From d36cac1a33e2d895305e7f0af27636d6d469c5f5 Mon Sep 17 00:00:00 2001
From: Mirna <mshetairy@google.com>
Date: Mon, 12 Oct 2020 11:07:57 +0200
Subject: [PATCH 01/19] Add NFC example application

---
 deploy.py             |  7 +++++++
 examples/nfct_test.rs | 20 ++++++++++++++++++++
 2 files changed, 27 insertions(+)
 create mode 100644 examples/nfct_test.rs

diff --git a/deploy.py b/deploy.py
index 5598797..b1a1de8 100755
--- a/deploy.py
+++ b/deploy.py
@@ -921,6 +921,13 @@ if __name__ == "__main__":
       const="console_test",
       help=("Compiles and installs the console_test example that tests the "
             "console driver with messages of various lengths."))
+  apps_group.add_argument(
+      "--nfct_test",
+      dest="application",
+      action="store_const",
+      const="console_test",
+      help=("Compiles and installs the console_test example that tests the "
+            "console driver with messages of various lengths."))
 
   main_parser.set_defaults(features=["with_ctap1"])
 
diff --git a/examples/nfct_test.rs b/examples/nfct_test.rs
new file mode 100644
index 0000000..a27d7c5
--- /dev/null
+++ b/examples/nfct_test.rs
@@ -0,0 +1,20 @@
+extern crate lang_items;
+
+use libtock_drivers::console::Console;
+use libtock_drivers::nfc;
+
+fn main(){
+    writeln!(console, "****************************************").unwrap();
+    writeln!(console, "nfct_test application is installed").unwrap();
+    writeln!(console, "****************************************").unwrap();
+
+    // 1. Subscribe to a SELECTED CALLBACK
+    // 2. Configure Type 4 tag
+    // [_.] Enable Tag emulation (currently the tag is always activated)
+    // loop {
+        // 1. Allow Receive Buffer
+        // 2. Subscribe to RECEIVE CALLBACK
+        // 3. Allow TX buffer
+        // 4. Subscribe to TX CALLBACK
+    // }
+}

From 0f6eeff486642e26750fa364a488d25d63acd93b Mon Sep 17 00:00:00 2001
From: Mirna <mshetairy@google.com>
Date: Mon, 12 Oct 2020 11:08:33 +0200
Subject: [PATCH 02/19] Add NFC driver to third_party/libtock-drivers/

---
 third_party/libtock-drivers/src/lib.rs |  1 +
 third_party/libtock-drivers/src/nfc.rs | 66 ++++++++++++++++++++++++++
 2 files changed, 67 insertions(+)
 create mode 100644 third_party/libtock-drivers/src/nfc.rs

diff --git a/third_party/libtock-drivers/src/lib.rs b/third_party/libtock-drivers/src/lib.rs
index bf62d05..e498a37 100644
--- a/third_party/libtock-drivers/src/lib.rs
+++ b/third_party/libtock-drivers/src/lib.rs
@@ -8,3 +8,4 @@ pub mod rng;
 pub mod timer;
 pub mod usb_ctap_hid;
 pub mod util;
+pub mod nfc;
diff --git a/third_party/libtock-drivers/src/nfc.rs b/third_party/libtock-drivers/src/nfc.rs
new file mode 100644
index 0000000..ee2dda3
--- /dev/null
+++ b/third_party/libtock-drivers/src/nfc.rs
@@ -0,0 +1,66 @@
+use crate::util;
+use core::cell::Cell;
+use libtock_core::{callback, syscalls};
+
+const DRIVER_NUMBER: usize = 0x30003;
+
+mod command_nr {
+    pub const TRANSMIT: usize = 1;
+    pub const RECEIVE: usize = 2;
+    pub const EMULATE: usize = 3;
+    pub const CONFIGURE: usize = 4;
+}
+
+mod subscribe_nr {
+    pub const TRANSMIT: usize = 1;
+    pub const RECEIVE: usize = 2;
+    pub const SELECT: usize = 3;
+}
+
+mod allow_nr {
+    pub const TRANSMIT: usize = 1;
+    pub const RECEIVE: usize = 2;
+}
+
+pub const TX_BUFFER_SIZE: usize = 256;
+pub const RX_BUFFER_SIZE: usize = 256;
+
+pub struct NfcTag {
+    tx_buffer: [u8; BUFFER_SIZE],
+    rx_buffer: [u8; BUFFER_SIZE],
+    tag_type: u8,
+}
+
+impl NfcTag {
+    pub fn new() -> Console {
+        Console {
+            tx_buffer: [0; TX_BUFFER_SIZE],
+            tx_buffer: [0; RX_BUFFER_SIZE],
+            tag_type: 0,
+        }
+    }
+
+    pub fn set_tag_type(&mut self, type: u8) {
+        self.tag_type = type;
+    }
+
+    pub fn selected(&self) -> bool {
+        let is_selected = Cell::new(false);
+        let mut is_selected_alarm = || is_selected.set(true);
+        let subscription = syscalls::subscribe::<callback::Identity0Consumer, _>(
+            DRIVER_NUMBER,
+            subscribe_nr::SELECT,
+            &mut is_selected_alarm,
+        );
+        if subscription.is_err() {
+            return;
+        }
+
+        util::yieldk_for(|| is_selected.get());
+        true
+    }
+
+    pub fn receive(&self) {
+
+    }
+}

From 929aaf3ba24d4523d021a92fdf3fa33a743e936a Mon Sep 17 00:00:00 2001
From: Mirna <mshetairy@google.com>
Date: Mon, 12 Oct 2020 13:31:06 +0200
Subject: [PATCH 03/19] Update in libtock-drivers/ and nfct_test.rs application

---
 deploy.py                              |   6 +-
 examples/nfct_test.rs                  |   2 +
 third_party/libtock-drivers/src/nfc.rs | 139 ++++++++++++++++++-------
 3 files changed, 105 insertions(+), 42 deletions(-)

diff --git a/deploy.py b/deploy.py
index b1a1de8..5cf210d 100755
--- a/deploy.py
+++ b/deploy.py
@@ -925,9 +925,9 @@ if __name__ == "__main__":
       "--nfct_test",
       dest="application",
       action="store_const",
-      const="console_test",
-      help=("Compiles and installs the console_test example that tests the "
-            "console driver with messages of various lengths."))
+      const="nfct_test",
+      help=("Compiles and installs the nfct_test example that tests the "
+            "NFC driver."))
 
   main_parser.set_defaults(features=["with_ctap1"])
 
diff --git a/examples/nfct_test.rs b/examples/nfct_test.rs
index a27d7c5..900bcd7 100644
--- a/examples/nfct_test.rs
+++ b/examples/nfct_test.rs
@@ -4,6 +4,8 @@ use libtock_drivers::console::Console;
 use libtock_drivers::nfc;
 
 fn main(){
+    let mut console = Console::new();
+
     writeln!(console, "****************************************").unwrap();
     writeln!(console, "nfct_test application is installed").unwrap();
     writeln!(console, "****************************************").unwrap();
diff --git a/third_party/libtock-drivers/src/nfc.rs b/third_party/libtock-drivers/src/nfc.rs
index ee2dda3..9fa950c 100644
--- a/third_party/libtock-drivers/src/nfc.rs
+++ b/third_party/libtock-drivers/src/nfc.rs
@@ -22,45 +22,106 @@ mod allow_nr {
     pub const RECEIVE: usize = 2;
 }
 
-pub const TX_BUFFER_SIZE: usize = 256;
-pub const RX_BUFFER_SIZE: usize = 256;
-
-pub struct NfcTag {
-    tx_buffer: [u8; BUFFER_SIZE],
-    rx_buffer: [u8; BUFFER_SIZE],
-    tag_type: u8,
+pub fn enable_emulation() {
+    emulate(true);
 }
 
-impl NfcTag {
-    pub fn new() -> Console {
-        Console {
-            tx_buffer: [0; TX_BUFFER_SIZE],
-            tx_buffer: [0; RX_BUFFER_SIZE],
-            tag_type: 0,
-        }
-    }
-
-    pub fn set_tag_type(&mut self, type: u8) {
-        self.tag_type = type;
-    }
-
-    pub fn selected(&self) -> bool {
-        let is_selected = Cell::new(false);
-        let mut is_selected_alarm = || is_selected.set(true);
-        let subscription = syscalls::subscribe::<callback::Identity0Consumer, _>(
-            DRIVER_NUMBER,
-            subscribe_nr::SELECT,
-            &mut is_selected_alarm,
-        );
-        if subscription.is_err() {
-            return;
-        }
-
-        util::yieldk_for(|| is_selected.get());
-        true
-    }
-
-    pub fn receive(&self) {
-
-    }
+pub fn disable_emulation() {
+    emulate(false);
+}
+
+pub fn emulate(enabled: bool) -> bool {
+    let result_code = syscalls::command(
+        DRIVER_NUMBER,
+        command_nr::EMULATE,
+        enabled as usize,
+        0
+    );
+    if result_code.is_err() {
+        return false;
+    }
+
+    true
+}
+
+pub fn selected() -> bool {
+    let is_selected = Cell::new(false);
+    let mut is_selected_alarm = || is_selected.set(true);
+    let subscription = syscalls::subscribe::<callback::Identity0Consumer, _>(
+        DRIVER_NUMBER,
+        subscribe_nr::SELECT,
+        &mut is_selected_alarm,
+    );
+    if subscription.is_err() {
+        return false;
+    }
+
+    util::yieldk_for(|| is_selected.get());
+    true
+}
+
+pub fn configure(tag_type: u8) -> bool {
+    let result_code = syscalls::command(
+        DRIVER_NUMBER,
+        command_nr::CONFIGURE,
+        tag_type as usize,
+        0
+    );
+    if result_code.is_err() {
+        return false;
+    }
+
+    true
+}
+
+pub fn receive(buf: &mut [u8]) -> bool {
+    let result = syscalls::allow(DRIVER_NUMBER, allow_nr::RECEIVE, buf);
+    if result.is_err() {
+        return false;
+    }
+
+    let done = Cell::new(false);
+    let mut alarm = || done.set(true);
+    let subscription = syscalls::subscribe::<callback::Identity0Consumer, _>(
+        DRIVER_NUMBER,
+        subscribe_nr::RECEIVE,
+        &mut alarm,
+    );
+    if subscription.is_err() {
+        return false;
+    }
+
+    let result_code = syscalls::command(DRIVER_NUMBER, command_nr::RECEIVE, 0, 0);
+    if result_code.is_err() {
+        return false;
+    }
+
+    util::yieldk_for(|| done.get());
+    true
+}
+
+pub fn transmit(buf: &mut [u8]) -> bool {
+    let result = syscalls::allow(DRIVER_NUMBER, allow_nr::TRANSMIT, buf);
+    if result.is_err() {
+        return false;
+    }
+
+    let done = Cell::new(false);
+    let mut alarm = || done.set(true);
+    let subscription = syscalls::subscribe::<callback::Identity0Consumer, _>(
+        DRIVER_NUMBER,
+        subscribe_nr::TRANSMIT,
+        &mut alarm,
+    );
+    if subscription.is_err() {
+        return false;
+    }
+
+    let result_code = syscalls::command(DRIVER_NUMBER, command_nr::TRANSMIT, 0, 0);
+    if result_code.is_err() {
+        return false;
+    }
+
+    util::yieldk_for(|| done.get());
+    true
 }

From 00ab3c8877a91f23ae72fb981063308adb5b52b7 Mon Sep 17 00:00:00 2001
From: Mirna <mshetairy@google.com>
Date: Mon, 12 Oct 2020 16:01:22 +0200
Subject: [PATCH 04/19] Fixes for some unsuccessful checks

---
 examples/nfct_test.rs                  | 14 ++++++++------
 third_party/libtock-drivers/src/lib.rs |  2 +-
 third_party/libtock-drivers/src/nfc.rs | 14 ++------------
 3 files changed, 11 insertions(+), 19 deletions(-)

diff --git a/examples/nfct_test.rs b/examples/nfct_test.rs
index 900bcd7..1432dfd 100644
--- a/examples/nfct_test.rs
+++ b/examples/nfct_test.rs
@@ -1,9 +1,11 @@
+extern crate alloc;
 extern crate lang_items;
 
+use core::fmt::Write;
 use libtock_drivers::console::Console;
-use libtock_drivers::nfc;
+// use libtock_drivers::nfc;
 
-fn main(){
+fn main() {
     let mut console = Console::new();
 
     writeln!(console, "****************************************").unwrap();
@@ -14,9 +16,9 @@ fn main(){
     // 2. Configure Type 4 tag
     // [_.] Enable Tag emulation (currently the tag is always activated)
     // loop {
-        // 1. Allow Receive Buffer
-        // 2. Subscribe to RECEIVE CALLBACK
-        // 3. Allow TX buffer
-        // 4. Subscribe to TX CALLBACK
+    // 1. Allow Receive Buffer
+    // 2. Subscribe to RECEIVE CALLBACK
+    // 3. Allow TX buffer
+    // 4. Subscribe to TX CALLBACK
     // }
 }
diff --git a/third_party/libtock-drivers/src/lib.rs b/third_party/libtock-drivers/src/lib.rs
index e498a37..ec8a2d7 100644
--- a/third_party/libtock-drivers/src/lib.rs
+++ b/third_party/libtock-drivers/src/lib.rs
@@ -3,9 +3,9 @@
 pub mod buttons;
 pub mod console;
 pub mod led;
+pub mod nfc;
 pub mod result;
 pub mod rng;
 pub mod timer;
 pub mod usb_ctap_hid;
 pub mod util;
-pub mod nfc;
diff --git a/third_party/libtock-drivers/src/nfc.rs b/third_party/libtock-drivers/src/nfc.rs
index 9fa950c..977b49b 100644
--- a/third_party/libtock-drivers/src/nfc.rs
+++ b/third_party/libtock-drivers/src/nfc.rs
@@ -31,12 +31,7 @@ pub fn disable_emulation() {
 }
 
 pub fn emulate(enabled: bool) -> bool {
-    let result_code = syscalls::command(
-        DRIVER_NUMBER,
-        command_nr::EMULATE,
-        enabled as usize,
-        0
-    );
+    let result_code = syscalls::command(DRIVER_NUMBER, command_nr::EMULATE, enabled as usize, 0);
     if result_code.is_err() {
         return false;
     }
@@ -61,12 +56,7 @@ pub fn selected() -> bool {
 }
 
 pub fn configure(tag_type: u8) -> bool {
-    let result_code = syscalls::command(
-        DRIVER_NUMBER,
-        command_nr::CONFIGURE,
-        tag_type as usize,
-        0
-    );
+    let result_code = syscalls::command(DRIVER_NUMBER, command_nr::CONFIGURE, tag_type as usize, 0);
     if result_code.is_err() {
         return false;
     }

From 9205974b509937abd0f587c80736a2807533fa18 Mon Sep 17 00:00:00 2001
From: Mirna <mshetairy@google.com>
Date: Thu, 15 Oct 2020 19:54:34 +0200
Subject: [PATCH 05/19] Update nfct_test example to test NFC driver.

---
 examples/nfct_test.rs | 67 ++++++++++++++++++++++++++++++++++++-------
 1 file changed, 56 insertions(+), 11 deletions(-)

diff --git a/examples/nfct_test.rs b/examples/nfct_test.rs
index 1432dfd..42176cd 100644
--- a/examples/nfct_test.rs
+++ b/examples/nfct_test.rs
@@ -1,24 +1,69 @@
+#![no_std]
+
 extern crate alloc;
 extern crate lang_items;
 
 use core::fmt::Write;
 use libtock_drivers::console::Console;
-// use libtock_drivers::nfc;
+use libtock_drivers::nfc::NfcTag;
+
+#[allow(dead_code)]
+/// Helper function to write a slice into a fixed
+/// length transmission buffer.
+fn write_tx_buffer(buf: &mut [u8], slice: &[u8]) {
+    for (i, &byte) in slice.iter().enumerate() {
+        buf[i] = byte;
+    }
+}
 
 fn main() {
     let mut console = Console::new();
 
     writeln!(console, "****************************************").unwrap();
     writeln!(console, "nfct_test application is installed").unwrap();
-    writeln!(console, "****************************************").unwrap();
 
-    // 1. Subscribe to a SELECTED CALLBACK
-    // 2. Configure Type 4 tag
-    // [_.] Enable Tag emulation (currently the tag is always activated)
-    // loop {
-    // 1. Allow Receive Buffer
-    // 2. Subscribe to RECEIVE CALLBACK
-    // 3. Allow TX buffer
-    // 4. Subscribe to TX CALLBACK
-    // }
+    // 1. Configure Type 4 tag
+    if NfcTag::configure(4) {
+        writeln!(console, " -- TAG CONFIGURED").unwrap();
+    }
+    // 2. Subscribe to a SELECTED CALLBACK
+    if NfcTag::selected() {
+        writeln!(console, " -- TAG SELECTED").unwrap();
+        // 0xfffff results in 1048575 / 13.56e6 = 77ms
+        NfcTag::set_framedelaymax(0xfffff);
+    }
+    /*
+    [_.] TODO: Enable Tag emulation (currently the tag is always activated)
+    needs field detection support in the driver level.
+    */
+    let mut rx_buf = [0; 64];
+    let mut unknown_cmd_cntr = 0;
+    loop {
+        NfcTag::receive(&mut rx_buf);
+        match rx_buf[0] {
+            0xe0 /* RATS */=> {
+                let mut answer_to_select = [0x05, 0x78, 0x80, 0xB1, 0x00];
+                let amount = answer_to_select.len();
+                NfcTag::transmit(&mut answer_to_select, amount);
+            }
+            0xc2 /* DESELECT */ => {
+                // Ignore the request
+                let mut command_error = [0x6A, 0x81];
+                let amount = command_error.len();
+                NfcTag::transmit(&mut command_error, amount);
+            }
+            0x02 | 0x03 /* APDU Prefix */ => {
+                let mut reply = [rx_buf[0], 0x90, 0x00];
+                let amount = reply.len();
+                NfcTag::transmit(&mut reply, amount);
+            }
+            _ => {
+                unknown_cmd_cntr += 1;
+            }
+        }
+        if unknown_cmd_cntr > 50 {
+            break;
+        }
+    }
+    writeln!(console, "****************************************").unwrap();
 }

From f09a9b4fae4b2f79a1d5575659f3dd7d0df00048 Mon Sep 17 00:00:00 2001
From: Mirna <mshetairy@google.com>
Date: Thu, 15 Oct 2020 19:55:39 +0200
Subject: [PATCH 06/19] Update libtock-drivers/ NFC driver

---
 third_party/libtock-drivers/src/nfc.rs | 211 ++++++++++++++-----------
 1 file changed, 119 insertions(+), 92 deletions(-)

diff --git a/third_party/libtock-drivers/src/nfc.rs b/third_party/libtock-drivers/src/nfc.rs
index 977b49b..8a0c7c6 100644
--- a/third_party/libtock-drivers/src/nfc.rs
+++ b/third_party/libtock-drivers/src/nfc.rs
@@ -9,6 +9,7 @@ mod command_nr {
     pub const RECEIVE: usize = 2;
     pub const EMULATE: usize = 3;
     pub const CONFIGURE: usize = 4;
+    pub const FRAMEDELAYMAX: usize = 5;
 }
 
 mod subscribe_nr {
@@ -22,96 +23,122 @@ mod allow_nr {
     pub const RECEIVE: usize = 2;
 }
 
-pub fn enable_emulation() {
-    emulate(true);
-}
-
-pub fn disable_emulation() {
-    emulate(false);
-}
-
-pub fn emulate(enabled: bool) -> bool {
-    let result_code = syscalls::command(DRIVER_NUMBER, command_nr::EMULATE, enabled as usize, 0);
-    if result_code.is_err() {
-        return false;
-    }
-
-    true
-}
-
-pub fn selected() -> bool {
-    let is_selected = Cell::new(false);
-    let mut is_selected_alarm = || is_selected.set(true);
-    let subscription = syscalls::subscribe::<callback::Identity0Consumer, _>(
-        DRIVER_NUMBER,
-        subscribe_nr::SELECT,
-        &mut is_selected_alarm,
-    );
-    if subscription.is_err() {
-        return false;
-    }
-
-    util::yieldk_for(|| is_selected.get());
-    true
-}
-
-pub fn configure(tag_type: u8) -> bool {
-    let result_code = syscalls::command(DRIVER_NUMBER, command_nr::CONFIGURE, tag_type as usize, 0);
-    if result_code.is_err() {
-        return false;
-    }
-
-    true
-}
-
-pub fn receive(buf: &mut [u8]) -> bool {
-    let result = syscalls::allow(DRIVER_NUMBER, allow_nr::RECEIVE, buf);
-    if result.is_err() {
-        return false;
-    }
-
-    let done = Cell::new(false);
-    let mut alarm = || done.set(true);
-    let subscription = syscalls::subscribe::<callback::Identity0Consumer, _>(
-        DRIVER_NUMBER,
-        subscribe_nr::RECEIVE,
-        &mut alarm,
-    );
-    if subscription.is_err() {
-        return false;
-    }
-
-    let result_code = syscalls::command(DRIVER_NUMBER, command_nr::RECEIVE, 0, 0);
-    if result_code.is_err() {
-        return false;
-    }
-
-    util::yieldk_for(|| done.get());
-    true
-}
-
-pub fn transmit(buf: &mut [u8]) -> bool {
-    let result = syscalls::allow(DRIVER_NUMBER, allow_nr::TRANSMIT, buf);
-    if result.is_err() {
-        return false;
-    }
-
-    let done = Cell::new(false);
-    let mut alarm = || done.set(true);
-    let subscription = syscalls::subscribe::<callback::Identity0Consumer, _>(
-        DRIVER_NUMBER,
-        subscribe_nr::TRANSMIT,
-        &mut alarm,
-    );
-    if subscription.is_err() {
-        return false;
-    }
-
-    let result_code = syscalls::command(DRIVER_NUMBER, command_nr::TRANSMIT, 0, 0);
-    if result_code.is_err() {
-        return false;
-    }
-
-    util::yieldk_for(|| done.get());
-    true
+pub struct NfcTag {}
+
+impl NfcTag {
+    pub fn enable_emulation() {
+        NfcTag::emulate(true);
+    }
+
+    pub fn disable_emulation() {
+        NfcTag::emulate(false);
+    }
+
+    pub fn emulate(enabled: bool) -> bool {
+        let result_code =
+            syscalls::command(DRIVER_NUMBER, command_nr::EMULATE, enabled as usize, 0);
+        if result_code.is_err() {
+            return false;
+        }
+
+        true
+    }
+
+    /// Subscribe to the tag being SELECTED callback.
+    pub fn selected() -> bool {
+        let is_selected = Cell::new(false);
+        let mut is_selected_alarm = || is_selected.set(true);
+        let subscription = syscalls::subscribe::<callback::Identity0Consumer, _>(
+            DRIVER_NUMBER,
+            subscribe_nr::SELECT,
+            &mut is_selected_alarm,
+        );
+        if subscription.is_err() {
+            return false;
+        }
+
+        util::yieldk_for(|| is_selected.get());
+        true
+    }
+
+    /// Configure the tag type command.
+    pub fn configure(tag_type: u8) -> bool {
+        let result_code =
+            syscalls::command(DRIVER_NUMBER, command_nr::CONFIGURE, tag_type as usize, 0);
+        if result_code.is_err() {
+            return false;
+        }
+
+        true
+    }
+
+    /// Set the maximum frame delay value to support
+    /// transmission with the reader.
+    pub fn set_framedelaymax(delay: u32) -> bool {
+        let result_code =
+            syscalls::command(DRIVER_NUMBER, command_nr::FRAMEDELAYMAX, delay as usize, 0);
+        if result_code.is_err() {
+            return false;
+        }
+
+        true
+    }
+
+    /// 1. Share with the driver a buffer.
+    /// 2. Subscribe to having a successful receive callback.
+    /// 3. Issue the request for reception.
+    pub fn receive(buf: &mut [u8]) -> bool {
+        let result = syscalls::allow(DRIVER_NUMBER, allow_nr::RECEIVE, buf);
+        if result.is_err() {
+            return false;
+        }
+
+        let done = Cell::new(false);
+        let mut alarm = || done.set(true);
+        let subscription = syscalls::subscribe::<callback::Identity0Consumer, _>(
+            DRIVER_NUMBER,
+            subscribe_nr::RECEIVE,
+            &mut alarm,
+        );
+        if subscription.is_err() {
+            return false;
+        }
+
+        let result_code = syscalls::command(DRIVER_NUMBER, command_nr::RECEIVE, 0, 0);
+        if result_code.is_err() {
+            return false;
+        }
+
+        util::yieldk_for(|| done.get());
+        true
+    }
+
+    /// 1. Share with the driver a buffer containing the app's reply.
+    /// 2. Subscribe to having a successful transmission callback.
+    /// 3. Issue the request for transmitting.
+    pub fn transmit(buf: &mut [u8], amount: usize) -> bool {
+        let result = syscalls::allow(DRIVER_NUMBER, allow_nr::TRANSMIT, buf);
+        if result.is_err() {
+            return false;
+        }
+
+        let done = Cell::new(false);
+        let mut alarm = || done.set(true);
+        let subscription = syscalls::subscribe::<callback::Identity0Consumer, _>(
+            DRIVER_NUMBER,
+            subscribe_nr::TRANSMIT,
+            &mut alarm,
+        );
+        if subscription.is_err() {
+            return false;
+        }
+
+        let result_code = syscalls::command(DRIVER_NUMBER, command_nr::TRANSMIT, amount, 0);
+        if result_code.is_err() {
+            return false;
+        }
+
+        util::yieldk_for(|| done.get());
+        true
+    }
 }

From 6b2fde242d45dcb2b1ed806f4b34690c24179f4b Mon Sep 17 00:00:00 2001
From: Mirna <29131616+MirnaMuhammad98@users.noreply.github.com>
Date: Fri, 16 Oct 2020 08:22:40 +0200
Subject: [PATCH 07/19] Delete nfct_test.rs

This branch is for the driver interface.
---
 examples/nfct_test.rs | 69 -------------------------------------------
 1 file changed, 69 deletions(-)
 delete mode 100644 examples/nfct_test.rs

diff --git a/examples/nfct_test.rs b/examples/nfct_test.rs
deleted file mode 100644
index 42176cd..0000000
--- a/examples/nfct_test.rs
+++ /dev/null
@@ -1,69 +0,0 @@
-#![no_std]
-
-extern crate alloc;
-extern crate lang_items;
-
-use core::fmt::Write;
-use libtock_drivers::console::Console;
-use libtock_drivers::nfc::NfcTag;
-
-#[allow(dead_code)]
-/// Helper function to write a slice into a fixed
-/// length transmission buffer.
-fn write_tx_buffer(buf: &mut [u8], slice: &[u8]) {
-    for (i, &byte) in slice.iter().enumerate() {
-        buf[i] = byte;
-    }
-}
-
-fn main() {
-    let mut console = Console::new();
-
-    writeln!(console, "****************************************").unwrap();
-    writeln!(console, "nfct_test application is installed").unwrap();
-
-    // 1. Configure Type 4 tag
-    if NfcTag::configure(4) {
-        writeln!(console, " -- TAG CONFIGURED").unwrap();
-    }
-    // 2. Subscribe to a SELECTED CALLBACK
-    if NfcTag::selected() {
-        writeln!(console, " -- TAG SELECTED").unwrap();
-        // 0xfffff results in 1048575 / 13.56e6 = 77ms
-        NfcTag::set_framedelaymax(0xfffff);
-    }
-    /*
-    [_.] TODO: Enable Tag emulation (currently the tag is always activated)
-    needs field detection support in the driver level.
-    */
-    let mut rx_buf = [0; 64];
-    let mut unknown_cmd_cntr = 0;
-    loop {
-        NfcTag::receive(&mut rx_buf);
-        match rx_buf[0] {
-            0xe0 /* RATS */=> {
-                let mut answer_to_select = [0x05, 0x78, 0x80, 0xB1, 0x00];
-                let amount = answer_to_select.len();
-                NfcTag::transmit(&mut answer_to_select, amount);
-            }
-            0xc2 /* DESELECT */ => {
-                // Ignore the request
-                let mut command_error = [0x6A, 0x81];
-                let amount = command_error.len();
-                NfcTag::transmit(&mut command_error, amount);
-            }
-            0x02 | 0x03 /* APDU Prefix */ => {
-                let mut reply = [rx_buf[0], 0x90, 0x00];
-                let amount = reply.len();
-                NfcTag::transmit(&mut reply, amount);
-            }
-            _ => {
-                unknown_cmd_cntr += 1;
-            }
-        }
-        if unknown_cmd_cntr > 50 {
-            break;
-        }
-    }
-    writeln!(console, "****************************************").unwrap();
-}

From 7e0a48ae1cbddd8b67937c0cde9ecaf18217e92b Mon Sep 17 00:00:00 2001
From: Mirna <mshetairy@google.com>
Date: Wed, 21 Oct 2020 10:39:17 +0200
Subject: [PATCH 08/19] Resolved Review Comments

---
 deploy.py                              |  7 ---
 third_party/libtock-drivers/src/nfc.rs | 72 ++++++++++++--------------
 2 files changed, 32 insertions(+), 47 deletions(-)

diff --git a/deploy.py b/deploy.py
index 5cf210d..5598797 100755
--- a/deploy.py
+++ b/deploy.py
@@ -921,13 +921,6 @@ if __name__ == "__main__":
       const="console_test",
       help=("Compiles and installs the console_test example that tests the "
             "console driver with messages of various lengths."))
-  apps_group.add_argument(
-      "--nfct_test",
-      dest="application",
-      action="store_const",
-      const="nfct_test",
-      help=("Compiles and installs the nfct_test example that tests the "
-            "NFC driver."))
 
   main_parser.set_defaults(features=["with_ctap1"])
 
diff --git a/third_party/libtock-drivers/src/nfc.rs b/third_party/libtock-drivers/src/nfc.rs
index 8a0c7c6..8e90b6b 100644
--- a/third_party/libtock-drivers/src/nfc.rs
+++ b/third_party/libtock-drivers/src/nfc.rs
@@ -1,5 +1,6 @@
 use crate::util;
 use core::cell::Cell;
+use libtock_core::result::{ENOMEM, SUCCESS};
 use libtock_core::{callback, syscalls};
 
 const DRIVER_NUMBER: usize = 0x30003;
@@ -23,25 +24,26 @@ mod allow_nr {
     pub const RECEIVE: usize = 2;
 }
 
+pub enum TransOrRecvStatus {
+    Error,
+    InvalidBuffer,
+    OOM,
+    Success,
+}
+
 pub struct NfcTag {}
 
 impl NfcTag {
-    pub fn enable_emulation() {
-        NfcTag::emulate(true);
+    pub fn enable_emulation() -> bool {
+        NfcTag::emulate(true)
     }
 
-    pub fn disable_emulation() {
-        NfcTag::emulate(false);
+    pub fn disable_emulation() -> bool {
+        NfcTag::emulate(false)
     }
 
-    pub fn emulate(enabled: bool) -> bool {
-        let result_code =
-            syscalls::command(DRIVER_NUMBER, command_nr::EMULATE, enabled as usize, 0);
-        if result_code.is_err() {
-            return false;
-        }
-
-        true
+    fn emulate(enabled: bool) -> bool {
+        syscalls::command(DRIVER_NUMBER, command_nr::EMULATE, enabled as usize, 0).is_ok()
     }
 
     /// Subscribe to the tag being SELECTED callback.
@@ -63,34 +65,21 @@ impl NfcTag {
 
     /// Configure the tag type command.
     pub fn configure(tag_type: u8) -> bool {
-        let result_code =
-            syscalls::command(DRIVER_NUMBER, command_nr::CONFIGURE, tag_type as usize, 0);
-        if result_code.is_err() {
-            return false;
-        }
-
-        true
+        syscalls::command(DRIVER_NUMBER, command_nr::CONFIGURE, tag_type as usize, 0).is_ok()
     }
 
-    /// Set the maximum frame delay value to support
-    /// transmission with the reader.
+    /// Set the maximum frame delay value to support transmission with the reader.
     pub fn set_framedelaymax(delay: u32) -> bool {
-        let result_code =
-            syscalls::command(DRIVER_NUMBER, command_nr::FRAMEDELAYMAX, delay as usize, 0);
-        if result_code.is_err() {
-            return false;
-        }
-
-        true
+        syscalls::command(DRIVER_NUMBER, command_nr::FRAMEDELAYMAX, delay as usize, 0).is_ok()
     }
 
     /// 1. Share with the driver a buffer.
     /// 2. Subscribe to having a successful receive callback.
     /// 3. Issue the request for reception.
-    pub fn receive(buf: &mut [u8]) -> bool {
+    pub fn receive(buf: &mut [u8; 256]) -> TransOrRecvStatus {
         let result = syscalls::allow(DRIVER_NUMBER, allow_nr::RECEIVE, buf);
         if result.is_err() {
-            return false;
+            return TransOrRecvStatus::InvalidBuffer;
         }
 
         let done = Cell::new(false);
@@ -101,25 +90,28 @@ impl NfcTag {
             &mut alarm,
         );
         if subscription.is_err() {
-            return false;
+            return TransOrRecvStatus::Error;
         }
 
-        let result_code = syscalls::command(DRIVER_NUMBER, command_nr::RECEIVE, 0, 0);
-        if result_code.is_err() {
-            return false;
+        let result_code =
+            unsafe { syscalls::raw::command(DRIVER_NUMBER, command_nr::RECEIVE, 0, 0) };
+        match result_code {
+            SUCCESS => (),
+            ENOMEM => return TransOrRecvStatus::OOM,
+            _ => return TransOrRecvStatus::Error,
         }
 
         util::yieldk_for(|| done.get());
-        true
+        TransOrRecvStatus::Success
     }
 
     /// 1. Share with the driver a buffer containing the app's reply.
     /// 2. Subscribe to having a successful transmission callback.
     /// 3. Issue the request for transmitting.
-    pub fn transmit(buf: &mut [u8], amount: usize) -> bool {
+    pub fn transmit(buf: &mut [u8], amount: usize) -> TransOrRecvStatus {
         let result = syscalls::allow(DRIVER_NUMBER, allow_nr::TRANSMIT, buf);
         if result.is_err() {
-            return false;
+            return TransOrRecvStatus::InvalidBuffer;
         }
 
         let done = Cell::new(false);
@@ -130,15 +122,15 @@ impl NfcTag {
             &mut alarm,
         );
         if subscription.is_err() {
-            return false;
+            return TransOrRecvStatus::Error;
         }
 
         let result_code = syscalls::command(DRIVER_NUMBER, command_nr::TRANSMIT, amount, 0);
         if result_code.is_err() {
-            return false;
+            return TransOrRecvStatus::Error;
         }
 
         util::yieldk_for(|| done.get());
-        true
+        TransOrRecvStatus::Success
     }
 }

From 8cb85563da781aa8a3e0f9c57269fe03a96a4f9a Mon Sep 17 00:00:00 2001
From: Mirna <mshetairy@google.com>
Date: Wed, 21 Oct 2020 19:30:58 +0200
Subject: [PATCH 09/19] Updated Functions Return Types

---
 third_party/libtock-drivers/src/nfc.rs | 90 ++++++++++++--------------
 1 file changed, 41 insertions(+), 49 deletions(-)

diff --git a/third_party/libtock-drivers/src/nfc.rs b/third_party/libtock-drivers/src/nfc.rs
index 8e90b6b..6bf685b 100644
--- a/third_party/libtock-drivers/src/nfc.rs
+++ b/third_party/libtock-drivers/src/nfc.rs
@@ -1,6 +1,7 @@
+use crate::result::TockError;
 use crate::util;
 use core::cell::Cell;
-use libtock_core::result::{ENOMEM, SUCCESS};
+use core::mem;
 use libtock_core::{callback, syscalls};
 
 const DRIVER_NUMBER: usize = 0x30003;
@@ -24,11 +25,10 @@ mod allow_nr {
     pub const RECEIVE: usize = 2;
 }
 
-pub enum TransOrRecvStatus {
-    Error,
-    InvalidBuffer,
-    OOM,
-    Success,
+#[allow(dead_code)]
+pub struct RecvOp {
+    pub result_code: usize,
+    pub recv_amount: usize,
 }
 
 pub struct NfcTag {}
@@ -76,61 +76,53 @@ impl NfcTag {
     /// 1. Share with the driver a buffer.
     /// 2. Subscribe to having a successful receive callback.
     /// 3. Issue the request for reception.
-    pub fn receive(buf: &mut [u8; 256]) -> TransOrRecvStatus {
-        let result = syscalls::allow(DRIVER_NUMBER, allow_nr::RECEIVE, buf);
-        if result.is_err() {
-            return TransOrRecvStatus::InvalidBuffer;
-        }
-
+    pub fn receive(buf: &mut [u8; 256]) -> Result<RecvOp, TockError> {
+        let result = syscalls::allow(DRIVER_NUMBER, allow_nr::RECEIVE, buf)?;
+        // set callback with 2 arguments, to receive ReturnCode and RX Amount
         let done = Cell::new(false);
-        let mut alarm = || done.set(true);
-        let subscription = syscalls::subscribe::<callback::Identity0Consumer, _>(
+        let result_code = Cell::new(None);
+        let recv_amount = Cell::new(None);
+        let mut callback = |result, amount| {
+            result_code.set(Some(result));
+            recv_amount.set(Some(amount));
+            done.set(true)
+        };
+        let subscription = syscalls::subscribe::<callback::Identity2Consumer, _>(
             DRIVER_NUMBER,
             subscribe_nr::RECEIVE,
-            &mut alarm,
-        );
-        if subscription.is_err() {
-            return TransOrRecvStatus::Error;
-        }
-
-        let result_code =
-            unsafe { syscalls::raw::command(DRIVER_NUMBER, command_nr::RECEIVE, 0, 0) };
-        match result_code {
-            SUCCESS => (),
-            ENOMEM => return TransOrRecvStatus::OOM,
-            _ => return TransOrRecvStatus::Error,
-        }
-
+            &mut callback,
+        )?;
+        syscalls::command(DRIVER_NUMBER, command_nr::RECEIVE, 0, 0)?;
         util::yieldk_for(|| done.get());
-        TransOrRecvStatus::Success
+        mem::drop(subscription);
+        mem::drop(result);
+        Ok(RecvOp {
+            result_code: result_code.get().unwrap(),
+            recv_amount: recv_amount.get().unwrap(),
+        })
     }
 
     /// 1. Share with the driver a buffer containing the app's reply.
     /// 2. Subscribe to having a successful transmission callback.
     /// 3. Issue the request for transmitting.
-    pub fn transmit(buf: &mut [u8], amount: usize) -> TransOrRecvStatus {
-        let result = syscalls::allow(DRIVER_NUMBER, allow_nr::TRANSMIT, buf);
-        if result.is_err() {
-            return TransOrRecvStatus::InvalidBuffer;
-        }
-
+    pub fn transmit(buf: &mut [u8], amount: usize) -> Result<usize, TockError> {
+        let result = syscalls::allow(DRIVER_NUMBER, allow_nr::TRANSMIT, buf)?;
+        // set callback with 1 argument, to receive ReturnCode
         let done = Cell::new(false);
-        let mut alarm = || done.set(true);
-        let subscription = syscalls::subscribe::<callback::Identity0Consumer, _>(
+        let result_code = Cell::new(None);
+        let mut callback = |result| {
+            result_code.set(Some(result));
+            done.set(true)
+        };
+        let subscription = syscalls::subscribe::<callback::Identity1Consumer, _>(
             DRIVER_NUMBER,
             subscribe_nr::TRANSMIT,
-            &mut alarm,
-        );
-        if subscription.is_err() {
-            return TransOrRecvStatus::Error;
-        }
-
-        let result_code = syscalls::command(DRIVER_NUMBER, command_nr::TRANSMIT, amount, 0);
-        if result_code.is_err() {
-            return TransOrRecvStatus::Error;
-        }
-
+            &mut callback,
+        )?;
+        syscalls::command(DRIVER_NUMBER, command_nr::TRANSMIT, amount, 0)?;
         util::yieldk_for(|| done.get());
-        TransOrRecvStatus::Success
+        mem::drop(subscription);
+        mem::drop(result);
+        Ok(result_code.get().unwrap())
     }
 }

From 59af769c6962ac154197546044c3523c54835a1e Mon Sep 17 00:00:00 2001
From: Mirna <mshetairy@google.com>
Date: Thu, 22 Oct 2020 12:10:43 +0200
Subject: [PATCH 10/19] Remove unnecessary `done.get()`

---
 third_party/libtock-drivers/src/nfc.rs | 14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)

diff --git a/third_party/libtock-drivers/src/nfc.rs b/third_party/libtock-drivers/src/nfc.rs
index 6bf685b..e18e283 100644
--- a/third_party/libtock-drivers/src/nfc.rs
+++ b/third_party/libtock-drivers/src/nfc.rs
@@ -79,13 +79,11 @@ impl NfcTag {
     pub fn receive(buf: &mut [u8; 256]) -> Result<RecvOp, TockError> {
         let result = syscalls::allow(DRIVER_NUMBER, allow_nr::RECEIVE, buf)?;
         // set callback with 2 arguments, to receive ReturnCode and RX Amount
-        let done = Cell::new(false);
         let result_code = Cell::new(None);
         let recv_amount = Cell::new(None);
         let mut callback = |result, amount| {
             result_code.set(Some(result));
-            recv_amount.set(Some(amount));
-            done.set(true)
+            recv_amount.set(Some(amount))
         };
         let subscription = syscalls::subscribe::<callback::Identity2Consumer, _>(
             DRIVER_NUMBER,
@@ -93,7 +91,7 @@ impl NfcTag {
             &mut callback,
         )?;
         syscalls::command(DRIVER_NUMBER, command_nr::RECEIVE, 0, 0)?;
-        util::yieldk_for(|| done.get());
+        util::yieldk_for(|| recv_amount.get().is_some());
         mem::drop(subscription);
         mem::drop(result);
         Ok(RecvOp {
@@ -108,19 +106,15 @@ impl NfcTag {
     pub fn transmit(buf: &mut [u8], amount: usize) -> Result<usize, TockError> {
         let result = syscalls::allow(DRIVER_NUMBER, allow_nr::TRANSMIT, buf)?;
         // set callback with 1 argument, to receive ReturnCode
-        let done = Cell::new(false);
         let result_code = Cell::new(None);
-        let mut callback = |result| {
-            result_code.set(Some(result));
-            done.set(true)
-        };
+        let mut callback = |result| result_code.set(Some(result));
         let subscription = syscalls::subscribe::<callback::Identity1Consumer, _>(
             DRIVER_NUMBER,
             subscribe_nr::TRANSMIT,
             &mut callback,
         )?;
         syscalls::command(DRIVER_NUMBER, command_nr::TRANSMIT, amount, 0)?;
-        util::yieldk_for(|| done.get());
+        util::yieldk_for(|| result_code.get().is_some());
         mem::drop(subscription);
         mem::drop(result);
         Ok(result_code.get().unwrap())

From 18c6406031b3c4b217990886ed7338ecfdbe7cd4 Mon Sep 17 00:00:00 2001
From: Mirna <mshetairy@google.com>
Date: Thu, 22 Oct 2020 15:10:36 +0200
Subject: [PATCH 11/19] Use return type `TockResult<T>`

---
 third_party/libtock-drivers/src/nfc.rs | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/third_party/libtock-drivers/src/nfc.rs b/third_party/libtock-drivers/src/nfc.rs
index e18e283..06dd748 100644
--- a/third_party/libtock-drivers/src/nfc.rs
+++ b/third_party/libtock-drivers/src/nfc.rs
@@ -1,4 +1,4 @@
-use crate::result::TockError;
+use crate::result::TockResult;
 use crate::util;
 use core::cell::Cell;
 use core::mem;
@@ -76,7 +76,7 @@ impl NfcTag {
     /// 1. Share with the driver a buffer.
     /// 2. Subscribe to having a successful receive callback.
     /// 3. Issue the request for reception.
-    pub fn receive(buf: &mut [u8; 256]) -> Result<RecvOp, TockError> {
+    pub fn receive(buf: &mut [u8; 256]) -> TockResult<RecvOp> {
         let result = syscalls::allow(DRIVER_NUMBER, allow_nr::RECEIVE, buf)?;
         // set callback with 2 arguments, to receive ReturnCode and RX Amount
         let result_code = Cell::new(None);
@@ -103,7 +103,7 @@ impl NfcTag {
     /// 1. Share with the driver a buffer containing the app's reply.
     /// 2. Subscribe to having a successful transmission callback.
     /// 3. Issue the request for transmitting.
-    pub fn transmit(buf: &mut [u8], amount: usize) -> Result<usize, TockError> {
+    pub fn transmit(buf: &mut [u8], amount: usize) -> TockResult<usize> {
         let result = syscalls::allow(DRIVER_NUMBER, allow_nr::TRANSMIT, buf)?;
         // set callback with 1 argument, to receive ReturnCode
         let result_code = Cell::new(None);

From b95b0682f9893de999e25ac978907a9229a5ac7c Mon Sep 17 00:00:00 2001
From: Mirna <mshetairy@google.com>
Date: Fri, 23 Oct 2020 19:25:36 +0200
Subject: [PATCH 12/19] Added NFC compile flag

---
 Cargo.toml | 1 +
 deploy.py  | 7 +++++++
 2 files changed, 8 insertions(+)

diff --git a/Cargo.toml b/Cargo.toml
index a11d0f7..00bd7d2 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -28,6 +28,7 @@ ram_storage = []
 verbose = ["debug_ctap", "libtock_drivers/verbose_usb"]
 with_ctap1 = ["crypto/with_ctap1"]
 with_ctap2_1 = []
+with_nfc = []
 
 [dev-dependencies]
 elf2tab = "0.6.0"
diff --git a/deploy.py b/deploy.py
index 5598797..358355d 100755
--- a/deploy.py
+++ b/deploy.py
@@ -846,6 +846,13 @@ if __name__ == "__main__":
       help=("Compiles the OpenSK application with backward compatible "
             "support for CTAP2.1 protocol."),
   )
+  main_parser.add_argument(
+      "--nfc",
+      action="append_const",
+      const="with_nfc",
+      dest="features",
+      help=("Compiles the OpenSK application with support for nfc."),
+  )
   main_parser.add_argument(
       "--regen-keys",
       action="store_true",

From a53569007d115252c6afea9ca014cb400974dade Mon Sep 17 00:00:00 2001
From: Mirna <mshetairy@google.com>
Date: Mon, 26 Oct 2020 12:56:53 +0200
Subject: [PATCH 13/19] Hide NFC behind feature flag

---
 third_party/libtock-drivers/src/lib.rs | 1 +
 1 file changed, 1 insertion(+)

diff --git a/third_party/libtock-drivers/src/lib.rs b/third_party/libtock-drivers/src/lib.rs
index ec8a2d7..8b8983c 100644
--- a/third_party/libtock-drivers/src/lib.rs
+++ b/third_party/libtock-drivers/src/lib.rs
@@ -3,6 +3,7 @@
 pub mod buttons;
 pub mod console;
 pub mod led;
+#[cfg(feature = "with_nfc")]
 pub mod nfc;
 pub mod result;
 pub mod rng;

From e37f63396c625d556b10a475e082d61f7638c3af Mon Sep 17 00:00:00 2001
From: Mirna <mshetairy@google.com>
Date: Mon, 26 Oct 2020 14:01:27 +0200
Subject: [PATCH 14/19] Revert #cfg change

---
 third_party/libtock-drivers/src/lib.rs | 1 -
 1 file changed, 1 deletion(-)

diff --git a/third_party/libtock-drivers/src/lib.rs b/third_party/libtock-drivers/src/lib.rs
index 8b8983c..ec8a2d7 100644
--- a/third_party/libtock-drivers/src/lib.rs
+++ b/third_party/libtock-drivers/src/lib.rs
@@ -3,7 +3,6 @@
 pub mod buttons;
 pub mod console;
 pub mod led;
-#[cfg(feature = "with_nfc")]
 pub mod nfc;
 pub mod result;
 pub mod rng;

From 64c66b91f526ee7e501d730687fa8b1d1378eeb7 Mon Sep 17 00:00:00 2001
From: Mirna <mshetairy@google.com>
Date: Tue, 27 Oct 2020 10:05:06 +0200
Subject: [PATCH 15/19] Fixed NFC feature flag

---
 Cargo.toml                             | 2 +-
 third_party/libtock-drivers/Cargo.toml | 1 +
 third_party/libtock-drivers/src/lib.rs | 1 +
 3 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/Cargo.toml b/Cargo.toml
index 00bd7d2..8faf8dd 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -28,7 +28,7 @@ ram_storage = []
 verbose = ["debug_ctap", "libtock_drivers/verbose_usb"]
 with_ctap1 = ["crypto/with_ctap1"]
 with_ctap2_1 = []
-with_nfc = []
+with_nfc = ["libtock_drivers/with_nfc"]
 
 [dev-dependencies]
 elf2tab = "0.6.0"
diff --git a/third_party/libtock-drivers/Cargo.toml b/third_party/libtock-drivers/Cargo.toml
index 74fe7ac..41e5c32 100644
--- a/third_party/libtock-drivers/Cargo.toml
+++ b/third_party/libtock-drivers/Cargo.toml
@@ -14,3 +14,4 @@ libtock_core = { path = "../../third_party/libtock-rs/core" }
 [features]
 debug_ctap = []
 verbose_usb = ["debug_ctap"]
+with_nfc=[]
diff --git a/third_party/libtock-drivers/src/lib.rs b/third_party/libtock-drivers/src/lib.rs
index ec8a2d7..8b8983c 100644
--- a/third_party/libtock-drivers/src/lib.rs
+++ b/third_party/libtock-drivers/src/lib.rs
@@ -3,6 +3,7 @@
 pub mod buttons;
 pub mod console;
 pub mod led;
+#[cfg(feature = "with_nfc")]
 pub mod nfc;
 pub mod result;
 pub mod rng;

From 31449fcc0df6cdeb54083b6ebed45bafd7a1d957 Mon Sep 17 00:00:00 2001
From: Mirna <mshetairy@google.com>
Date: Tue, 27 Oct 2020 10:06:11 +0200
Subject: [PATCH 16/19] Added setup function for driver existence checking

---
 third_party/libtock-drivers/src/nfc.rs | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/third_party/libtock-drivers/src/nfc.rs b/third_party/libtock-drivers/src/nfc.rs
index 06dd748..5902160 100644
--- a/third_party/libtock-drivers/src/nfc.rs
+++ b/third_party/libtock-drivers/src/nfc.rs
@@ -7,6 +7,7 @@ use libtock_core::{callback, syscalls};
 const DRIVER_NUMBER: usize = 0x30003;
 
 mod command_nr {
+    pub const CHECK: usize = 0;
     pub const TRANSMIT: usize = 1;
     pub const RECEIVE: usize = 2;
     pub const EMULATE: usize = 3;
@@ -34,6 +35,11 @@ pub struct RecvOp {
 pub struct NfcTag {}
 
 impl NfcTag {
+    /// Check the existence of an NFC driver.
+    pub fn setup() -> bool {
+        syscalls::command(DRIVER_NUMBER, command_nr::CHECK, 0, 0).is_ok()
+    }
+
     pub fn enable_emulation() -> bool {
         NfcTag::emulate(true)
     }

From ce446f571cee0185fa3a7b4612f94f7846f2c022 Mon Sep 17 00:00:00 2001
From: Mirna <mshetairy@google.com>
Date: Wed, 28 Oct 2020 19:11:09 +0200
Subject: [PATCH 17/19] Resolve Comments

---
 third_party/libtock-drivers/src/nfc.rs | 29 ++++++++++++++------------
 1 file changed, 16 insertions(+), 13 deletions(-)

diff --git a/third_party/libtock-drivers/src/nfc.rs b/third_party/libtock-drivers/src/nfc.rs
index 5902160..bf2a249 100644
--- a/third_party/libtock-drivers/src/nfc.rs
+++ b/third_party/libtock-drivers/src/nfc.rs
@@ -13,6 +13,7 @@ mod command_nr {
     pub const EMULATE: usize = 3;
     pub const CONFIGURE: usize = 4;
     pub const FRAMEDELAYMAX: usize = 5;
+    pub const SELECTED: usize = 6;
 }
 
 mod subscribe_nr {
@@ -27,6 +28,7 @@ mod allow_nr {
 }
 
 #[allow(dead_code)]
+#[derive(Clone, Copy)]
 pub struct RecvOp {
     pub result_code: usize,
     pub recv_amount: usize,
@@ -65,6 +67,11 @@ impl NfcTag {
             return false;
         }
 
+        let result = syscalls::command(DRIVER_NUMBER, command_nr::SELECTED, 0, 0);
+        if result.is_err() {
+            return false;
+        }
+
         util::yieldk_for(|| is_selected.get());
         true
     }
@@ -83,27 +90,23 @@ impl NfcTag {
     /// 2. Subscribe to having a successful receive callback.
     /// 3. Issue the request for reception.
     pub fn receive(buf: &mut [u8; 256]) -> TockResult<RecvOp> {
-        let result = syscalls::allow(DRIVER_NUMBER, allow_nr::RECEIVE, buf)?;
+        let _result = syscalls::allow(DRIVER_NUMBER, allow_nr::RECEIVE, buf)?;
         // set callback with 2 arguments, to receive ReturnCode and RX Amount
-        let result_code = Cell::new(None);
-        let recv_amount = Cell::new(None);
+        let recv_data = Cell::new(None);
         let mut callback = |result, amount| {
-            result_code.set(Some(result));
-            recv_amount.set(Some(amount))
+            recv_data.set(Some(RecvOp {
+                result_code: result,
+                recv_amount: amount,
+            }))
         };
-        let subscription = syscalls::subscribe::<callback::Identity2Consumer, _>(
+        let _subscription = syscalls::subscribe::<callback::Identity2Consumer, _>(
             DRIVER_NUMBER,
             subscribe_nr::RECEIVE,
             &mut callback,
         )?;
         syscalls::command(DRIVER_NUMBER, command_nr::RECEIVE, 0, 0)?;
-        util::yieldk_for(|| recv_amount.get().is_some());
-        mem::drop(subscription);
-        mem::drop(result);
-        Ok(RecvOp {
-            result_code: result_code.get().unwrap(),
-            recv_amount: recv_amount.get().unwrap(),
-        })
+        util::yieldk_for(|| recv_data.get().is_some());
+        Ok(recv_data.get().unwrap())
     }
 
     /// 1. Share with the driver a buffer containing the app's reply.

From 3d71da0bf5e0fe27ae00ee685351cd5e0d1771fc Mon Sep 17 00:00:00 2001
From: Mirna <mshetairy@google.com>
Date: Wed, 28 Oct 2020 20:28:53 +0200
Subject: [PATCH 18/19] Unify drop pattern

---
 third_party/libtock-drivers/src/nfc.rs | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/third_party/libtock-drivers/src/nfc.rs b/third_party/libtock-drivers/src/nfc.rs
index bf2a249..24ff50b 100644
--- a/third_party/libtock-drivers/src/nfc.rs
+++ b/third_party/libtock-drivers/src/nfc.rs
@@ -90,7 +90,7 @@ impl NfcTag {
     /// 2. Subscribe to having a successful receive callback.
     /// 3. Issue the request for reception.
     pub fn receive(buf: &mut [u8; 256]) -> TockResult<RecvOp> {
-        let _result = syscalls::allow(DRIVER_NUMBER, allow_nr::RECEIVE, buf)?;
+        let result = syscalls::allow(DRIVER_NUMBER, allow_nr::RECEIVE, buf)?;
         // set callback with 2 arguments, to receive ReturnCode and RX Amount
         let recv_data = Cell::new(None);
         let mut callback = |result, amount| {
@@ -99,13 +99,15 @@ impl NfcTag {
                 recv_amount: amount,
             }))
         };
-        let _subscription = syscalls::subscribe::<callback::Identity2Consumer, _>(
+        let subscription = syscalls::subscribe::<callback::Identity2Consumer, _>(
             DRIVER_NUMBER,
             subscribe_nr::RECEIVE,
             &mut callback,
         )?;
         syscalls::command(DRIVER_NUMBER, command_nr::RECEIVE, 0, 0)?;
         util::yieldk_for(|| recv_data.get().is_some());
+        mem::drop(subscription);
+        mem::drop(result);
         Ok(recv_data.get().unwrap())
     }
 

From 9e89803cb8f6031cd52224c7c9eb3540a46828dc Mon Sep 17 00:00:00 2001
From: Mirna <mshetairy@google.com>
Date: Thu, 29 Oct 2020 22:51:51 +0200
Subject: [PATCH 19/19] Removed Select syscalls, handled in the driver

---
 third_party/libtock-drivers/src/nfc.rs | 30 --------------------------
 1 file changed, 30 deletions(-)

diff --git a/third_party/libtock-drivers/src/nfc.rs b/third_party/libtock-drivers/src/nfc.rs
index 24ff50b..a67e944 100644
--- a/third_party/libtock-drivers/src/nfc.rs
+++ b/third_party/libtock-drivers/src/nfc.rs
@@ -12,14 +12,11 @@ mod command_nr {
     pub const RECEIVE: usize = 2;
     pub const EMULATE: usize = 3;
     pub const CONFIGURE: usize = 4;
-    pub const FRAMEDELAYMAX: usize = 5;
-    pub const SELECTED: usize = 6;
 }
 
 mod subscribe_nr {
     pub const TRANSMIT: usize = 1;
     pub const RECEIVE: usize = 2;
-    pub const SELECT: usize = 3;
 }
 
 mod allow_nr {
@@ -54,38 +51,11 @@ impl NfcTag {
         syscalls::command(DRIVER_NUMBER, command_nr::EMULATE, enabled as usize, 0).is_ok()
     }
 
-    /// Subscribe to the tag being SELECTED callback.
-    pub fn selected() -> bool {
-        let is_selected = Cell::new(false);
-        let mut is_selected_alarm = || is_selected.set(true);
-        let subscription = syscalls::subscribe::<callback::Identity0Consumer, _>(
-            DRIVER_NUMBER,
-            subscribe_nr::SELECT,
-            &mut is_selected_alarm,
-        );
-        if subscription.is_err() {
-            return false;
-        }
-
-        let result = syscalls::command(DRIVER_NUMBER, command_nr::SELECTED, 0, 0);
-        if result.is_err() {
-            return false;
-        }
-
-        util::yieldk_for(|| is_selected.get());
-        true
-    }
-
     /// Configure the tag type command.
     pub fn configure(tag_type: u8) -> bool {
         syscalls::command(DRIVER_NUMBER, command_nr::CONFIGURE, tag_type as usize, 0).is_ok()
     }
 
-    /// Set the maximum frame delay value to support transmission with the reader.
-    pub fn set_framedelaymax(delay: u32) -> bool {
-        syscalls::command(DRIVER_NUMBER, command_nr::FRAMEDELAYMAX, delay as usize, 0).is_ok()
-    }
-
     /// 1. Share with the driver a buffer.
     /// 2. Subscribe to having a successful receive callback.
     /// 3. Issue the request for reception.