common: HashWriter move to common

src/apps/common/hash_writer.py

@@ -0,0 +1,16 @@
+
+class HashWriter:
+
+    def __init__(self, hashfunc):
+        self.ctx = hashfunc()
+        self.buf = bytearray(1)  # used in append()
+
+    def extend(self, buf: bytearray):
+        self.ctx.update(buf)
+
+    def append(self, b: int):
+        self.buf[0] = b
+        self.ctx.update(self.buf)
+
+    def getvalue(self) -> bytes:
+        return self.ctx.digest()

src/apps/wallet/sign_tx/segwit_bip143.py

@@ -3,6 +3,7 @@ from trezor.messages.SignTx import SignTx
 from trezor.messages import InputScriptType, FailureType
 
 from apps.wallet.sign_tx.writers import *
+from apps.common.hash_writer import HashWriter
 
 
 class Bip143Error(ValueError):

src/apps/wallet/sign_tx/signing.py

@@ -16,6 +16,7 @@ from apps.wallet.sign_tx.segwit_bip143 import *
 from apps.wallet.sign_tx.scripts import *
 from apps.wallet.sign_tx.writers import *
 from apps.wallet.sign_tx.tx_weight_calculator import *
+from apps.common.hash_writer import HashWriter
 
 # the number of bip32 levels used in a wallet (chain and address)
 _BIP32_WALLET_DEPTH = const(2)

src/apps/wallet/sign_tx/writers.py

@@ -112,20 +112,3 @@ def get_tx_hash(w, double: bool, reverse: bool=False) -> bytes:
     if reverse:
         d = bytes(reversed(d))
     return d
-
-
-class HashWriter:
-
-    def __init__(self, hashfunc):
-        self.ctx = hashfunc()
-        self.buf = bytearray(1)  # used in append()
-
-    def extend(self, buf: bytearray):
-        self.ctx.update(buf)
-
-    def append(self, b: int):
-        self.buf[0] = b
-        self.ctx.update(self.buf)
-
-    def getvalue(self) -> bytes:
-        return self.ctx.digest()