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#![doc = include_str!("../README.md")]
use itertools::Itertools;
#[cfg(feature = "ral")]
mod macros;
/// A DCD command.
#[derive(Default, Clone, Debug, Eq, PartialEq)]
pub enum Command {
/// Dummy command --- may behave as a small delay.
#[default]
Nop,
/// DCD command for writing a value to an address; [`Write`].
Write(Write),
/// DCD command for polling an address until the value matches a given bitmask condition; [`Check`].
Check(Check),
}
/*
// TODO(summivox): not ready
impl Command {
pub fn with_count(self, count: u32) -> Self {
match self {
Self::Check(check) => Self::Check(check.with_count(count)),
_ => panic!("`with_count` can only be called on a `Check` command."),
}
}
}
*/
/// DCD command for writing a value to an address.
#[derive(Default, Clone, Debug, Eq, PartialEq)]
pub struct Write {
/// Width of the bus write.
pub width: Width,
/// Writing operation --- see [`WriteOp`].
pub op: WriteOp,
/// Address to be written to. Note that the ROM may enforce valid address ranges.
pub address: u32,
pub value: u32,
}
/// DCD command for polling an address until the value matches a given bitmask condition.
#[derive(Default, Clone, Debug, Eq, PartialEq)]
pub struct Check {
/// Width of the bus read.
pub width: Width,
/// Condition to check --- see [`CheckCond`].
pub cond: CheckCond,
/// Address to read from. Unlike [`Write::address`], any address is valid.
pub address: u32,
/// Bitmask to check the value against --- see [`CheckCond`].
pub mask: u32,
/// Optional poll count:
/// - `None` => poll indefinitely
/// - `Some(0)` => equivalent to [`Command::Nop`]
/// - `Some(x) if x > 0` => poll at most `x` times; if the condition still is not satisfied,
/// the boot ROM will abandon interpreting the rest of the DCD.
pub count: Option<u32>,
}
/*
// TODO(summivox): not ready
impl Check {
pub fn with_count(self, count: u32) -> Self {
Self { count: Some(count), ..self }
}
}
*/
/// Byte width of the bus read/write.
#[derive(Default, Debug, Copy, Clone, Eq, PartialEq)]
#[repr(u8)]
pub enum Width {
/// 1 byte / 8 bit
B1 = 0b001u8,
/// 2 bytes / 16 bit
B2 = 0b010u8,
/// 4 bytes / 32 bit
#[default]
B4 = 0b100u8,
}
impl Width {
/// ```
/// # use imxrt_dcd::Width;
/// assert_eq!(Width::from_num_bytes(1), Width::B1);
/// assert_eq!(Width::from_num_bytes(2), Width::B2);
/// assert_eq!(Width::from_num_bytes(4), Width::B4);
/// ```
pub const fn from_num_bytes(num_bytes: usize) -> Self {
match num_bytes {
1 => Self::B1,
2 => Self::B2,
4 => Self::B4,
_ => panic!("invalid width"),
}
}
/// Returns the width of the given RAL register instance, i.e. `&RWRegister<u32>` and friends.
///
/// Since `RWRegister<T>` is a newtype wrapper of `T`, this works on primitives too.
/// ```
/// # use imxrt_dcd::Width;
/// let a = 1u8;
/// let b = 2u16;
/// let c = 3i32;
/// assert_eq!(Width::from_reg(&a), Width::B1);
/// assert_eq!(Width::from_reg(&b), Width::B2);
/// assert_eq!(Width::from_reg(&c), Width::B4);
/// ```
pub const fn from_reg<T>(_: &T) -> Self {
Self::from_num_bytes(core::mem::size_of::<T>())
}
}
/// [`Write`] operation variants.
#[derive(Default, Debug, Copy, Clone, Eq, PartialEq)]
#[repr(u8)]
pub enum WriteOp {
/// `*address = value` --- direct write
#[default]
Write = 0b00_000u8,
/// `*address &= !value` --- clear bits (read-modify-write)
Clear = 0b01_000u8,
/// `*address |= value` --- set bits (read-modify-write)
Set = 0b11_000u8,
}
/// [`Check`] condition variants.
#[derive(Default, Debug, Copy, Clone, Eq, PartialEq)]
#[repr(u8)]
pub enum CheckCond {
#[default]
/// `(*address & mask) == 0` --- All masked bits are 0 in value
AllClear = 0b00_000u8,
/// `(*address & mask) != mask` --- Some masked bits are 0 in value
AnyClear = 0b01_000u8,
/// `(*address & mask) == mask` --- All masked bits are 1 in value
AllSet = 0b10_000u8,
/// `(*address & mask) != 0` --- Some masked bits are 1 in value
AnySet = 0b11_000u8,
}
///////////////////////////////////////////////////////////////////////////
fn dcd_header(byte_len: u16) -> [u8; 4] {
let mut header = [0xD2, 0x00, 0x00, 0x41];
header[1..=2].copy_from_slice(&byte_len.to_be_bytes()[0..=1]);
header
}
const NOP_HEADER: [u8; 4] = [0xC0, 0x00, 0x04, 0x00];
impl Write {
fn byte_len(group_size: usize) -> u16 {
let n = 4 + group_size * 8;
assert!(n <= u16::MAX as usize);
n as u16
}
fn header(&self, group_size: usize) -> [u8; 4] {
let mut header = [0xCC, 0x00, 0x00, self.width as u8 | self.op as u8];
header[1..=2].copy_from_slice(&Self::byte_len(group_size).to_be_bytes()[0..=1]);
header
}
fn payload(&self) -> [u8; 8] {
let mut payload = [0u8; 8];
payload[0..4].copy_from_slice(&self.address.to_be_bytes()[0..4]);
payload[4..8].copy_from_slice(&self.value.to_be_bytes()[0..4]);
payload
}
}
impl Check {
fn byte_len(&self) -> u16 {
if self.count.is_some() {
16
} else {
12
}
}
fn header(&self) -> [u8; 4] {
let mut header = [0xCF, 0x00, 0x00, self.width as u8 | self.cond as u8];
header[1..=2].copy_from_slice(&self.byte_len().to_be_bytes()[0..=1]);
header
}
fn payload(&self) -> [u8; 8] {
let mut payload = [0u8; 8];
payload[0..4].copy_from_slice(&self.address.to_be_bytes()[0..4]);
payload[4..8].copy_from_slice(&self.mask.to_be_bytes()[0..4]);
payload
}
fn payload_with_count(&self) -> [u8; 12] {
let mut payload = [0u8; 12];
payload[0..4].copy_from_slice(&self.address.to_be_bytes()[0..4]);
payload[4..8].copy_from_slice(&self.mask.to_be_bytes()[0..4]);
payload[8..12].copy_from_slice(&self.count.unwrap().to_be_bytes()[0..4]);
payload
}
}
fn group_key(index: usize, command: &Command) -> (usize, Width, WriteOp) {
match command {
&Command::Write(Write {
width, op, ..
}) => (usize::MAX, width, op),
_ => (index, Width::default(), WriteOp::default()),
}
}
///////////////////////////////////////////////////////////////////////////
/// Serializes given commands as a complete DCD block into a byte stream.
/// Consecutive write commands with the same width and op are automatically combined.
///
/// While the ROM may enforce tighter byte size limits, this
///
/// Returns the number of bytes written or error.
///
/// # Examples
///
/// See [crate-level doc](crate).
///
pub fn serialize(mut w: impl std::io::Write, commands: &[Command]) -> std::io::Result<usize> {
if commands.is_empty() {
return Ok(0);
}
// count num of bytes first
let mut byte_len: usize = 4; // DCD header
for (_, mut group) in &commands
.into_iter()
.enumerate()
.group_by(|&(index, command)| group_key(index, command))
{
let Some((_, head)) = group.next() else { continue; };
match head {
Command::Nop => {
byte_len += 4;
}
Command::Check(check) => {
byte_len += check.byte_len() as usize;
}
Command::Write(_) => {
byte_len += Write::byte_len(group.count() + 1) as usize;
}
}
}
if byte_len > u16::MAX as usize {
return Err(std::io::Error::new(
std::io::ErrorKind::InvalidInput,
"DCD byte length too large",
));
}
w.write_all(&dcd_header(byte_len as u16))?;
for (_, mut group) in &commands
.into_iter()
.enumerate()
.group_by(|&(index, command)| group_key(index, command))
{
let Some((_, head)) = group.next() else { continue; };
match head {
Command::Nop => {
w.write_all(&NOP_HEADER)?;
}
Command::Check(check) => {
w.write_all(&check.header())?;
if check.count.is_some() {
w.write_all(&check.payload_with_count())?;
} else {
w.write_all(&check.payload())?;
}
}
Command::Write(write) => {
let (counter, rest) = group.tee();
w.write_all(&write.header(counter.count() + 1))?;
w.write_all(&write.payload())?;
for (_, command) in rest {
if let Command::Write(write) = command {
w.write_all(&write.payload())?;
}
}
}
}
}
Ok(byte_len)
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
#[rustfmt::skip]
fn serialize_simple() {
let mut buf = vec![];
let byte_len = serialize(
&mut buf,
&[
Command::Nop,
Command::Write(Write {
width: Width::B4,
op: WriteOp::Write,
address: 0x01234567,
value: 0xdeadbeef,
}),
Command::Check(Check {
width: Width::B2,
cond: CheckCond::AnySet,
address: 0x89abcdef,
mask: 0x55aa55aa,
count: Some(16),
}),
Command::Check(Check {
width: Width::B1,
cond: CheckCond::AnyClear,
address: 0x89abcdef,
mask: 0x55aa55aa,
count: None,
}),
],
)
.expect("IO failure");
assert_eq!(byte_len, 48);
assert_eq!(
&buf,
&[
// DCD header
0xD2, 0, 48, 0x41,
// nop
0xC0, 0x00, 0x04, 0x00,
// write
0xCC, 0, 12, 0x04, 0x01, 0x23, 0x45, 0x67, 0xde, 0xad, 0xbe, 0xef,
// check with count
0xCF, 0, 16, 0x1a, 0x89, 0xab, 0xcd, 0xef, 0x55, 0xaa, 0x55, 0xaa, 0, 0, 0, 16,
// check without
0xCF, 0, 12, 0x09, 0x89, 0xab, 0xcd, 0xef, 0x55, 0xaa, 0x55, 0xaa,
]
);
}
#[test]
#[rustfmt::skip]
fn serialize_merge() {
let mut buf = vec![];
let byte_len = serialize(
&mut buf,
&[
// the following 3 writes should be merged
Command::Write(Write {
width: Width::B4,
op: WriteOp::Write,
address: 0x01234567,
value: 0xdeadbeef,
}),
Command::Write(Write {
width: Width::B4,
op: WriteOp::Write,
address: 0x89abcdef,
value: 0x13370000,
}),
Command::Write(Write {
width: Width::B4,
op: WriteOp::Write,
address: 0x55aa55aa,
value: 0xaa55aa55,
}),
Command::Nop,
// this is not merged because of the NOP in the middle
Command::Write(Write {
width: Width::B4,
op: WriteOp::Write,
address: 0x89abcdef,
value: 0x13370000,
}),
// this is not merged with the previous because they differ in width
Command::Write(Write {
width: Width::B2,
op: WriteOp::Write,
address: 0x89abcdef,
value: 0x13370000,
}),
// this is not merged (ditto)
Command::Write(Write {
width: Width::B4,
op: WriteOp::Write,
address: 0x55aa55aa,
value: 0xaa55aa55,
}),
],
).expect("IO failure");
assert_eq!(byte_len, 72);
assert_eq!(
&buf,
&[
// DCD header
0xD2, 0, 72, 0x41,
// write header
0xCC, 0, 28, 0x04,
// write
0x01, 0x23, 0x45, 0x67, 0xde, 0xad, 0xbe, 0xef,
// write
0x89, 0xab, 0xcd, 0xef, 0x13, 0x37, 0x00, 0x00,
// write
0x55, 0xaa, 0x55, 0xaa, 0xaa, 0x55, 0xaa, 0x55,
// nop
0xC0, 0x00, 0x04, 0x00,
// write header
0xCC, 0, 12, 0x04,
// write
0x89, 0xab, 0xcd, 0xef, 0x13, 0x37, 0x00, 0x00,
// write header
0xCC, 0, 12, 0x02,
// write
0x89, 0xab, 0xcd, 0xef, 0x13, 0x37, 0x00, 0x00,
// write header
0xCC, 0, 12, 0x04,
// write
0x55, 0xaa, 0x55, 0xaa, 0xaa, 0x55, 0xaa, 0x55,
]
);
}
}