Migrated source code from Simantics SVN

[simantics/platform.git] / bundles / org.simantics.lz4 / src / net / jpountz / lz4 / LZ4Compressor.java

diff --git a/bundles/org.simantics.lz4/src/net/jpountz/lz4/LZ4Compressor.java b/bundles/org.simantics.lz4/src/net/jpountz/lz4/LZ4Compressor.java
new file mode 100644 (file)
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--- /dev/null
+++ b/bundles/org.simantics.lz4/src/net/jpountz/lz4/LZ4Compressor.java
@@ -0,0 +1,126 @@
+package net.jpountz.lz4;
+
+/*
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import java.nio.ByteBuffer;
+import java.util.Arrays;
+
+/**
+ * LZ4 compressor.
+ * <p>
+ * Instances of this class are thread-safe.
+ */
+public abstract class LZ4Compressor {
+
+  /** Return the maximum compressed length for an input of size <code>length</code>. */
+  @SuppressWarnings("static-method")
+  public final int maxCompressedLength(int length) {
+    return LZ4Utils.maxCompressedLength(length);
+  }
+
+  /**
+   * Compress <code>src[srcOff:srcOff+srcLen]</code> into
+   * <code>dest[destOff:destOff+destLen]</code> and return the compressed
+   * length.
+   *
+   * This method will throw a {@link LZ4Exception} if this compressor is unable
+   * to compress the input into less than <code>maxDestLen</code> bytes. To
+   * prevent this exception to be thrown, you should make sure that
+   * <code>maxDestLen >= maxCompressedLength(srcLen)</code>.
+   *
+   * @throws LZ4Exception if maxDestLen is too small
+   * @return the compressed size
+   */
+  public abstract int compress(byte[] src, int srcOff, int srcLen, byte[] dest, int destOff, int maxDestLen);
+
+  /**
+   * Compress <code>src[srcOff:srcOff+srcLen]</code> into
+   * <code>dest[destOff:destOff+destLen]</code> and return the compressed
+   * length.
+   *
+   * This method will throw a {@link LZ4Exception} if this compressor is unable
+   * to compress the input into less than <code>maxDestLen</code> bytes. To
+   * prevent this exception to be thrown, you should make sure that
+   * <code>maxDestLen >= maxCompressedLength(srcLen)</code>.
+   *
+   * {@link ByteBuffer} positions remain unchanged.
+   *
+   * @throws LZ4Exception if maxDestLen is too small
+   * @return the compressed size
+   */
+  public abstract int compress(ByteBuffer src, int srcOff, int srcLen, ByteBuffer dest, int destOff, int maxDestLen);
+
+  /**
+   * Convenience method, equivalent to calling
+   * {@link #compress(byte[], int, int, byte[], int, int) compress(src, srcOff, srcLen, dest, destOff, dest.length - destOff)}.
+   */
+  public final int compress(byte[] src, int srcOff, int srcLen, byte[] dest, int destOff) {
+    return compress(src, srcOff, srcLen, dest, destOff, dest.length - destOff);
+  }
+
+  /**
+   * Convenience method, equivalent to calling
+   * {@link #compress(byte[], int, int, byte[], int) compress(src, 0, src.length, dest, 0)}.
+   */
+  public final int compress(byte[] src, byte[] dest) {
+    return compress(src, 0, src.length, dest, 0);
+  }
+
+  /**
+   * Convenience method which returns <code>src[srcOff:srcOff+srcLen]</code>
+   * compressed.
+   * <p><b><span style="color:red">Warning</span></b>: this method has an
+   * important overhead due to the fact that it needs to allocate a buffer to
+   * compress into, and then needs to resize this buffer to the actual
+   * compressed length.</p>
+   * <p>Here is how this method is implemented:</p>
+   * <pre>
+   * final int maxCompressedLength = maxCompressedLength(srcLen);
+   * final byte[] compressed = new byte[maxCompressedLength];
+   * final int compressedLength = compress(src, srcOff, srcLen, compressed, 0);
+   * return Arrays.copyOf(compressed, compressedLength);
+   * </pre>
+   */
+  public final byte[] compress(byte[] src, int srcOff, int srcLen) {
+    final int maxCompressedLength = maxCompressedLength(srcLen);
+    final byte[] compressed = new byte[maxCompressedLength];
+    final int compressedLength = compress(src, srcOff, srcLen, compressed, 0);
+    return Arrays.copyOf(compressed, compressedLength);
+  }
+
+  /**
+   * Convenience method, equivalent to calling
+   * {@link #compress(byte[], int, int) compress(src, 0, src.length)}.
+   */
+  public final byte[] compress(byte[] src) {
+    return compress(src, 0, src.length);
+  }
+
+  /**
+   * Compress <code>src</code> into <code>dest</code>. Calling this method
+   * will update the positions of both {@link ByteBuffer}s.
+   */
+  public final void compress(ByteBuffer src, ByteBuffer dest) {
+    final int cpLen = compress(src, src.position(), src.remaining(), dest, dest.position(), dest.remaining());
+    src.position(src.limit());
+    dest.position(dest.position() + cpLen);
+  }
+
+  @Override
+  public String toString() {
+    return getClass().getSimpleName();
+  }
+
+}