Split usb_report_descriptor into usb_hid_{item,usage}

This is cleaner IMO.

* usb_hid_item deals with parsing the report descriptor.
* usb_hid_usage has tables that define each usage.

Cargo.toml

@@ -1,5 +1,6 @@
 [workspace]
 members = [
-	"usb_report_descriptor",
+	"usb_hid_item",
+	"usb_hid_usage",
 	"usb_request",
 ]

README.md

@@ -2,5 +2,6 @@
 
 ## Crates
 
-* [`usb_report_descriptor`](usb_report_descriptor) item parser for HID Report descriptors.
+* [`usb_hid_item`](usb_hid_item) HID item parser for report descriptors.
+* [`usb_hid_usage`](usb_hid_usage) HID usage pages.
 * [`usb_request`](usb_request) request formatter & descriptor parser.

usb_hid_item/Cargo.toml

@@ -1,5 +1,5 @@
 [package]
-name = "usb_report_descriptor"
+name = "usb_hid_item"
 version = "0.1.0"
 edition = "2021"
 license = "MIT"

usb_hid_item/README.md

@@ -1,4 +1,4 @@
-# Report descriptor item parser
+# HID report descriptor item parser
 
 ## Example
 

usb_hid_item/src/lib.rs

@@ -1,10 +1,6 @@
 #![doc = include_str!("../README.md")]
 #![cfg_attr(not(test), no_std)]
 
-pub mod usage;
-
-pub use usage::{Usage, UsagePage};
-
 use core::fmt;
 
 #[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
@@ -16,7 +12,7 @@ pub enum Item<'a> {
     Feature(MainFlags),
     EndCollection,
 
-    UsagePage(UsagePage),
+    UsagePage(u16),
     LogicalMin(i32),
     LogicalMax(i32),
     PhysicalMin(i32),
@@ -29,9 +25,10 @@ pub enum Item<'a> {
     Push,
     Pop,
 
-    Usage(Usage),
+    Usage16(u16),
-    UsageMin(u32),
+    Usage32(u16, u16),
-    UsageMax(u32),
+    UsageMin(u16),
+    UsageMax(u16),
     DesignatorIndex(u32),
     DesignatorMin(u32),
     DesignatorMax(u32),
@@ -77,7 +74,7 @@ impl<'a> Item<'a> {
     const STRING_MAX: u8 = 0x98;
     const DELIMITER: u8 = 0xa8;
 
-    fn parse(data: &'a [u8], usage_page: u16) -> Result<(Self, &'a [u8]), ParseError> {
+    fn parse(data: &'a [u8]) -> Result<(Self, &'a [u8]), ParseError> {
         use ParseError::*;
         let prefix = *data.get(0).ok_or(Truncated)?;
         let (size, tag);
@@ -133,7 +130,7 @@ impl<'a> Item<'a> {
             Self::FEATURE => Self::Feature(MainFlags(d32u()?)),
             Self::END_COLLECTION => d_empty(Self::EndCollection)?,
 
-            Self::USAGE_PAGE => Self::UsagePage(UsagePage::from_raw(d16u()?)),
+            Self::USAGE_PAGE => Self::UsagePage(d16u()?),
             Self::LOGI_MIN => Self::LogicalMin(d32i()?),
             Self::LOGI_MAX => Self::LogicalMax(d32i()?),
             Self::PHYS_MIN => Self::PhysicalMin(d32i()?),
@@ -146,20 +143,18 @@ impl<'a> Item<'a> {
             Self::PUSH => Self::Push,
             Self::POP => Self::Pop,
 
-            Self::USAGE => Self::Usage(match d {
+            Self::USAGE => match d {
-                &[] => Usage::from_raw(usage_page, 0),
+                &[] => Self::Usage16(u16::from_le_bytes([0, 0])),
-                &[a] => Usage::from_raw(usage_page, u16::from_le_bytes([a, 0])),
+                &[a] => Self::Usage16(u16::from_le_bytes([a, 0])),
-                &[a, b] => Usage::from_raw(usage_page, u16::from_le_bytes([a, b])),
+                &[a, b] => Self::Usage16(u16::from_le_bytes([a, b])),
-                &[a, b, c] => {
+                &[a, b, c] => Self::Usage32(u16::from_le_bytes([c, 0]), u16::from_le_bytes([a, b])),
-                    Usage::from_raw(u16::from_le_bytes([c, 0]), u16::from_le_bytes([a, b]))
-                }
                 &[a, b, c, d] => {
-                    Usage::from_raw(u16::from_le_bytes([c, d]), u16::from_le_bytes([a, b]))
+                    Self::Usage32(u16::from_le_bytes([c, d]), u16::from_le_bytes([a, b]))
                 }
                 _ => return Err(UnexpectedData),
-            }),
+            },
-            Self::USAGE_MIN => Self::UsageMin(d32u()?),
+            Self::USAGE_MIN => Self::UsageMin(d16u()?),
-            Self::USAGE_MAX => Self::UsageMax(d32u()?),
+            Self::USAGE_MAX => Self::UsageMax(d16u()?),
             Self::DESIGNATOR_INDEX => Self::DesignatorIndex(d32u()?),
             Self::DESIGNATOR_MIN => Self::DesignatorMin(d32u()?),
             Self::DESIGNATOR_MAX => Self::DesignatorMax(d32u()?),
@@ -250,7 +245,6 @@ pub enum ParseError {
 
 pub struct Parser<'a> {
     data: &'a [u8],
-    usage_page: u16,
 }
 
 impl<'a> Iterator for Parser<'a> {
@@ -259,21 +253,14 @@ impl<'a> Iterator for Parser<'a> {
     fn next(&mut self) -> Option<Self::Item> {
         (!self.data.is_empty()).then(|| {
             let e;
-            (e, self.data) = Item::parse(self.data, self.usage_page)?;
+            (e, self.data) = Item::parse(self.data)?;
-            match &e {
-                Item::UsagePage(p) => self.usage_page = p.as_raw(),
-                _ => {}
-            }
             Ok(e)
         })
     }
 }
 
 pub fn parse(data: &[u8]) -> Parser<'_> {
-    Parser {
+    Parser { data }
-        data,
-        usage_page: 0,
-    }
 }
 
 #[cfg(test)]
@@ -298,12 +285,12 @@ mod tests {
     fn qemu_usb_tablet() {
         let mut it = parse(QEMU_USB_TABLET);
         let it = &mut it;
-        tk(it, Item::UsagePage(UsagePage::GenericDesktop));
+        tk(it, Item::UsagePage(0x1));
-        tk(it, Item::Usage(Usage::GenericDesktop(usage::generic_desktop::Usage::Mouse)));
+        tk(it, Item::Usage16(0x2));
         tk(it, Item::Collection(Collection::Application));
-        tk(it, Item::Usage(Usage::GenericDesktop(usage::generic_desktop::Usage::Pointer)));
+        tk(it, Item::Usage16(0x1));
         tk(it, Item::Collection(Collection::Physical));
-        tk(it, Item::UsagePage(UsagePage::Button));
+        tk(it, Item::UsagePage(0x9));
         tk(it, Item::UsageMin(1));
         tk(it, Item::UsageMax(3));
         tk(it, Item::LogicalMin(0));
@@ -314,9 +301,9 @@ mod tests {
         tk(it, Item::ReportCount(1));
         tk(it, Item::ReportSize(5));
         tk(it, Item::Input(MainFlags(0b1))); // constant
-        tk(it, Item::UsagePage(UsagePage::GenericDesktop));
+        tk(it, Item::UsagePage(1));
-        tk(it, Item::Usage(Usage::GenericDesktop(usage::generic_desktop::Usage::X)));
+        tk(it, Item::Usage16(0x30));
-        tk(it, Item::Usage(Usage::GenericDesktop(usage::generic_desktop::Usage::Y)));
+        tk(it, Item::Usage16(0x31));
         tk(it, Item::LogicalMin(0));
         tk(it, Item::LogicalMax(0x7fff));
         tk(it, Item::PhysicalMin(0));
@@ -324,8 +311,8 @@ mod tests {
         tk(it, Item::ReportSize(16));
         tk(it, Item::ReportCount(2));
         tk(it, Item::Input(MainFlags(0b010))); // absolute, variable, data
-        tk(it, Item::UsagePage(UsagePage::GenericDesktop));
+        tk(it, Item::UsagePage(1));
-        tk(it, Item::Usage(Usage::GenericDesktop(usage::generic_desktop::Usage::Wheel)));
+        tk(it, Item::Usage16(0x38));
         tk(it, Item::LogicalMin(-0x7f));
         tk(it, Item::LogicalMax(0x7f));
         tk(it, Item::PhysicalMin(0));

usb_hid_usage/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "usb_hid_usage"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

usb_hid_usage/src/button.rs

@@ -0,0 +1,17 @@
+use core::num::NonZeroU16;
+
+pub const PAGE: u16 = 0x09;
+
+#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub enum Usage {
+    NoButton,
+    Button(NonZeroU16),
+}
+
+impl TryFrom<u16> for Usage {
+    type Error = super::UnknownUsage;
+
+    fn try_from(n: u16) -> Result<Self, Self::Error> {
+        Ok(NonZeroU16::new(n).map_or(Self::NoButton, Self::Button))
+    }
+}

usb_hid_usage/src/lib.rs

@@ -0,0 +1,63 @@
+//!
+//! ## References
+//!
+//! * <https://www.usb.org/sites/default/files/hut1_3_0.pdf>
+
+#![no_std]
+
+macro_rules! usage {
+    { [$page:literal] $($i:literal $v:ident)* } => {
+        pub const PAGE: u16 = $page;
+
+        #[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
+        #[non_exhaustive]
+        pub enum Usage {
+            $($v,)*
+        }
+
+        impl TryFrom<u16> for Usage {
+            type Error = super::UnknownUsage;
+
+            fn try_from(n: u16) -> Result<Self, Self::Error> {
+                Ok(match n {
+                    $($i => Self::$v,)*
+                    _ => return Err(super::UnknownUsage),
+                })
+            }
+        }
+    };
+}
+
+macro_rules! page {
+    { $($v:ident $m:ident)* } => {
+        $(pub mod $m;)*
+
+        #[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
+        #[non_exhaustive]
+        pub enum UsagePage {
+            $($v,)*
+        }
+
+        impl TryFrom<u16> for UsagePage {
+            type Error = UnknownPage;
+
+            fn try_from(n: u16) -> Result<Self, Self::Error> {
+                Ok(match n {
+                    $($m::PAGE => Self::$v,)*
+                    _ => return Err(UnknownPage),
+                })
+            }
+        }
+    };
+}
+
+page! {
+    GenericDesktop generic_desktop
+    Button button
+}
+
+#[derive(Debug)]
+pub struct UnknownUsage;
+
+#[derive(Debug)]
+pub struct UnknownPage;

usb_report_descriptor/src/usage/button.rs

@@ -1,3 +0,0 @@
-usage! {
-    [0x09]
-}

usb_report_descriptor/src/usage/mod.rs

@@ -1,75 +0,0 @@
-//! ## References
-//!
-//! * <https://www.usb.org/sites/default/files/hut1_3_0.pdf>
-
-macro_rules! usage {
-    { [$page:literal] $($i:literal $v:ident)* } => {
-        pub const PAGE: u16 = $page;
-
-        #[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
-        #[non_exhaustive]
-        pub enum Usage {
-            $($v,)*
-            Unknown(u16),
-        }
-
-        pub(crate) fn from_raw(raw: u16) -> Usage {
-            use Usage::*;
-            match raw {
-                $($i => $v,)*
-                r => Unknown(r),
-            }
-        }
-    };
-}
-
-pub mod generic_desktop;
-pub mod button;
-
-macro_rules! page {
-    { $($v:ident $m:ident)* } => {
-        #[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
-        #[non_exhaustive]
-        pub enum UsagePage {
-            $($v,)*
-            Unknown(u16),
-        }
-
-        impl UsagePage {
-            pub(crate) fn from_raw(raw: u16) -> Self {
-                match raw {
-                    $($m::PAGE => Self::$v,)*
-                    r => Self::Unknown(r),
-                }
-            }
-
-            pub(crate) fn as_raw(&self) -> u16 {
-                match self {
-                    $(Self::$v => $m::PAGE,)*
-                    Self::Unknown(n) => *n,
-                }
-            }
-        }
-
-        #[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
-        #[non_exhaustive]
-        pub enum Usage {
-            $($v($m::Usage),)*
-            Unknown(u16, u16),
-        }
-
-        impl Usage {
-            pub(crate) fn from_raw(page: u16, id: u16) -> Self {
-                match page {
-                    $($m::PAGE => Self::$v($m::from_raw(id)),)*
-                    _ => Self::Unknown(page, id),
-                }
-            }
-        }
-    };
-}
-
-page! {
-    GenericDesktop generic_desktop
-    Button button
-}