Fixed bug with writing hex files with small chains of bytes.

Author: Alexander Belchenko

intelhex/__init__.py

@@ -560,17 +560,26 @@ def write_hex_file(self, f, write_start_addr=True):
                                           cur_ix,
                                           min(cur_ix+chain_len+1, addr_len))
                         chain_len = ix - cur_ix     # real chain_len
+                        # there could be small holes in the chain
+                        # but we will catch them by try-except later
+                        # so for big continuous files we will work
+                        # at maximum possible speed
                     else:
                         chain_len = 1               # real chain_len
 
                     bin = array('B', '\0'*(5+chain_len))
-                    bin[0] = chain_len
                     bytes = divmod(low_addr, 256)
                     bin[1] = bytes[0]   # msb of low_addr
                     bin[2] = bytes[1]   # lsb of low_addr
                     bin[3] = 0          # rectype
-                    for i in xrange(chain_len):
-                        bin[4+i] = self._buf[cur_addr+i]
+                    try:    # if there is small holes we'll catch them
+                        for i in range(chain_len):
+                            bin[4+i] = self._buf[cur_addr+i]
+                    except KeyError:
+                        # we catch a hole so we should shrink the chain
+                        chain_len = i
+                        bin = bin[:5+i]
+                    bin[0] = chain_len
                     bin[4+chain_len] = (-sum(bin)) & 0x0FF    # chksum
                     fwrite(':' + hexlify(bin.tostring()).translate(table) + '\n')
 

intelhex/test.py

@@ -344,6 +344,12 @@
 :00000001FF
 """
 
+hex_bug_lp_341051 = """\
+:020FEC00E4E738
+:040FF00022E122E1F7
+:00000001FF
+"""
+
 
 ##
 # Test cases
@@ -489,6 +495,14 @@ def test_write_hexfile(self):
         sio.close()
         self.assertEqualWrittenData(hex_simple, s)
 
+    def test_write_hex_bug_341051(self):
+        ih = intelhex.IntelHex(StringIO(hex_bug_lp_341051))
+        sio = StringIO()
+        ih.tofile(sio, format='hex')
+        s = sio.getvalue()
+        sio.close()
+        self.assertEqualWrittenData(hex_bug_lp_341051, s)
+
     def test_write_hex_first_extended_linear_address(self):
         ih = IntelHex({0x20000: 0x01})
         sio = StringIO()