Initial Amulet LCD ASCII PD

This is a protocol decoder for the 'ASCII' protocol used by
Amulet Technologies LCDs.

Currently some commands are not implemented yet. I also lack capture data
from a display that will use replies other than ACK and NACK.

Reads are untested as I have no suitable captures.

The PD copes with bus errors (there is an actual bug in the device I'm
reverse engineering) and most of the commands are implemented.

The unimplemented commands should generally consume the correct
number of bytes from the bus, the exception to this are the drawing
commands, because there are actually at least two revisions of them
with different payloads, that are really hard to detect in greedy
algorithm.

3 files changed, 804 insertions, 0 deletions

diff --git a/decoders/amulet_ascii/__init__.py b/decoders/amulet_ascii/__init__.py
new file mode 100644
index 0000000..7d2c8c3
--- /dev/null
+++ b/decoders/amulet_ascii/__init__.py
@@ -0,0 +1,28 @@
+##
+## This file is part of the libsigrokdecode project.
+##
+## Copyright (C) 2019 Vesa-Pekka Palmu <vpalmu@depili.fi>
+##
+## 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, see <http://www.gnu.org/licenses/>.
+##
+
+'''
+This decoder stacks on top of the 'uart' PD and decodes the ASCII protocol
+for Amulet LCD display controllers.
+
+Currently the decoder treats both RX and TX the same way, decoding all
+message types.
+'''
+
+from .pd import Decoder
diff --git a/decoders/amulet_ascii/lists.py b/decoders/amulet_ascii/lists.py
new file mode 100644
index 0000000..92e27a9
--- /dev/null
+++ b/decoders/amulet_ascii/lists.py
@@ -0,0 +1,73 @@
+##
+## This file is part of the libsigrokdecode project.
+##
+## Copyright (C) 2019 Vesa-Pekka Palmu <vpalmu@depili.fi>
+##
+## 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, see <http://www.gnu.org/licenses/>.
+##
+
+from collections import OrderedDict
+
+# OrderedDict which maps command IDs to their names and descriptions.
+cmds = OrderedDict([
+    (0xA0, ('PAGE', 'Jump to page')),
+    (0xD0, ('GBV', 'Get byte variable')),
+    (0xD1, ('GWV', 'Get word variable')),
+    (0xD2, ('GSV', 'Get string variable')),
+    (0xD3, ('GLV', 'Get label variable')),
+    (0xD4, ('GRPC', 'Get RPC buffer')),
+    (0xD5, ('SBV', 'Set byte variable')),
+    (0xD6, ('SWV', 'Set word variable')),
+    (0xD7, ('SSV', 'Set string variable')),
+    (0xD8, ('RPC', 'Invoke RPC')),
+    (0xD9, ('LINE', 'Draw line')),
+    (0xDA, ('RECT', 'Draw rectangle')),
+    (0xDB, ('FRECT', 'Draw filled rectangle')),
+    (0xDC, ('PIXEL', 'Draw pixel')),
+    (0xDD, ('GBVA', 'Get byte variable array')),
+    (0xDE, ('GWVA', 'Get word variable array')),
+    (0xDF, ('SBVA', 'Set byte variable array')),
+    (0xE0, ('GBVR', 'Get byte variable reply')),
+    (0xE1, ('GWVR', 'Get word variable reply')),
+    (0xE2, ('GSVR', 'Get string variable reply')),
+    (0xE3, ('GLVR', 'Get label variable reply')),
+    (0xE4, ('GRPCR', 'Get RPC buffer reply')),
+    (0xE5, ('SBVR', 'Set byte variable reply')),
+    (0xE6, ('SWVR', 'Set word variable reply')),
+    (0xE7, ('SSVR', 'Set string variable reply')),
+    (0xE8, ('RPCR', 'Invoke RPC reply')),
+    (0xE9, ('LINER', 'Draw line reply')),
+    (0xEA, ('RECTR', 'Draw rectangle')),
+    (0xEB, ('FRECTR', 'Draw filled rectangle reply')),
+    (0xEC, ('PIXELR', 'Draw pixel reply')),
+    (0xED, ('GBVAR', 'Get byte variable array reply')),
+    (0xEE, ('GWVAR', 'Get word variable array reply')),
+    (0xEF, ('SBVAR', 'Set byte variable array reply')),
+    (0xF0, ('ACK', 'Acknowledgment')),
+    (0xF1, ('NACK', 'Negative acknowledgment')),
+    (0xF2, ('SWVA', 'Set word variable array')),
+    (0xF3, ('SWVAR', 'Set word variable array reply')),
+    (0xF4, ('GCV', 'Get color variable')),
+    (0xF5, ('GCVR', 'Get color variable reply')),
+    (0xF6, ('SCV', 'Set color variable')),
+    (0xF7, ('SCVR', 'Set color variable reply')),
+])
+
+cmds_with_high_bytes = [
+    0xA0, # PAGE - Page change
+    0xD7, # SVV - Set string variable
+    0xE7, # SVVR - Set string variable reply
+    0xE2, # GSVR - Get string variable reply
+    0xE3, # GLVR - Get label variable reply
+]
diff --git a/decoders/amulet_ascii/pd.py b/decoders/amulet_ascii/pd.py
new file mode 100644
index 0000000..bd8c4d0
--- /dev/null
+++ b/decoders/amulet_ascii/pd.py
@@ -0,0 +1,703 @@
+##
+## This file is part of the libsigrokdecode project.
+##
+## Copyright (C) 2019 Vesa-Pekka Palmu <vpalmu@depili.fi>
+##
+## 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 3 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, see <http://www.gnu.org/licenses/>.
+##
+
+import sigrokdecode as srd
+from math import ceil
+from .lists import *
+
+L = len(cmds)
+RX = 0
+TX = 1
+rxtx_channels = ('RX', 'TX')
+
+# Don't forget to keep this in sync with 'cmds' is lists.py.
+class Ann:
+    PAGE, GBV, GWV, GSV, GLV, GRPC, SBV, SWV, SSV, RPC, LINE, RECT, FRECT, \
+    PIXEL, GBVA, GWVA, SBVA, GBVR, GWVR, GSVR, GLVR, GRPCR, SBVR, SWVR, SSVR, \
+    RPCR, LINER, RECTR, FRECTR, PIXELR, GBVAR, GWVAR, SBVAR, ACK, NACK, SWVA, \
+    SWVAR, GCV, GCVR, SCV, SCVR, BIT, FIELD, WARN = range(L + 3)
+
+def cmd_annotation_classes():
+    return tuple([tuple([cmd[0].lower(), cmd[1]]) for cmd in cmds.values()])
+
+class Decoder(srd.Decoder):
+    api_version = 3
+    id = 'amulet_ascii'
+    name = 'Amulet ASCII'
+    longname = 'Amulet LCD ASCII'
+    desc = 'Amulet Technologies LCD controller ASCII protocol.'
+    license = 'gplv3+'
+    inputs = ['uart']
+    outputs = []
+    tags = ['Display']
+    annotations = cmd_annotation_classes() + (
+        ('bit', 'Bit'),
+        ('field', 'Field'),
+        ('warning', 'Warning'),
+    )
+    annotation_rows = (
+        ('bits', 'Bits', (L + 0,)),
+        ('fields', 'Fields', (L + 1,)),
+        ('commands', 'Commands', tuple(range(len(cmds)))),
+        ('warnings', 'Warnings', (L + 2,)),
+    )
+    options = (
+        {'id': 'ms_chan', 'desc': 'Master -> slave channel',
+            'default': rxtx_channels[0], 'values': rxtx_channels},
+        {'id': 'sm_chan', 'desc': 'Slave -> master channel',
+            'default': rxtx_channels[1], 'values': rxtx_channels},
+    )
+
+    def __init__(self):
+        self.reset()
+
+    def reset(self):
+        self.state = None
+        self.cmdstate = None
+
+        # Build dict mapping command keys to handler functions. Each
+        # command in 'cmds' (defined in lists.py) has a matching
+        # handler self.handle_<shortname>.
+        def get_handler(cmd):
+            s = 'handle_%s' % cmds[cmd][0].lower().replace('/', '_')
+            return getattr(self, s)
+        self.cmd_handlers = dict((cmd, get_handler(cmd)) for cmd in cmds.keys())
+
+    def start(self):
+        self.out_ann = self.register(srd.OUTPUT_ANN)
+
+    def putx(self, data):
+        # Simplification, most annotations span exactly one SPI byte/packet.
+        self.put(self.ss, self.es, self.out_ann, data)
+
+    def putf(self, data):
+        self.put(self.ss_field, self.es_field, self.out_ann, data)
+
+    def putc(self, data):
+        self.put(self.ss_cmd, self.es_cmd, self.out_ann, data)
+
+    def cmd_ann_list(self):
+        x, s = cmds[self.state][0], cmds[self.state][1]
+        return ['Command: %s (%s)' % (s, x), 'Command: %s' % s,
+                'Cmd: %s' % s, 'Cmd: %s' % x, x]
+
+    def emit_cmd_byte(self):
+        self.ss_cmd = self.ss
+        self.putx([Ann.FIELD, self.cmd_ann_list()])
+
+    def emit_addr_bytes(self, pdata):
+        if self.cmdstate == 2:
+            self.ss_field = self.ss
+            self.addr = chr(pdata)
+            self.putx([Ann.BIT, ['Address high nibble: %c' % (pdata),
+                 'Addr high 0x%c' % (pdata), 'Addr h 0x%c' % (pdata)]])
+        elif self.cmdstate == 3:
+            self.es_field = self.es
+            self.addr += chr(pdata)
+            self.addr = int(self.addr, 16)
+            self.putx([Ann.BIT, ['Address low nibble: %c' % (pdata),
+                 'Addr low 0x%c' % (pdata), 'Addr l 0x%c' % (pdata)]])
+            self.putf([Ann.FIELD, ['Address: 0x%02X' % self.addr,
+                'Addr: 0x%02X' % self.addr, '0x%02X' % self.addr]])
+
+    def emit_cmd_end(self, data):
+        self.es_cmd = self.es
+        self.putc(data)
+        self.state = None
+
+    def handle_read(self, data):
+        if self.cmdstate == 1:
+            self.emit_cmd_byte()
+            self.addr = 0
+        elif self.cmdstate == 2:
+            self.emit_addr_bytes(pdata)
+        elif self.cmdstate == 3:
+            self.emit_addr_bytes(pdata)
+        self.cmdstate += 1
+
+    def handle_set_common(self, pdata):
+        if self.cmdstate == 1:
+            self.addr = 0
+        self.emit_addr_bytes(pdata)
+
+    def emit_not_implemented(self, data):
+        self.es_cmd = self.es
+        self.putc([Ann.WARN, ['Command not decoded', 'Not decoded']])
+        self.emit_cmd_end(data)
+
+    def handle_string(self, pdata, ann_class):
+        # TODO: unicode / string modifiers...
+        self.handle_set_common(pdata)
+        if self.cmdstate == 4:
+            self.ss_field = self.ss
+            self.value = ''
+        if pdata == 0x00:
+            # Null terminated string ends.
+            self.es_field = self.es
+            self.putx([Ann.BIT, ['NULL']])
+            self.putf([Ann.FIELD, ['Value: %s' % (self.value),
+                'Val: %s' % (self.value), '%s' % (self.value)]])
+            self.emit_cmd_end([ann_class, self.cmd_ann_list()])
+            return
+        if self.cmdstate > 3:
+            self.value += chr(pdata)
+            self.putx([Ann.BIT, ['%c' % (pdata)]])
+        self.cmdstate += 1
+
+    # Command handlers
+
+    # Page change 0xA0, 0x02, index_high, index_low, checksum
+    def handle_page(self, pdata):
+        if self.cmdstate == 2:
+            if pdata == 0x02:
+                self.ss_field = self.ss_cmd
+                self.es_field = self.es
+                self.putf([Ann.FIELD, self.cmd_ann_list()])
+                self.checksum = 0xA0 + 0x02
+            else:
+                self.putx([Ann.WARN, ['Illegal second byte for page change',
+                                      'Illegal byte']])
+                self.state = None
+        elif self.cmdstate == 3:
+            self.ss_field = self.ss
+            self.checksum += pdata
+            self.page[0] = pdata
+        elif self.cmdstate == 4:
+            self.checksum += pdata
+            self.page[1] = pdata
+            self.es_field = self.es
+            if self.page[0] == self.page [1] == 0xFF:
+                # Soft reset trigger
+                self.putf(Ann.WARN, ['Soft reset', 'Reset'])
+            else:
+                page = chr(self.page[0]) + chr(self.page[1])
+                self.putf(Ann.FIELD, ['Page index: 0x%s' % (page),
+                                      'Page: 0x%s' % (page), '0x%s' % (page)])
+        elif self.cmdstate == 5:
+            self.checksum += pdata
+            if (self.checksum & 0xFF) != 0:
+                self.putx([Ann.WARN, ['Checksum error', 'Error', 'ERR']])
+            else:
+                self.putx([Ann.FIELD, ['Checksum OK', 'OK']])
+            self.emit_cmd_end(Ann.PAGE)
+        self.cmdstate += 1
+
+    # Value reads: command byte, address high nibble, address low nibble
+
+    # Get byte value
+    def handle_gbv(self, pdata):
+        self.handle_read(pdata)
+        self.emit_cmd_end([Ann.GBV, self.cmd_ann_list()])
+
+    # Get word value
+    def handle_gwv(self, pdata):
+        self.handle_read(pdata)
+        self.emit_cmd_end([Ann.GWV, self.cmd_ann_list()])
+
+    # Get string value
+    def handle_gsv(self, pdata):
+        self.handle_read(pdata)
+        self.emit_cmd_end([Ann.GSV, self.cmd_ann_list()])
+
+    # Get label value
+    def handle_glv(self, pdata):
+        self.handle_read(pdata)
+        self.emit_cmd_end([Ann.GLV, self.cmd_ann_list()])
+
+    # Get RPC buffer
+    def handle_grpc(self, pdata):
+        if self.cmdstate == 2:
+            self.ss_field = self.ss
+            self.flags = int(chr(pdata), 16) << 4
+        elif self.cmdstate == 3:
+            self.flags += int(chr(pdata), 16)
+            self.es_field = self.es
+            self.putf([Ann.FIELD, ['RPC flag: 0x%02X' % (self.flags)]])
+            self.emit_cmd_end([Ann.GRPC, self.cmd_ann_list()])
+
+    # Get byte value array
+    def handle_gbva(self, pdata):
+        self.handle_read(pdata)
+        self.emit_cmd_end([Ann.GBVA, self.cmd_ann_list()])
+
+    # Get word value array
+    def handle_gwva(self, pdata):
+        self.handle_read(pdata)
+        self.emit_cmd_end([Ann.GWVA, self.cmd_ann_list()])
+
+    # Get color variable
+    def handle_gcv(self, pdata):
+        self.handle_read(pdata)
+        self.emit_cmd_end([Ann.GCV, self.cmd_ann_list()])
+
+    # Value setters: command byte, address high nibble, address low nibble, data bytes
+
+    # Set byte value data = high nibble, low nibble
+    def handle_sbv(self, pdata):
+        self.handle_set_common(pdata)
+        if self.cmdstate == 4:
+            self.ss_field = self.ss
+            self.value = chr(pdata)
+        elif self.cmdstate == 5:
+            self.value += chr(pdata)
+            self.es_field = self.es
+            self.putf([Ann.FIELD, ['Value: 0x%s' % self.value,
+                'Val: 0x%s' % self.value, '0x%s' % self.value]])
+            self.emit_cmd_end([Ann.SBV, self.cmd_ann_list()])
+        self.cmdstate += 1
+
+    # Set word value, msb high, msb low, lsb high, lsb low
+    def handle_swv(self, pdata):
+        self.handle_set_common(pdata)
+        if self.cmdstate > 3:
+            nibble = self.cmdstate - 4
+            if nibble == 0:
+                self.ss_field = self.ss
+                self.value = 0
+            self.value += int(chr(pdata), 16) << 12 - (4 * nibble)
+            if nibble == 3:
+                self.es_field = self.es
+                self.putf([Ann.FIELD, ['Value: 0x%04x' % self.value,
+                    'Val: 0x%04x' % self.value, '0x%04x' % self.value]])
+                self.emit_cmd_end([Ann.SWV, self.cmd_ann_list()])
+                return
+        self.cmdstate += 1
+
+    # Set string value, null terminated utf8 strings
+    def handle_ssv(self, pdata):
+        self.handle_string(pdata, Ann.SSV)
+
+    # Set byte value array
+    def handle_sbva(self, pdata):
+        nibble = (self.cmdstate - 3) % 2
+        if self.cmdstate == 2:
+            self.addr = int(chr(pdata), 16) << 4
+            self.ss_field = self.ss
+            self.putx([Ann.BIT, ['Address high nibble: %c' % (pdata),
+                 'Addr high 0x%c' % (pdata), '0x%c' % (pdata)]])
+        elif self.cmdstate == 3:
+            self.addr += int(chr(pdata), 16)
+            self.es_field = self.ss
+            self.putx([Ann.BIT, ['Address low nibble: %c' % (pdata),
+                 'Addr low 0x%c' % (pdata), '0x%c' % (pdata)]])
+            self.putf([Ann.FIELD, ['Address: 0x%02X' % self.addr,
+                'Addr: 0x%02X' % self.addr, '0x%02X' % self.addr]])
+        elif stage == 2:
+            if pdata == 0x00:
+                # Null terminated list
+                self.emit_cmd_end([Ann.SBVA, self.cmd_ann_list()])
+                return
+            self.value = int(chr(pdata), 16) << 4
+        else:
+            self.value += int(chr(pdata), 16)
+            self.es_field = self.es
+            self.putf([Ann.FIELD, ['Value 0x%02X' % (self.value),
+                                   '0x%02X' % (self.value)]])
+        self.cmdstate += 1
+
+    # Set word value array
+    def handle_swva(self, pdata):
+        nibble = (self.cmdstate - 3) % 4
+        if self.cmdstate == 2:
+            self.addr = int(chr(pdata), 16) << 4
+            self.ss_field = self.ss
+            self.putx([Ann.BIT, ['Address high nibble: %c' % (pdata),
+                  'Addr high 0x%c' % (pdata), '0x%c' % (pdata)]])
+        elif self.cmdstate == 3:
+            self.addr += int(chr(pdata), 16)
+            self.es_field = self.ss
+            self.putx([Ann.BIT, ['Address low nibble: %c' % (pdata),
+                 'Addr low 0x%c' % (pdata), '0x%c' % (pdata)]])
+            self.putf([Ann.FIELD, ['Address: 0x%02X' % self.addr,
+                 'Addr: 0x%02X' % self.addr, '0x%02X' % self.addr]])
+            self.value = 0
+        else:
+            self.value += int(chr(pdata), 16) << 12 - (4 * nibble)
+            if nibble == 0:
+                if pdata == 0x00:
+                    # Null terminated list
+                    self.emit_cmd_end([Ann.SWVA, self.cmd_ann_list()])
+                    return
+                self.ss_field = self.ss
+            if nibble == 3:
+                self.es_field = self.es
+                self.putf([Ann.FIELD, ['Value 0x%04X' % (self.value),
+                                       '0x%04X' % (self.value)]])
+                self.cmdstate += 1
+
+    # Set color variable
+    def handle_scv(self, pdata):
+        if self.cmdstate == 8:
+            self.emit_not_implemented([Ann.SCV, self.cmd_ann_list()])
+        self.cmdstate += 1
+
+    # RPC trigger
+    def handle_rpc(self, pdata):
+        self.handle_read(pdata)
+        self.emit_cmd_end([Ann.RPC, self.cmd_ann_list()])
+
+    # Drawing
+
+    # Decode pair of (x,y) 16bit coordinates
+    def decode_coords(self, pdata):
+        if self.cmdstate == 1:
+            self.coords[0] = 0
+            self.coords[1] = 0
+            self.coords[2] = 0
+            self.coords[3] = 0
+        if self.cmdstate < 18:
+            # Coordinates
+            nibble = (self.cmdstate - 1) % 4
+            i = (self.cmdstate - 1) / 4
+            self.coords[i] += int(chr(pdata), 16) << 12 - (4 * nibble)
+            if nibble == 0:
+                self.ss_field = self.ss
+            elif nibble == 3:
+                self.es_field = self.es
+                self.putf([Ann.FIELD, ['Coordinate 0x%04X' % (self.coords[i])],
+                                      ['0x%04X' % (self.coords[i])]])
+
+    # TODO: There are actually two protocol revisions for drawing.
+    # Both use 4 bytes for 16bit x and y pairs for start and end.
+    # The older follows this by a pattern selector and then line weight.
+    # Newer version has 6 bytes for 8bit RGB color...
+
+    # Draw line
+    def handle_line(self, pdata):
+        decode_coords(pdata)
+        if self.cmdstate == 18:
+            self.es_cmd = self.es
+            self.putc([Ann.LINE, self.cmd_ann_list()])
+            self.putc([Ann.WARN, ['Line pattern / Color not implemented']])
+            self.state = None
+        self.cmdstate += 1
+
+    # Draw rectange
+    def handle_rect(self, pdata):
+        decode_coords(pdata)
+        if self.cmdstate == 18:
+            self.es_cmd = self.es
+            self.putc([Ann.RECT, self.cmd_ann_list()])
+            self.putc([Ann.WARN, ['Line pattern / Color not implemented']])
+            self.state = None
+        self.cmdstate += 1
+
+    # Draw filled rectangle
+    def handle_frect(self, pdata):
+        decode_coords(pdata)
+        if self.cmdstate == 18:
+            self.es_cmd = self.es
+            self.putc([Ann.FRECT, self.cmd_ann_list()])
+            self.putc([Ann.WARN, ['Fill pattern / Color not implemented']])
+            self.state = None
+        self.cmdstate += 1
+
+    # Draw pixel
+    def handle_pixel(self, pdata):
+        self.es_cmd = self.es
+        self.putc([Ann.WARN, ['Draw pixel documentation is missing.', 'Undocumented']])
+        self.state = None
+
+    # Replies
+    def handle_gbvr(self, pdata):
+        self.emit_add_bytes(pdata)
+        if self.cmdstate == 4:
+            self.ss_field = self.ss
+            self.value = int(chr(pdata), 16) << 4
+            self.putx([Ann.BIT, ['High nibble 0x%s' % (pdata), '0x%s' % (pdata)]])
+        elif self.cmdstate == 5:
+            self.value += int(chr(pdata), 16)
+            self.putx([Ann.BIT, ['Low nibble 0x%s' % (pdata), '0x%s' % (pdata)]])
+            self.es_field = self.es
+            self.putf([Ann.FIELD, ['Value: 0x%02X' % (self.value),
+                                   '0x%02X' % (self.value)]])
+            self.emit_cmd_end([Ann.GBVR, self.cmd_ann_list()])
+        self.cmdstate += 1
+
+    def handle_gwvr(self, pdata):
+        self.emit_add_bytes(pdata)
+        if self.cmdstate > 3:
+            nibble = self.cmdstate - 3
+            if nibble == 0:
+                self.value = 0
+                self.ss_field = self.ss
+            self.value += int(chr(pdata), 16) << 12 - (4 * nibble)
+            self.putx([Ann.BIT, ['0x%s' % (pdata)]])
+            if nibble == 3:
+                self.putf([Ann.FIELD, ['Value: 0x%04x' % (self.value),
+                                       '0x%04X' % (self.value)]])
+                self.es_cmd = self.ss
+                self.emit_cmd_end([Ann.GWVR, self.cmd_ann_list()])
+        self.cmdstate += 1
+
+    def handle_gsvr(self, pdata):
+        self.handle_string(pdata, Ann.GSVR)
+
+    def handle_glvr(self, pdata):
+        self.handle_string(pdata, Ann.GLVR)
+
+    def handle_grpcr(self, pdata):
+        self.handle_addr(pdata)
+        if self.cmdstate > 3:
+            nibble = (self.cmdstate - 3) % 2
+            if nibble == 0:
+                if pdata == 0x00:
+                    self.emit_cmd_end([Ann.GRPCR, self.cmd_ann_list()])
+                    return
+                self.value = int(chr(pdata), 16) << 4
+                self.ss_field = self.ss
+                self.putx([Ann.BIT, ['0x%s' % (pdata)]])
+            if nibble == 2:
+                self.value += int(chr(pdata), 16)
+                self.es_field = self.es
+                self.putx([Ann.BIT, ['0x%s' % (pdata)]])
+                self.putf([Ann.FIELD, ['0x%02X' % (self.value)]])
+        self.cmdstate += 1
+
+    def handle_sbvr(self, pdata):
+        self.handle_set_common(pdata)
+        if self.cmdstate == 4:
+            self.ss_field = self.ss
+            self.value = chr(pdata)
+        elif self.cmdstate == 5:
+            self.value += chr(pdata)
+            self.es_field = self.es
+            self.putf([Ann.FIELD, ['Value: 0x%s' % self.value,
+                'Val: 0x%s' % self.value, '0x%s' % self.value]])
+            self.emit_cmd_end([Ann.SBVR, self.cmd_ann_list()])
+        self.cmdstate += 1
+
+    def handle_swvr(self, pdata):
+        self.handle_set_common(pdata)
+        if self.cmdstate == 4:
+            self.ss_field = self.ss
+            self.value = (pdata - 0x30) << 4
+        elif self.cmdstate == 5:
+            self.value += (pdata - 0x30)
+            self.value = self.value << 8
+        elif self.cmdstate == 6:
+            self.value += (pdata - 0x30) << 4
+        elif self.cmdstate == 7:
+            self.value += (pdata - 0x30)
+            self.es_field = self.es
+            self.putf([Ann.FIELD, ['Value: 0x%04x' % self.value,
+                'Val: 0x%04x' % self.value, '0x%04x' % self.value]])
+            self.emit_cmd_end([Ann.SWVR, self.cmd_ann_list()])
+            self.state = None
+        self.cmdstate += 1
+
+    def handle_ssvr(self, pdata):
+        self.handle_string(pdata, Ann.SSVR)
+
+    def handle_rpcr(self, pdata):
+        self.handle_read(pdata)
+        self.emit_cmd_end([Ann.RPCR, self.cmd_ann_list()])
+
+    def handle_liner(self, pdata):
+        decode_coords(pdata)
+        if self.cmdstate == 18:
+            self.es_cmd = self.es
+            self.putc([Ann.LINER, self.cmd_ann_list()])
+            self.putc([Ann.WARN, ['Line pattern / Color not implemented']])
+            self.state = None
+        self.cmdstate += 1
+
+    def handle_rectr(self, pdata):
+        decode_coords(pdata)
+        if self.cmdstate == 18:
+            self.es_cmd = self.es
+            self.putc([Ann.RECTR, self.cmd_ann_list()])
+            self.putc([Ann.WARN, ['Line pattern / Color not implemented']])
+            self.state = None
+        self.cmdstate += 1
+
+    def handle_frectr(self, pdata):
+        decode_coords(pdata)
+        if self.cmdstate == 18:
+            self.es_cmd = self.es
+            self.putc([Ann.FRECTR, self.cmd_ann_list()])
+            self.putc([Ann.WARN, ['Line pattern / Color not implemented']])
+            self.state = None
+        self.cmdstate += 1
+
+    def handle_pixelr(self, pdata):
+        self.es_cmd = self.es
+        self.putc([Ann.WARN,['Draw pixel documentation is missing.', 'Undocumented']])
+        self.state = None
+
+    def handle_gbvar(self, pdata):
+        nibble = (self.cmdstate - 3) % 2
+        if self.cmdstate == 2:
+            self.addr = int(chr(pdata), 16) << 4
+            self.ss_field = self.ss
+            self.putx([Ann.BIT, ['Address high nibble: %c' % (pdata),
+                 'Addr high 0x%c' % (pdata), '0x%c' % (pdata)]])
+        elif self.cmdstate == 3:
+            self.addr += int(chr(pdata), 16)
+            self.es_field = self.ss
+            self.putx([Ann.BIT, ['Address low nibble: %c' % (pdata),
+                 'Addr low 0x%c' % (pdata), '0x%c' % (pdata)]])
+            self.putf([Ann.FIELD, ['Address: 0x%02X' % self.addr,
+                'Addr: 0x%02X' % self.addr, '0x%02X' % self.addr]])
+        elif stage == 2:
+            if pdata == 0x00:
+                # Null terminated list
+                self.emit_cmd_end([Ann.GBVAR, self.cmd_ann_list()])
+                return
+            self.value = int(chr(pdata), 16) << 4
+        else:
+            self.value += int(chr(pdata), 16)
+            self.es_field = self.es
+            self.putf([Ann.FIELD, ['Value 0x%02X' % (self.value),
+                                   '0x%02X' % (self.value)]])
+        self.cmdstate += 1
+
+    def handle_gwvar(self, pdata):
+        nibble = (self.cmdstate - 3) % 4
+        if self.cmdstate == 2:
+            self.addr = int(chr(pdata), 16) << 4
+            self.ss_field = self.ss
+            self.putx([Ann.BIT, ['Address high nibble: %c' % (pdata),
+                  'Addr high 0x%c' % (pdata), '0x%c' % (pdata)]])
+        elif self.cmdstate == 3:
+            self.addr += int(chr(pdata), 16)
+            self.es_field = self.ss
+            self.putx([Ann.BIT, ['Address low nibble: %c' % (pdata),
+                 'Addr low 0x%c' % (pdata), '0x%c' % (pdata)]])
+            self.putf([Ann.FIELD, ['Address: 0x%02X' % self.addr,
+                 'Addr: 0x%02X' % self.addr, '0x%02X' % self.addr]])
+            self.value = 0
+        else:
+            self.value += int(chr(pdata), 16) << 12 - (4 * nibble)
+            if nibble == 0:
+                if pdata == 0x00:
+                    # Null terminated list
+                    self.emit_cmd_end([Ann.GWVAR, self.cmd_ann_list()])
+                    return
+                self.ss_field = self.ss
+            if nibble == 3:
+                self.es_field = self.es
+                self.putf([Ann.FIELD, ['Value 0x%04X' % (self.value),
+                                       '0x%04X' % (self.value)]])
+                self.cmdstate += 1
+
+    # Get byte variable array reply
+    def handle_sbvar(self, pdata):
+        nibble = (self.cmdstate - 3) % 2
+        if self.cmdstate == 2:
+            self.addr = int(chr(pdata), 16) << 4
+            self.ss_field = self.ss
+            self.putx([Ann.BIT, ['Address high nibble: %c' % (pdata),
+                 'Addr high 0x%c' % (pdata), '0x%c' % (pdata)]])
+        elif self.cmdstate == 3:
+            self.addr += int(chr(pdata), 16)
+            self.es_field = self.ss
+            self.putx([Ann.BIT, ['Address low nibble: %c' % (pdata),
+                 'Addr low 0x%c' % (pdata), '0x%c' % (pdata)]])
+            self.putf([Ann.FIELD, ['Address: 0x%02X' % self.addr,
+                'Addr: 0x%02X' % self.addr, '0x%02X' % self.addr]])
+        elif stage == 2:
+            if pdata == 0x00:
+                # Null terminated list
+                self.emit_cmd_end([Ann.SBVAR, self.cmd_ann_list()])
+                return
+            self.value = int(chr(pdata), 16) << 4
+        else:
+            self.value += int(chr(pdata), 16)
+            self.es_field = self.es
+            self.putf([Ann.FIELD, ['Value 0x%02X' % (self.value),
+                                   '0x%02X' % (self.value)]])
+        self.cmdstate += 1
+
+    # Set word variable array reply
+    def handle_swvar(self, pdata):
+        nibble = (self.cmdstate - 3) % 4
+        if self.cmdstate == 2:
+            self.addr = int(chr(pdata), 16) << 4
+            self.ss_field = self.ss
+            self.putx([Ann.BIT, ['Address high nibble: %c' % (pdata),
+                  'Addr high 0x%c' % (pdata), '0x%c' % (pdata)]])
+        elif self.cmdstate == 3:
+            self.addr += int(chr(pdata), 16)
+            self.es_field = self.ss
+            self.putx([Ann.BIT, ['Address low nibble: %c' % (pdata),
+                 'Addr low 0x%c' % (pdata), '0x%c' % (pdata)]])
+            self.putf([Ann.FIELD, ['Address: 0x%02X' % self.addr,
+                 'Addr: 0x%02X' % self.addr, '0x%02X' % self.addr]])
+            self.value = 0
+        else:
+            self.value += int(chr(pdata), 16) << 12 - (4 * nibble)
+            if nibble == 0:
+                if pdata == 0x00:
+                    # Null terminated list
+                    self.emit_cmd_end([Ann.SWVAR, self.cmd_ann_list()])
+                    return
+                self.ss_field = self.ss
+            if nibble == 3:
+                self.es_field = self.es
+                self.putf([Ann.FIELD, ['Value 0x%04X' % (self.value),
+                                       '0x%04X' % (self.value)]])
+                self.cmdstate += 1
+
+    def handle_gcvr(self, pdata):
+        if self.cmdstate == 8:
+            self.emit_not_implemented([Ann.SCV, self.cmd_ann_list()])
+        self.cmdstate += 1
+
+    def handle_scvr(self, pdata):
+        if self.cmdstate == 8:
+            self.emit_not_implemented([Ann.SCV, self.cmd_ann_list()])
+        self.cmdstate += 1
+
+    # ACK & NACK
+
+    def handle_ack(self, pdata):
+        self.putx([Ann.ACK, self.cmd_ann_list()])
+        self.state = None
+
+    def handle_nack(self, pdata):
+        self.putx([Ann.NACK, self.cmd_ann_list()])
+        self.state = None
+
+    def decode(self, ss, es, data):
+        ptype, rxtx, pdata = data
+
+        self.ss, self.es = ss, es
+
+        if ptype != 'DATA':
+            return
+
+        # Handle commands.
+        try:
+            abort_current = (0xD0 <= pdata[0] <= 0xF7) and \
+                (not (self.state in cmds_with_high_bytes)) and \
+                self.state != None
+            if abort_current:
+                self.putx([Ann.WARN, ['Command aborted by invalid byte', 'Abort']])
+                self.state = pdata[0]
+                self.emit_cmd_byte()
+                self.cmdstate = 1
+            if (self.state is None):
+                self.state = pdata[0]
+                self.emit_cmd_byte()
+                self.cmdstate = 1
+            self.cmd_handlers[self.state](pdata[0])
+        except KeyError:
+            self.putx([Ann.WARN, ['Unknown command: 0x%02x' % pdata[0]]])
+            self.state = None