Changed Get64(.) to GetLow64()

The function Get64(.) has a bug in case the width is not divisible by 64.
Since it is only ever used as Get64(0) this simply changes it to this
special case. Additionally, an assert is added, and a cast to prevent
a compiler error.

src/addrman.cpp

@@ -14,12 +14,12 @@ int CAddrInfo::GetTriedBucket(const std::vector<unsigned char> &nKey) const
     CDataStream ss1(SER_GETHASH, 0);
     std::vector<unsigned char> vchKey = GetKey();
     ss1 << nKey << vchKey;
-    uint64_t hash1 = Hash(ss1.begin(), ss1.end()).Get64();
+    uint64_t hash1 = Hash(ss1.begin(), ss1.end()).GetLow64();
 
     CDataStream ss2(SER_GETHASH, 0);
     std::vector<unsigned char> vchGroupKey = GetGroup();
     ss2 << nKey << vchGroupKey << (hash1 % ADDRMAN_TRIED_BUCKETS_PER_GROUP);
-    uint64_t hash2 = Hash(ss2.begin(), ss2.end()).Get64();
+    uint64_t hash2 = Hash(ss2.begin(), ss2.end()).GetLow64();
     return hash2 % ADDRMAN_TRIED_BUCKET_COUNT;
 }
 
@@ -29,11 +29,11 @@ int CAddrInfo::GetNewBucket(const std::vector<unsigned char> &nKey, const CNetAd
     std::vector<unsigned char> vchGroupKey = GetGroup();
     std::vector<unsigned char> vchSourceGroupKey = src.GetGroup();
     ss1 << nKey << vchGroupKey << vchSourceGroupKey;
-    uint64_t hash1 = Hash(ss1.begin(), ss1.end()).Get64();
+    uint64_t hash1 = Hash(ss1.begin(), ss1.end()).GetLow64();
 
     CDataStream ss2(SER_GETHASH, 0);
     ss2 << nKey << vchSourceGroupKey << (hash1 % ADDRMAN_NEW_BUCKETS_PER_SOURCE_GROUP);
-    uint64_t hash2 = Hash(ss2.begin(), ss2.end()).Get64();
+    uint64_t hash2 = Hash(ss2.begin(), ss2.end()).GetLow64();
     return hash2 % ADDRMAN_NEW_BUCKET_COUNT;
 }
 

src/uint256.h

@@ -203,7 +203,7 @@ public:
     {
         // prefix operator
         int i = 0;
-        while (--pn[i] == -1 && i < WIDTH-1)
+        while (--pn[i] == (uint32_t)-1 && i < WIDTH-1)
             i++;
         return *this;
     }
@@ -370,9 +370,10 @@ public:
         return sizeof(pn);
     }
 
-    uint64_t Get64(int n=0) const
+    uint64_t GetLow64() const
     {
-        return pn[2*n] | (uint64_t)pn[2*n+1] << 32;
+        assert(WIDTH >= 2);
+        return pn[0] | (uint64_t)pn[1] << 32;
     }
 
 //    unsigned int GetSerializeSize(int nType=0, int nVersion=PROTOCOL_VERSION) const