Exactly. Normally you use second-level tables for the long codes. In the first table, if code doesn't reach a leaf, tbl[code] holds a pointer to the next table

Exactly. Normally you use second-level tables for the long codes. In the first table, if code doesn't reach a leaf, tbl[code] holds a pointer to the next table to use. For example, here's JPEG XL's Huffman decoder: https://github.com/libjxl/libjxl/blob/1c67f4eff0464e6241f36548b8119f6a64e7f0cc/lib/jxl/dec_huffman.cc#L239-L253 https://github.com/libjxl/libjxl/blob/1c67f4eff0464e6241f365.... The branch uses a second table if the code was too long.