Treat OP_1NEGATE as a small integer

petertodd · Mar 12, 2024 · 6ad2414 · 6ad2414
1 parent 173a73e
commit 6ad2414
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Showing 2 changed files with 15 additions and 12 deletions.
diff --git a/bitcoin/core/script.py b/bitcoin/core/script.py
@@ -53,27 +53,31 @@ def encode_op_pushdata(d):
     @staticmethod
     def encode_op_n(n):
         """Encode a small integer op, returning an opcode"""
-        if not (0 <= n <= 16):
-            raise ValueError('Integer must be in range 0 <= n <= 16, got %d' % n)
+        if not (-1 <= n <= 16):
+            raise ValueError('Integer must be in range -1 <= n <= 16, got %d' % n)
 
         if n == 0:
             return OP_0
+        elif n == -1:
+            return OP_1NEGATE
         else:
             return CScriptOp(OP_1 + n-1)
 
     def decode_op_n(self):
         """Decode a small integer opcode, returning an integer"""
         if self == OP_0:
             return 0
-
-        if not (self == OP_0 or OP_1 <= self <= OP_16):
-            raise ValueError('op %r is not an OP_N' % self)
-
-        return int(self - OP_1+1)
+        elif self == OP_1NEGATE:
+            return -1
+        else:
+            if not (OP_1 <= self <= OP_16):
+                raise ValueError('op %r is not an OP_N' % self)
+            else:
+                return int(self - OP_1+1)
 
     def is_small_int(self):
         """Return true if the op pushes a small integer to the stack"""
-        if 0x51 <= self <= 0x60 or self == 0:
+        if self == OP_0 or OP_1 <= self <= OP_16 or self == OP_1NEGATE:
             return True
         else:
             return False
@@ -516,10 +520,8 @@ def __coerce_instance(cls, other):
         if isinstance(other, CScriptOp):
             other = bytes([other])
         elif isinstance(other, int):
-            if 0 <= other <= 16:
+            if -1 <= other <= 16:
                 other = bytes([CScriptOp.encode_op_n(other)])
-            elif other == -1:
-                other = bytes([OP_1NEGATE])
             else:
                 other = CScriptOp.encode_op_pushdata(bitcoin.core._bignum.bn2vch(other))
         elif isinstance(other, (bytes, bytearray)):

diff --git a/bitcoin/tests/test_script.py b/bitcoin/tests/test_script.py
@@ -54,6 +54,7 @@ def t(n, op):
             self.assertEqual(actual, n)
             self.assertTrue(isinstance(actual, int))
 
+        t(-1, OP_1NEGATE)
         t(0, OP_0)
         t(1, OP_1)
         t(2, OP_2)
@@ -108,7 +109,7 @@ def T(serialized_script, expected_tokens, test_roundtrip=True):
 
         # numbers
         T('00', [0x0])
-        T('4f', [OP_1NEGATE])
+        T('4f', [-1])
         T('51', [0x1])
         T('52', [0x2])
         T('53', [0x3])