Fix detection of hexadecimal assembly numbers which do not start with $0

1 files changed, 5 insertions, 3 deletions

diff --git a/pp2cc.py b/pp2cc.py
index a1d1bbd..0e3fe28 100755
--- a/pp2cc.py
+++ b/pp2cc.py
@@ -724,10 +724,12 @@ class Parse(object):
             if str.startswith("$0"):
                 return int(str[2:], 16)
             else:
-                # anything with a leading 8 or higher is padded... assembler
-                # bug?
+                # if the leftmost bit of a 4-bit group is set, the preceding
+                # bits should be 1 as well. E.g. $7 end with 0111 and is
+                # therefore interpreted as 7 where $8 ends with 1111 which is
+                # interpreted as -1 (all bits are set)
                 val = str[1:]
-                if int(val[1]) >= 8:
+                if int(val[1], 16) & 0b1000:
                     hexsize = len(hex(pow(2, self.WORDSIZE) - 1)[2:])
                     val = val.rjust(hexsize, "F")
                 return int(val, 16)