diff --git a/reference/bin2c.py b/reference/bin2c.py
new file mode 100644
index 0000000..336b4ee
--- /dev/null
+++ b/reference/bin2c.py
@@ -0,0 +1,51 @@
+#!/usr/bin/env python
+
+from argparse import ArgumentParser
+import os
+
+def main():
+    parser = ArgumentParser()
+    parser.add_argument('src_bin', metavar='SRC', help='source binary data')
+    parser.add_argument('dst_out', metavar='DST', help='destination c source')
+    args = parser.parse_args()
+
+    with open(args.src_bin, 'rb') as f:
+        in_data = f.read()
+
+    transtab = str.maketrans('-.', '__')
+    varname = os.path.basename(args.src_bin).translate(transtab)
+
+    out_data = ''
+
+    data_len = len(in_data)
+    n = 0
+    while n < data_len:
+        out_data += '  '
+        for i in range(12):
+            out_data += '0x%02X' % in_data[n]
+            n += 1
+            if n == data_len:
+                break
+            elif i == 11:
+                out_data += ','
+            else:
+                out_data += ', '
+
+        out_data += '\n'
+        if n >= data_len:
+            break
+
+    source_code = \
+f'''#include <stddef.h>
+#include <stdint.h>
+
+const size_t {varname}_len = {data_len};
+const __attribute__((aligned(4))) uint8_t {varname}[] = {{
+{out_data}}};
+'''
+
+    with open(args.dst_out, 'w') as f:
+        f.write(source_code)
+
+if __name__ == '__main__':
+    main()
\ No newline at end of file
diff --git a/reference/mkfrogfs.py b/reference/mkfrogfs.py
new file mode 100644
index 0000000..5045092
--- /dev/null
+++ b/reference/mkfrogfs.py
@@ -0,0 +1,194 @@
+#!/usr/bin/env python
+
+import configparser
+import csv
+import gzip
+import os
+import sys
+from argparse import ArgumentParser
+from struct import Struct
+from zlib import crc32
+
+import heatshrink2
+
+frogfs_fs_header_t = Struct('<IBBHIHH')
+# magic, len, version_major, version_minor, binary_len, num_objects, reserved
+FROGFS_MAGIC = 0x676F7246 # Frog
+FROGFS_VERSION_MAJOR = 1
+FROGFS_VERSION_MINOR = 0
+
+frogfs_hashtable_entry_t = Struct('<II')
+# hash, offset
+
+frogfs_sorttable_entry_t = Struct('<I')
+# offset
+
+frogfs_object_header_t = Struct('<BBHHH')
+# type, len, index, path_len, reserved
+FROGFS_TYPE_FILE = 0
+FROGFS_TYPE_DIR  = 1
+
+frogfs_file_header_t = Struct('<IIHBB')
+# data_len, file_len, flags, compression, reserved
+FROGFS_FLAG_GZIP  = (1 << 0)
+FROGFS_FLAG_CACHE = (1 << 1)
+FROGFS_COMPRESSION_NONE       = 0
+FROGFS_COMPRESSION_HEATSHRINK = 1
+
+frogfs_heatshrink_header_t = Struct('<BBH')
+# window_sz2, lookahead_sz2
+
+frogfs_crc32_footer_t = Struct('<I')
+# crc32
+
+def djb2_hash(s):
+    hash = 5381
+    for c in s.encode('utf8'):
+        hash = ((hash << 5) + hash ^ c) & 0xFFFFFFFF
+    return hash
+
+def load_state(path):
+    state = dict()
+    state_file = os.path.join(args.src_dir, '.state')
+    with open(state_file, newline='') as f:
+        index = 0
+        reader = csv.reader(f, quoting=csv.QUOTE_NONNUMERIC)
+        for data in reader:
+            path, type, _, flags, _, compressor = data
+            hash = djb2_hash(path)
+            flags = () if not flags else tuple(flags.split(','))
+            if 'discard' in flags:
+                continue
+            state[(hash, path)] = {
+                'index': index,
+                'type': type,
+                'flags': flags,
+                'compressor': compressor,
+            }
+            index += 1
+
+    return state
+
+def make_dir_object(item):
+    print(f'{item[0][0]:08x} {item[0][1]:<34s} dir')
+
+    path = item[0][1].encode('utf8') + b'\0'
+    path = path.ljust((len(path) + 3) // 4 * 4, b'\0')
+    header = frogfs_object_header_t.pack(FROGFS_TYPE_DIR,
+            frogfs_object_header_t.size, item[1]['index'], len(path), 0)
+    return header + path
+
+def make_file_object(item, data):
+    global config
+
+    flags = 0
+    compression = FROGFS_COMPRESSION_NONE
+    initial_data_len = len(data)
+    inital_data = data
+
+    if 'cache' in item[1]['flags']:
+        flags |= FROGFS_FLAG_CACHE
+
+    if item[1]['compressor'] == 'gzip':
+        flags |= FROGFS_FLAG_GZIP
+        level = int(config['gzip']['level'])
+        level = min(max(level, 0), 9)
+        data = gzip.compress(data, level)
+    elif item[1]['compressor'] == 'heatshrink':
+        compression = FROGFS_COMPRESSION_HEATSHRINK
+        window_sz2 = int(config['heatshrink']['window_sz2'])
+        lookahead_sz2 = int(config['heatshrink']['lookahead_sz2'])
+        data = frogfs_heatshrink_header_t.pack(window_sz2, lookahead_sz2, 0) + \
+                heatshrink2.compress(data, window_sz2=window_sz2,
+                lookahead_sz2=lookahead_sz2)
+
+    data_len = len(data)
+
+    if data_len >= initial_data_len:
+        flags &= ~FROGFS_FLAG_GZIP
+        compression = FROGFS_COMPRESSION_NONE
+        data = inital_data
+        data_len = initial_data_len
+
+    if initial_data_len < 1024:
+        initial_data_len_str = f'{initial_data_len:d} B'
+        data_len_str = f'{data_len:d} B'
+    elif initial_data_len < 1024 * 1024:
+        initial_data_len_str = f'{initial_data_len / 1024:.1f} KiB'
+        data_len_str = f'{data_len / 1024:.1f} KiB'
+    else:
+        initial_data_len_str = f'{initial_data_len / 1024 / 1024:.1f} MiB'
+        data_len_str = f'{data_len / 1024 / 1024:.1f} MiB'
+
+    percent = 100.0
+    if initial_data_len > 0:
+        percent *= data_len / initial_data_len
+
+    stats = f'{initial_data_len_str:<9s} -> {data_len_str:<9s} ({percent:.1f}%)'
+    print(f'{item[0][0]:08x} {item[0][1]:<34s} file {stats}')
+
+    if flags & FROGFS_FLAG_GZIP:
+        initial_data_len = data_len
+
+    path = item[0][1].encode('utf8') + b'\0'
+    path = path.ljust((len(path) + 3) // 4 * 4, b'\0')
+    header = frogfs_object_header_t.pack(FROGFS_TYPE_FILE,
+            frogfs_object_header_t.size + frogfs_file_header_t.size,
+            item[1]['index'], len(path), 0) + frogfs_file_header_t.pack(
+            data_len, initial_data_len, flags, compression, 0)
+
+    return header + path + data
+
+def main():
+    global args, config
+
+    parser = ArgumentParser()
+    parser.add_argument('src_dir', metavar='SRC', help='source directory')
+    parser.add_argument('dst_bin', metavar='DST', help='destination binary')
+    parser.add_argument('--config', help='user configuration')
+    args = parser.parse_args()
+
+    config = configparser.ConfigParser()
+    config.read(os.path.join(args.src_dir, '.config'))
+
+    state = load_state(args.src_dir)
+
+    num_objects = len(state)
+    offset = frogfs_fs_header_t.size + \
+            (frogfs_hashtable_entry_t.size * num_objects) + \
+            (frogfs_sorttable_entry_t.size * num_objects)
+    hashtable = b''
+    sorttable = bytearray(frogfs_sorttable_entry_t.size * num_objects)
+    objects = b''
+
+    for item in state.items():
+        abspath = os.path.join(args.src_dir, item[0][1])
+        if item[1]['type'] == 'dir':
+            object = make_dir_object(item)
+        elif item[1]['type'] == 'file':
+            if not os.path.exists(abspath):
+                continue
+            with open(abspath, 'rb') as f:
+                data = f.read()
+            object = make_file_object(item, data)
+        else:
+            print(f'unknown object type {type}', file=sys.stderr)
+            sys.exit(1)
+        hashtable += frogfs_hashtable_entry_t.pack(item[0][0], offset)
+        frogfs_sorttable_entry_t.pack_into(sorttable,
+                frogfs_sorttable_entry_t.size * item[1]['index'], offset)
+        objects += object
+        offset += len(object)
+
+    binary_len = offset + frogfs_crc32_footer_t.size
+    header = frogfs_fs_header_t.pack(FROGFS_MAGIC, frogfs_fs_header_t.size,
+            FROGFS_VERSION_MAJOR, FROGFS_VERSION_MINOR, binary_len, num_objects,
+            0)
+    binary = header + hashtable + sorttable + objects
+    binary += frogfs_crc32_footer_t.pack(crc32(binary) & 0xFFFFFFFF)
+
+    with open(args.dst_bin, 'wb') as f:
+        f.write(binary)
+
+if __name__ == '__main__':
+    main()
\ No newline at end of file
diff --git a/reference/preprocess.py b/reference/preprocess.py
new file mode 100644
index 0000000..52a8257
--- /dev/null
+++ b/reference/preprocess.py
@@ -0,0 +1,335 @@
+#!/usr/bin/env python
+
+import csv
+from configparser import ConfigParser
+import json
+import os
+import shutil
+import subprocess
+import sys
+from argparse import ArgumentParser
+from collections import OrderedDict
+from fnmatch import fnmatch
+
+script_dir = os.path.dirname(os.path.realpath(__file__))
+used_preprocessors = set()
+
+def load_config(user_config_file=None):
+    global config
+
+    defaults_file = os.path.join(script_dir, '..', 'frogfs_defaults.json')
+    with open(defaults_file) as f:
+        config = json.load(f)
+
+    user_config = OrderedDict()
+    if user_config_file:
+        if not os.path.exists(user_config_file):
+            print('{user_config_file} cannot be opened', file=sys.stderr)
+            sys.exit(1)
+        with open(user_config_file) as f:
+            user_config = json.load(f)
+    else:
+        print("Not loading user config file")
+
+    def merge_section(sec_name):
+        if sec_name in user_config:
+            for subsec_name, subsec in user_config[sec_name].items():
+                if subsec is None:
+                    if subsec_name in config[sec_name]:
+                        del config[sec_name][subsec_name]
+                else:
+                    if sec_name == 'filters':
+                        if subsec_name not in config[sec_name]:
+                            config[sec_name] = []
+                        if isinstance(config[sec_name][subsec_name], str):
+                            config[sec_name][subsec_name] = \
+                                    [config[sec_name][subsec_name]]
+                        if isinstance(subsec, str):
+                            subsec = [subsec]
+                        config[sec_name][subsec_name] += subsec
+                    else:
+                        config[sec_name][subsec_name] = subsec
+
+    for sec_name in ('preprocessors', 'compressors', 'filters'):
+        merge_section(sec_name)
+        for subsec_name, subsec in config.get(sec_name, OrderedDict()).items():
+            if isinstance(subsec, str):
+                config[sec_name][subsec_name] = [subsec]
+            elif isinstance(subsec, dict):
+                for subsubsec_name, subsubsec in subsec.items():
+                    if isinstance(subsubsec, str):
+                        subsec[subsubsec_name] = [subsubsec]
+
+    class pattern_sort:
+        def __init__(self, path, *args):
+            self.pattern, _ = path
+
+        def __lt__(self, other):
+            if self.pattern == '*':
+                return False
+            if other.pattern == '*':
+                return True
+            if self.pattern.startswith('*') and \
+                    not other.pattern.startswith('*'):
+                return False
+            if not self.pattern.startswith('*') and \
+                    other.pattern.startswith('*'):
+                return True
+            return self.pattern < other.pattern
+
+    config['filters'] = OrderedDict(sorted(config['filters'].items(),
+            key = pattern_sort))
+
+    preprocessors = list(config['preprocessors'].keys())
+    actions = list()
+    for action in preprocessors + ['cache', 'discard']:
+        actions.append(action)
+        actions.append('no-' + action)
+    actions += ['skip-preprocessing', 'gzip', 'heatshrink', 'uncompressed']
+    config['actions'] = actions
+
+    for filter, actions in config['filters'].items():
+        for action in actions:
+            if action not in config['actions']:
+                print(f"Unknown action `{action}' for filter `{filter}'",
+                        file=sys.stderr)
+                sys.exit(1)
+
+def get_preprocessors(path):
+    global config, used_preprocessors
+
+    preprocessors = OrderedDict()
+    for pattern, actions in config['filters'].items():
+        if fnmatch(path, pattern):
+            for action in actions:
+                enable = not action.startswith('no-')
+                if not enable:
+                    action = action[3:]
+                if action in config['preprocessors']:
+                    if enable:
+                        preprocessors[action] = None
+                        used_preprocessors.add(action)
+                    else:
+                        try:
+                            del preprocessors[action]
+                        except:
+                            pass
+                    preprocessors[action] = enable
+        if 'skip-preprocessing' in actions:
+            return ()
+
+    return tuple(preprocessors)
+
+def get_flags(path):
+    global config
+
+    flags = OrderedDict()
+    for pattern, actions in config['filters'].items():
+        if fnmatch(path, pattern):
+            for action in actions:
+                enable = not action.startswith('no-')
+                if not enable:
+                    action = action[3:]
+                if action in ('cache', 'discard', 'skip'):
+                    flags[action] = enable
+
+    return flags
+
+def get_compressor(path):
+    global config
+
+    compressor = 'uncompressed'
+    for pattern, actions in config['filters'].items():
+        if fnmatch(path, pattern):
+            for action in actions:
+                if action in ('gzip', 'heatshrink', 'uncompressed'):
+                    compressor = action
+    return compressor
+
+def load_state(dst_dir):
+    state = dict()
+    state_file = os.path.join(dst_dir, '.state')
+    if os.path.exists(state_file):
+        with open(state_file, newline='') as f:
+            reader = csv.reader(f, quoting=csv.QUOTE_NONNUMERIC)
+            for data in reader:
+                path, type, mtime, flags, preprocessors, compressor = data
+                state[path] = {
+                    'type': type,
+                    'mtime': mtime,
+                    'preprocessors': () if not preprocessors else \
+                            tuple(preprocessors.split(',')),
+                    'flags': () if not flags else tuple(flags.split(',')),
+                    'compressor': compressor,
+                }
+    return state
+
+def save_state(dst_dir, state):
+    with open(os.path.join(dst_dir, '.state'), 'w', newline='') as f:
+        writer = csv.writer(f, quoting=csv.QUOTE_NONNUMERIC)
+        for path, data in state.items():
+            row = (path, data['type'], data['mtime'],
+                    ','.join(data['flags']),
+                    ','.join(data['preprocessors']),
+                    data['compressor'])
+            writer.writerow(row)
+
+    dotconfig = ConfigParser()
+    dotconfig['gzip'] = {
+        'level': config['compressors']['gzip']['level'],
+    }
+    dotconfig['heatshrink'] = {
+        'window_sz2': config['compressors']['heatshrink']['window_sz2'],
+        'lookahead_sz2': config['compressors']['heatshrink']['lookahead_sz2'],
+    }
+    with open(os.path.join(dst_dir, '.config'), 'w') as f:
+        dotconfig.write(f)
+
+def build_state(src_dir):
+    state = dict()
+    for dir, _, files in os.walk(src_dir, followlinks=True):
+        reldir = os.path.relpath(dir, src_dir).replace('\\', '/').lstrip('.') \
+                .lstrip('/')
+        absdir = os.path.abspath(dir)
+        if reldir and os.path.exists(absdir):
+            state[reldir] = {
+                'type': 'dir',
+                'mtime': os.path.getmtime(absdir),
+                'preprocessors': (),
+                'flags': (),
+                'compressor': 'uncompressed',
+            }
+        for file in files:
+            relfile = os.path.join(reldir, file).replace('\\','/').lstrip('/')
+            absfile = os.path.join(absdir, file)
+            if os.path.exists(absfile):
+                state[relfile] = {
+                    'type': 'file',
+                    'mtime': os.path.getmtime(absfile),
+                    'preprocessors': get_preprocessors(relfile),
+                    'flags': get_flags(relfile),
+                    'compressor': get_compressor(relfile),
+                }
+    return state
+
+def install_preprocessors(config, root_dir):
+    global used_preprocessors
+
+    # Work around a bug in npm -- if `node_modules` doesn't exist it will
+    # create one at some random path above. Sometimes. Depending on the version.
+    # Except on Tuesdays in Norway.
+    node_modules = os.path.join(root_dir.replace('/', os.path.sep), 'node_modules')
+    if not os.path.exists(node_modules):
+        os.mkdir(node_modules)
+
+    for name in used_preprocessors:
+        preprocessor = config['preprocessors'][name]
+        if 'install' in preprocessor:
+            install = preprocessor['install']
+            subprocess.check_call(install, shell=True, cwd=root_dir)
+        elif 'npm' in preprocessor:
+            for npm in preprocessor['npm']:
+                test_path = os.path.join(root_dir.replace('/', os.path.sep),
+                                         'node_modules',
+                                         npm.replace('/', os.path.sep))
+                if not os.path.exists(test_path):
+                    subprocess.check_call(f'npm install {npm}', shell=True, cwd=root_dir)
+
+def preprocess(path, preprocessors):
+    global config
+
+    src_abs = os.path.join(args.src_dir, path)
+    dst_abs = os.path.join(args.dst_dir, path)
+    if os.path.isdir(src_abs):
+        if os.path.isdir(dst_abs):
+            pass
+        else:
+            os.mkdir(dst_abs)
+    else:
+        os.makedirs(os.path.dirname(dst_abs), exist_ok=True)
+
+        with open(src_abs, 'rb') as f:
+            data = f.read()
+
+        if preprocessors:
+            print(f'       - preprocessing {path}', file=sys.stderr)
+
+        for preprocessor in preprocessors:
+            print(f'         - running {preprocessor}')
+            command = config['preprocessors'][preprocessor]['command']
+            if command[0].startswith('tools/'):
+                command[0] = os.path.join(script_dir, command[0][6:])
+            # These are implemented as `.cmd` files on Windows, which explicitly
+            # requires them to be run under `cmd /c`
+            if os.name == 'nt':
+                command = ["cmd", "/c"] + command
+            process = subprocess.Popen(command, stdin=subprocess.PIPE,
+                    stdout=subprocess.PIPE, shell=True)
+            data = process.communicate(input=data)[0]
+
+        with open(dst_abs, 'wb') as f:
+            f.write(data)
+
+def main():
+    global args, config
+
+    parser = ArgumentParser()
+    parser.add_argument('src_dir', metavar='SRC', help='source directory')
+    parser.add_argument('dst_dir', metavar='DST', help='destination directory')
+    parser.add_argument('--config', help='user configuration')
+    parser.add_argument('--root', metavar='ROOT', help='build root directory')
+    args = parser.parse_args()
+
+    load_config(args.config)
+
+    old_state = load_state(args.dst_dir)
+    new_state = build_state(args.src_dir)
+
+    print(f"Root: {args.root}")
+    install_preprocessors(config, args.root)
+
+    old_paths = set(old_state.keys())
+    new_paths = set(new_state.keys())
+
+    delete_paths = old_paths - new_paths
+    copy_paths = new_paths - old_paths
+    compare_paths = old_paths & new_paths
+
+    if not delete_paths and not copy_paths and not compare_paths:
+        sys.exit(0)
+
+    for path in delete_paths:
+        dst_abs = os.path.join(args.dst_dir, path)
+        if os.path.exists(dst_abs):
+            if os.path.isdir(dst_abs):
+                shutil.rmtree(dst_abs, True)
+            else:
+                os.unlink(dst_abs)
+
+    for path in copy_paths:
+        preprocess(path, new_state[path]['preprocessors'])
+
+    changes = bool(delete_paths or copy_paths)
+    for path in compare_paths:
+        if old_state[path]['type'] != new_state[path]['type'] or \
+                old_state[path]['preprocessors'] != \
+                        new_state[path]['preprocessors'] or \
+                old_state[path]['mtime'] < new_state[path]['mtime']:
+
+            changes = True
+
+            dst_abs = os.path.join(args.dst_dir, path)
+
+            if os.path.exists(dst_abs):
+                if os.path.isdir(dst_abs):
+                    shutil.rmtree(dst_abs, True)
+                else:
+                    os.unlink(dst_abs)
+
+            preprocess(path, new_state[path]['preprocessors'])
+
+    if changes:
+        save_state(args.dst_dir, new_state)
+
+if __name__ == '__main__':
+    main()
diff --git a/reference/requirements.txt b/reference/requirements.txt
new file mode 100644
index 0000000..1df6f7a
--- /dev/null
+++ b/reference/requirements.txt
@@ -0,0 +1 @@
+heatshrink2>=0.12.0
diff --git a/reference/zeroify.py b/reference/zeroify.py
new file mode 100644
index 0000000..474e88a
--- /dev/null
+++ b/reference/zeroify.py
@@ -0,0 +1,8 @@
+#!/usr/bin/env python
+
+import sys
+
+
+if __name__ == '__main__':
+    data = sys.stdin.buffer.read()
+    sys.stdout.buffer.write(data + b'\0')