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//! Instrumentation Trace Macrocell
use core::{fmt, mem, ptr, slice};
use aligned::Aligned;
use peripheral::Stim;
// NOTE assumes that `bytes` is 32-bit aligned
unsafe fn write_words(stim: &Stim, bytes: &[u32]) {
let mut p = bytes.as_ptr();
for _ in 0..bytes.len() {
while !stim.is_fifo_ready() {}
stim.write_u32(ptr::read(p));
p = p.offset(1);
}
}
struct Port<'p>(&'p Stim);
impl<'p> fmt::Write for Port<'p> {
fn write_str(&mut self, s: &str) -> fmt::Result {
write_all(self.0, s.as_bytes());
Ok(())
}
}
/// Writes a `buffer` to the ITM `port`
pub fn write_all(port: &Stim, buffer: &[u8]) {
unsafe {
let mut len = buffer.len();
let mut ptr = buffer.as_ptr();
// 0x01 OR 0x03
if ptr as usize % 2 == 1 {
while !port.is_fifo_ready() {}
port.write_u8(*ptr);
// 0x02 OR 0x04
ptr = ptr.offset(1);
len -= 1;
}
// 0x02
if ptr as usize % 4 == 2 {
while !port.is_fifo_ready() {}
port.write_u16(ptr::read(ptr as *const u16));
// 0x04
ptr = ptr.offset(2);
len -= 2;
}
write_aligned(port, mem::transmute(slice::from_raw_parts(ptr, len)));
}
}
/// Writes a 4-byte aligned `buffer` to the ITM `port`
///
/// # Examples
///
/// ``` ignore
/// let mut buffer: Aligned<u32, _> = Aligned([0; 14]);
///
/// buffer.copy_from_slice(b"Hello, world!\n");
///
/// itm::write_aligned(&itm.stim[0], &buffer);
///
/// // Or equivalently
/// itm::write_aligned(&itm.stim[0], &Aligned(*b"Hello, world!\n"));
/// ```
pub fn write_aligned(port: &Stim, buffer: &Aligned<u32, [u8]>) {
unsafe {
let len = buffer.len();
if len == 0 {
return;
}
let split = len & !0b11;
write_words(
port,
slice::from_raw_parts(buffer.as_ptr() as *const u32, split >> 2),
);
// 3 bytes or less left
let mut left = len & 0b11;
let mut ptr = buffer.as_ptr().offset(split as isize);
// at least 2 bytes left
if left > 1 {
while !port.is_fifo_ready() {}
port.write_u16(ptr::read(ptr as *const u16));
ptr = ptr.offset(2);
left -= 2;
}
// final byte
if left == 1 {
while !port.is_fifo_ready() {}
port.write_u8(*ptr);
}
}
}
/// Writes `fmt::Arguments` to the ITM `port`
pub fn write_fmt(port: &Stim, args: fmt::Arguments) {
use core::fmt::Write;
Port(port).write_fmt(args).ok();
}
/// Writes a string to the ITM `port`
pub fn write_str(port: &Stim, string: &str) {
write_all(port, string.as_bytes())
}
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