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
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
//! Implements the `ChangeHost` feature (ID `0x1814`) that selects which host /
//! RF channel a multi-host device is connected to.
//!
//! Version 2 adds two items this module documents as reverse-engineered from
//! Logi Options+ 2.8 (`devio::Feature1814ChangeHost`), because the public
//! `x1814` specification stops before them: `getCapabilities` (function 4)
//! and the host-change announcement (event 0) that
//! [`decode_host_change_request`] decodes.
use openlogi_hidpp_derive::Feature;
use crate::{
feature::FeatureEndpoint,
protocol::v20::{self, Hidpp20Error},
};
bitflags::bitflags! {
/// Host-switching capabilities reported by [`ChangeHostFeature::get_host_info`].
#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
#[cfg_attr(feature = "serde", derive(serde::Serialize))]
pub struct ChangeHostCapabilities: u8 {
/// Enhanced host switching is enabled: on a failed connection the device
/// falls back to another host with a non-zero cookie before returning to
/// the original host.
const ENHANCED_HOST_SWITCH = 1 << 0;
}
}
bitflags::bitflags! {
/// Capabilities reported by [`ChangeHostFeature::get_capabilities`].
#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
#[cfg_attr(feature = "serde", derive(serde::Serialize))]
pub struct ChangeHostFeatureCapabilities: u8 {
/// The device announces a host change that the user starts on it,
/// before it leaves the current host (see [`decode_host_change_request`]).
///
/// REVERSE-ENGINEERED: Logi Options+ 2.8 reads bit 0 of the
/// `getCapabilities` reply. It calls a keyboard that sets the bit on
/// feature version 2 or later "firmware coupled easy switch capable",
/// and moves linked mice only for such a keyboard.
const ANNOUNCES_HOST_CHANGE = 1 << 0;
}
}
/// The first feature version that implements
/// [`ChangeHostFeature::get_capabilities`] and the host-change announcement
/// (reverse-engineered, see the module documentation).
pub const ANNOUNCEMENT_MIN_VERSION: u8 = 2;
/// A host change that the user started on the device itself. The device
/// announces it before it leaves the current host.
#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
#[cfg_attr(feature = "serde", derive(serde::Serialize))]
pub struct HostChangeRequest {
/// Zero-based host that the device leaves.
pub from: u8,
/// Zero-based host that the device switches to.
pub to: u8,
}
/// Decode a host-change announcement from `message`.
///
/// The announcement is event 0 of the `ChangeHost` feature at
/// `feature_index` on `device_index`, with software ID 0. Its first two
/// payload bytes are the source host and the destination host. Every other
/// message returns `None`. This includes the reply to
/// [`ChangeHostFeature::get_host_info`], which also uses function 0 but
/// carries the non-zero software ID of the requester.
///
/// REVERSE-ENGINEERED: Logi Options+ 2.8 decodes event 0 with at least two
/// payload bytes as `ChangeHostRequestedEvent { from: payload[0], to:
/// payload[1] }`. An MX Keys Mini on a Bolt receiver sent `[1, 0]` when the
/// user pressed its key for host 1 while it was on host 2 (OpenLogi #1717).
#[must_use]
pub fn decode_host_change_request(
message: &v20::Message,
device_index: u8,
feature_index: u8,
) -> Option<HostChangeRequest> {
let header = message.header();
if header.device_index != device_index
|| header.feature_index != feature_index
|| header.function_id.to_lo() != 0
|| header.software_id.to_lo() != 0
{
return None;
}
let payload = message.extend_payload();
Some(HostChangeRequest {
from: payload[0],
to: payload[1],
})
}
/// Host configuration returned by [`ChangeHostFeature::get_host_info`].
#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
#[cfg_attr(feature = "serde", derive(serde::Serialize))]
#[non_exhaustive]
pub struct ChangeHostInfo {
/// Number of hosts / RF channels.
pub host_count: u8,
/// Current host index, in `0..host_count`.
pub current_host: u8,
/// Host-switching capabilities.
pub capabilities: ChangeHostCapabilities,
}
/// Implements the `ChangeHost` / `0x1814` feature.
#[derive(Clone, Feature)]
#[creatable(id = 0x1814, version = 0)]
pub struct ChangeHostFeature {
/// The endpoint this feature talks to.
endpoint: FeatureEndpoint,
}
impl ChangeHostFeature {
/// Retrieves the host count, current host and host-switching flags.
pub async fn get_host_info(&self) -> Result<ChangeHostInfo, Hidpp20Error> {
let payload = self.endpoint.call(0, [0; 3]).await?.extend_payload();
Ok(ChangeHostInfo {
host_count: payload[0],
current_host: payload[1],
capabilities: ChangeHostCapabilities::from_bits_retain(payload[2]),
})
}
/// Selects `host` as the current host.
///
/// This is sent fire-and-forget: a successful switch usually resets the
/// device, so no response is awaited. The device drops off the current host
/// once it acts on the request.
pub async fn set_current_host(&self, host: u8) -> Result<(), Hidpp20Error> {
self.endpoint.notify(1, [host, 0, 0]).await
}
/// Retrieves the persistent per-host cookie bytes.
///
/// `host_count` is the value from [`ChangeHostInfo::host_count`]; the device
/// returns one cookie byte per host and does not delimit the list.
pub async fn get_cookies(&self, host_count: u8) -> Result<Vec<u8>, Hidpp20Error> {
let count = usize::from(host_count);
let payload = self.endpoint.call(2, [0; 3]).await?.extend_payload();
if count > payload.len() {
return Err(Hidpp20Error::UnsupportedResponse);
}
Ok(payload[..count].to_vec())
}
/// Writes the persistent `cookie` byte for `host`.
///
/// Cookies are arbitrary software-defined bytes stored in the device's
/// non-volatile memory; the firmware clears a host's cookie when a new host
/// connects to that slot.
pub async fn set_cookie(&self, host: u8, cookie: u8) -> Result<(), Hidpp20Error> {
self.endpoint.call(3, [host, cookie, 0]).await?;
Ok(())
}
/// Retrieves the capabilities of feature version
/// [`ANNOUNCEMENT_MIN_VERSION`] and later (`getCapabilities`, function 4).
///
/// Unknown bits are kept. Older versions do not implement the function.
pub async fn get_capabilities(&self) -> Result<ChangeHostFeatureCapabilities, Hidpp20Error> {
let payload = self.endpoint.call(4, [0; 3]).await?.extend_payload();
Ok(ChangeHostFeatureCapabilities::from_bits_retain(payload[0]))
}
}
#[cfg(test)]
mod tests {
use super::{HostChangeRequest, decode_host_change_request};
use crate::nibble::U4;
use crate::protocol::v20::{Message, MessageHeader};
fn report(device_index: u8, feature_index: u8, function: u8, software: u8) -> Message {
let header = MessageHeader {
device_index,
feature_index,
function_id: U4::from_lo(function),
software_id: U4::from_lo(software),
};
Message::Short(header, [1, 0, 0])
}
#[test]
fn decodes_the_source_host_then_the_destination_host() {
assert_eq!(
decode_host_change_request(&report(1, 4, 0, 0), 1, 4),
Some(HostChangeRequest { from: 1, to: 0 })
);
}
#[test]
fn ignores_replies_other_events_features_and_devices() {
for (message, why) in [
(
report(1, 4, 0, 1),
"a getHostInfo reply carries a software ID",
),
(report(1, 4, 1, 0), "another event of the feature"),
(report(1, 5, 0, 0), "another feature"),
(report(2, 4, 0, 0), "another device on the receiver"),
] {
assert_eq!(decode_host_change_request(&message, 1, 4), None, "{why}");
}
}
}