From 467121c9621ccb70c456c53d2c62a4e0cfeace32 Mon Sep 17 00:00:00 2001
From: Guillaume Endignoux <guillaumee@google.com>
Date: Fri, 10 Jul 2020 10:11:07 +0200
Subject: [PATCH] Update third_party/libtock-drivers to support OpenSK.

---
 third_party/libtock-drivers/Cargo.toml     |  71 +--
 third_party/libtock-drivers/src/buttons.rs | 191 +++----
 third_party/libtock-drivers/src/console.rs |  99 ++--
 third_party/libtock-drivers/src/led.rs     | 161 ++----
 third_party/libtock-drivers/src/lib.rs     |  23 +-
 third_party/libtock-drivers/src/result.rs  |  68 ++-
 third_party/libtock-drivers/src/rng.rs     |  51 +-
 third_party/libtock-drivers/src/timer.rs   | 558 +++------------------
 third_party/libtock-drivers/src/util.rs    |   9 +
 9 files changed, 394 insertions(+), 837 deletions(-)
 create mode 100644 third_party/libtock-drivers/src/util.rs

diff --git a/third_party/libtock-drivers/Cargo.toml b/third_party/libtock-drivers/Cargo.toml
index f5cb932f..9f67f8c4 100644
--- a/third_party/libtock-drivers/Cargo.toml
+++ b/third_party/libtock-drivers/Cargo.toml
@@ -1,67 +1,16 @@
 [package]
-name = "libtock"
-version = "0.2.0"
-authors = ["Tock Project Developers <tock-dev@googlegroups.com>"]
+name = "libtock_drivers"
+version = "0.1.0"
+authors = [
+  "Tock Project Developers <tock-dev@googlegroups.com>"
+  "Guillaume Endignoux <guillaumee@google.com>",
+]
 license = "MIT/Apache-2.0"
 edition = "2018"
 
-[features]
-alloc = ["libtock_core/alloc"]
-custom_panic_handler = ["libtock_core/custom_panic_handler"]
-custom_alloc_error_handler = ["libtock_core/custom_alloc_error_handler"]
-__internal_disable_gpio_in_integration_test = []
-
 [dependencies]
-libtock_core = { path = "core" }
-libtock_codegen = { path = "codegen" }
-futures = { version = "0.3.1", default-features = false, features = ["unstable", "cfg-target-has-atomic"] }
-
-[dev-dependencies]
-corepack = { version = "0.4.0", default-features = false, features = ["alloc"] }
-# We pin the serde version because newer serde versions may not be compatible
-# with the nightly toolchain used by libtock-rs.
-serde = { version = "=1.0.84", default-features = false, features = ["derive"] }
-
-[[example]]
-name = "alloc_error"
-path = "examples-features/alloc_error.rs"
-required-features = ["alloc", "custom_alloc_error_handler"]
-
-[[example]]
-name = "ble_scanning"
-path = "examples-features/ble_scanning.rs"
-required-features = ["alloc"]
-
-[[example]]
-name = "libtock_test"
-path = "examples-features/libtock_test.rs"
-required-features = ["alloc"]
+libtock_core = { path = "../../third_party/libtock-rs/core" }
 
-[[example]]
-name = "panic"
-path = "examples-features/panic.rs"
-required-features = ["custom_panic_handler"]
-
-[[example]]
-name = "simple_ble"
-path = "examples-features/simple_ble.rs"
-required-features = ["alloc"]
-
-[profile.dev]
-panic = "abort"
-lto = true
-debug = true
-
-[profile.release]
-panic = "abort"
-lto = true
-debug = true
-
-[workspace]
-exclude = [ "tock" ]
-members = [
-    "codegen",
-    "core",
-    "test_runner",
-    "tools/print_sizes",
-]
+[features]
+debug_ctap = []
+verbose_usb = ["debug_ctap"]
diff --git a/third_party/libtock-drivers/src/buttons.rs b/third_party/libtock-drivers/src/buttons.rs
index aac5cb22..5ab985fc 100644
--- a/third_party/libtock-drivers/src/buttons.rs
+++ b/third_party/libtock-drivers/src/buttons.rs
@@ -1,10 +1,7 @@
-use crate::callback::CallbackSubscription;
-use crate::callback::Consumer;
-use crate::result::OtherError;
-use crate::result::OutOfRangeError;
-use crate::result::TockResult;
-use crate::syscalls;
+use crate::result::{OtherError, TockResult};
 use core::marker::PhantomData;
+use libtock_core::callback::{CallbackSubscription, Consumer};
+use libtock_core::syscalls;
 
 const DRIVER_NUMBER: usize = 0x00003;
 
@@ -19,87 +16,98 @@ mod subscribe_nr {
     pub const SUBSCRIBE_CALLBACK: usize = 0;
 }
 
-#[non_exhaustive]
-pub struct ButtonsDriverFactory;
-
-impl ButtonsDriverFactory {
-    pub fn init_driver(&mut self) -> TockResult<ButtonsDriver> {
-        let buttons_driver = ButtonsDriver {
-            num_buttons: syscalls::command(DRIVER_NUMBER, command_nr::COUNT, 0, 0)?,
-            lifetime: PhantomData,
-        };
-        Ok(buttons_driver)
-    }
+pub fn with_callback<CB>(callback: CB) -> WithCallback<CB> {
+    WithCallback { callback }
 }
 
-pub struct ButtonsDriver<'a> {
-    num_buttons: usize,
-    lifetime: PhantomData<&'a ()>,
+pub struct WithCallback<CB> {
+    callback: CB,
 }
 
-impl<'a> ButtonsDriver<'a> {
-    pub fn num_buttons(&self) -> usize {
-        self.num_buttons
+struct ButtonConsumer;
+
+impl<CB: FnMut(usize, ButtonState)> Consumer<WithCallback<CB>> for ButtonConsumer {
+    fn consume(data: &mut WithCallback<CB>, button_num: usize, state: usize, _: usize) {
+        (data.callback)(button_num, state.into());
     }
+}
 
-    /// Returns the button at 0-based index `button_num`
-    pub fn get(&self, button_num: usize) -> Result<Button, OutOfRangeError> {
-        if button_num < self.num_buttons {
-            Ok(Button {
-                button_num,
-                lifetime: PhantomData,
-            })
-        } else {
-            Err(OutOfRangeError)
-        }
+impl<CB: FnMut(usize, ButtonState)> WithCallback<CB> {
+    pub fn init(&mut self) -> TockResult<Buttons> {
+        let count = syscalls::command(DRIVER_NUMBER, command_nr::COUNT, 0, 0)?;
+
+        let subscription = syscalls::subscribe::<ButtonConsumer, _>(
+            DRIVER_NUMBER,
+            subscribe_nr::SUBSCRIBE_CALLBACK,
+            self,
+        )?;
+
+        Ok(Buttons {
+            count: count as usize,
+            subscription,
+        })
     }
+}
 
-    pub fn buttons(&self) -> Buttons {
-        Buttons {
-            num_buttons: self.num_buttons,
+pub struct Buttons<'a> {
+    count: usize,
+    #[allow(dead_code)] // Used in drop
+    subscription: CallbackSubscription<'a>,
+}
+
+#[derive(Copy, Clone, Debug)]
+pub enum ButtonsError {
+    NotSupported,
+    SubscriptionFailed,
+}
+
+impl<'a> Buttons<'a> {
+    pub fn iter_mut(&mut self) -> ButtonIter {
+        ButtonIter {
             curr_button: 0,
+            button_count: self.count,
             lifetime: PhantomData,
         }
     }
-
-    pub fn subscribe<CB: Fn(usize, ButtonState)>(
-        &self,
-        callback: &'a mut CB,
-    ) -> TockResult<CallbackSubscription> {
-        syscalls::subscribe::<ButtonsEventConsumer, _>(
-            DRIVER_NUMBER,
-            subscribe_nr::SUBSCRIBE_CALLBACK,
-            callback,
-        )
-        .map_err(Into::into)
-    }
 }
 
-struct ButtonsEventConsumer;
+#[derive(Copy, Clone, Debug)]
+pub enum ButtonState {
+    Pressed,
+    Released,
+}
 
-impl<CB: Fn(usize, ButtonState)> Consumer<CB> for ButtonsEventConsumer {
-    fn consume(callback: &mut CB, button_num: usize, button_state: usize, _: usize) {
-        let button_state = match button_state {
+impl From<usize> for ButtonState {
+    fn from(state: usize) -> ButtonState {
+        match state {
             0 => ButtonState::Released,
             1 => ButtonState::Pressed,
-            _ => return,
-        };
-        callback(button_num, button_state);
+            _ => unreachable!(),
+        }
     }
 }
 
-pub struct Buttons<'a> {
-    num_buttons: usize,
+impl<'a, 'b> IntoIterator for &'b mut Buttons<'a> {
+    type Item = ButtonHandle<'b>;
+    type IntoIter = ButtonIter<'b>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.iter_mut()
+    }
+}
+
+pub struct ButtonIter<'a> {
     curr_button: usize,
+    button_count: usize,
     lifetime: PhantomData<&'a ()>,
 }
 
-impl<'a> Iterator for Buttons<'a> {
-    type Item = Button<'a>;
+impl<'a> Iterator for ButtonIter<'a> {
+    type Item = ButtonHandle<'a>;
 
     fn next(&mut self) -> Option<Self::Item> {
-        if self.curr_button < self.num_buttons {
-            let item = Button {
+        if self.curr_button < self.button_count {
+            let item = ButtonHandle {
                 button_num: self.curr_button,
                 lifetime: PhantomData,
             };
@@ -111,57 +119,52 @@ impl<'a> Iterator for Buttons<'a> {
     }
 }
 
-#[derive(Copy, Clone, Debug, Eq, PartialEq)]
-pub enum ButtonState {
-    Pressed,
-    Released,
-}
-
-impl From<ButtonState> for bool {
-    fn from(button_state: ButtonState) -> Self {
-        match button_state {
-            ButtonState::Released => false,
-            ButtonState::Pressed => true,
-        }
-    }
-}
-
-pub struct Button<'a> {
+pub struct ButtonHandle<'a> {
     button_num: usize,
     lifetime: PhantomData<&'a ()>,
 }
 
-impl<'a> Button<'a> {
-    pub fn button_num(&self) -> usize {
-        self.button_num
-    }
-
-    pub fn read(&self) -> TockResult<ButtonState> {
-        let button_state = syscalls::command(DRIVER_NUMBER, command_nr::READ, self.button_num, 0)?;
-        match button_state {
-            0 => Ok(ButtonState::Released),
-            1 => Ok(ButtonState::Pressed),
-            _ => Err(OtherError::ButtonsDriverInvalidState.into()),
-        }
-    }
-
-    pub fn enable_interrupt(&self) -> TockResult<()> {
+impl<'a> ButtonHandle<'a> {
+    pub fn enable(&mut self) -> TockResult<Button> {
         syscalls::command(
             DRIVER_NUMBER,
             command_nr::ENABLE_INTERRUPT,
             self.button_num,
             0,
         )?;
-        Ok(())
+
+        Ok(Button { handle: self })
     }
 
-    pub fn disable_interrupt(&self) -> TockResult<()> {
+    pub fn disable(&mut self) -> TockResult<()> {
         syscalls::command(
             DRIVER_NUMBER,
             command_nr::DISABLE_INTERRUPT,
             self.button_num,
             0,
         )?;
+
         Ok(())
     }
 }
+
+pub struct Button<'a> {
+    handle: &'a ButtonHandle<'a>,
+}
+
+#[derive(Copy, Clone, Debug)]
+pub enum ButtonError {
+    ActivationFailed,
+}
+
+impl<'a> Button<'a> {
+    pub fn read(&self) -> TockResult<ButtonState> {
+        let button_state =
+            syscalls::command(DRIVER_NUMBER, command_nr::READ, self.handle.button_num, 0)?;
+        match button_state {
+            0 => Ok(ButtonState::Released),
+            1 => Ok(ButtonState::Pressed),
+            _ => Err(OtherError::ButtonsDriverInvalidState.into()),
+        }
+    }
+}
diff --git a/third_party/libtock-drivers/src/console.rs b/third_party/libtock-drivers/src/console.rs
index a94fc13a..3c93803f 100644
--- a/third_party/libtock-drivers/src/console.rs
+++ b/third_party/libtock-drivers/src/console.rs
@@ -1,11 +1,7 @@
-use crate::callback::Identity0Consumer;
-use crate::executor;
-use crate::futures;
-use crate::result::TockResult;
-use crate::syscalls;
+use crate::util;
 use core::cell::Cell;
 use core::fmt;
-use core::mem;
+use libtock_core::{callback, syscalls};
 
 const DRIVER_NUMBER: usize = 1;
 
@@ -21,62 +17,97 @@ mod allow_nr {
     pub const SHARE_BUFFER: usize = 1;
 }
 
-#[non_exhaustive]
-pub struct ConsoleDriver;
+const BUFFER_SIZE: usize = 1024;
 
-impl ConsoleDriver {
-    pub fn create_console(self) -> Console {
+pub struct Console {
+    allow_buffer: [u8; BUFFER_SIZE],
+    count_pending: usize,
+}
+
+impl Console {
+    pub fn new() -> Console {
         Console {
-            allow_buffer: [0; 64],
+            allow_buffer: [0; BUFFER_SIZE],
+            count_pending: 0,
         }
     }
-}
 
-pub struct Console {
-    allow_buffer: [u8; 64],
-}
+    fn is_empty(&self) -> bool {
+        self.count_pending == 0
+    }
 
-impl Console {
-    pub fn write<S: AsRef<[u8]>>(&mut self, text: S) -> TockResult<()> {
+    fn is_full(&self) -> bool {
+        self.allow_buffer.len() == self.count_pending
+    }
+
+    fn available_len(&self) -> usize {
+        self.allow_buffer.len() - self.count_pending
+    }
+
+    pub fn write<S: AsRef<[u8]>>(&mut self, text: S) {
         let mut not_written_yet = text.as_ref();
         while !not_written_yet.is_empty() {
-            let num_bytes_to_print = self.allow_buffer.len().min(not_written_yet.len());
-            self.allow_buffer[..num_bytes_to_print]
+            let num_bytes_to_print = self.available_len().min(not_written_yet.len());
+            self.allow_buffer[self.count_pending..(self.count_pending + num_bytes_to_print)]
                 .copy_from_slice(&not_written_yet[..num_bytes_to_print]);
-            self.flush(num_bytes_to_print)?;
+            self.count_pending += num_bytes_to_print;
+
+            if self.is_full() {
+                self.flush();
+            }
+
             not_written_yet = &not_written_yet[num_bytes_to_print..];
         }
-        Ok(())
     }
 
-    fn flush(&mut self, num_bytes_to_print: usize) -> TockResult<()> {
-        let shared_memory = syscalls::allow(
+    pub fn flush(&mut self) {
+        if self.is_empty() {
+            // Don't trigger any syscall if the buffer is empty.
+            return;
+        }
+
+        let count = self.count_pending;
+        // Clear the buffer even in case of error, to avoid an infinite loop.
+        self.count_pending = 0;
+
+        let result = syscalls::allow(
             DRIVER_NUMBER,
             allow_nr::SHARE_BUFFER,
-            &mut self.allow_buffer[..num_bytes_to_print],
-        )?;
+            &mut self.allow_buffer[..count],
+        );
+        if result.is_err() {
+            return;
+        }
 
         let is_written = Cell::new(false);
         let mut is_written_alarm = || is_written.set(true);
-        let subscription = syscalls::subscribe::<Identity0Consumer, _>(
+        let subscription = syscalls::subscribe::<callback::Identity0Consumer, _>(
             DRIVER_NUMBER,
             subscribe_nr::SET_ALARM,
             &mut is_written_alarm,
-        )?;
-
-        syscalls::command(DRIVER_NUMBER, command_nr::WRITE, num_bytes_to_print, 0)?;
+        );
+        if subscription.is_err() {
+            return;
+        }
 
-        unsafe { executor::block_on(futures::wait_until(|| is_written.get())) };
+        let result_code = syscalls::command(DRIVER_NUMBER, command_nr::WRITE, count, 0);
+        if result_code.is_err() {
+            return;
+        }
 
-        mem::drop(subscription);
-        mem::drop(shared_memory);
+        util::yieldk_for(|| is_written.get());
+    }
+}
 
-        Ok(())
+impl Drop for Console {
+    fn drop(&mut self) {
+        self.flush();
     }
 }
 
 impl fmt::Write for Console {
     fn write_str(&mut self, string: &str) -> Result<(), fmt::Error> {
-        self.write(string).map_err(|_| fmt::Error)
+        self.write(string);
+        Ok(())
     }
 }
diff --git a/third_party/libtock-drivers/src/led.rs b/third_party/libtock-drivers/src/led.rs
index c505cf94..e086fcc7 100644
--- a/third_party/libtock-drivers/src/led.rs
+++ b/third_party/libtock-drivers/src/led.rs
@@ -1,7 +1,5 @@
-use crate::result::OutOfRangeError;
-use crate::result::TockResult;
-use crate::syscalls::command;
-use core::marker::PhantomData;
+use crate::result::{OtherError, TockError, TockResult};
+use libtock_core::syscalls;
 
 const DRIVER_NUMBER: usize = 0x00002;
 
@@ -12,150 +10,75 @@ mod command_nr {
     pub const TOGGLE: usize = 3;
 }
 
-#[non_exhaustive]
-pub struct LedsDriverFactory;
-
-impl LedsDriverFactory {
-    pub fn init_driver(&mut self) -> TockResult<LedsDriver> {
-        let driver = LedsDriver {
-            num_leds: command(DRIVER_NUMBER, command_nr::COUNT, 0, 0)?,
-            lifetime: PhantomData,
-        };
-        Ok(driver)
-    }
+pub struct Led {
+    led_num: usize,
 }
 
-pub struct LedsDriver<'a> {
-    num_leds: usize,
-    lifetime: PhantomData<&'a ()>,
+pub fn count() -> TockResult<usize> {
+    let count = syscalls::command(DRIVER_NUMBER, command_nr::COUNT, 0, 0)?;
+    Ok(count)
 }
 
-impl<'a> LedsDriver<'a> {
-    pub fn num_leds(&self) -> usize {
-        self.num_leds
-    }
-
-    pub fn leds(&self) -> Leds {
-        Leds {
-            num_leds: self.num_leds,
-            curr_led: 0,
-            lifetime: PhantomData,
-        }
-    }
-
-    /// Returns the led at 0-based index `led_num`
-    pub fn get(&self, led_num: usize) -> Result<Led, OutOfRangeError> {
-        if led_num < self.num_leds {
-            Ok(Led {
-                led_num,
-                lifetime: PhantomData,
-            })
-        } else {
-            Err(OutOfRangeError)
-        }
+pub fn get(led_num: usize) -> TockResult<Led> {
+    let led_count = count()?;
+    if led_num < led_count {
+        Ok(Led { led_num })
+    } else {
+        Err(TockError::Other(OtherError::OutOfRange))
     }
 }
 
-pub struct Leds<'a> {
-    num_leds: usize,
-    curr_led: usize,
-    lifetime: PhantomData<&'a ()>,
+pub fn all() -> TockResult<LedIter> {
+    let led_count = count()?;
+    Ok(LedIter {
+        curr_led: 0,
+        led_count,
+    })
 }
 
-impl<'a> Iterator for Leds<'a> {
-    type Item = Led<'a>;
-
-    fn next(&mut self) -> Option<Self::Item> {
-        if self.curr_led < self.num_leds {
-            let item = Led {
-                led_num: self.curr_led,
-                lifetime: PhantomData,
-            };
-            self.curr_led += 1;
-            Some(item)
+impl Led {
+    pub fn set_state(&self, state: bool) -> TockResult<()> {
+        if state {
+            self.on()
         } else {
-            None
-        }
-    }
-}
-
-pub struct Led<'a> {
-    led_num: usize,
-    lifetime: PhantomData<&'a ()>,
-}
-
-impl<'a> Led<'a> {
-    pub fn led_num(&self) -> usize {
-        self.led_num
-    }
-
-    pub fn set(&self, state: impl Into<LedState>) -> TockResult<()> {
-        match state.into() {
-            LedState::On => self.on(),
-            LedState::Off => self.off(),
+            self.off()
         }
     }
 
     pub fn on(&self) -> TockResult<()> {
-        command(DRIVER_NUMBER, command_nr::ON, self.led_num, 0)?;
+        syscalls::command(DRIVER_NUMBER, command_nr::ON, self.led_num, 0)?;
         Ok(())
     }
 
     pub fn off(&self) -> TockResult<()> {
-        command(DRIVER_NUMBER, command_nr::OFF, self.led_num, 0)?;
+        syscalls::command(DRIVER_NUMBER, command_nr::OFF, self.led_num, 0)?;
         Ok(())
     }
 
     pub fn toggle(&self) -> TockResult<()> {
-        command(DRIVER_NUMBER, command_nr::TOGGLE, self.led_num, 0)?;
+        syscalls::command(DRIVER_NUMBER, command_nr::TOGGLE, self.led_num, 0)?;
         Ok(())
     }
 }
 
-#[derive(Copy, Clone, Debug, Eq, PartialEq)]
-pub enum LedState {
-    On,
-    Off,
+#[derive(Copy, Clone)]
+pub struct LedIter {
+    curr_led: usize,
+    led_count: usize,
 }
 
-impl From<bool> for LedState {
-    fn from(from_value: bool) -> Self {
-        if from_value {
-            LedState::On
+impl Iterator for LedIter {
+    type Item = Led;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        if self.curr_led < self.led_count {
+            let item = Led {
+                led_num: self.curr_led,
+            };
+            self.curr_led += 1;
+            Some(item)
         } else {
-            LedState::Off
+            None
         }
     }
 }
-
-#[cfg(test)]
-mod test {
-    use super::command_nr;
-    use super::DRIVER_NUMBER;
-    use crate::result::TockResult;
-    use crate::syscalls;
-    use crate::syscalls::raw::Event;
-
-    #[test]
-    pub fn single_led_can_be_enabled() {
-        let events = syscalls::raw::run_recording_events::<TockResult<()>, _>(|next_return| {
-            let mut drivers = unsafe { crate::drivers::retrieve_drivers_unsafe() };
-
-            next_return.set(1);
-
-            let leds_driver = drivers.leds.init_driver()?;
-            next_return.set(0);
-
-            let led = leds_driver.get(0)?;
-            led.on()?;
-            Ok(())
-        });
-        assert_eq!(
-            events,
-            vec![
-                Event::Command(DRIVER_NUMBER, command_nr::COUNT, 0, 0),
-                Event::Command(DRIVER_NUMBER, command_nr::ON, 0, 0),
-            ]
-        );
-    }
-}
diff --git a/third_party/libtock-drivers/src/lib.rs b/third_party/libtock-drivers/src/lib.rs
index eb13b94f..bf62d051 100644
--- a/third_party/libtock-drivers/src/lib.rs
+++ b/third_party/libtock-drivers/src/lib.rs
@@ -1,25 +1,10 @@
-#![cfg_attr(not(test), no_std)]
+#![no_std]
 
-pub mod adc;
-pub mod ble_composer;
-pub mod ble_parser;
 pub mod buttons;
 pub mod console;
-pub mod debug;
-pub mod drivers;
-pub mod electronics;
-pub mod executor;
-pub mod futures;
-pub mod gpio;
-pub mod hmac;
-pub mod leds;
+pub mod led;
 pub mod result;
 pub mod rng;
-pub mod sensors;
-pub mod simple_ble;
-pub mod temperature;
 pub mod timer;
-
-pub use drivers::retrieve_drivers;
-pub use libtock_codegen::main;
-pub use libtock_core::*;
+pub mod usb_ctap_hid;
+pub mod util;
diff --git a/third_party/libtock-drivers/src/result.rs b/third_party/libtock-drivers/src/result.rs
index 84af6bfd..5021c3aa 100644
--- a/third_party/libtock-drivers/src/result.rs
+++ b/third_party/libtock-drivers/src/result.rs
@@ -4,6 +4,32 @@ pub use libtock_core::result::*;
 
 pub type TockResult<T> = Result<T, TockError>;
 
+// We sometimes need to handle errors in a `TockResult` by calling `unwrap`. However,
+// `Result::unwrap` requires that the error type implements `core::fmt::Debug`. Under the hood,
+// this requires dynamic dispatch, which has non-negligible overhead on code size. Therefore errors
+// don't derive from `Debug` in libtock-rs.
+//
+// Instead one can call `.ok().unwrap()` which relies on `Option::unwrap` and doesn't require any
+// debugging of the error type.
+//
+// This trait allows to flexibly use `Result::unwrap` or `Option::unwrap` and is configured to do
+// so depending on the `debug_ctap` feature.
+pub trait FlexUnwrap<T> {
+    fn flex_unwrap(self) -> T;
+}
+
+impl<T> FlexUnwrap<T> for TockResult<T> {
+    #[cfg(feature = "debug_ctap")]
+    fn flex_unwrap(self) -> T {
+        self.unwrap()
+    }
+
+    #[cfg(not(feature = "debug_ctap"))]
+    fn flex_unwrap(self) -> T {
+        self.ok().unwrap()
+    }
+}
+
 #[derive(Copy, Clone)]
 pub enum TockError {
     Subscribe(SubscribeError),
@@ -13,10 +39,47 @@ pub enum TockError {
     Other(OtherError),
 }
 
-#[cfg(not(any(target_arch = "arm", target_arch = "riscv32")))]
+#[cfg(feature = "debug_ctap")]
 impl core::fmt::Debug for TockError {
     fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
-        writeln!(f, "impl Debug only for test builds")
+        match self {
+            TockError::Subscribe(SubscribeError {
+                driver_number,
+                subscribe_number,
+                return_code,
+            }) => f
+                .debug_struct("SubscribeError")
+                .field("driver", driver_number)
+                .field("subscribe", subscribe_number)
+                .field("return_code", return_code)
+                .finish(),
+            TockError::Command(CommandError {
+                driver_number,
+                command_number,
+                arg1,
+                arg2,
+                return_code,
+            }) => f
+                .debug_struct("CommandError")
+                .field("driver", driver_number)
+                .field("command", command_number)
+                .field("arg1", arg1)
+                .field("arg2", arg2)
+                .field("return_code", return_code)
+                .finish(),
+            TockError::Allow(AllowError {
+                driver_number,
+                allow_number,
+                return_code,
+            }) => f
+                .debug_struct("AllowError")
+                .field("driver", driver_number)
+                .field("allow", allow_number)
+                .field("return_code", return_code)
+                .finish(),
+            TockError::Format => f.write_str("TockError::Format"),
+            TockError::Other(e) => e.fmt(f),
+        }
     }
 }
 
@@ -45,6 +108,7 @@ impl From<fmt::Error> for TockError {
 }
 
 #[derive(Copy, Clone)]
+#[cfg_attr(feature = "debug_ctap", derive(Debug))]
 pub enum OtherError {
     ButtonsDriverInvalidState,
     GpioDriverInvalidState,
diff --git a/third_party/libtock-drivers/src/rng.rs b/third_party/libtock-drivers/src/rng.rs
index 039fa776..96ae953c 100644
--- a/third_party/libtock-drivers/src/rng.rs
+++ b/third_party/libtock-drivers/src/rng.rs
@@ -1,9 +1,6 @@
-use crate::callback::Identity0Consumer;
-use crate::futures;
-use crate::result::TockResult;
-use crate::syscalls;
+use crate::util;
 use core::cell::Cell;
-use core::mem;
+use libtock_core::{callback, syscalls};
 
 const DRIVER_NUMBER: usize = 0x40001;
 
@@ -19,24 +16,30 @@ mod allow_nr {
     pub const SHARE_BUFFER: usize = 0;
 }
 
-#[non_exhaustive]
-pub struct RngDriver;
-
-impl RngDriver {
-    pub async fn fill_buffer(&mut self, buf: &mut [u8]) -> TockResult<()> {
-        let buf_len = buf.len();
-        let shared_memory = syscalls::allow(DRIVER_NUMBER, allow_nr::SHARE_BUFFER, buf)?;
-        let is_filled = Cell::new(false);
-        let mut is_filled_alarm = || is_filled.set(true);
-        let subscription = syscalls::subscribe::<Identity0Consumer, _>(
-            DRIVER_NUMBER,
-            subscribe_nr::BUFFER_FILLED,
-            &mut is_filled_alarm,
-        )?;
-        syscalls::command(DRIVER_NUMBER, command_nr::REQUEST_RNG, buf_len, 0)?;
-        futures::wait_until(|| is_filled.get()).await;
-        mem::drop(subscription);
-        mem::drop(shared_memory);
-        Ok(())
+pub fn fill_buffer(buf: &mut [u8]) -> bool {
+    let buf_len = buf.len();
+
+    let result = syscalls::allow(DRIVER_NUMBER, allow_nr::SHARE_BUFFER, buf);
+    if result.is_err() {
+        return false;
+    }
+
+    let is_filled = Cell::new(false);
+    let mut is_filled_alarm = || is_filled.set(true);
+    let subscription = syscalls::subscribe::<callback::Identity0Consumer, _>(
+        DRIVER_NUMBER,
+        subscribe_nr::BUFFER_FILLED,
+        &mut is_filled_alarm,
+    );
+    if subscription.is_err() {
+        return false;
     }
+
+    let result_code = syscalls::command(DRIVER_NUMBER, command_nr::REQUEST_RNG, buf_len, 0);
+    if result_code.is_err() {
+        return false;
+    }
+
+    util::yieldk_for(|| is_filled.get());
+    return true;
 }
diff --git a/third_party/libtock-drivers/src/timer.rs b/third_party/libtock-drivers/src/timer.rs
index 946c6e5f..f3faadd5 100644
--- a/third_party/libtock-drivers/src/timer.rs
+++ b/third_party/libtock-drivers/src/timer.rs
@@ -1,17 +1,12 @@
-//! Async timer driver. Can be used for (non-busy)  sleeping.
-
-use crate::callback::CallbackSubscription;
-use crate::callback::Consumer;
-use crate::futures;
-use crate::result::OtherError;
-use crate::result::TockError;
-use crate::result::TockResult;
-use crate::result::EALREADY;
-use crate::syscalls;
+use crate::result::{FlexUnwrap, OtherError, TockError, TockResult};
+use crate::util;
 use core::cell::Cell;
 use core::isize;
 use core::marker::PhantomData;
 use core::ops::{Add, AddAssign, Sub};
+use libtock_core::callback::{CallbackSubscription, Consumer};
+use libtock_core::result::{CommandError, EALREADY};
+use libtock_core::syscalls;
 
 const DRIVER_NUMBER: usize = 0x00000;
 
@@ -27,6 +22,33 @@ mod subscribe_nr {
     pub const SUBSCRIBE_CALLBACK: usize = 0;
 }
 
+pub fn sleep(duration: Duration<isize>) -> TockResult<()> {
+    let expired = Cell::new(false);
+    let mut with_callback = with_callback(|_, _| expired.set(true));
+
+    let mut timer = with_callback.init().flex_unwrap();
+    let timer_alarm = timer.set_alarm(duration).flex_unwrap();
+
+    util::yieldk_for(|| expired.get());
+
+    match timer.stop_alarm(timer_alarm) {
+        Ok(())
+        | Err(TockError::Command(CommandError {
+            return_code: EALREADY,
+            ..
+        })) => Ok(()),
+        Err(e) => Err(e),
+    }
+}
+
+pub fn with_callback<CB>(callback: CB) -> WithCallback<'static, CB> {
+    WithCallback {
+        callback,
+        clock_frequency: ClockFrequency { hz: 0 },
+        phantom: PhantomData,
+    }
+}
+
 pub struct WithCallback<'a, CB> {
     callback: CB,
     clock_frequency: ClockFrequency,
@@ -136,13 +158,13 @@ impl<'a> Timer<'a> {
     }
 }
 
-#[derive(Copy, Clone, Debug)]
+#[derive(Copy, Clone, Debug, PartialEq)]
 pub struct ClockFrequency {
     hz: usize,
 }
 
 impl ClockFrequency {
-    pub fn hz(self) -> usize {
+    pub fn hz(&self) -> usize {
         self.hz
     }
 }
@@ -154,21 +176,53 @@ pub struct ClockValue {
 }
 
 impl ClockValue {
-    pub fn num_ticks(self) -> isize {
+    pub const fn new(num_ticks: isize, clock_hz: usize) -> ClockValue {
+        ClockValue {
+            num_ticks,
+            clock_frequency: ClockFrequency { hz: clock_hz },
+        }
+    }
+
+    pub fn num_ticks(&self) -> isize {
         self.num_ticks
     }
 
-    pub fn ms(self) -> isize {
-        if self.num_ticks.abs() < isize::MAX / 1000 {
-            (1000 * self.num_ticks) / self.clock_frequency.hz() as isize
-        } else {
-            1000 * (self.num_ticks / self.clock_frequency.hz() as isize)
-        }
+    // Computes (value * factor) / divisor, even when value * factor >= isize::MAX.
+    fn scale_int(value: isize, factor: isize, divisor: isize) -> isize {
+        // As long as isize is not i64, this should be fine. If not, this is an alternative:
+        // factor * (value / divisor) + ((value % divisor) * factor) / divisor
+        ((value as i64 * factor as i64) / divisor as i64) as isize
     }
 
-    pub fn ms_f64(self) -> f64 {
+    pub fn ms(&self) -> isize {
+        ClockValue::scale_int(self.num_ticks, 1000, self.clock_frequency.hz() as isize)
+    }
+
+    pub fn ms_f64(&self) -> f64 {
         1000.0 * (self.num_ticks as f64) / (self.clock_frequency.hz() as f64)
     }
+
+    pub fn wrapping_add(self, duration: Duration<isize>) -> ClockValue {
+        // This is a precision preserving formula for scaling an isize.
+        let duration_ticks =
+            ClockValue::scale_int(duration.ms, self.clock_frequency.hz() as isize, 1000);
+        ClockValue {
+            num_ticks: self.num_ticks.wrapping_add(duration_ticks),
+            clock_frequency: self.clock_frequency,
+        }
+    }
+
+    pub fn wrapping_sub(self, other: ClockValue) -> Option<Duration<isize>> {
+        if self.clock_frequency == other.clock_frequency {
+            let clock_duration = ClockValue {
+                num_ticks: self.num_ticks - other.num_ticks,
+                clock_frequency: self.clock_frequency,
+            };
+            Some(Duration::from_ms(clock_duration.ms()))
+        } else {
+            None
+        }
+    }
 }
 
 pub struct Alarm {
@@ -278,467 +332,3 @@ where
         self.ms += duration.ms();
     }
 }
-
-#[derive(Copy, Clone, Default, PartialEq, Eq)]
-pub(crate) struct ActiveTimer {
-    instant: u32,
-    set_at: u32,
-}
-
-/// Context for the time driver.
-/// You can create a context as follows:
-/// ```no_run
-/// # use libtock::result::TockResult;
-/// # async fn doc() -> TockResult<()> {
-/// let mut drivers = libtock::retrieve_drivers()?;
-/// let mut timer_context = drivers.timer;
-/// # Ok(())
-/// # }
-/// ```
-#[non_exhaustive]
-pub struct DriverContext {
-    pub(crate) active_timer: Cell<Option<ActiveTimer>>,
-}
-
-impl DriverContext {
-    /// Create a driver timer from a context.
-    pub fn create_timer_driver(&mut self) -> TimerDriver {
-        TimerDriver {
-            callback: Callback,
-            context: self,
-        }
-    }
-
-    pub fn with_callback<CB>(&mut self, callback: CB) -> WithCallback<CB> {
-        WithCallback {
-            callback,
-            clock_frequency: ClockFrequency { hz: 0 },
-            phantom: PhantomData,
-        }
-    }
-}
-
-/// Timer driver instance. You can create a TimerDriver from a DriverContext as follows:
-/// ```no_run
-/// # use libtock::result::TockResult;
-/// # async fn doc() -> TockResult<()> {
-/// # let mut drivers = libtock::retrieve_drivers()?;
-/// # let mut timer_context = drivers.timer;
-/// let mut timer_driver = timer_context.create_timer_driver();
-/// let timer_driver = timer_driver.activate()?;
-/// # Ok(())
-/// # }
-/// ```
-pub struct TimerDriver<'a> {
-    callback: Callback,
-    context: &'a DriverContext,
-}
-
-struct Callback;
-
-struct ParallelTimerConsumer;
-
-impl<'a> Consumer<Callback> for ParallelTimerConsumer {
-    fn consume(_: &mut Callback, _: usize, _: usize, _: usize) {}
-}
-
-/// Activated time driver. Updates current time in the context and manages
-/// active alarms.
-/// Example usage (sleep for 1 second):
-/// ```no_run
-/// # use libtock::result::TockResult;
-/// # use libtock::timer::Duration;
-/// # async fn doc() -> TockResult<()> {
-/// # let mut drivers = libtock::retrieve_drivers()?;
-/// # let mut timer_driver = drivers.timer.create_timer_driver();
-/// let timer_driver = timer_driver.activate()?;
-/// timer_driver.sleep(Duration::from_ms(1000)).await?;
-/// # Ok(())
-/// # }
-/// ```
-pub struct ParallelSleepDriver<'a> {
-    _callback_subscription: CallbackSubscription<'a>,
-    context: &'a DriverContext,
-}
-
-impl<'a> TimerDriver<'a> {
-    /// Activate the timer driver, will return a ParallelSleepDriver which
-    /// can used to sleep.
-    pub fn activate(&'a mut self) -> TockResult<ParallelSleepDriver<'a>> {
-        let subscription = syscalls::subscribe::<ParallelTimerConsumer, _>(
-            DRIVER_NUMBER,
-            subscribe_nr::SUBSCRIBE_CALLBACK,
-            &mut self.callback,
-        )?;
-        let driver = ParallelSleepDriver {
-            _callback_subscription: subscription,
-            context: &self.context,
-        };
-        Ok(driver)
-    }
-}
-
-impl<'a> ParallelSleepDriver<'a> {
-    /// Sleep for the given duration
-    pub async fn sleep(&self, duration: Duration<usize>) -> TockResult<()> {
-        let now = get_current_ticks()?;
-        let freq = get_clock_frequency()?;
-        let alarm_instant = Self::compute_alarm_instant(duration.ms, now, freq)?;
-        let this_alarm = ActiveTimer {
-            instant: alarm_instant as u32,
-            set_at: now as u32,
-        };
-
-        let suspended_timer: Cell<Option<ActiveTimer>> = Cell::new(None);
-
-        futures::wait_until(|| {
-            self.activate_current_timer(this_alarm, &suspended_timer)
-                .unwrap_or(false)
-        })
-        .await;
-
-        Ok(())
-    }
-
-    fn activate_timer(&self, timer: ActiveTimer) -> TockResult<()> {
-        set_alarm_at(timer.instant as usize)?;
-        let now = get_current_ticks()?;
-        if !is_over(timer, now as u32) {
-            self.context.active_timer.set(Some(timer));
-        } else {
-            self.wakeup_soon()?;
-        }
-        Ok(())
-    }
-
-    fn wakeup_soon(&self) -> TockResult<()> {
-        self.context.active_timer.set(None);
-
-        for i in 0.. {
-            let now = get_current_ticks()?;
-
-            let next_timer = ActiveTimer {
-                instant: now as u32 + i,
-                set_at: now as u32,
-            };
-            set_alarm_at(next_timer.instant as usize)?;
-            let now = get_current_ticks()?;
-            if !is_over(next_timer, now as u32) {
-                break;
-            } else {
-                stop_alarm_at(next_timer.instant as usize)?;
-            }
-        }
-        Ok(())
-    }
-
-    fn compute_alarm_instant(
-        duration_ms: usize,
-        num_ticks: usize,
-        freq: usize,
-    ) -> TockResult<usize> {
-        let ticks = match duration_ms.checked_mul(freq) {
-            Some(x) => x / 1000,
-            None => {
-                // Divide the largest of the two operands by 1000, to improve precision of the
-                // result.
-                if duration_ms > freq {
-                    match (duration_ms / 1000).checked_mul(freq) {
-                        Some(y) => y,
-                        None => {
-                            return Err(TockError::Other(OtherError::TimerDriverDurationOutOfRange))
-                        }
-                    }
-                } else {
-                    match (freq / 1000).checked_mul(duration_ms) {
-                        Some(y) => y,
-                        None => {
-                            return Err(TockError::Other(OtherError::TimerDriverDurationOutOfRange))
-                        }
-                    }
-                }
-            }
-        };
-        let alarm_instant = num_ticks + ticks;
-        Ok(alarm_instant)
-    }
-
-    fn activate_current_timer(
-        &self,
-        this_alarm: ActiveTimer,
-        suspended_timer: &Cell<Option<ActiveTimer>>,
-    ) -> TockResult<bool> {
-        let now = get_current_ticks()?;
-
-        if let Some(active) = self.context.active_timer.get() {
-            if left_is_later(active, this_alarm) {
-                suspended_timer.set(Some(active));
-                self.activate_timer(this_alarm)?;
-            }
-        } else {
-            self.activate_timer(this_alarm)?;
-        }
-        if is_over(this_alarm, now as u32) {
-            if let Some(paused) = suspended_timer.get() {
-                self.activate_timer(paused)?;
-            } else {
-                self.context.active_timer.set(None);
-            }
-            Ok(true)
-        } else {
-            Ok(false)
-        }
-    }
-}
-
-fn get_current_ticks() -> TockResult<usize> {
-    syscalls::command(DRIVER_NUMBER, command_nr::GET_CLOCK_VALUE, 0, 0).map_err(|err| err.into())
-}
-fn set_alarm_at(instant: usize) -> TockResult<()> {
-    syscalls::command(DRIVER_NUMBER, command_nr::SET_ALARM, instant, 0)
-        .map(|_| ())
-        .map_err(|err| err.into())
-}
-
-fn stop_alarm_at(instant: usize) -> TockResult<()> {
-    match syscalls::command(DRIVER_NUMBER, command_nr::STOP_ALARM, instant, 0) {
-        Ok(_) => Ok(()),
-        Err(error) => match error.return_code {
-            EALREADY => Ok(()),
-            _ => Err(TockError::Command(error)),
-        },
-    }
-}
-
-fn get_clock_frequency() -> TockResult<usize> {
-    syscalls::command(DRIVER_NUMBER, command_nr::GET_CLOCK_FREQUENCY, 0, 0)
-        .map_err(|err| err.into())
-}
-
-fn is_over(timer: ActiveTimer, now: u32) -> bool {
-    now.wrapping_sub(timer.set_at) >= timer.instant.wrapping_sub(timer.set_at)
-}
-
-fn left_is_later(alarm_1: ActiveTimer, alarm_2: ActiveTimer) -> bool {
-    if alarm_1.set_at <= alarm_1.instant && alarm_2.set_at <= alarm_2.instant {
-        return alarm_1.instant > alarm_2.instant;
-    }
-    if alarm_1.set_at <= alarm_1.instant && alarm_2.set_at >= alarm_2.instant {
-        return false;
-    }
-    if alarm_1.set_at >= alarm_1.instant && alarm_2.set_at <= alarm_2.instant {
-        return true;
-    }
-    if alarm_1.set_at >= alarm_1.instant && alarm_2.set_at >= alarm_2.instant {
-        return alarm_1.instant > alarm_2.instant;
-    }
-    false
-}
-
-#[cfg(test)]
-mod test {
-    use super::*;
-    #[test]
-    pub fn duration_bigger_than_frequency() {
-        let x = ParallelSleepDriver::compute_alarm_instant(10000, 0, 1000)
-            .ok()
-            .unwrap();
-        assert_eq!(x, 10000);
-    }
-
-    #[test]
-    pub fn frequency_bigger_than_duration() {
-        let x = ParallelSleepDriver::compute_alarm_instant(1000, 0, 10000)
-            .ok()
-            .unwrap();
-        assert_eq!(x, 10000);
-    }
-
-    #[test]
-    pub fn fails_if_duration_is_too_large() {
-        let x =
-            ParallelSleepDriver::compute_alarm_instant(core::usize::MAX, 0, core::usize::MAX - 1);
-        assert!(x.is_err());
-    }
-
-    #[test]
-    pub fn fails_if_frequency_is_too_large() {
-        let x =
-            ParallelSleepDriver::compute_alarm_instant(core::usize::MAX - 1, 0, core::usize::MAX);
-        assert!(x.is_err());
-    }
-
-    #[test]
-    pub fn alarm_before_systick_wrap_expired() {
-        assert_eq!(
-            super::is_over(
-                super::ActiveTimer {
-                    instant: 2u32,
-                    set_at: 1u32
-                },
-                3u32
-            ),
-            true
-        );
-    }
-
-    #[test]
-    pub fn alarm_before_systick_wrap_not_expired() {
-        assert_eq!(
-            super::is_over(
-                super::ActiveTimer {
-                    instant: 3u32,
-                    set_at: 1u32
-                },
-                2u32
-            ),
-            false
-        );
-    }
-
-    #[test]
-    pub fn alarm_after_systick_wrap_expired() {
-        assert_eq!(
-            super::is_over(
-                super::ActiveTimer {
-                    instant: 1u32,
-                    set_at: 3u32
-                },
-                2u32
-            ),
-            true
-        );
-    }
-
-    #[test]
-    pub fn alarm_after_systick_wrap_time_before_systick_wrap_not_expired() {
-        assert_eq!(
-            super::is_over(
-                super::ActiveTimer {
-                    instant: 1u32,
-                    set_at: 3u32
-                },
-                4u32
-            ),
-            false
-        );
-    }
-
-    #[test]
-    pub fn alarm_after_systick_wrap_time_after_systick_wrap_not_expired() {
-        assert_eq!(
-            super::is_over(
-                super::ActiveTimer {
-                    instant: 1u32,
-                    set_at: 3u32
-                },
-                0u32
-            ),
-            false
-        );
-    }
-
-    #[test]
-    pub fn left_later_than_the_other_both_not_wrapped() {
-        let later = super::ActiveTimer {
-            instant: 3u32,
-            set_at: 1u32,
-        };
-        let earlier = super::ActiveTimer {
-            instant: 2u32,
-            set_at: 1u32,
-        };
-        assert_eq!(super::left_is_later(later, earlier), true);
-    }
-
-    #[test]
-    pub fn right_later_than_the_other_both_not_wrapped() {
-        let later = super::ActiveTimer {
-            instant: 2u32,
-            set_at: 1u32,
-        };
-        let earlier = super::ActiveTimer {
-            instant: 3u32,
-            set_at: 1u32,
-        };
-        assert_eq!(super::left_is_later(later, earlier), false);
-    }
-
-    #[test]
-    pub fn left_later_left_wrapped() {
-        let later = super::ActiveTimer {
-            instant: 1u32,
-            set_at: 3u32,
-        };
-        let earlier = super::ActiveTimer {
-            instant: 2u32,
-            set_at: 1u32,
-        };
-        assert_eq!(super::left_is_later(later, earlier), true);
-    }
-
-    #[test]
-    pub fn right_later_right_wrapped() {
-        let later = super::ActiveTimer {
-            instant: 3u32,
-            set_at: 1u32,
-        };
-        let earlier = super::ActiveTimer {
-            instant: 1u32,
-            set_at: 3u32,
-        };
-        assert_eq!(super::left_is_later(later, earlier), false);
-    }
-
-    #[test]
-    pub fn left_later_both_wrapped() {
-        let later = super::ActiveTimer {
-            instant: 2u32,
-            set_at: 3u32,
-        };
-        let earlier = super::ActiveTimer {
-            instant: 1u32,
-            set_at: 3u32,
-        };
-        assert_eq!(super::left_is_later(later, earlier), true);
-    }
-
-    #[test]
-    pub fn right_later_both_wrapped() {
-        let later = super::ActiveTimer {
-            instant: 1u32,
-            set_at: 3u32,
-        };
-        let earlier = super::ActiveTimer {
-            instant: 2u32,
-            set_at: 3u32,
-        };
-        assert_eq!(super::left_is_later(later, earlier), false);
-    }
-
-    #[test]
-    pub fn inequality_is_strict() {
-        let later = super::ActiveTimer {
-            instant: 2u32,
-            set_at: 1u32,
-        };
-        let earlier = super::ActiveTimer {
-            instant: 2u32,
-            set_at: 1u32,
-        };
-        assert_eq!(super::left_is_later(later, earlier), false);
-    }
-
-    #[test]
-    pub fn inequality_is_strict_wrapped() {
-        let later = super::ActiveTimer {
-            instant: 1u32,
-            set_at: 2u32,
-        };
-        let earlier = super::ActiveTimer {
-            instant: 1u32,
-            set_at: 2u32,
-        };
-        assert_eq!(super::left_is_later(later, earlier), false);
-    }
-}
diff --git a/third_party/libtock-drivers/src/util.rs b/third_party/libtock-drivers/src/util.rs
new file mode 100644
index 00000000..dee7943d
--- /dev/null
+++ b/third_party/libtock-drivers/src/util.rs
@@ -0,0 +1,9 @@
+use libtock_core::syscalls;
+
+pub fn yieldk_for<F: Fn() -> bool>(cond: F) {
+    while !cond() {
+        unsafe {
+            syscalls::raw::yieldk();
+        }
+    }
+}