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Subject: Re: Format of HCI LE Advertising Report Event
From:   Johan Hedberg <johan.hedberg@gmail.com>
In-Reply-To: <20190123102452.o5xvunjcsx57pdwl@scytale>
Date:   Wed, 23 Jan 2019 12:37:10 +0200
Cc:     linux-bluetooth@vger.kernel.org
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Message-Id: <282271E8-D3D1-4AEC-8B57-BA03F3FF7D36@gmail.com>
References: <20190123102452.o5xvunjcsx57pdwl@scytale>
To:     =?utf-8?Q?Micha=C5=82_Lowas-Rzechonek?= 
        <michal.lowas-rzechonek@silvair.com>
Sender: linux-bluetooth-owner@vger.kernel.org
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Hi Micha=C5=82,


> On 23 Jan 2019, at 12.24, Micha=C5=82 Lowas-Rzechonek =
<michal.lowas-rzechonek@silvair.com> wrote:
> I've been reading Bluetooth Core spec v5.0, looking for a way to
> optimize sending LE Advertising Report events through HCI.
>=20
> It turns out that spec allows concatenating a few reports into a =
single
> HCI frame: 7.7.65.2 says that "The Controller may queue these
> advertising reports and send information from multiple devices in one =
LE
> Advertising Report event. So far, so good.
>=20
> The question I have is about the exact format of this event. Wording =
and
> tables in the spec suggest that fields from concatenated reports =
should
> be interleaved in the HCI frame, that is for num_reports =3D 2, fields
> should be ordered as follows:
>=20
> event_type[0]
> event_type[1]
> address_type[0]
> address_type[1]
> address[0]
> address[1]
> length[0]
> length[1]
> data[0]
> data[1]
> rssi[0]
> rssi[1]
>=20
> I don't this format is "natural", if I were to choose I would rather
> simply concatenate a few reports.

See Vol 2, Part E, section 5.2 (page 728 in the pdf):
=E2=80=9C
=E2=80=A2 Arrayed parameters are specified using the following notation: =
ParameterA[i]. If more than one set of arrayed parameters are specified =
(e.g. ParameterA[i], ParameterB[i]), then, unless noted otherwise, the =
order of the parameters are as follows: ParameterA[0], ParameterB[0], =
ParameterA[1], ParameterB[1], ParameterA[2], ParameterB[2], ... =
ParameterA[n], ParameterB[n]
=E2=80=9C

Johan=