lpc55-hal 0.5.0

Hardware Abstraction Layer (HAL) for the NXP LPC55S6x ARM Cortex-33 microcontrollers
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

use core::{cmp::min, slice};

use usb_device::{Result, UsbError};
use vcell::VolatileCell;

use super::constants::{UsbAccessType, EP_MEM_ADDR, EP_MEM_SIZE, EP_REGISTERS_SIZE};

// The USB FS peripheral is flexible about which SRAM to use.
// - On the one hand, the USB HS has no access to regular SRAM, and
// must use "USB1_SRAM" at 0x4010_0000 (size 0x4000, 4KB). We can also
// use this for USB FS.
// - On the other, we could use a stack-allocated or static buffer.
//   --> do this too later on

pub struct EndpointBuffer(&'static mut [VolatileCell<UsbAccessType>]);

const EP_MEM_PTR: *mut VolatileCell<UsbAccessType> =
    EP_MEM_ADDR as *mut VolatileCell<UsbAccessType>;

impl EndpointBuffer {
    pub fn new(offset: usize, size: usize) -> Self {
        let addr = unsafe { EP_MEM_PTR.add(offset) };
        let mem = unsafe { slice::from_raw_parts_mut(addr, size) };
        Self(mem)
    }

    pub fn read(&self, buf: &mut [u8]) {
        // for i in 0..min(buf.len(), self.0.len()) {
        //     buf[i] = self.0[i].get();
        // }
        let count = min(buf.len(), self.0.len());
        for (i, entry) in buf.iter_mut().enumerate().take(count) {
            *entry = self.0[i].get();
        }
    }

    pub fn write(&self, buf: &[u8]) {
        // for i in 0..min(buf.len(), self.0.len()) {
        //     self.0[i].set(buf[i]);
        // }
        let count = min(buf.len(), self.0.len());
        for (i, entry) in buf.iter().enumerate().take(count) {
            self.0[i].set(*entry);
        }
    }

    pub fn offset(&self) -> usize {
        let buffer_address = self.0.as_ptr() as usize;
        buffer_address - EP_MEM_PTR as usize
    }

    pub fn addr(&self) -> u32 {
        self.0.as_ptr() as u32
    }

    // blee... capacity
    pub fn capacity(&self) -> usize {
        self.0.len()
    }

    pub fn is_empty(&self) -> bool {
        self.0.len() == 0
    }
}

pub struct EndpointMemoryAllocator {
    next_free_offset: usize,
}

// NOTE: This is a bump allocator.
// Think about https://fitzgeraldnick.com/2019/11/01/always-bump-downwards.html
// (cf. https://lib.rs/crates/bumpalo)
impl EndpointMemoryAllocator {
    const ALIGN: usize = 64;

    pub fn new() -> Self {
        // keep endpoint registers at top
        Self {
            next_free_offset: EP_REGISTERS_SIZE,
        }
    }

    pub fn allocate_buffer(&mut self, size: usize) -> Result<EndpointBuffer> {
        let next_free_addr = EP_MEM_ADDR + self.next_free_offset;

        // buffers have to be 64 byte aligned
        let addr = (next_free_addr + EndpointMemoryAllocator::ALIGN - 1)
            & !(EndpointMemoryAllocator::ALIGN - 1);
        // let addr = if next_free_addr & 0x3f > 0 {
        //     (next_free_addr & !0x3f) + 64
        // } else {
        //     next_free_addr
        // };

        let offset = addr - EP_MEM_ADDR;
        if offset + size > EP_MEM_SIZE {
            return Err(UsbError::EndpointMemoryOverflow);
        }

        self.next_free_offset = offset + size;
        Ok(EndpointBuffer::new(offset, size))
    }
}

impl Default for EndpointMemoryAllocator {
    fn default() -> Self {
        EndpointMemoryAllocator::new()
    }
}