pw_bluetooth: Add RFCOMM emboss definitions

Change-Id: If78080b72ebdc49dc15b96afa8807fb51bcf9bac Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/248027 Reviewed-by: Ben Lawson <[email protected]> Commit-Queue: Austin Foxley <[email protected]> Reviewed-by: Edward Shin <[email protected]> Docs-Not-Needed: Ben Lawson <[email protected]> Lint: Lint 🤖 <[email protected]>
google · Nov 11, 2024 · a7362ec · a7362ec
1 parent 447364e
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diff --git a/pw_bluetooth/BUILD.bazel b/pw_bluetooth/BUILD.bazel
@@ -244,6 +244,19 @@ cc_library(
     deps = [":_emboss_l2cap_frames"],
 )
 
+emboss_cc_library(
+    name = "_emboss_rfcomm_frames",
+    srcs = ["public/pw_bluetooth/rfcomm_frames.emb"],
+    enable_enum_traits = False,
+    visibility = ["//visibility:private"],
+)
+
+cc_library(
+    name = "emboss_rfcomm_frames",
+    includes = ["public"],
+    deps = [":_emboss_rfcomm_frames"],
+)
+
 cc_library(
     name = "emboss_hci",
     deps = [
@@ -266,6 +279,7 @@ pw_cc_test(
         ":emboss_hci",
         ":emboss_hci_test",
         ":emboss_l2cap_frames",
+        ":emboss_rfcomm_frames",
         "//third_party/fuchsia:stdcompat",
     ],
 )

diff --git a/pw_bluetooth/BUILD.gn b/pw_bluetooth/BUILD.gn
@@ -167,6 +167,11 @@ if (dir_pw_third_party_emboss != "") {
     source = "public/pw_bluetooth/l2cap_frames.emb"
   }
 
+  emboss_cc_library("emboss_rfcomm_frames") {
+    public_configs = [ ":emboss_include_path" ]
+    source = "public/pw_bluetooth/rfcomm_frames.emb"
+  }
+
   group("emboss_hci_group") {
     public_configs = [ ":emboss_include_path" ]
     public_deps = [
@@ -199,6 +204,8 @@ if (dir_pw_third_party_emboss != "") {
   }
   group("emboss_l2cap_frames") {
   }
+  group("emboss_rfcomm_frames") {
+  }
 }
 
 pw_test_group("tests") {
@@ -254,6 +261,7 @@ pw_test("emboss_test") {
     ":emboss_hci_group",
     ":emboss_hci_test",
     ":emboss_l2cap_frames",
+    ":emboss_rfcomm_frames",
     "$dir_pw_third_party/fuchsia:stdcompat",
   ]
 }

diff --git a/pw_bluetooth/CMakeLists.txt b/pw_bluetooth/CMakeLists.txt
@@ -157,6 +157,11 @@ emboss_cc_library(pw_bluetooth.emboss_l2cap_frames
     public/pw_bluetooth/l2cap_frames.emb
 )
 
+emboss_cc_library(pw_bluetooth.emboss_rfcomm_frames
+  SOURCES
+    public/pw_bluetooth/rfcomm_frames.emb
+)
+
 emboss_cc_library(pw_bluetooth.emboss_att
   SOURCES
     public/pw_bluetooth/att.emb
@@ -197,6 +202,7 @@ pw_target_link_targets("pw_bluetooth._public_config"
     pw_bluetooth.emboss_hci_events
     pw_bluetooth.emboss_hci_h4
     pw_bluetooth.emboss_l2cap_frames
+    pw_bluetooth.emboss_rfcomm_frames
 )
 
 pw_add_test(pw_bluetooth.emboss_test
@@ -210,6 +216,7 @@ pw_add_test(pw_bluetooth.emboss_test
     pw_bluetooth.emboss_hci_group
     pw_bluetooth.emboss_hci_test
     pw_bluetooth.emboss_l2cap_frames
+    pw_bluetooth.emboss_rfcomm_frames
     pw_third_party.fuchsia.stdcompat
   GROUPS
     modules

diff --git a/pw_bluetooth/emboss_test.cc b/pw_bluetooth/emboss_test.cc
@@ -29,6 +29,7 @@
 #include "pw_bluetooth/hci_test.emb.h"
 #include "pw_bluetooth/hci_android.emb.h"    // IWYU pragma: keep
 #include "pw_bluetooth/l2cap_frames.emb.h"  // IWYU pragma: keep
+#include "pw_bluetooth/rfcomm_frames.emb.h"  // IWYU pragma: keep
 // clang-format on
 
 namespace pw::bluetooth {

diff --git a/pw_bluetooth/public/pw_bluetooth/rfcomm_frames.emb b/pw_bluetooth/public/pw_bluetooth/rfcomm_frames.emb
@@ -0,0 +1,103 @@
+# Copyright 2024 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.
+
+# This file contains 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.
+
+[$default byte_order: "LittleEndian"]
+[(cpp) namespace: "pw::bluetooth::emboss"]
+# ========================= RFCOMM Frame Format =================================
+# RFCOMM Spec v1.2
+# Also see: ETSI TS 07.10
+
+enum RfcommFrameType:
+  -- ETSI TS 07.10 section 5.2.1.3
+  [maximum_bits: 8]
+  SET_ASYNC_BALANCED_MODE = 0x2f
+  UNNUMBERED_ACK = 0x63
+  DISCONNECT_MODE = 0x0f
+  DISCONNECT = 0xc3
+  UNNUMBERED_INFORMATION_WITH_HEADER_CHECK = 0xef
+  UNNUMBERED_INFORMATION_WITH_HEADER_CHECK_AND_POLL_FINAL = 0xff
+    -- RFCOMM extension. With Poll/Final bit set in UIH control byte, a credits
+    -- field is the first byte of the payload.
+
+enum RfcommFixedChannel:
+  [maximum_bits: 8]
+  CONTROL = 0
+
+enum RfcommCommandResponse:
+  -- Commands from the initiator and responses from the responder
+  -- have C/R = 0. Commands from the responder and responses from
+  -- the initiator have C/R = 1.
+  [maximum_bits: 1]
+  COMMAND  = 0
+  RESPONSE = 1
+
+enum RfcommDirection:
+  [maximum_bits: 1]
+  RESPONDER = 0
+  INITIATOR = 1
+
+enum RfcommLengthExtended:
+  [maximum_bits: 1]
+  NORMAL = 1
+  EXTENDED = 0
+
+struct RfcommFrame:
+  -- RFCOMM ETSI TS 07.10 frame
+  [requires: extended_address == true]
+  0    [+1]  bits:
+    0  [+1]  Flag                   extended_address
+    1  [+1]  RfcommCommandResponse  command_response
+    2  [+1]  RfcommDirection        direction
+    3  [+5]  UInt                   channel
+      -- ETSI TS 07.10 section 5.2.1.2
+
+  1    [+1]  RfcommFrameType        control
+    -- ETSI TS 07.10 section 5.2.1.3
+
+  2    [+1]  bits:
+    0  [+1]  RfcommLengthExtended   length_extended_flag
+    1  [+7]  UInt                   length
+      -- ETSI TS 07.10 section 5.2.1.4
+
+  if length_extended_flag == RfcommLengthExtended.EXTENDED:
+    3  [+1]                UInt                     length_extended
+      -- ETSI TS 07.10 section 5.2.1.4
+
+  let information_length = $present(length_extended) ? length * 256 + length_extended : length
+    -- Length of the '5.2.1.4 Information Field'. May include the RFCOMM credits
+    -- field which appears at start.
+
+  let credits_offset = $present(length_extended) ? 4 : 3
+  if control == RfcommFrameType.UNNUMBERED_INFORMATION_WITH_HEADER_CHECK_AND_POLL_FINAL && channel != 0:
+    credits_offset  [+1]                UInt                     credits
+      -- Credits field can appears as first byte of information when Poll/Final
+      -- bit is set on UIH frames and channel is not control (0).
+
+  let payload_length = $present(credits) ? information_length - 1 : information_length
+  let payload_offset = $present(credits) ? credits_offset + 1 : credits_offset
+  payload_offset  [+payload_length]           UInt:8[payload_length]           payload
+    -- Payload is the RFCOMM payload contained in the 'Information Field' which
+    -- may start with credits.
+
+  let fcs_offset = payload_offset + payload_length
+  fcs_offset  [+1]  UInt                   fcs
+    -- Frame checksum. See: GSM 07.10 TS 101 369 V6.3.0
+    -- SABM, DISC, UA, DM frame types:
+    --   FCS should be calculated over address, control and length fields.
+    -- UIH frame type:
+    --   FCS should be calculated over address and control fields.