gistfile1.diff

diff --git a/vm/builtin/bignum.cpp b/vm/builtin/bignum.cpp
index 163f207..23cb377 100644
--- a/vm/builtin/bignum.cpp
+++ b/vm/builtin/bignum.cpp
@@ -96,24 +96,6 @@ namespace rubinius {
       return res;
   }
 
-  static void twos_complement(mp_int *a)
-  {
-    long i = a->used;
-    BDIGIT_DBL num;
-
-    while (i--) {
-      DIGIT(a,i) = (~DIGIT(a,i)) & (DIGIT_RADIX-1);
-    }
-
-    i = 0; num = 1;
-    do {
-      num += DIGIT(a,i);
-      DIGIT(a,i++) = num & (DIGIT_RADIX-1);
-      num = num >> DIGIT_BIT;
-    } while (i < a->used);
-
-  }
-
 #define BITWISE_OP_AND 1
 #define BITWISE_OP_OR  2
 #define BITWISE_OP_XOR 3
@@ -123,19 +105,22 @@ namespace rubinius {
     mp_int   a,   b;
     mp_int *d1, *d2;
     int i, sign,  l1,  l2;
-
+    char origin_sign_x = x->sign;
+    char origin_sign_y = y->sign;
     mp_init(&a);
     mp_init(&b);
 
     if (y->sign == MP_NEG) {
       mp_copy(MPST, y, &b);
-      twos_complement(&b);
+      mp_neg(MPST, &b, &b);
+      mp_sub_d(MPST, &b, 1, &b);
       y = &b;
     }
 
     if (x->sign == MP_NEG) {
       mp_copy(MPST, x, &a);
-      twos_complement(&a);
+      mp_neg(MPST, &a, &a);
+      mp_sub_d(MPST, &a, 1, &a);
       x = &a;
     }
 
@@ -176,7 +161,7 @@ namespace rubinius {
         }
         break;
       case BITWISE_OP_XOR:
-        if (x->sign != y->sign) n->sign = MP_NEG;
+        if (origin_sign_x != origin_sign_y) n->sign = MP_NEG;
         for (i=0; i < l1; i++) {
           DIGIT(n,i) = DIGIT(d1,i) ^ DIGIT(d2,i);
         }
@@ -186,7 +171,11 @@ namespace rubinius {
         break;
     }
 
-    if (n->sign == MP_NEG) twos_complement(n);
+    if (n->sign == MP_NEG) {
+      mp_neg(MPST, n, n);
+      n->sign = MP_NEG;
+      mp_sub_d(MPST, n, 1, n);
+    }