added unsigned option for int_{from,to}_bytes

riscemu/Exceptions.py

@@ -7,6 +7,8 @@ class RiscemuBaseException(BaseException):
         pass
 
 
+# Parsing exceptions:
+
 class ParseException(RiscemuBaseException):
     def __init__(self, msg, data=None):
         super().__init__()
@@ -42,6 +44,8 @@ def ASSERT_IN(a1, a2):
         raise ParseException("ASSERTION_FAILED: Expected {} to not be in {}".format(a1, a2), (a1, a2))
 
 
+# MMU Exceptions
+
 class MemoryAccessException(RiscemuBaseException):
     def __init__(self, msg, addr, size, op):
         super(MemoryAccessException, self).__init__()
@@ -71,6 +75,8 @@ class OutOfMemoryEsception(RiscemuBaseException):
         )
 
 
+# CPU Exceptions
+
 class UnimplementedInstruction(RiscemuBaseException):
     def __init__(self, ins: 'LoadedInstruction'):
         self.ins = ins
@@ -81,6 +87,7 @@ class UnimplementedInstruction(RiscemuBaseException):
             repr(self.ins)
         )
 
+
 class InvalidRegisterException(RiscemuBaseException):
     def __init__(self, reg):
         self.reg = reg
@@ -91,5 +98,18 @@ class InvalidRegisterException(RiscemuBaseException):
             self.reg
         )
 
+
 def INS_NOT_IMPLEMENTED(ins):
-    raise UnimplementedInstruction(ins)
+    raise UnimplementedInstruction(ins)
+
+
+class  NumberFormatException(RiscemuBaseException):
+    def __init__(self, msg):
+        super().__init__()
+        self.msg = msg
+
+    def message(self):
+        return "{}({})".format(
+            self.__class__.__name__,
+            self.msg
+        )

riscemu/helpers.py

@@ -1,3 +1,5 @@
+from .Exceptions import NumberFormatException
+
 def align_addr(addr: int, to_bytes: int = 8):
     """
     align an address to `to_bytes` (meaning addr & to_bytes = 0)
@@ -14,16 +16,18 @@ def parse_numeric_argument(arg: str):
     return int(arg)
 
 
-def int_to_bytes(val, bytes=4):
+def int_to_bytes(val, bytes=4, unsigned=False):
     """
     int -> byte (two's complement)
     """
+    if unsigned and val < 0:
+        raise NumberFormatException("unsigned negative number!")
     return bytearray([
         (val >> ((bytes-i-1) * 8)) & 0xFF for i in range(bytes)
     ])
 
 
-def int_from_bytes(bytes):
+def int_from_bytes(bytes, unsigned=False):
     """
     byte -> int (two's complement)
     """
@@ -32,10 +36,11 @@ def int_from_bytes(bytes):
         num = num << 8
         num += b
     sign = num >> (len(bytes) * 8 - 1)
-    if sign:
+    if sign and not unsigned:
         return num - 2 ** (8 * len(bytes))
     return num
 
+
 FMT_ORANGE = '\033[33m'
 FMT_GRAY = '\033[37m'
 FMT_BOLD = '\033[1m'