Exemplo n.º 1
0
bool readReference(IBitStream& bstr, unsigned& reference, unsigned huffmanNumber) {
    int code = bstr.read(2);
    if (code == 3) {
        reference = bstr.read(32);
        return true;
    }
    int bitlen = BitLength(huffmanNumber);
    assert(bitlen >= 2);
    reference = (code << (bitlen - 2)) | bstr.read(bitlen - 2);
    return true;
}
Exemplo n.º 2
0
void LenTable::Read(IBitStream &bitstr) {
    symidx2nodeidx.clear();
    nodes.clear();

    int count = bitstr.read(32);
    int bitsPerLen = bitstr.read(8);
    int idxBitSize = BitLength(count);

    symidx2nodeidx.resize(count);
    for (unsigned& nodeIdx : symidx2nodeidx) {
        nodeIdx = -1; // in case the root has a leaf as a child
    }
    nodes.resize(count - 1);
    int rootIdx = nodes.size() - 1;
    nodes.at(rootIdx) = {0,0,-1,-1};
    nextNodePosition = 0;
    for (int i = 0; i < count; ++i) {
        int symidx = bitstr.read(idxBitSize);
        int len = bitstr.read(bitsPerLen);
        placeSymidx(symidx, rootIdx, len);
    }
}
Exemplo n.º 3
0
int LenTable::Decode(IBitStream &bitstr, unsigned &symIdx) const {
    const HuffmanNode* node = &nodes.back();
    int len = 0;
    for (;;) {
        len++;
        int bit = bitstr.read(1);
        if (bit) { // right
            if (node->right < 0) { // leaf
                symIdx = -1 - node->right;
                return len;
            }
            node = &nodes.at(node->right - 1);
        } else { // left
            if (node->left < 0) { // leaf
                symIdx = -1 - node->left;
                return len;
            }
            node = &nodes.at(node->left - 1);
        }
    }
    // unreachable
}