diff --git a/dat.py b/dat.py
new file mode 100644
index 0000000..bf382d1
--- /dev/null
+++ b/dat.py
@@ -0,0 +1,62 @@
+import xml.etree.ElementTree
+import hashdb
+
+class DatImportError(Exception):
+    '''This error is raised when a DAT import fails.'''
+
+# TODO: l o g g i n g
+
+# TODO: Consider using a context object to avoid keeping large XML trees in memory.
+class Dat:
+    '''A Dat object processes DAT files into the data structures defined in hashdb. '''
+    def __init__(self, filename):
+        '''Open the given DAT file and gather metadata from it.'''
+
+        xml_tree = xml.etree.ElementTree.parse(filename)
+        self._xml_root = xml_tree.getroot()
+
+        dat_header = self._xml_root.find('header')
+        self.info = hashdb.DatInfo(name=dat_header.find('name').text,
+                                   description=dat_header.find('description').text,
+                                   platform=None,
+                                   version=dat_header.find('version').text)
+
+    def set_platform(self, platform_info):
+        '''
+        Set a platform for this DAT file.
+        DAT files don't include platform metadata, but are all platform-specific.
+        '''
+        new_info = hashdb.DatInfo(name=self.info.name,
+                                  description=self.info.description,
+                                  platform=platform_info.shortcode,
+                                  version=self.info.version)
+        self.info = new_info
+
+    def set_name(self, new_name):
+        '''
+        Override the DAT file's name.
+        DAT files often have less-than-helpful names.
+        '''
+        new_info = hashdb.DatInfo(name=new_name,
+                                  description=self.info.description,
+                                  platform=self.info.platform,
+                                  version=self.info.version)
+        self.info = new_info
+
+    def read_all_hashes(self):
+        '''Read every hash in the DAT file and return it as a large list of RomInfo tuples.'''
+        if self.info.platform is None:
+            raise DatImportError('DAT platform not set.')
+
+        rom_info_list = []
+        all_rom_entries = self._xml_root.findall('.//rom')
+
+        for rom in all_rom_entries:
+            rom_info = hashdb.RomInfo(sha1sum=rom.get('sha1'),
+                                      filename=rom.get('name'),
+                                      platform=self.info.platform,
+                                      datorigin=self.info.name)
+
+            rom_info_list.append(rom_info)
+
+        return rom_info_list
diff --git a/hashdb.py b/hashdb.py
new file mode 100644
index 0000000..e12000d
--- /dev/null
+++ b/hashdb.py
@@ -0,0 +1,159 @@
+import collections
+import hashlib
+import sqlite3
+
+# TODO: Decide on a way to auto-download DATs.
+# TODO: l o g g i n g
+HASH_CHUNK_SIZE = 10485760 # 10mb
+SQL_AND = ' AND '
+SQL_OR = ' OR '
+
+# TODO: Figure out how to do some kind of type checking for these named tuples.
+RomInfo = collections.namedtuple('RomInfo', 'sha1sum, filename, platform, datorigin')
+DatInfo = collections.namedtuple('DatInfo', 'name, description, platform, version')
+PlatformInfo = collections.namedtuple('PlatformInfo', 'shortcode, fullname, aliases')
+
+ORPHAN_DAT = DatInfo('', 'Orphaned hashes', 'nonexistent', '1')
+
+# TODO: This should go in the eventual romdb class.
+def get_file_sha1sum(filename):
+    sha1sum = hashlib.sha1()
+    with open(filename, 'rb') as file_contents:
+        while True:
+            chunk = file_contents.read(HASH_CHUNK_SIZE)
+            if not chunk:
+                break
+            sha1sum.update(chunk)
+
+    return sha1sum.hexdigest()
+
+def _build_sql_constraints(inclusive, constraints):
+    if constraints == {}:
+        return ('', [])
+
+    if inclusive:
+        logical_separator = SQL_AND
+    else:
+        logical_separator = SQL_OR
+
+    sql_constraint_string = 'WHERE '
+    sql_parameter_list = []
+    for key, value in constraints.items():
+        sql_constraint_string += '%s=?%s' % (key, logical_separator)
+        sql_parameter_list.append(value)
+
+    # Trim off the last ', '
+    sql_constraint_string = sql_constraint_string[0:-len(logical_separator)]
+
+    return (sql_constraint_string, sql_parameter_list)
+
+class HashDB:
+    # TODO: Low-priority: Probably design this around using multiple hash algorithms eventually.
+    def __init__(self, filename):
+        """
+        If db file does not exist, create it and create necessary tables.
+        Either way, create a connection and a cursor.
+        """
+        # TODO: This process needs real error handling.
+        self._connection = sqlite3.connect(filename)
+
+        with self._connection:
+            # TODO: sha1sums.datorigin should be treated as a list. 
+            self._connection.execute('CREATE TABLE IF NOT EXISTS sha1sums (sha1sum PRIMARY KEY, '
+                                     'filename NOT NULL, platform NOT NULL, datorigin);')
+
+            # TODO: Consider moving image-dat association to dats table.
+            self._connection.execute('CREATE TABLE IF NOT EXISTS dats (name PRIMARY KEY, '
+                                     'description, platform NOT NULL, version NOT NULL);')
+
+            # TODO: Add support for custom roms not tracked in DAT releases.
+            # INSERT INTO dats (name="custom", description="Personally added hashes.", version=1);
+
+            self._connection.execute('CREATE TABLE IF NOT EXISTS platforms (shortcode PRIMARY KEY, '
+                                     'fullname NOT NULL, aliases );')
+            print('Database initialized.')
+
+
+    def add_hash(self, rom_info):
+        """ Add a hash to the database. """
+        # INSERT INTO sha1sums (sha1sum, filename, platform, datorigin);
+        with self._connection:
+            self._connection.execute('INSERT INTO sha1sums VALUES (?, ?, ?, ?)', rom_info)
+
+    def add_hash_list(self, rom_info_list):
+        '''Add many hashes to the database. '''
+        with self._connection:
+            for rom_info in rom_info_list:
+                self._connection.execute('INSERT INTO sha1sums VALUES (?, ?, ?, ?)', rom_info)
+
+    def remove_hash(self, rom_info):
+        """ Remove a hash from the database. """
+        # DELETE FROM sha1sums WHERE sha1sum=sha1sum;
+        with self._connection:
+            self._connection.execute('DELETE FROM sha1sums WHERE sha1sum=?;', [rom_info.sha1sum])
+
+    def remove_hash_list(self, rom_info_list):
+        '''Remove many hashes from the database. '''
+        with self._connection:
+            for rom_info in rom_info_list:
+                self._connection.execute('DELETE FROM sha1sums WHERE sha1sum=?;', [rom_info.sha1sum])
+
+    def add_platform(self, platform_info):
+        """ Add a platform shortcode to the database. """
+        # TODO: Collisions need user input to resolve, so remove this try block later.
+        try:
+            with self._connection:
+                self._connection.execute('INSERT INTO platforms VALUES (?, ?, ?);', platform_info)
+        except sqlite3.IntegrityError:
+            print('Warning: %s is already in database.' % platform_info.shortcode)
+
+    def update_platform_aliases(self, shortcode, aliases):
+        """ Change the list of aliases for a platform shortcode """
+        # UPDATE platforms SET aliases=aliases WHERE shortcode=shortcode;
+
+    def remove_platform(self, platform_info):
+        """ Remove a platform and all associated DATs and hashes from the database. """
+        # DELETE FROM sha1sums WHERE platform=shortcode;
+        # DELETE FROM dats WHERE platform=shortcode;
+        # DELETE FROM platform WHERE platform=shortcode;
+        with self._connection:
+            self._connection.execute('DELETE FROM sha1sums WHERE platform=?;',
+                                     [platform_info.shortcode])
+            self._connection.execute('DELETE FROM dats WHERE platform=?;',
+                                     [platform_info.shortcode])
+            self._connection.execute('DELETE FROM platforms WHERE shortcode=?;',
+                                     [platform_info.shortcode])
+
+    def add_dat(self, dat_info):
+        '''Add a DAT's metadata to the database. '''
+        with self._connection:
+            self._connection.execute('INSERT INTO platforms VALUES (?, ?, ?, ?);', dat_info)
+
+    def remove_dat(self, dat_info):
+        """ Delete a DAT and all of its' hashes from the database. """
+        # DELETE FROM sha1sums WHERE datorigin=name;
+        # DELETE FROM dats WHERE name=name;
+
+        with self._connection:
+            # TODO: Support multiple dat sources for the same hash.
+            self._connection.execute('DELETE FROM sha1sums WHERE datorigin=?;', [dat_info.name])
+            self._connection.execute('DELETE FROM dats WHERE name=?;', [dat_info.name])
+
+    def hash_search(self, inclusive=True, **constraints):
+        '''Search for hashes, given the parameters. '''
+
+        sql_where_clause, sql_parameters = _build_sql_constraints(inclusive, constraints)
+
+        rom_info_list = []
+        with self._connection:
+            cursor = self._connection.cursor()
+            sql_query = 'SELECT * FROM sha1sums %s;' % sql_where_clause
+            cursor.execute(sql_query, sql_parameters)
+            print(sql_query)
+            rows = cursor.fetchall()
+
+            for row in rows:
+                rom_info = RomInfo(*row)
+                rom_info_list.append(rom_info)
+
+        return rom_info_list
diff --git a/lark b/lark
new file mode 100755
index 0000000..bb13842
--- /dev/null
+++ b/lark
@@ -0,0 +1,99 @@
+#!/usr/bin/python3
+"""
+lark
+Verify and sort game ROM images.
+
+Intended features:
+    DAT downloading
+    File validation
+    File renaming/moving
+    Nice Beets-inspired UI.
+    Release grouping (maybe, this might require another large external database)
+
+UI notes
+
+# Key terms
+    - hash          Unique identifier for each ROM image.
+    - image         ROM image, ripped from physical media.
+    - dat           List of hashes, with associated filenames.
+    - platform      The original hardware on which the image was intended to run.
+
+# Verbs
+    - list [hash, dat, platform, image]
+        List items in the database.
+
+    - import [datfile, imagefile]
+        Process and add external items to the database.
+
+    - add [platform, hash]
+        Manually add items to the database.
+
+    - remove [hash, dat, platform]
+        Delete items from the database.
+"""
+# TODO: Write decent UI
+import hashlib
+import sys
+import os
+import xdg.BaseDirectory
+
+import dat
+import hashdb
+
+HASH_CHUNK_SIZE = 10485760 # 10mb
+SQLITE_FILENAME = 'lark.db'
+
+data_path = os.path.join(xdg.BaseDirectory.xdg_data_home, 'lark')
+
+def get_sha1sum(filename):
+    sha1sum = hashlib.sha1()
+    with open(filename, 'rb') as file_contents:
+        while True:
+            chunk = file_contents.read(HASH_CHUNK_SIZE)
+            if not chunk:
+                break
+            sha1sum.update(chunk)
+
+    return sha1sum.hexdigest()
+
+
+'''
+smd_dat = dat(SMD_DAT_PATH)
+# TODO: Default to '.'
+# TODO: Use a proper arg parser.
+search_dir = sys.argv[1]
+for filename in os.listdir(search_dir):
+    # TODO: Ignore or descend into directories.
+    # TODO: Compare hashes
+    file_path = os.path.abspath(os.path.join(search_dir, filename))
+    file_sha1 = get_sha1sum(file_path)
+    search_result = smd_dat.search_by_sha1(file_sha1)
+    if search_result:
+        rom_data = search_result[0]
+        print('File %s matches database entry for %s.' % (filename, rom_data.filename))
+    else:
+        print('File %s is not in database.' % filename)
+'''
+# Test code! :D
+# TODO: Write test code that doesn't depend on external resources.
+SMD_DAT_PATH = '/home/lumia/Downloads/Sega - Mega Drive - Genesis (20200303-035539).dat'
+TEST_HASH = 'cfbf98c36c776677290a872547ac47c53d2761d6'
+smd_platform= hashdb.PlatformInfo(shortcode='smd', fullname='Sega - Genesis - Megadrive',
+                                    aliases='')
+db = hashdb.HashDB(os.path.join(data_path, SQLITE_FILENAME))
+db.add_platform(smd_platform)
+
+smd_dat = dat.Dat(SMD_DAT_PATH)
+smd_dat.set_platform(smd_platform)
+#hashes = smd_dat.read_all_hashes()
+
+#db.add_hash_list(hashes)
+
+smd_hashes = db.hash_search(datorigin=smd_dat.info.name)
+print(len(smd_hashes))
+#print(hashdb._build_sql_constraints(hashdb.SQL_OR, {'butt':'yes', 'platform':'smd'}))
+#print(db.hash_search(platform='smd'))
+#db.remove_platform(smd_platform)
+#db.remove_dat(smd_dat.info)
+print(hashdb._build_sql_constraints(True, {'sha1sum':TEST_HASH.upper()}))
+print(db.hash_search(sha1sum=TEST_HASH.upper()))
diff --git a/readme.md b/readme.md
new file mode 100644
index 0000000..fb58781
--- /dev/null
+++ b/readme.md
@@ -0,0 +1,24 @@
+# Lark
+
+Lark is a ROM organizer that uses known hash lists to validate and sort ROM files into a library
+directory structure.
+
+## Current features
+* Nothing really works yet.
+
+## Planned features
+* Validate ROM images.
+* Download DAT files
+* Rename/move ROM files
+* Maintain a database of present ROMs
+* A nice, Beets-like interface
+* Grouping ROMS in archive files
+
+## Known issues
+* This probably isn't terribly efficient. It's Python parsing XML into an SQLite database and I only
+  know pretty basic database design.
+
+* Python's `xml.etree` module has a couple of known security issues[1]. Stick to importing DATs from
+known places and it shouldn't be an issue.
+
+[1] - https://docs.python.org/3/library/xml.html#xml-vulnerabilities
diff --git a/romdb.py b/romdb.py
new file mode 100644
index 0000000..01c4591
--- /dev/null
+++ b/romdb.py
@@ -0,0 +1,8 @@
+# romdb
+# Manage a file structure of ROM images.
+'''
+romimage table schema
+
+CREATE TABLE romimage (current_filename PRIMARY KEY, ideal_filename UNIQUE TEXT, sha1sum UNIQUE
+                       TEXT)
+'''