pw_bluetooth: Add l2cap_frames.emb

Create an emboss file to contain frames defined in L2CAP. Currently only
supports K-Frames (used in credit-based flow control), but can be
expanded to other frames.

Change-Id: I202690e03ea8da41153afd65cbc293c1d5474828
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/185751
Reviewed-by: Ben Lawson <benlawson@google.com>
Commit-Queue: Jason Graffius <jgraff@google.com>
Reviewed-by: Faraaz Sareshwala <fsareshwala@google.com>
Reviewed-by: Josh Conner <joshconner@google.com>

3 files changed, 46 insertions, 0 deletions

diff --git a/pw_bluetooth/BUILD.gn b/pw_bluetooth/BUILD.gn
index 9ef081ce0..cbff17112 100644
--- a/pw_bluetooth/BUILD.gn
+++ b/pw_bluetooth/BUILD.gn
@@ -113,6 +113,11 @@ if (dir_pw_third_party_emboss != "") {
     deps = [ ":emboss_hci_common" ]
   }
 
+  emboss_cc_library("emboss_l2cap_frames") {
+    public_configs = [ ":emboss_include_path" ]
+    source = "public/pw_bluetooth/l2cap_frames.emb"
+  }
+
   group("emboss_hci_group") {
     public_configs = [ ":emboss_include_path" ]
     public_deps = [
@@ -135,6 +140,8 @@ if (dir_pw_third_party_emboss != "") {
   }
   group("emboss_hci_group") {
   }
+  group("emboss_l2cap_frames") {
+  }
 }
 
 pw_test_group("tests") {
@@ -176,6 +183,7 @@ pw_test("emboss_test") {
     ":emboss_hci_events",
     ":emboss_hci_test",
     ":emboss_hci_vendor",
+    ":emboss_l2cap_frames",
   ]
 }
 
diff --git a/pw_bluetooth/emboss_test.cc b/pw_bluetooth/emboss_test.cc
index 10de11f9d..563351bf5 100644
--- a/pw_bluetooth/emboss_test.cc
+++ b/pw_bluetooth/emboss_test.cc
@@ -15,6 +15,7 @@
 #include "pw_bluetooth/hci_events.emb.h"
 #include "pw_bluetooth/hci_test.emb.h"
 #include "pw_bluetooth/hci_vendor.emb.h"
+#include "pw_bluetooth/l2cap_frames.emb.h"
 #include "pw_unit_test/framework.h"
 
 namespace pw::bluetooth {
diff --git a/pw_bluetooth/public/pw_bluetooth/l2cap_frames.emb b/pw_bluetooth/public/pw_bluetooth/l2cap_frames.emb
new file mode 100644
index 000000000..b227f4788
--- /dev/null
+++ b/pw_bluetooth/public/pw_bluetooth/l2cap_frames.emb
@@ -0,0 +1,37 @@
+# Copyright 2023 The Pigweed Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may not
+# use this file except in compliance with the License. You may obtain a copy of
+# the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations under
+# the License.
+
+[$default byte_order: "LittleEndian"]
+[(cpp) namespace: "pw::bluetooth::emboss"]
+
+# This file contins Emboss definitions for the logical link control and
+# adaptation protocol (l2cap) frames found in the Bluetooth core specification.
+# The Emboss compiler is used to generate a C++ header from this file.
+
+# ========================= Data Packet Format =================================
+# Core Spec v5.4 Vol 3, Part A, Section 3
+#
+# ========== 3.4 Credit-Based Flow Control Frames ==========
+
+struct KFrameSduHeader:
+  -- 3.4.2
+  -- A frame header for a K-Frame (credit based flow control) SDU.
+  0 [+2]  UInt  sdu_length
+
+struct KFramePduHeader:
+  -- 3.4.1
+  -- A frame header for a K-Frame (credit based flow control) PDU.
+  0     [+2]  UInt  pdu_length
+  $next [+2]  UInt  channel_id
+