commands: conserve write cycles
When a record or a binary file is written the card goes throth a full
flash/eeprom write cycle at this location, even when the data does not
change. This can be optimized by reading before writing in order to
compere if the data we are about to write is actually different.
Change-Id: Ifd1b80d3ede15a7caa29077a37ac7cf58c9053f1
Related: OS#4963
diff --git a/pySim/commands.py b/pySim/commands.py
index 9aed588..65c3891 100644
--- a/pySim/commands.py
+++ b/pySim/commands.py
@@ -144,9 +144,17 @@
raise ValueError('Failed to read (offset %d)' % (offset))
return total_data, sw
- def update_binary(self, ef, data, offset=0, verify=False):
+ def update_binary(self, ef, data, offset=0, verify=False, conserve=False):
+ data_length = len(data) // 2
+
+ # Save write cycles by reading+comparing before write
+ if conserve:
+ data_current, sw = self.read_binary(ef, data_length, offset)
+ if data_current == data:
+ return None, sw
+
self.select_path(ef)
- pdu = self.cla_byte + 'd6%04x%02x' % (offset, len(data) // 2) + data
+ pdu = self.cla_byte + 'd6%04x%02x' % (offset, data_length) + data
res = self._tp.send_apdu_checksw(pdu)
if verify:
self.verify_binary(ef, data, offset)
@@ -163,7 +171,7 @@
pdu = self.cla_byte + 'b2%02x04%02x' % (rec_no, rec_length)
return self._tp.send_apdu(pdu)
- def update_record(self, ef, rec_no, data, force_len=False, verify=False):
+ def update_record(self, ef, rec_no, data, force_len=False, verify=False, conserve=False):
r = self.select_path(ef)
if not force_len:
rec_length = self.__record_len(r)
@@ -171,6 +179,14 @@
raise ValueError('Invalid data length (expected %d, got %d)' % (rec_length, len(data) // 2))
else:
rec_length = len(data) // 2
+
+ # Save write cycles by reading+comparing before write
+ if conserve:
+ data_current, sw = self.read_record(ef, rec_no)
+ data_current = data_current[0:rec_length*2]
+ if data_current == data:
+ return None, sw
+
pdu = (self.cla_byte + 'dc%02x04%02x' % (rec_no, rec_length)) + data
res = self._tp.send_apdu_checksw(pdu)
if verify: