Changes between Version 67 and Version 68 of HashSourceCodes

Timestamp:

Apr 27, 2019, 9:40:54 AM (6 years ago)

Author:

os

Comment:

added Dart

HashSourceCodes

@@ -2089 +2089 @@
 }
 }}}
+
+== Dart ==
+Taken from https://github.com/NBTX/opensubtitles_hash/blob/master/opensubtitles_hash.dart
+Check also https://pub.dartlang.org/packages/opensubtitles_hash
+    
+///
+/// Copyright 2019 SamJakob (NBTX, ApolloTV)
+///
+/// Permission is hereby granted, free of charge, to any person
+/// obtaining a copy of this software and associated documentation
+/// files (the "Software"), to deal in the Software without
+/// restriction, including without limitation the rights to use,
+/// copy, modify, merge, publish, distribute, sublicense, and/or
+/// sell copies of the Software, and to permit persons to whom the
+/// Software is furnished to do so, subject to the following
+/// conditions:
+///
+/// The above copyright notice and this permission notice shall be
+/// included in all copies or substantial portions of the Software.
+///
+/// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+/// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+/// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+/// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+/// HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+/// WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+/// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+/// OTHER DEALINGS IN THE SOFTWARE.
+
+library opensubtitles_hash;
+
+import 'dart:async';
+import 'dart:io';
+
+///
+/// Simple Dart implementation of the OpenSubtitles hash algorithm.
+///
+/// Hash code is based on Media Player Classic. In natural language
+/// it calculates: size + 64bit checksum of the first and last 64k
+///
+/// (even if they overlap because the file is smaller than
+/// * 128k).
+///
+/// Example Usage:
+/// --------------
+/// String hash = await OpenSubtitlesHasher.computeFileHash(
+///   new File('./breakdance.avi')
+/// );
+///
+/// String hash = await OpenSubtitlesHasher.computeURLHash(
+///   "http://www.opensubtitles.org/addons/avi/breakdance.avi"
+/// )
+///
+class OpenSubtitlesHasher {
+
+  // 64 * 1024
+  static const HASH_CHUNK_SIZE = 65536;
+
+  static Future<String> computeURLHash(String url, {
+    Map<String, dynamic> headers,
+    bool followRedirects = false
+  }) async {
+
+    HttpClient client = new HttpClient();
+    HttpClientResponse response;
+    response = await client.getUrl(Uri.parse(url))
+      .then((HttpClientRequest request){
+        // Add headers if they have been provided...
+        if(headers != null){
+          headers.forEach((String name, dynamic value){
+            request.headers.add(name, value.toString());
+          });
+        }
+
+        request.followRedirects = followRedirects;
+        return request.close();
+      });
+
+    List<List<int>> responseData = await response.toList();
+    return await computeHash(
+      responseData.expand((i) => i).toList()
+    );
+
+  }
+
+  static Future<String> computeFileHash(File file) async {
+    return await computeHash(await file.readAsBytes());
+  }
+
+  ///
+  /// Computes the hash of the byte array parameter.
+  ///
+  /// This is used by [computeURLHash] and [computeFileHash].
+  ///
+  static Future<String> computeHash(List<int> subtitleFile) async {
+    List<int> data = new List.filled(8, 0, growable: true);
+
+    /// Perform a shift on the first 8 entries
+    /// in [data] relative to the size of the file.
+    int temp = subtitleFile.length;
+    for(var i = 0; i < 8; i++){
+      data[i] = temp & 255;
+      temp = temp >> 8;
+    }
+
+    /// Read bytes from 0 to [HASH_CHUNK_SIZE]
+    /// and add the value to the corresponding
+    /// position in [data].
+    for(var i = 0; i < HASH_CHUNK_SIZE; i++){
+      data[(i + 8) % 8] += subtitleFile[i];
+    }
+
+    /// Read the last [HASH_CHUNK_SIZE] bytes
+    /// and add the value to the corresponding
+    /// position in [data].
+    int startReference = subtitleFile.length - HASH_CHUNK_SIZE;
+    for(var i = startReference; i < subtitleFile.length; i++){
+      int fileOffset = i - startReference;
+      data[(fileOffset + 8) % 8] += subtitleFile[i];
+    }
+
+    return _binl2hex(data);
+  }
+
+  static _binl2hex(a) {
+    var b = 255,
+        c = 7,
+        d = '0123456789abcdef',
+        e = '';
+
+    a[1] += a[0] >> 8;
+    a[0] = a[0] & b;
+    a[2] += a[1] >> 8;
+    a[1] = a[1] & b;
+    a[3] += a[2] >> 8;
+    a[2] = a[2] & b;
+    a[4] += a[3] >> 8;
+    a[3] = a[3] & b;
+    a[5] += a[4] >> 8;
+    a[4] = a[4] & b;
+    a[6] += a[5] >> 8;
+    a[5] = a[5] & b;
+    a[7] += a[6] >> 8;
+    a[6] = a[6] & b;
+    a[7] = a[7] & b;
+    for (c; c > -1; c--) {
+        e += d[(a[c] >> 4 & 15)] + d[(a[c] & 15)];
+    }
+    return e;
+  }
+
+}