org.http4s.hpack.HuffmanEncoder.scala Maven / Gradle / Ivy
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/*
* Copyright 2022 http4s.org
*
* 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.
*/
/*
* Copyright 2014 Twitter, Inc.
*
* 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.
*/
package org.http4s.hpack;
import java.io.IOException;
import java.io.OutputStream;
/** Creates a new Huffman encoder with the specified Huffman coding.
* @param codes the Huffman codes indexed by symbol
* @param lengths the length of each Huffman code
*/
private[http4s] final class HuffmanEncoder(codes: Array[Int], lengths: Array[Byte]) {
/** Compresses the input string literal using the Huffman coding.
* @param out the output stream for the compressed data
* @param data the string literal to be Huffman encoded
* @throws IOException if an I/O error occurs.
* @see org.http4s.hpack.HuffmanEncoder#encode(OutputStream, byte[], int, int)
*/
@throws[IOException]
def encode(out: OutputStream, data: Array[Byte]): Unit =
encode(out, data, 0, data.length);
/** Compresses the input string literal using the Huffman coding.
* @param out the output stream for the compressed data
* @param data the string literal to be Huffman encoded
* @param off the start offset in the data
* @param len the number of bytes to encode
* @throws IOException if an I/O error occurs. In particular,
* an IOException may be thrown if the
* output stream has been closed.
*/
@throws[IOException]
def encode(out: OutputStream, data: Array[Byte], off: Int, len: Int): Unit = {
if (out == null) {
throw new NullPointerException("out");
} else if (data == null) {
throw new NullPointerException("data");
} else if (
off < 0 || len < 0 || (off + len) < 0 || off > data.length || (off + len) > data.length
) {
throw new IndexOutOfBoundsException();
} else if (len == 0) {
return;
}
var current = 0L;
var n = 0;
var i = 0
while (i < len) {
val b = data(off + i) & 0xff;
val code = codes(b);
val nbits = lengths(b);
current <<= nbits;
current |= code;
n += nbits;
while (n >= 8) {
n -= 8;
out.write(((current >> n).toInt));
}
i += 1
}
if (n > 0) {
current <<= (8 - n);
current |= (0xff >>> n); // this should be EOS symbol
out.write(current.toInt);
}
}
/** Returns the number of bytes required to Huffman encode the input string literal.
* @param data the string literal to be Huffman encoded
* @return the number of bytes required to Huffman encode data
*/
def getEncodedLength(data: Array[Byte]): Int = {
if (data == null) {
throw new NullPointerException("data");
}
var len = 0L;
var i = 0
while (i < data.length) {
val b = data(i)
len += lengths(b & 0xff);
i += 1
}
return ((len + 7) >> 3).toInt;
}
}