "Offset {} is not erased", offset);
            *mem_byte = *new_byte;
        }

        Ok(())
    }

    fn erase(&mut self, from: u32, to: u32) -> Result<(), MemFlashError> {
        let from = from as usize;
        let to = to as usize;
        assert!(from % ERASE_SIZE == 0);
        assert!(to % ERASE_SIZE == 0, "To: {}, erase size: {}", to, ERASE_SIZE);
        for i in from..to {
            self.mem[i] = 0xFF;
        }
        Ok(())
    }

    pub fn program(&mut self, offset: u32, bytes: &[u8]) -> Result<(), MemFlashError> {
        let offset = offset as usize;
        assert!(bytes.len() % WRITE_SIZE == 0);
        assert!(offset % WRITE_SIZE == 0);
        assert!(offset + bytes.len() <= SIZE);

        self.mem[offset..offset + bytes.len()].copy_from_slice(bytes);

        Ok(())
    }
}

impl<const SIZE: usize, const ERASE_SIZE: usize, const WRITE_SIZE: usize> Default for MemFlash<SIZE, ERASE_SIZE, WRITE_SIZE> {
    fn default() -> Self {
        Self::new(0xFF)
    }
}

impl<const SIZE: usize, const ERASE_SIZE: usize, const WRITE_SIZE: usize> ErrorType for MemFlash<SIZE, ERASE_SIZE, WRITE_SIZE> {
    type Error = MemFlashError;
}

impl NorFlashError for MemFlashError {
    fn kind(&self) -> NorFlashErrorKind {
        NorFlashErrorKind::Other
    }
}

impl<const SIZE: usize, const ERASE_SIZE: usize, const WRITE_SIZE: usize> ReadNorFlash
    for MemFlash<SIZE, ERASE_SIZE, WRITE_SIZE>
{
    const READ_SIZE: usize = 1;

    fn read(&mut self, offset: u32, bytes: &mut [u8]) -> Result<(), Self::Error> {
        self.read(offset, bytes)
    }

    fn capacity(&self) -> usize {
        SIZE
    }
}

impl<const SIZE: usize, const ERASE_SIZE: usize, const WRITE_SIZE: usize> NorFlash for MemFlash<SIZE, ERASE_SIZE, WRITE_SIZE> {
    const WRITE_SIZE: usize = WRITE_SIZE;
    const ERASE_SIZE: usize = ERASE_SIZE;

    fn write(&mut self, offset: u32, bytes: &[u8]) -> Result<(), Self::Error> {
        self.write(offset, bytes)
    }

    fn erase(&mut self, from: u32, to: u32) -> Result<(), Self::Error> {
        self.erase(from, to)
    }
}

#[cfg(feature = "nightly")]
impl<const SIZE: usize, const ERASE_SIZE: usize, const WRITE_SIZE: usize> AsyncReadNorFlash
    for MemFlash<SIZE, ERASE_SIZE, WRITE_SIZE>
{
    const READ_SIZE: usize = 1;

    async fn read(&mut self, offset: u32, bytes: &mut [u8]) -> Result<(), Self::Error> {
        self.read(offset, bytes)
    }

    fn capacity(&self) -> usize {
        SIZE
    }
}

#[cfg(feature = "nightly")]
impl<const SIZE: usize, const ERASE_SIZE: usize, const WRITE_SIZE: usize> AsyncNorFlash
    for MemFlash<SIZE, ERASE_SIZE, WRITE_SIZE>
{
    const WRITE_SIZE: usize = WRITE_SIZE;
    const ERASE_SIZE: usize = ERASE_SIZE;

    async fn write(&mut self, offset: u32, bytes: &[u8]) -> Result<(), Self::Error> {
        self.write(offset, bytes)
    }

    async fn erase(&mut self, from: u32, to: u32) -> Result<(), Self::Error> {
        self.erase(from, to)
    }
}

#[cfg(test)]
mod tests {
    use crate::MemFlash;

    #[test]
    fn test_write() {
        let mut flash = MemFlash::<1024, 4, 1>::new(0xFF);
        flash.erase(0, 1024).unwrap();
        flash.write(512, b"hello").unwrap();

        let mut rx = [0; 5];
        flash.read(512, &mut rx).unwrap();
        assert_eq!(&rx, b"hello");
    }
}