From 05200284d2149abe9bbb17cc883b9b9a2ffd42de Mon Sep 17 00:00:00 2001
From: uael <uael@google.com>
Date: Thu, 23 Feb 2023 20:58:28 +0000
Subject: [PATCH] a2dp: get rid of `construct` dependency

---
 bumble/a2dp.py | 75 ++++++++++++++++++++++++++++++--------------------
 setup.cfg      |  1 -
 2 files changed, 45 insertions(+), 31 deletions(-)

diff --git a/bumble/a2dp.py b/bumble/a2dp.py
index de9f5f4..772846a 100644
--- a/bumble/a2dp.py
+++ b/bumble/a2dp.py
@@ -18,7 +18,6 @@
 import struct
 import logging
 from collections import namedtuple
-import construct
 
 from .company_ids import COMPANY_IDENTIFIERS
 from .sdp import (
@@ -258,17 +257,6 @@ class SbcMediaCodecInformation(
     A2DP spec - 4.3.2 Codec Specific Information Elements
     '''
 
-    BIT_FIELDS = construct.Bitwise(
-        construct.Sequence(
-            construct.BitsInteger(4),
-            construct.BitsInteger(4),
-            construct.BitsInteger(4),
-            construct.BitsInteger(2),
-            construct.BitsInteger(2),
-            construct.BitsInteger(8),
-            construct.BitsInteger(8),
-        )
-    )
     SAMPLING_FREQUENCY_BITS = {16000: 1 << 3, 32000: 1 << 2, 44100: 1 << 1, 48000: 1}
     CHANNEL_MODE_BITS = {
         SBC_MONO_CHANNEL_MODE: 1 << 3,
@@ -284,9 +272,22 @@ class SbcMediaCodecInformation(
     }
 
     @staticmethod
-    def from_bytes(data):
+    def from_bytes(data: bytes) -> 'SbcMediaCodecInformation':
+        sampling_frequency = (data[0] >> 4) & 0x0F
+        channel_mode = (data[0] >> 0) & 0x0F
+        block_length = (data[1] >> 4) & 0x0F
+        subbands = (data[1] >> 2) & 0x03
+        allocation_method = (data[1] >> 0) & 0x03
+        minimum_bitpool_value = (data[2] >> 0) & 0xFF
+        maximum_bitpool_value = (data[3] >> 0) & 0xFF
         return SbcMediaCodecInformation(
-            *SbcMediaCodecInformation.BIT_FIELDS.parse(data)
+            sampling_frequency,
+            channel_mode,
+            block_length,
+            subbands,
+            allocation_method,
+            minimum_bitpool_value,
+            maximum_bitpool_value,
         )
 
     @classmethod
@@ -335,8 +336,17 @@ class SbcMediaCodecInformation(
             maximum_bitpool_value=maximum_bitpool_value,
         )
 
-    def __bytes__(self):
-        return self.BIT_FIELDS.build(self)
+    def __bytes__(self) -> bytes:
+        return bytes(
+            [
+                (self.sampling_frequency << 4) | self.channel_mode,
+                (self.block_length << 4)
+                | (self.subbands << 2)
+                | self.allocation_method,
+                self.minimum_bitpool_value,
+                self.maximum_bitpool_value,
+            ]
+        )
 
     def __str__(self):
         channel_modes = ['MONO', 'DUAL_CHANNEL', 'STEREO', 'JOINT_STEREO']
@@ -367,16 +377,6 @@ class AacMediaCodecInformation(
     A2DP spec - 4.5.2 Codec Specific Information Elements
     '''
 
-    BIT_FIELDS = construct.Bitwise(
-        construct.Sequence(
-            construct.BitsInteger(8),
-            construct.BitsInteger(12),
-            construct.BitsInteger(2),
-            construct.BitsInteger(2),
-            construct.BitsInteger(1),
-            construct.BitsInteger(23),
-        )
-    )
     OBJECT_TYPE_BITS = {
         MPEG_2_AAC_LC_OBJECT_TYPE: 1 << 7,
         MPEG_4_AAC_LC_OBJECT_TYPE: 1 << 6,
@@ -400,9 +400,15 @@ class AacMediaCodecInformation(
     CHANNELS_BITS = {1: 1 << 1, 2: 1}
 
     @staticmethod
-    def from_bytes(data):
+    def from_bytes(data: bytes) -> 'AacMediaCodecInformation':
+        object_type = data[0]
+        sampling_frequency = (data[1] << 4) | ((data[2] >> 4) & 0x0F)
+        channels = (data[2] >> 2) & 0x03
+        rfa = 0
+        vbr = (data[3] >> 7) & 0x01
+        bitrate = ((data[3] & 0x7F) << 16) | (data[4] << 8) | data[5]
         return AacMediaCodecInformation(
-            *AacMediaCodecInformation.BIT_FIELDS.parse(data)
+            object_type, sampling_frequency, channels, rfa, vbr, bitrate
         )
 
     @classmethod
@@ -430,8 +436,17 @@ class AacMediaCodecInformation(
             bitrate=bitrate,
         )
 
-    def __bytes__(self):
-        return self.BIT_FIELDS.build(self)
+    def __bytes__(self) -> bytes:
+        return bytes(
+            [
+                self.object_type & 0xFF,
+                (self.sampling_frequency >> 4) & 0xFF,
+                (((self.sampling_frequency & 0x0F) << 4) | (self.channels << 2)) & 0xFF,
+                ((self.vbr << 7) | ((self.bitrate >> 16) & 0x7F)) & 0xFF,
+                ((self.bitrate >> 8) & 0xFF) & 0xFF,
+                self.bitrate & 0xFF,
+            ]
+        )
 
     def __str__(self):
         object_types = [
diff --git a/setup.cfg b/setup.cfg
index 3be6bcc..ef3dbdf 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -32,7 +32,6 @@ include-package-data = True
 install_requires =
     appdirs >= 1.4
     click >= 7.1.2; platform_system!='Emscripten'
-    construct >= 2.10
     cryptography == 35; platform_system!='Emscripten'
     grpcio >= 1.46; platform_system!='Emscripten'
     libusb1 >= 2.0.1; platform_system!='Emscripten'