Repository: leonardt/hwtypes

Issue:
semantics for Bitvector concat is opposite of magma concat
semantics for magma.concat is concat(lsbs,msbs) while hwtypes.BitVector.concat is concat(msbs,lsbs)

We should unify the semantics. I would prefer magma's version but at the end of the day, it does not matter.

Comments:

Patch:
diff --git a/hwtypes/bit_vector.py b/hwtypes/bit_vector.py
index 885b2cb..e7f0010 100644
--- a/hwtypes/bit_vector.py
+++ b/hwtypes/bit_vector.py
@@ -175,6 +175,10 @@ class BitVector(AbstractBitVector):
     def __repr__(self):
         return "BitVector[{size}]({value})".format(value=self._value, size=self.size)
 
+    @property
+    def value(self):
+        return self._value
+
     def __setitem__(self, index, value):
         if isinstance(index, slice):
             raise NotImplementedError()
@@ -211,10 +215,11 @@ class BitVector(AbstractBitVector):
     def __len__(self):
         return self.size
 
-    # Note: In concat(x, y), the MSB of the result is the MSB of x.
-    @classmethod
-    def concat(cls, x, y):
-        return cls.unsized_t[x.size+y.size](y.bits() + x.bits())
+    def concat(self, other):
+        T = type(self).unsized_t
+        if not isinstance(other, T):
+            raise TypeError(f'value must of type {T}')
+        return T[self.size+other.size](self.value | (other.value << self.size))
 
     def bvnot(self):
         return type(self)(~self.as_uint())
@@ -246,12 +251,12 @@ class BitVector(AbstractBitVector):
     @bv_cast
     def bvrol(self, other):
         other = other.as_uint() % len(self)
-        return self.concat( self[other:], self[0:other] )
+        return self[:other].concat(self[other:])
 
     @bv_cast
     def bvror(self, other):
         other = (len(self) - other.as_uint()) % len(self)
-        return self.concat( self[other:], self[0:other] )
+        return self[:other].concat(self[other:])
 
     @bv_cast
     def bvcomp(self, other):
@@ -400,7 +405,7 @@ class BitVector(AbstractBitVector):
             raise ValueError()
 
         T = type(self).unsized_t
-        return T.concat(T[1](self[-1]).repeat(ext), self)
+        return self.concat(T[1](self[-1]).repeat(ext))
 
     def ext(self, ext):
         return self.zext(other)
@@ -411,7 +416,7 @@ class BitVector(AbstractBitVector):
             raise ValueError()
 
         T = type(self).unsized_t
-        return T.concat(T[ext](0), self)
+        return self.concat(T[ext](0))
 
     @staticmethod
     def random(width):
diff --git a/hwtypes/bit_vector_abc.py b/hwtypes/bit_vector_abc.py
index 616ee76..1521849 100644
--- a/hwtypes/bit_vector_abc.py
+++ b/hwtypes/bit_vector_abc.py
@@ -176,10 +176,8 @@ class AbstractBitVector(metaclass=AbstractBitVectorMeta):
     def __len__(self) -> int:
         pass
 
-    #could still be staticmethod but I think thats annoying
-    @classmethod
     @abstractmethod
-    def concat(cls, x, y) -> 'AbstractBitVector':
+    def concat(self, other) -> 'AbstractBitVector':
         pass
 
     @abstractmethod
diff --git a/hwtypes/fp_vector.py b/hwtypes/fp_vector.py
index 9fd7320..3e1f0f0 100644
--- a/hwtypes/fp_vector.py
+++ b/hwtypes/fp_vector.py
@@ -269,15 +269,15 @@ class FPVector(AbstractFPVector):
         sign_bit = BitVector[1](gmpy2.is_signed(self._value))
 
         if self.fp_is_zero():
-            return BitVector.concat(sign_bit, BitVector[cls.size-1](0))
+            return BitVector[cls.size-1](0).concat(sign_bit)
         elif self.fp_is_infinite():
             exp_bits = BitVector[cls.exponent_size](-1)
             mantissa_bits = BitVector[cls.mantissa_size](0)
-            return BitVector.concat(BitVector.concat(sign_bit, exp_bits), mantissa_bits)
+            return mantissa_bits.concat(exp_bits).concat(sign_bit)
         elif self.fp_is_NaN():
             exp_bits = BitVector[cls.exponent_size](-1)
             mantissa_bits = BitVector[cls.mantissa_size](1)
-            return BitVector.concat(BitVector.concat(sign_bit, exp_bits), mantissa_bits)
+            return mantissa_bits.concat(exp_bits).concat(sign_bit)
 
 
         bias = (1 << (cls.exponent_size - 1)) - 1
@@ -307,7 +307,7 @@ class FPVector(AbstractFPVector):
             mantissa = BitVector[cls.mantissa_size+1](mantissa_int)
         exp_bits = BitVector[cls.exponent_size](exp)
         mantissa_bits = mantissa[:cls.mantissa_size]
-        return BitVector.concat(BitVector.concat(sign_bit, exp_bits), mantissa_bits)
+        return mantissa_bits.concat(exp_bits).concat(sign_bit)
 
     @classmethod
     @set_context
diff --git a/hwtypes/smt_bit_vector.py b/hwtypes/smt_bit_vector.py
index 892dcdc..0b46323 100644
--- a/hwtypes/smt_bit_vector.py
+++ b/hwtypes/smt_bit_vector.py
@@ -231,7 +231,7 @@ class SMTBitVector(AbstractBitVector):
                 raise ValueError('Iterable is not the correct size')
             cls = type(self)
             B1 = cls.unsized_t[1]
-            self._value = ft.reduce(cls.concat, map(B1, reversed(value))).value
+            self._value = ft.reduce(lambda acc, elem : acc.concat(elem), map(B1, value)).value
         elif isinstance(value, int):
             self._value =  smt.BV(value % (1 << self.size), self.size)
 
@@ -320,9 +320,11 @@ class SMTBitVector(AbstractBitVector):
     def __len__(self):
         return self.size
 
-    @classmethod
-    def concat(cls, x, y):
-        return cls.unsized_t[x.size + y.size](smt.BVConcat(x.value, y.value))
+    def concat(self, other):
+        T = type(self).unsized_t
+        if not isinstance(other, T):
+            raise TypeError(f'value must of type {T}')
+        return T[self.size + other.size](smt.BVConcat(other.value, self.value))
 
     def bvnot(self):
         return type(self)(smt.BVNot(self.value))
diff --git a/hwtypes/z3_bit_vector.py b/hwtypes/z3_bit_vector.py
index c555656..9947eb1 100644
--- a/hwtypes/z3_bit_vector.py
+++ b/hwtypes/z3_bit_vector.py
@@ -229,7 +229,7 @@ class z3BitVector(AbstractBitVector):
                 raise ValueError('Iterable is not the correct size')
             cls = type(self)
             B1 = cls.unsized_t[1]
-            self._value = ft.reduce(cls.concat, map(B1, reversed(value))).value
+            self._value = ft.reduce(lambda acc, elem : acc.concat(elem), map(B1, value)).value
         elif isinstance(value, int):
             self._value =  z3.BitVecVal(value, self.size)
 
@@ -318,9 +318,11 @@ class z3BitVector(AbstractBitVector):
     def __len__(self):
         return self.size
 
-    @classmethod
-    def concat(cls, x, y):
-        return cls.unsized_t[x.size + y.size](z3.Concat(x.value, y.value))
+    def concat(self, other):
+        T = type(self).unsized_t
+        if not isinstance(other, T):
+            raise TypeError(f'value must of type {T}')
+        return T[self.size + other.size](z3.Concat(other.value, self.value))
 
     def bvnot(self):
         return type(self)(~self.value)


Test patch:
diff --git a/tests/test_concat.py b/tests/test_concat.py
index 7f9f6af..1a5dfa6 100644
--- a/tests/test_concat.py
+++ b/tests/test_concat.py
@@ -1,8 +1,25 @@
 from hwtypes import BitVector
+import random
 
-def test_concat():
+NTESTS = 10
+MAX_BITS = 128
+
+def test_concat_const():
     a = BitVector[4](4)
     b = BitVector[4](1)
-    c = BitVector.concat(a, b)
-    expected = BitVector[8]([1,0,0,0,0,0,1,0])
+    c = a.concat(b)
+    print(a.binary_string())
+    print(c.binary_string())
+    expected = BitVector[8]([0,0,1,0,1,0,0,0])
     assert expected == c
+
+def test_concat_random():
+    for _ in range(NTESTS):
+        n1 = random.randint(1, MAX_BITS)
+        n2 = random.randint(1, MAX_BITS)
+        a = BitVector.random(n1)
+        b = BitVector.random(n2)
+        c = a.concat(b)
+        assert c.size == a.size + b.size
+        assert c == BitVector[n1 + n2](a.bits() + b.bits())
+        assert c.binary_string() == b.binary_string() + a.binary_string()
diff --git a/tests/test_fp.py b/tests/test_fp.py
index 20628da..d44a34d 100644
--- a/tests/test_fp.py
+++ b/tests/test_fp.py
@@ -125,7 +125,7 @@ def _c_type_vector(T):
 
     return vector
 
-NTESTS = 100
+NTESTS = 128
 
 @pytest.mark.parametrize("mode", [
     RoundingMode.RNE,
@@ -247,6 +247,37 @@ def test_reinterpret_bv(FT):
             assert bv1[:ms] != 0
             assert bv2[:ms] != 0
 
+def test_reinterpret_bv_corner():
+    for _ in range(NTESTS):
+        FT = FPVector[random.randint(3, 16),
+                      random.randint(2, 64),
+                      random.choice(list(RoundingMode)),
+                      True]
+        bv_pinf = BitVector[FT.mantissa_size](0).concat(BitVector[FT.exponent_size](-1)).concat(BitVector[1](0))
+        bv_ninf = BitVector[FT.mantissa_size](0).concat(BitVector[FT.exponent_size](-1)).concat(BitVector[1](1))
+        pinf = FT.reinterpret_from_bv(bv_pinf)
+        ninf = FT.reinterpret_from_bv(bv_ninf)
+        assert pinf.reinterpret_as_bv() == bv_pinf
+        assert ninf.reinterpret_as_bv() == bv_ninf
+        assert pinf.fp_is_positive()
+        assert pinf.fp_is_infinite()
+        assert ninf.fp_is_negative()
+        assert ninf.fp_is_infinite()
+
+        bv_pz = BitVector[FT.size](0)
+        bv_nz = BitVector[FT.size-1](0).concat(BitVector[1](1))
+        pz = FT.reinterpret_from_bv(bv_pz)
+        nz = FT.reinterpret_from_bv(bv_nz)
+        assert pz.reinterpret_as_bv() == bv_pz
+        assert nz.reinterpret_as_bv() == bv_nz
+        assert pz.fp_is_zero()
+        assert nz.fp_is_zero()
+
+        bv_nan = BitVector[FT.mantissa_size](1).concat(BitVector[FT.exponent_size](-1)).concat(BitVector[1](0))
+        nan = FT.reinterpret_from_bv(bv_nan)
+        assert nan.reinterpret_as_bv() == bv_nan
+        assert nan.fp_is_NaN()
+
 @pytest.mark.parametrize("CT, FT", [
     (_c_type_vector(ctypes.c_float), FPVector[8, 23, RoundingMode.RNE, True]),
     (_c_type_vector(ctypes.c_double), FPVector[11, 52, RoundingMode.RNE, True]),])