Update the test encoding to support python3

Since Python3 handles encoding differently than Python2,
a change in the way the data is encoded and sent to the target is needed.
1. Change the test data to be sent as hex string
2. Convert the characters to binary bytes.

This is done because the mbed tools translate the encoding differently
(mbed-greentea, and mbed-htrunner)

tests/scripts/mbedtls_test.py

@@ -89,24 +89,20 @@ class TestDataParser(object):
         :param data_f: Data file object
         :return:
         """
-        while True:
-            line = data_f.readline().strip()
+        for line in data_f:
+            line = line.strip()
             if not line:
-                break
+                continue
             # Read test name
             name = line
 
             # Check dependencies
             dependencies = []
-            line = data_f.readline().strip()
-            if not line:
-                break
+            line = next(data_f).strip()
             match = re.search('depends_on:(.*)', line)
             if match:
                 dependencies = [int(x) for x in match.group(1).split(':')]
-                line = data_f.readline().strip()
-                if not line:
-                    break
+                line = next(data_f).strip()
 
             # Read test vectors
             line = line.replace('\\n', '\n')
@@ -265,20 +261,20 @@ class MbedTlsTest(BaseHostTest):
         for typ, param in parameters:
             if typ == 'int' or typ == 'exp':
                 i = int(param)
-                data_bytes += 'I' if typ == 'int' else 'E'
+                data_bytes += b'I' if typ == 'int' else b'E'
                 self.align_32bit(data_bytes)
                 data_bytes += self.int32_to_big_endian_bytes(i)
             elif typ == 'char*':
                 param = param.strip('"')
                 i = len(param) + 1  # + 1 for null termination
-                data_bytes += 'S'
+                data_bytes += b'S'
                 self.align_32bit(data_bytes)
                 data_bytes += self.int32_to_big_endian_bytes(i)
-                data_bytes += bytearray(list(param))
-                data_bytes += '\0'   # Null terminate
+                data_bytes += bytes(param, 'ascii')
+                data_bytes += b'\0'   # Null terminate
             elif typ == 'hex':
                 binary_data = self.hex_str_bytes(param)
-                data_bytes += 'H'
+                data_bytes += b'H'
                 self.align_32bit(data_bytes)
                 i = len(binary_data)
                 data_bytes += self.int32_to_big_endian_bytes(i)
@@ -313,7 +309,7 @@ class MbedTlsTest(BaseHostTest):
 
         param_bytes, length = self.test_vector_to_bytes(function_id,
                                                         dependencies, args)
-        self.send_kv(bytes(length).decode(), bytes(param_bytes).decode())
+        self.send_kv(length.hex(), param_bytes.hex())
 
     @staticmethod
     def get_result(value):

tests/suites/target_test.function

@@ -59,10 +59,43 @@ int verify_dependencies( uint8_t count, uint8_t * dep_p )
     return( DEPENDENCY_SUPPORTED );
 }
 
+/**
+ * \brief       Receives hex string on serial interface, and converts to a byte.
+ *
+ * \param none
+ *
+ * \return      unsigned int8
+ */
+uint8_t receive_byte()
+{
+    uint8_t byte;
+    uint8_t c;
+
+    c = greentea_getc();
+    if( c >= '0' && c <= '9' )
+        c -= '0';
+    else if( c >= 'a' && c <= 'f' )
+        c = ( c -'a' ) + 10;
+    else if( c >= 'A' && c <= 'F' )
+        c = ( c - 'A' ) + 10;
+
+    byte = c * 0x10;
+
+    c = greentea_getc();
+    if( c >= '0' && c <= '9' )
+        c -= '0';
+    else if( c >= 'a' && c <= 'f' )
+        c = ( c -'a' ) + 10;
+    else if( c >= 'A' && c <= 'F' )
+        c = ( c - 'A' ) + 10;
+
+    byte += c ;
+    return( byte);
+}
 
 /**
  * \brief       Receives unsigned integer on serial interface.
- *              Integers are encoded in network order.
+ *              Integers are encoded in network order, and sent as hex ascii string.
  *
  * \param none
  *
@@ -71,10 +104,10 @@ int verify_dependencies( uint8_t count, uint8_t * dep_p )
 uint32_t receive_uint32()
 {
     uint32_t value;
-    value =  (uint8_t)greentea_getc() << 24;
-    value |= (uint8_t)greentea_getc() << 16;
-    value |= (uint8_t)greentea_getc() << 8;
-    value |= (uint8_t)greentea_getc();
+    value =  receive_byte() << 24;
+    value |= receive_byte() << 16;
+    value |= receive_byte() << 8;
+    value |= receive_byte();
     return( (uint32_t)value );
 }
 
@@ -132,7 +165,7 @@ uint8_t * receive_data( uint32_t * data_len )
     greentea_getc(); // read ';' received after key i.e. *data_len
 
     for( i = 0; i < *data_len; i++ )
-        data[i] = greentea_getc();
+        data[i] = receive_byte();
 
     /* Read closing braces */
     for( i = 0; i < 2; i++ )