async def read_cmd(iface: io.HID) -> Cmd:
desc_init = frame_init()
desc_cont = frame_cont()
buf, = await loop.select(iface.iface_num())
# log.debug(__name__, 'read init %s', buf)
ifrm = overlay_struct(buf, desc_init)
bcnt = ifrm.bcnt
data = ifrm.data
datalen = len(data)
seq = 0
if ifrm.cmd & _TYPE_MASK == _TYPE_CONT:
# unexpected cont packet, abort current msg
log.warning(__name__, '_TYPE_CONT')
return None
if datalen < bcnt:
databuf = bytearray(bcnt)
utils.memcpy(databuf, 0, data, 0, bcnt)
data = databuf
else:
data = data[:bcnt]
while datalen < bcnt:
buf, = await loop.select(iface.iface_num())
# log.debug(__name__, 'read cont %s', buf)
cfrm = overlay_struct(buf, desc_cont)
if cfrm.seq == _CMD_INIT:
# _CMD_INIT frame, cancels current channel
ifrm = overlay_struct(buf, desc_init)
data = ifrm.data[:ifrm.bcnt]
break
if cfrm.cid != ifrm.cid:
# cont frame for a different channel, reply with BUSY and skip
log.warning(__name__, '_ERR_CHANNEL_BUSY')
send_cmd(cmd_error(cfrm.cid, _ERR_CHANNEL_BUSY), iface)
continue
if cfrm.seq != seq:
# cont frame for this channel, but incorrect seq number, abort
# current msg
log.warning(__name__, '_ERR_INVALID_SEQ')
send_cmd(cmd_error(cfrm.cid, _ERR_INVALID_SEQ), iface)
return None
datalen += utils.memcpy(data, datalen, cfrm.data, 0, bcnt - datalen)
seq += 1
return Cmd(ifrm.cid, ifrm.cmd, data)
async def send_cmd(cmd: Cmd, iface: io.HID) -> None:
init_desc = frame_init()
cont_desc = frame_cont()
offset = 0
seq = 0
datalen = len(cmd.data)
buf, frm = make_struct(init_desc)
frm.cid = cmd.cid
frm.cmd = cmd.cmd
frm.bcnt = datalen
offset += utils.memcpy(frm.data, 0, cmd.data, offset, datalen)
iface.write(buf)
if offset < datalen:
frm = overlay_struct(buf, cont_desc)
write = loop.wait(iface.iface_num() | io.POLL_WRITE)
while offset < datalen:
frm.seq = seq
offset += utils.memcpy(frm.data, 0, cmd.data, offset, datalen)
while True:
await write
if iface.write(buf) > 0:
break
seq += 1