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hardware-register
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lib: replae `usize` with `Register` 

This ensures we can't write to random values in memory.

Signed-off-by: Sean Cross <sean@xobs.io>
This commit is contained in:
Sean Cross 2020-09-27 11:31:59 +08:00
parent 02bb380848
commit 30a9171031
1 changed files with 26 additions and 10 deletions
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36
src/lib.rs
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@ -1,4 +1,15 @@
use std::convert::TryInto;
pub struct Register {
/// Offset of this register within this CSR
offset: usize,
}
impl Register {
pub const fn new(offset: usize) -> Register {
Register { offset }
}
}
pub struct Field {
/// A bitmask we use to AND to the value, unshifted.
/// E.g. for a width of `3` bits, this mask would be 0b111.
@ -66,22 +77,26 @@ where
pub fn new(base: *mut T) -> Self {
CSR { base }
}
pub fn r(&mut self, reg: usize, field: Field) -> T {
pub fn r(&mut self, reg: Register, field: Field) -> T {
let usize_base: *mut usize = unsafe { core::mem::transmute(&self.base) };
((unsafe { usize_base.add(reg).read_volatile() } >> field.offset) & field.mask)
((unsafe { usize_base.add(reg.offset).read_volatile() } >> field.offset) & field.mask)
.try_into()
.unwrap_or_default()
}
pub fn rw(&mut self, reg: usize, field: Field, value: T) {
pub fn rw(&mut self, reg: Register, field: Field, value: T) {
let usize_base: *mut usize = unsafe { core::mem::transmute(&self.base) };
let value_as_usize: usize = value.try_into().unwrap_or_default() << field.offset;
let previous = unsafe { usize_base.add(reg).read_volatile() } & ! field.mask;
unsafe { usize_base.add(reg).write_volatile(previous | value_as_usize)};
let previous = unsafe { usize_base.add(reg.offset).read_volatile() } & !field.mask;
unsafe {
usize_base
.add(reg.offset)
.write_volatile(previous | value_as_usize)
};
}
pub fn ow(&mut self, reg: usize, field: Field, value: T) {
pub fn ow(&mut self, reg: Register, field: Field, value: T) {
let usize_base: *mut usize = unsafe { core::mem::transmute(&self.base) };
let value_as_usize: usize = value.try_into().unwrap_or_default() << field.offset;
unsafe { usize_base.add(reg).write_volatile(value_as_usize)};
unsafe { usize_base.add(reg.offset).write_volatile(value_as_usize) };
}
}
@ -89,14 +104,15 @@ where
mod tests {
pub mod pac {
pub mod audio {
pub const RX_CTL: usize = 0x0c;
pub const RX_CTL: crate::Register = crate::Register::new(0x0c);
pub const RX_CTL_ENABLE: crate::Field = crate::Field::new(1, 0);
pub const RX_CTL_RESET: crate::Field = crate::Field::new(1, 1);
}
pub mod uart {
pub const RXTX: usize = 0x00;
pub const RXTX: crate::Register = crate::Register::new(0x00);
pub const RXTX_RXTX: crate::Field = crate::Field::new(8, 0);
pub const TXFULL: usize = 0x04;
pub const TXFULL: crate::Register = crate::Register::new(0x04);
pub const TXFULL_TXFULL: crate::Field = crate::Field::new(1, 0);
}
}