lookupAddress

    pub fn lookupAddress(self: *const ElfDynLib, vername: []const u8, name: []const u8) ?usize {
        const maybe_versym = if (self.verdef == null) null else self.versym;

        const OK_TYPES = (1 << elf.STT_NOTYPE | 1 << elf.STT_OBJECT | 1 << elf.STT_FUNC | 1 << elf.STT_COMMON);
        const OK_BINDS = (1 << elf.STB_GLOBAL | 1 << elf.STB_WEAK | 1 << elf.STB_GNU_UNIQUE);

        switch (self.hash_table) {
            .dt_hash => |hashtab| {
                var i: usize = 0;
                while (i < hashtab[1]) : (i += 1) {
                    if (0 == (@as(u32, 1) << @as(u5, @intCast(self.syms[i].st_info & 0xf)) & OK_TYPES)) continue;
                    if (0 == (@as(u32, 1) << @as(u5, @intCast(self.syms[i].st_info >> 4)) & OK_BINDS)) continue;
                    if (0 == self.syms[i].st_shndx) continue;
                    if (!mem.eql(u8, name, mem.sliceTo(self.strings + self.syms[i].st_name, 0))) continue;
                    if (maybe_versym) |versym| {
                        if (!checkver(self.verdef.?, versym[i], vername, self.strings))
                            continue;
                    }
                    return @intFromPtr(self.memory.ptr) + self.syms[i].st_value;
                }
            },
            .dt_gnu_hash => |gnu_hash_header| {
                const GnuHashSection = switch (@bitSizeOf(usize)) {
                    32 => GnuHashSection32,
                    64 => GnuHashSection64,
                    else => |bit_size| @compileError("Unsupported bit size " ++ bit_size),
                };

                const gnu_hash_section: GnuHashSection = .fromPtr(gnu_hash_header);
                const hash = elf.gnu_hash.calculate(name);

                const bloom_index = (hash / @bitSizeOf(usize)) % gnu_hash_header.bloom_size;
                const bloom_val = gnu_hash_section.bloom[bloom_index];

                const bit_index_0 = hash % @bitSizeOf(usize);
                const bit_index_1 = (hash >> @intCast(gnu_hash_header.bloom_shift)) % @bitSizeOf(usize);

                const one: usize = 1;
                const bit_mask: usize = (one << @intCast(bit_index_0)) | (one << @intCast(bit_index_1));

                if (bloom_val & bit_mask != bit_mask) {
                    // Symbol is not in bloom filter, so it definitely isn't here.
                    return null;
                }

                const bucket_index = hash % gnu_hash_header.nbuckets;
                const chain_index = gnu_hash_section.buckets[bucket_index] - gnu_hash_header.symoffset;

                const chains = gnu_hash_section.chain;
                const hash_as_entry: elf.gnu_hash.ChainEntry = @bitCast(hash);

                var current_index = chain_index;
                var at_end_of_chain = false;
                while (!at_end_of_chain) : (current_index += 1) {
                    const current_entry = chains[current_index];
                    at_end_of_chain = current_entry.end_of_chain;

                    if (current_entry.hash != hash_as_entry.hash) continue;

                    // check that symbol matches
                    const symbol_index = current_index + gnu_hash_header.symoffset;
                    const symbol = self.syms[symbol_index];

                    if (0 == (@as(u32, 1) << @as(u5, @intCast(symbol.st_info & 0xf)) & OK_TYPES)) continue;
                    if (0 == (@as(u32, 1) << @as(u5, @intCast(symbol.st_info >> 4)) & OK_BINDS)) continue;
                    if (0 == symbol.st_shndx) continue;

                    const symbol_name = mem.sliceTo(self.strings + symbol.st_name, 0);
                    if (!mem.eql(u8, name, symbol_name)) {
                        continue;
                    }

                    if (maybe_versym) |versym| {
                        if (!checkver(self.verdef.?, versym[symbol_index], vername, self.strings)) {
                            continue;
                        }
                    }

                    return @intFromPtr(self.memory.ptr) + symbol.st_value;
                }
            },
        }

        return null;
    }