org.brotli.dec.Utils Maven / Gradle / Ivy
/* Copyright 2015 Google Inc. All Rights Reserved.
Distributed under MIT license.
See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
*/
package org.brotli.dec;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.UnsupportedEncodingException;
import java.nio.Buffer;
import java.nio.ByteBuffer;
/**
* A set of utility methods.
*/
final class Utils {
private static final byte[] BYTE_ZEROES = new byte[1024];
private static final int[] INT_ZEROES = new int[1024];
/**
* Fills byte array with zeroes.
*
* Current implementation uses {@link System#arraycopy}, so it should be used for length not
* less than 16.
*
* @param dest array to fill with zeroes
* @param offset the first byte to fill
* @param length number of bytes to change
*/
static void fillBytesWithZeroes(byte[] dest, int start, int end) {
int cursor = start;
while (cursor < end) {
int step = Math.min(cursor + 1024, end) - cursor;
System.arraycopy(BYTE_ZEROES, 0, dest, cursor, step);
cursor += step;
}
}
/**
* Fills int array with zeroes.
*
*
Current implementation uses {@link System#arraycopy}, so it should be used for length not
* less than 16.
*
* @param dest array to fill with zeroes
* @param offset the first item to fill
* @param length number of item to change
*/
static void fillIntsWithZeroes(int[] dest, int start, int end) {
int cursor = start;
while (cursor < end) {
int step = Math.min(cursor + 1024, end) - cursor;
System.arraycopy(INT_ZEROES, 0, dest, cursor, step);
cursor += step;
}
}
static void copyBytes(byte[] dst, int target, byte[] src, int start, int end) {
System.arraycopy(src, start, dst, target, end - start);
}
static void copyBytesWithin(byte[] bytes, int target, int start, int end) {
System.arraycopy(bytes, start, bytes, target, end - start);
}
static int readInput(State s, byte[] dst, int offset, int length) {
try {
return s.input.read(dst, offset, length);
} catch (IOException e) {
throw new BrotliRuntimeException("Failed to read input", e);
}
}
static InputStream makeEmptyInput() {
return new ByteArrayInputStream(new byte[0]);
}
static void closeInput(State s) throws IOException {
s.input.close();
s.input = makeEmptyInput();
}
static byte[] toUsAsciiBytes(String src) {
try {
// NB: String#getBytes(String) is present in JDK 1.1, while other variants require JDK 1.6 and
// above.
return src.getBytes("US-ASCII");
} catch (UnsupportedEncodingException e) {
throw new RuntimeException(e); // cannot happen
}
}
static ByteBuffer asReadOnlyBuffer(ByteBuffer src) {
return src.asReadOnlyBuffer();
}
static int isReadOnly(ByteBuffer src) {
return src.isReadOnly() ? 1 : 0;
}
static int isDirect(ByteBuffer src) {
return src.isDirect() ? 1 : 0;
}
// Crazy pills factory: code compiled for JDK8 does not work on JRE9.
static void flipBuffer(Buffer buffer) {
buffer.flip();
}
static int isDebugMode() {
boolean assertsEnabled = Boolean.parseBoolean(System.getProperty("BROTLI_ENABLE_ASSERTS"));
return assertsEnabled ? 1 : 0;
}
// See BitReader.LOG_BITNESS
static int getLogBintness() {
boolean isLongExpensive = Boolean.parseBoolean(System.getProperty("BROTLI_32_BIT_CPU"));
return isLongExpensive ? 5 : 6;
}
}