srd: Split USB decoder in two PDs (which stack).

The 'usb_signalling' decoder just decodes symbols from D+/D- levels,
handles bit stuffing and outputs the symbols and (potential) packets.

The 'usb_protocol' decoder takes that output and tried to parse USB
packets from it (SOF, SETUP, IN, OUT, DATA0, and so on).
This is the base decoder on top of which various others will stack
later on.

The two new PDs are work in progress, so we still keep the old 'usb' PD
around for a little while, until the two new ones are fully working and
well-tested.

1 files changed, 47 insertions, 0 deletions

diff --git a/decoders/usb_protocol/__init__.py b/decoders/usb_protocol/__init__.py
new file mode 100644
index 0000000..a19304e
--- /dev/null
+++ b/decoders/usb_protocol/__init__.py
@@ -0,0 +1,47 @@
+##
+## This file is part of the sigrok project.
+##
+## Copyright (C) 2012 Uwe Hermann <uwe@hermann-uwe.de>
+##
+## This program is free software; you can redistribute it and/or modify
+## it under the terms of the GNU General Public License as published by
+## the Free Software Foundation; either version 2 of the License, or
+## (at your option) any later version.
+##
+## This program is distributed in the hope that it will be useful,
+## but WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+## GNU General Public License for more details.
+##
+## You should have received a copy of the GNU General Public License
+## along with this program; if not, write to the Free Software
+## Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+##
+
+'''
+USB (low-speed and full-speed) protocol decoder.
+
+Protocol layer (USB spec, chapter 8):
+
+Bit/byte ordering: Bits are sent onto the bus LSB-first. Multibyte fields
+are transmitted in little-endian order (i.e., LSB to MSB).
+
+SYNC field: All packets begin with a SYNC field (8 bits).
+
+Packet field format: Packets start with an SOP (Start Of Packet) delimiter
+that is part of the SYNC field, and end with an EOP (End Of Packet).
+
+PID: A PID (packet identifier) follows the SYNC field of every packet. A PID
+consists of a 4-bit packet type field, and a 4 bit check field.
+The check field is the one's complement of the packet type field.
+
+Protocol output format:
+TODO
+
+Details:
+https://en.wikipedia.org/wiki/USB
+http://www.usb.org/developers/docs/
+'''
+
+from .usb_protocol import *
+