rippled/modules/ripple_app/shamap/ripple_SHAMapNode.cpp

//------------------------------------------------------------------------------
/*
    Copyright (c) 2011-2013, OpenCoin, Inc.
*/
//==============================================================================

SETUP_LOG (SHAMapNode)

// canonicalize the hash to a node ID for this depth
SHAMapNode::SHAMapNode (int depth, uint256 const& hash) : mNodeID (hash), mDepth (depth), mHash (0)
{
    assert ((depth >= 0) && (depth < 65));
    mNodeID &= smMasks[depth];
}

SHAMapNode::SHAMapNode (const void* ptr, int len) : mHash (0)
{
    if (len < 33)
        mDepth = -1;
    else
    {
        memcpy (mNodeID.begin (), ptr, 32);
        mDepth = * (static_cast<const unsigned char*> (ptr) + 32);
    }
}
std::string SHAMapNode::getString () const
{
    static boost::format NodeID ("NodeID(%s,%s)");

    if ((mDepth == 0) && (mNodeID.isZero ()))
        return "NodeID(root)";

    return str (boost::format (NodeID)
                % lexicalCastThrow <std::string> (mDepth)
                % mNodeID.GetHex ());
}

uint256 SHAMapNode::smMasks[65];

// VFALCO TODO use a static initializer to do this instead
bool SMN_j = SHAMapNode::ClassInit ();

// set up the depth masks
bool SHAMapNode::ClassInit ()
{
    uint256 selector;

    for (int i = 0; i < 64; i += 2)
    {
        // VFALCO TODO group these statics together in an object
        smMasks[i] = selector;
        * (selector.begin () + (i / 2)) = 0xF0;
        smMasks[i + 1] = selector;
        * (selector.begin () + (i / 2)) = 0xFF;
    }

    smMasks[64] = selector;
    return true;
}


bool SHAMapNode::operator< (const SHAMapNode& s) const
{
    if (s.mDepth < mDepth) return true;

    if (s.mDepth > mDepth) return false;

    return mNodeID < s.mNodeID;
}

bool SHAMapNode::operator> (const SHAMapNode& s) const
{
    if (s.mDepth < mDepth) return false;

    if (s.mDepth > mDepth) return true;

    return mNodeID > s.mNodeID;
}

bool SHAMapNode::operator<= (const SHAMapNode& s) const
{
    if (s.mDepth < mDepth) return true;

    if (s.mDepth > mDepth) return false;

    return mNodeID <= s.mNodeID;
}

bool SHAMapNode::operator>= (const SHAMapNode& s) const
{
    if (s.mDepth < mDepth) return false;

    if (s.mDepth > mDepth) return true;

    return mNodeID >= s.mNodeID;
}

uint256 SHAMapNode::getNodeID (int depth, uint256 const& hash)
{
    assert ((depth >= 0) && (depth <= 64));
    return hash & smMasks[depth];
}

void SHAMapNode::addIDRaw (Serializer& s) const
{
    s.add256 (mNodeID);
    s.add8 (mDepth);
}

std::string SHAMapNode::getRawString () const
{
    Serializer s (33);
    addIDRaw (s);
    return s.getString ();
}

// This can be optimized to avoid the << if needed
SHAMapNode SHAMapNode::getChildNodeID (int m) const
{
    assert ((m >= 0) && (m < 16));

    uint256 child (mNodeID);
    child.begin ()[mDepth / 2] |= (mDepth & 1) ? m : (m << 4);

    return SHAMapNode (mDepth + 1, child, true);
}

// Which branch would contain the specified hash
int SHAMapNode::selectBranch (uint256 const& hash) const
{
#if RIPPLE_VERIFY_NODEOBJECT_KEYS

    if (mDepth >= 64)
    {
        assert (false);
        return -1;
    }

    if ((hash & smMasks[mDepth]) != mNodeID)
    {
        Log::out() << "selectBranch(" << getString ();
        Log::out() << "  " << hash << " off branch";
        assert (false);
        return -1;  // does not go under this node
    }

#endif

    int branch = * (hash.begin () + (mDepth / 2));

    if (mDepth & 1)
        branch &= 0xf;
    else
        branch >>= 4;

    assert ((branch >= 0) && (branch < 16));

    return branch;
}

void SHAMapNode::dump () const
{
    WriteLog (lsDEBUG, SHAMapNode) << getString ();
}