sdcard_spi: add support for CMD24 including payload data

The previous implementation advanced from the start of CMD24 to IDLE.
This commit introduces support for the data phase and data response of
CMD24. Which results in improved usability of the decoder output, and
reduced probability of false positives (don't detect "commands" in the
payload data).

This commit addresses the missing CMD24 handling part of bug #1365.

1 files changed, 58 insertions, 5 deletions

diff --git a/decoders/sdcard_spi/pd.py b/decoders/sdcard_spi/pd.py
index 8b43cd7..0fa2dd7 100644
--- a/decoders/sdcard_spi/pd.py
+++ b/decoders/sdcard_spi/pd.py
@@ -60,6 +60,8 @@ class Decoder(srd.Decoder):
         self.blocklen = 0
         self.read_buf = []
         self.cmd_str = ''
+        self.start_token_found = False # for CMD24
+        self.is_cmd24 = False
 
     def start(self):
         self.out_ann = self.register(srd.OUTPUT_ANN)
@@ -152,7 +154,7 @@ class Decoder(srd.Decoder):
             self.putb([135, ['End bit: %d (Warning: Must be 1!)' % bit]])
 
         # Handle command.
-        if cmd in (0, 1, 9, 16, 17, 41, 49, 55, 59):
+        if cmd in (0, 1, 9, 16, 17, 24, 41, 49, 55, 59):
             self.state = 'HANDLE CMD%d' % cmd
             self.cmd_str = '%s%d (%s)' % (s, cmd, self.cmd_name(cmd))
         else:
@@ -224,6 +226,13 @@ class Decoder(srd.Decoder):
         self.read_buf = []
         self.state = 'GET RESPONSE R1'
 
+    def handle_cmd24(self):
+        # CMD24: WRITE_SINGLE_BLOCK
+        self.putc(24, 'Write a block to address 0x%04x' % self.arg)
+        self.is_cmd24 = True # Reminder for handler of R1 to not switch
+        # to IDLE but to a specific function to handle the outgoing data.
+        self.state = 'GET RESPONSE R1'
+
     def handle_cmd49(self):
         self.state = 'GET RESPONSE R1'
 
@@ -328,7 +337,10 @@ class Decoder(srd.Decoder):
         # Bit 7: Always set to 0
         putbit(7, ['Bit 7 (always 0)'])
 
-        self.state = 'IDLE'
+        if self.is_cmd24:
+            self.state = 'HANDLE DATA BLOCK CMD24'
+        else:
+            self.state = 'IDLE'
 
     def handle_response_r1b(self, res):
         # TODO
@@ -350,6 +362,43 @@ class Decoder(srd.Decoder):
         # TODO
         pass
 
+    def handle_data_cmd24(self, mosi):
+        if self.start_token_found:
+            if len(self.read_buf) == 0:
+                self.ss_data = self.ss
+            self.read_buf.append(mosi)
+            if self.blocklen == 0: # FIXME
+                print("warning: setting blocklength to 512")
+                self.blocklen = 512
+            # Wait until block transfer completed.
+            if len(self.read_buf) < self.blocklen:
+                return
+            self.es_data = self.es
+            self.put(self.ss_data, self.es_data, self.out_ann, [24, ['Block data: %s' % self.read_buf]])
+            self.read_buf = []
+            self.state = 'DATA RESPONSE'
+        elif mosi == 0xfe:
+            self.put(self.ss, self.es, self.out_ann, [24, ['Data Start Token']])
+            self.start_token_found = True
+
+    def handle_data_response(self, miso):
+        miso &= 0x1F
+        if miso & 0x10 or not miso & 0x01:
+            # This is not the byte we are waiting for.
+            # Should we return to IDLE here?
+            return
+        self.put(self.miso_bits[7][1], self.miso_bits[5][2], self.out_ann, [134, ['don\'t care']])
+        self.put(self.miso_bits[4][1], self.miso_bits[4][2], self.out_ann, [134, ['0']])
+        if miso == 0x05:
+            self.put(self.miso_bits[3][1], self.miso_bits[1][2], self.out_ann, [134, ['Data accepted']])
+        elif miso == 0x0B:
+            self.put(self.miso_bits[3][1], self.miso_bits[1][2], self.out_ann, [134, ['Data rejected (CRC error)']])
+        elif miso == 0x0D:
+            self.put(self.miso_bits[3][1], self.miso_bits[1][2], self.out_ann, [134, ['Data rejected (write error)']])
+        self.put(self.miso_bits[0][1], self.miso_bits[0][2], self.out_ann, [134, ['1']])
+        self.put(self.ss, self.es, self.out_ann, [24, ['Data Response']]) # Assume cmd24 initiated the transfer.
+        self.state = 'IDLE'
+
     def decode(self, ss, es, data):
         ptype, mosi, miso = data
 
@@ -389,10 +438,14 @@ class Decoder(srd.Decoder):
             # Ignore stray 0xff bytes, some devices seem to send those!?
             if miso == 0xff: # TODO?
                 return
-
             # Call the respective handler method for the response.
+            # The handler must set new state (IDLE in most cases)!
             s = 'handle_response_%s' % self.state[13:].lower()
             handle_response = getattr(self, s)
             handle_response(miso)
-
-            self.state = 'IDLE'
+        elif self.state == 'HANDLE DATA BLOCK CMD24':
+            handle_data_cmd24 = getattr(self, 'handle_data_cmd24')
+            handle_data_cmd24(mosi)
+        elif self.state == 'DATA RESPONSE':
+            handle_data_response = getattr(self, 'handle_data_response')
+            handle_data_response(miso)