bignum_mod_raw.py: Refactoring BignumModRawOperation

This patch modifies the BignumModRawOperation class to
provide special access to key members commonly used
in tests.

It binds the module's getters to conversion functions
which enable automatic conversions such as:

* hex to int.
* zero padding hex strings.
* common Montgomery constants such as R, R^2 and R^01
  are now be calculated upon access.

class `BignumModRawOperationArchSplit` is also updated to
utilise the new design.

Signed-off-by: Minos Galanakis <minos.galanakis@arm.com>

scripts/mbedtls_dev/bignum_mod_raw.py

@@ -53,40 +53,75 @@ class BignumModRawTarget(test_data_generation.BaseTarget, metaclass=ABCMeta):
 # BEGIN MERGE SLOT 7
 class BignumModRawOperation(bignum_common.OperationCommon, BignumModRawTarget, metaclass=ABCMeta):
     #pylint: disable=abstract-method
-    pass
+    """Target for bignum mod_raw test case generation."""
+
+    def __init__(self, val_n: str, val_a: str, val_b: str = "0", bits_in_limb: int = 64) -> None:
+        super().__init__(val_a=val_a, val_b=val_b)
+        self.val_n = val_n
+        self.bits_in_limb = bits_in_limb
+
+    @property
+    def int_n(self) -> int:
+        return bignum_common.hex_to_int(self.val_n)
+
+    @property
+    def boundary(self) -> int:
+        data_in = [self.int_a, self.int_b, self.int_n]
+        return max([n for n in data_in if n is not None])
+
+    @property
+    def limbs(self) -> int:
+        return bignum_common.limbs_mpi(self.boundary, self.bits_in_limb)
+
+    @property
+    def hex_digits(self) -> int:
+        return 2 * (self.limbs * self.bits_in_limb // 8)
+
+    @property
+    def hex_n(self) -> str:
+        return "{:x}".format(self.int_n).zfill(self.hex_digits)
+
+    @property
+    def hex_a(self) -> str:
+        return "{:x}".format(self.int_a).zfill(self.hex_digits)
+
+    @property
+    def hex_b(self) -> str:
+        return "{:x}".format(self.int_b).zfill(self.hex_digits)
+
+    @property
+    def r(self) -> int: # pylint: disable=invalid-name
+        l = bignum_common.limbs_mpi(self.int_n, self.bits_in_limb)
+        return bignum_common.bound_mpi_limbs(l, self.bits_in_limb)
+
+    @property
+    def r_inv(self) -> int:
+        return bignum_common.invmod(self.r, self.int_n)
+
+    @property
+    def r_sqrt(self) -> int: # pylint: disable=invalid-name
+        return pow(self.r, 2)
 
 class BignumModRawOperationArchSplit(BignumModRawOperation):
     #pylint: disable=abstract-method
-    """Common features for bignum core operations where the result depends on
+    """Common features for bignum mod raw operations where the result depends on
     the limb size."""
 
-    def __init__(self, val_a: str, val_b: str, bits_in_limb: int) -> None:
+    limb_sizes = [32, 64] # type: List[int]
-        super().__init__(val_a, val_b)
-        bound_val = max(self.int_a, self.int_b)
-        self.bits_in_limb = bits_in_limb
-        self.bound = bignum_common.bound_mpi(bound_val, self.bits_in_limb)
-        limbs = bignum_common.limbs_mpi(bound_val, self.bits_in_limb)
-        byte_len = limbs * self.bits_in_limb // 8
-        self.hex_digits = 2 * byte_len
-        if self.bits_in_limb == 32:
-            self.dependencies = ["MBEDTLS_HAVE_INT32"]
-        elif self.bits_in_limb == 64:
-            self.dependencies = ["MBEDTLS_HAVE_INT64"]
-        else:
-            raise ValueError("Invalid number of bits in limb!")
-        self.arg_a = self.arg_a.zfill(self.hex_digits)
-        self.arg_b = self.arg_b.zfill(self.hex_digits)
-        self.arg_a_int = bignum_common.hex_to_int(self.arg_a)
-        self.arg_b_int = bignum_common.hex_to_int(self.arg_b)
 
-    def pad_to_limbs(self, val) -> str:
+    def __init__(self, val_n: str, val_a: str, val_b: str = "0", bits_in_limb: int = 64) -> None:
-        return "{:x}".format(val).zfill(self.hex_digits)
+        super().__init__(val_n=val_n, val_a=val_a, val_b=val_b, bits_in_limb=bits_in_limb)
+
+        if bits_in_limb not in self.limb_sizes:
+            raise ValueError("Invalid number of bits in limb!")
+
+        self.dependencies = ["MBEDTLS_HAVE_INT{:d}".format(bits_in_limb)]
 
     @classmethod
     def generate_function_tests(cls) -> Iterator[test_case.TestCase]:
         for a_value, b_value in cls.get_value_pairs():
-            yield cls(a_value, b_value, 32).create_test_case()
+            for bil in cls.limb_sizes:
-            yield cls(a_value, b_value, 64).create_test_case()
+                yield cls(a_value, b_value, bits_in_limb=bil).create_test_case()
 # END MERGE SLOT 7
 
 # BEGIN MERGE SLOT 8