wire: use memoryview() asap in the parsing process

src/trezor/wire/wire_codec.py

@@ -76,8 +76,10 @@ Receives report payloads.
 Sends (msg_type, data_len) to target, followed by data chunks.
 Throws EOFError after last data chunk, in case of valid checksum.
 Throws MessageChecksumError to target if data doesn't match the checksum.
+
+Pass report payloads as `memoryview` for cheaper slicing.
 '''
-    message = memoryview((yield))  # read first report
+    message = yield  # read first report
     msg_type, data_len, data_tail = parse_message(message)
 
     target = genfunc(msg_type, data_len, session_id, *args)
@@ -95,7 +97,7 @@ Throws MessageChecksumError to target if data doesn't match the checksum.
         checksum = ubinascii.crc32(data_chunk, checksum)
 
         if data_len > 0:
-            data_tail = memoryview((yield))  # read next report
+            data_tail = yield  # read next report
 
     msg_footer = data_tail[:_MSG_FOOTER_LEN]
     if len(msg_footer) < _MSG_FOOTER_LEN:

src/trezor/wire/wire_codec_v1.py

@@ -40,6 +40,8 @@ Receives report payloads.
 Sends (msg_type, data_len) to target, followed by data chunks.
 Throws EOFError after last data chunk, in case of valid checksum.
 Throws MessageChecksumError to target if data doesn't match the checksum.
+
+Pass report payloads as `memoryview` for cheaper slicing.
 '''
 
     message = yield  # read first report

src/trezor/wire/wire_io.py

@@ -1,19 +1,19 @@
-import ubinascii
+from ubinascii import hexlify
 from micropython import const
 from trezor import msg, loop, log
 
-_DEFAULT_IFACE = const(0xFF00) # TODO: use proper interface
+_DEFAULT_IFACE = const(0xFF00)  # TODO: use proper interface
 
 
 def read_report_stream(target, iface=_DEFAULT_IFACE):
     while True:
         report, = yield loop.Select(iface)
-        log.debug(__name__, 'read  report %s', ubinascii.hexlify(report))
-        target.send(report)
+        log.debug(__name__, 'read report %s', hexlify(report))
+        target.send(memoryview(report))
 
 
 def write_report_stream(iface=_DEFAULT_IFACE):
     while True:
         report = yield
-        log.debug(__name__, 'write report %s', ubinascii.hexlify(report))
+        log.debug(__name__, 'write report %s', hexlify(report))
         msg.send(iface, report)