sdk/fidl/fuchsia.bluetooth.gatt/constants.fidl

// Copyright 2019 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

library fuchsia.bluetooth.gatt;

const uint16 MAX_VALUE_LENGTH = 512;

// Maximum number of ReadByTypeResults that fit in a FIDL message.
const uint16 MAX_READ_BY_TYPE_RESULTS = 189;

// From Bluetooth Core Spec v5.2, Vol 3, Part F, 3.4.4.2.
const uint16 MAX_READ_BY_TYPE_VALUE_LENGTH = 253;

// The maximum number of attributes that can be contained in an attribute database.
const uint16 MAX_ATTRIBUTE_COUNT = 0xFFFF;

// The maximum number of services allowed. While the specification does not define an upper
// limit, this number is here to impose a bound on FIDL messages.
//
// This number is calculated based on 1 attribute per service declaration for a database that
// contains no characteristics.
const uint16 MAX_SERVICE_COUNT = MAX_ATTRIBUTE_COUNT;

// The maximum number of characteristics allowed. While the specification does not define an upper
// limit, this number is here to impose a bound on FIDL messages.
//
// This number is calculated based on 2 attributes per characteristic and excluding the service
// declaration attribute. I.e. this is the number of characteristics that can be represented in a
// database with a single service and no characteristic descriptors.
const uint16 MAX_CHARACTERISTIC_COUNT = 0x7FFF; // (MAX_ATTRIBUTE_COUNT - 1) / 2;

// The maximum number of characteristic descriptors allowed. While the specification does not define
// an upper limit, this number is here to impose a bound on FIDL messages.
//
// This number is calculated based on 1 attribute per descriptor and excluding the service and
// characteristic declaration attributes. I.e. this is the number of characteristics that can be
// represented in a database with a single service and a single characteristic.
const uint16 MAX_DESCRIPTOR_COUNT = 0xFFFC; // MAX_ATTRIBUTE_COUNT - 3;