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//! GET WINDOW, SET WINDOW and SCAN. Sections 2-9, 2-10 and 2-7
use super::{MOVE_TIMEOUT, PROBE_TIMEOUT, Session, malformed};
use crate::{
error::Error,
protocol::{
caps::set_window::ScanKind,
cdbs::{GetWindow, Scan, SetWindow},
data::{CooperativeAction, Rect},
image::Layout,
window::{self, GetWindowHeader, SetWindowHeader, Window},
},
transport::Data,
};
use tracing::*;
impl Session {
/// One GET WINDOW, exactly as asked: header plus descriptors, unparsed
fn get_window_raw(&mut self, cmd: GetWindow) -> Result<Vec<u8>, Error> {
let mut buf = vec![0u8; cmd.allocation_length()];
let completion = self.run(&cmd.cdb(), Data::In(&mut buf), PROBE_TIMEOUT)?;
buf.truncate(completion.transferred);
Ok(buf)
}
/// Read back every window descriptor the unit currently holds
///
/// Two passes: a transfer longer than what is there gets refused, so the
/// header has to say how much there is first
pub fn windows(&mut self) -> Result<Vec<Window>, Error> {
let probe = self.get_window_raw(GetWindow::all(window::HEADER as u32))?;
let (probe, _) =
GetWindowHeader::from_bytes(&probe).map_err(|e| malformed(e.to_string()))?;
let data = self.get_window_raw(GetWindow::all(2 + u32::from(probe.data_length)))?;
let (header, descriptors) =
GetWindowHeader::from_bytes(&data).map_err(|e| malformed(e.to_string()))?;
let stride = usize::from(header.descriptor_length);
debug!(stride, bytes = descriptors.len(), "window descriptors");
if stride < window::LENGTH {
return Err(malformed(format!(
"descriptor stride of {stride} is shorter than the {} bytes 2-10-3 defines",
window::LENGTH
)));
}
descriptors
.chunks_exact(stride)
.map(|d| Window::try_from(d).map_err(|e| malformed(e.to_string())))
.collect()
}
/// Whether the stage has to home before it can reach this window
///
/// Only an image window sits in a frame; a thumbnail spans everything. With
/// no table read or written there is nothing to judge against
fn homes_to_reach(&self, window: &Window) -> bool {
if !window.scanning_kind.contains(ScanKind::IMAGE) {
return false;
}
let Some(frames) = self.frames().filter(|f| !f.frames.is_empty()) else {
return false;
};
let (left, top) = window.origin;
frames
.holding(Rect {
top,
left,
bottom: top + window.size.1,
right: left + window.size.0,
})
.is_none()
}
/// Define one window, which is also what moves the stage
///
/// An image window inside a known frame steps straight to it; one no frame
/// holds sends the mechanism out to its home stop first. The unit takes it
/// either way and the image is the same, so this says so rather than refusing
pub fn set_window(&mut self, window: &Window) -> Result<(), Error> {
window.validate(&self.caps)?;
if self.homes_to_reach(window) {
warn!(
id = window.id,
?window.origin,
?window.size,
"no frame holds this window, so the stage will home to reach it"
);
}
let header = SetWindowHeader {
descriptor_length: window::LENGTH as u16,
};
let mut payload = Vec::with_capacity(window::HEADER + window::LENGTH);
payload.extend_from_slice(&header.to_bytes());
payload.extend_from_slice(&window.to_bytes());
let cmd = SetWindow::new(payload.len() as u32);
debug!(
id = window.id,
?window.origin,
?window.size,
"setting window"
);
// The descriptor is the one place a pass's geometry actually lives, so
// it is what a capture of another driver has to be compared against
if enabled!(Level::TRACE) {
let hex: Vec<String> = payload.iter().map(|b| format!("{b:02X}")).collect();
trace!(id = window.id, bytes = hex.join(" "), "set window payload");
}
// setting windows is not a cooperative action
self.transport
.execute(&cmd.cdb(), Data::Out(&payload), MOVE_TIMEOUT)?;
Ok(())
}
/// Scan the windows named, and hand back what it will produce
///
/// 2-7: the unit answers, then scans, so this returns once it has started
/// and [`test_unit_ready`](Session::test_unit_ready) says when the data is
/// there.
///
/// A cooperative request is not a blocker. The captures read the
/// `DataType::Cooperation` record and
/// send SCAN again with nothing in between: it says what the host will owe
/// the *data*, not what has to happen before the scan runs. Whatever it
/// asks for comes back on [`Started::cooperations`] for the caller to honor
/// once the image is read.
pub fn scan(&mut self, windows: &[Window]) -> Result<Started, Error> {
// Checks every rule spanning the set on the way
let ids: Vec<u8> = windows.iter().map(|w| w.id).collect();
let cmd = Scan::new(ids.len() as u8);
debug!("scan cmd {:02x?}", &cmd.cdb());
// 2-7: the unit answers, then asks what the host will owe the data.
// `run_handshake` reads the `DataType::Cooperation` record, sends SCAN
// again with nothing in between, and hands the record back so the
// caller can honor it once the image is read
let (_, cooperations) = self.run_handshake(&cmd.cdb(), Data::Out(&ids), MOVE_TIMEOUT)?;
debug!(?ids, ?cooperations, "scanning");
let truncation = cooperations.iter().find_map(|c| match c {
CooperativeAction::Truncate(t) => Some(t),
_ => None,
});
let mut layout = Layout::new(&self.caps, windows, self.divisor, truncation)?;
layout.multiline_registered = CooperativeAction::any_multiline_registration(&cooperations);
Ok(Started {
layout,
cooperations,
})
}
}
/// A scan that has started
#[derive(Debug, Clone)]
pub struct Started {
/// What the stream will look like
pub layout: Layout,
/// What the unit asked the host to do with the data, if anything. Reading
/// the record is what lets the scan proceed; honoring it is the caller's
pub cooperations: Vec<CooperativeAction>,
}