BSDIFF support

rom-patcher-js/modules/RomPatcher.format.bdf.js

@@ -0,0 +1,62 @@
+/* BDF module for Rom Patcher JS v20250914 - Marc Robledo 2025 - http://www.marcrobledo.com/license */
+/* File format specification: https://www.daemonology.net/bsdiff/ */
+
+const bz2 = require('./bz2/bz2');
+
+const BDF_MAGIC='BSDIFF40';
+
+if(typeof module !== "undefined" && module.exports){
+	module.exports = BDF;
+}
+
+function BDF(){
+    this.records=[];
+    this.patchedSize=0;
+}
+
+BDF.prototype.apply=function(file){
+    var tempFile=new BinFile(this.patchedSize);
+    
+    for (const record of this.records) {
+        for (const b of record.diff) {
+            tempFile.writeU8(file.readU8() + b);
+        }
+        tempFile.writeBytes(record.extra);
+        file.seek(file.offset + record.skip);
+    }
+    return tempFile;
+}
+
+BDF.MAGIC = BDF_MAGIC;
+
+BDF.fromFile=function(file){
+    var patch=new BDF();
+
+    file.seek(8);
+    file.littleEndian=true;
+    var controlSize=file.readU64();
+    var diffSize=file.readU64();
+    patch.patchedSize=file.readU64();
+
+    var controlCompressed=file.readBytes(controlSize);
+    var diffCompressed=file.readBytes(diffSize);
+    var extraCompressed=file.readBytes(file.fileSize-file.offset);
+
+    var controlFile=new BinFile(bz2.decompress(controlCompressed));
+    controlFile.littleEndian=true;
+    var diffFile=new BinFile(bz2.decompress(diffCompressed));
+    var extraFile=new BinFile(bz2.decompress(extraCompressed));
+
+    while(!controlFile.isEOF()){
+        var diffLen=controlFile.readU64();
+        var extraLen=controlFile.readU64();
+        var skip=controlFile.readU64();
+        if(skip&(1<<63))
+            skip=-(skip&~(1<<63));
+        var diff=diffFile.readBytes(diffLen);
+        var extra=extraFile.readBytes(extraLen);
+        patch.records.push({diff, extra, skip});
+    }
+
+    return patch;
+}