Partial fix for issue #24

Author: Ayuto

addons/source-python/plugins/es_emulator/eventscripts/esc/cmds/maths.py

@@ -7,6 +7,28 @@
 
 root = lambda a, b: pow(a, 1.0/b)
 
+# https://stackoverflow.com/a/14246007
+def correct(value, bits, signed):
+    base = 1 << bits
+    value %= base
+    return value - base if signed and value.bit_length() == bits else value
+
+byte, sbyte, word, sword, dword, sdword, qword, sqword = (
+    lambda v: correct(v, 8, False), lambda v: correct(v, 8, True),
+    lambda v: correct(v, 16, False), lambda v: correct(v, 16, True),
+    lambda v: correct(v, 32, False), lambda v: correct(v, 32, True),
+    lambda v: correct(v, 64, False), lambda v: correct(v, 64, True)
+)
+
+def emulate_datatype_overflow(value):
+    # int?
+    if int(value) == value:
+        # Emulate a signed int
+        return sdword(value)
+    
+    # TODO: Handle float overflow
+    return value
+
 _math_operators = {
   '+': add, 'add': add,
   '-': sub, 'subract': sub,
@@ -24,16 +46,17 @@ def math(argv):
   val = sv[var]
   if val.isstring():
     raise ValueError('math function called on a non-numeric value: %s, %s' % (var, val.strval))
-  val = NUM(val)
+  val = emulate_datatype_overflow(NUM(val))
   if op in _math_operators:
     if len(argv) < 3:
       raise SyntaxError
     val2 = argv[2]
     if val2.isstring():
       raise ValueError('math function called on a non-numeric value: %s' % val2.strval)
-    sv[argv[0]] = _math_operators[op](val, NUM(val2))
+    sv[argv[0]] = emulate_datatype_overflow(
+        _math_operators[op](val, emulate_datatype_overflow(NUM(val2))))
   elif op in _math_functions:
-    sv[argv[0]] = eval(op)(val)
+    sv[argv[0]] = emulate_datatype_overflow(eval(op)(val))
   else:
     raise SyntaxError('bad operation "%s"' % op)