zlib-tiny/src-java/CRC32C.java at master · source-c/zlib-tiny · GitHub

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package zlib_tiny;

import java.util.zip.Checksum;

/**

* CRC32C checksum implementation with automatic hardware acceleration.

* <p>

* This class generates a CRC32C checksum as defined by RFC 3720 Section B.4.

* It automatically detects and uses the JDK's hardware-accelerated implementation

* (available in Java 9+) when present, falling back to a portable software

* implementation otherwise.

* <p>

* The hardware-accelerated path uses CPU intrinsics (SSE4.2 on x86, CRC extensions

* on ARM) and can be 30-40x faster than the software implementation for large data.

* <p>

* The software fallback is ported from Google's cloud package (2011) and works

* correctly on all platforms regardless of Java version.

public final class CRC32C implements Checksum {

/**

* Indicates whether the JDK's hardware-accelerated CRC32C is available.

private static final boolean JDK_CRC32C_AVAILABLE;

/**

* The JDK CRC32C class, if available (null otherwise).

private static final Class<?> JDK_CRC32C_CLASS;

static {

Class<?> clazz = null;

boolean available = false;

try {

clazz = Class.forName("java.util.zip.CRC32C");

// Verify we can instantiate it

clazz.getDeclaredConstructor().newInstance();

available = true;

} catch (Exception ignored) {

// JDK CRC32C not available, will use software fallback

}

JDK_CRC32C_CLASS = clazz;

JDK_CRC32C_AVAILABLE = available;

}

/**

* Returns true if the JDK's hardware-accelerated CRC32C is being used.

* Useful for diagnostics and testing.

* @return true if hardware acceleration is available and in use

public static boolean isHardwareAccelerated() {

return JDK_CRC32C_AVAILABLE;

}

// Delegate to JDK implementation when available

private final Checksum delegate;

// Software implementation state (used only when JDK not available)

private long crc;

public CRC32C() {

if (JDK_CRC32C_AVAILABLE) {

try {

delegate = (Checksum) JDK_CRC32C_CLASS.getDeclaredConstructor().newInstance();

} catch (Exception e) {

// Should never happen since we verified in static init

throw new RuntimeException("Failed to instantiate JDK CRC32C", e);

}

crc = 0; // unused but must initialize

} else {

delegate = null;

crc = 0;

}

@Override

public void update(int b) {

if (delegate != null) {

delegate.update(b);

} else {

long newCrc = crc ^ LONG_MASK;

newCrc = updateByte((byte) b, newCrc);

crc = newCrc ^ LONG_MASK;

}

@Override

public void update(byte[] bArray, int off, int len) {

if (delegate != null) {

delegate.update(bArray, off, len);

} else {

updateSoftware(bArray, off, len);

}

/**

* Updates the checksum with the entire byte array.

* Convenience method that delegates to update(byte[], int, int).

* @param bArray the byte array to update with

public void update(byte[] bArray) {

update(bArray, 0, bArray.length);

}

@Override

public long getValue() {

if (delegate != null) {

return delegate.getValue();

}

return crc;

}

@Override

public void reset() {

if (delegate != null) {

delegate.reset();

} else {

crc = 0;

}

// ========== Software Implementation ==========

private static final long[] CRC_TABLE = {

0x00000000L, 0xf26b8303L, 0xe13b70f7L, 0x1350f3f4L,

0xc79a971fL, 0x35f1141cL, 0x26a1e7e8L, 0xd4ca64ebL,

0x8ad958cfL, 0x78b2dbccL, 0x6be22838L, 0x9989ab3bL,

0x4d43cfd0L, 0xbf284cd3L, 0xac78bf27L, 0x5e133c24L,

0x105ec76fL, 0xe235446cL, 0xf165b798L, 0x030e349bL,

0xd7c45070L, 0x25afd373L, 0x36ff2087L, 0xc494a384L,

0x9a879fa0L, 0x68ec1ca3L, 0x7bbcef57L, 0x89d76c54L,

0x5d1d08bfL, 0xaf768bbcL, 0xbc267848L, 0x4e4dfb4bL,

0x20bd8edeL, 0xd2d60dddL, 0xc186fe29L, 0x33ed7d2aL,

0xe72719c1L, 0x154c9ac2L, 0x061c6936L, 0xf477ea35L,

0xaa64d611L, 0x580f5512L, 0x4b5fa6e6L, 0xb93425e5L,

0x6dfe410eL, 0x9f95c20dL, 0x8cc531f9L, 0x7eaeb2faL,

0x30e349b1L, 0xc288cab2L, 0xd1d83946L, 0x23b3ba45L,

0xf779deaeL, 0x05125dadL, 0x1642ae59L, 0xe4292d5aL,

0xba3a117eL, 0x4851927dL, 0x5b016189L, 0xa96ae28aL,

0x7da08661L, 0x8fcb0562L, 0x9c9bf696L, 0x6ef07595L,

0x417b1dbcL, 0xb3109ebfL, 0xa0406d4bL, 0x522bee48L,

0x86e18aa3L, 0x748a09a0L, 0x67dafa54L, 0x95b17957L,

0xcba24573L, 0x39c9c670L, 0x2a993584L, 0xd8f2b687L,

0x0c38d26cL, 0xfe53516fL, 0xed03a29bL, 0x1f682198L,

0x5125dad3L, 0xa34e59d0L, 0xb01eaa24L, 0x42752927L,

0x96bf4dccL, 0x64d4cecfL, 0x77843d3bL, 0x85efbe38L,

0xdbfc821cL, 0x2997011fL, 0x3ac7f2ebL, 0xc8ac71e8L,

0x1c661503L, 0xee0d9600L, 0xfd5d65f4L, 0x0f36e6f7L,

0x61c69362L, 0x93ad1061L, 0x80fde395L, 0x72966096L,

0xa65c047dL, 0x5437877eL, 0x4767748aL, 0xb50cf789L,

0xeb1fcbadL, 0x197448aeL, 0x0a24bb5aL, 0xf84f3859L,

0x2c855cb2L, 0xdeeedfb1L, 0xcdbe2c45L, 0x3fd5af46L,

0x7198540dL, 0x83f3d70eL, 0x90a324faL, 0x62c8a7f9L,

0xb602c312L, 0x44694011L, 0x5739b3e5L, 0xa55230e6L,

0xfb410cc2L, 0x092a8fc1L, 0x1a7a7c35L, 0xe811ff36L,

0x3cdb9bddL, 0xceb018deL, 0xdde0eb2aL, 0x2f8b6829L,

0x82f63b78L, 0x709db87bL, 0x63cd4b8fL, 0x91a6c88cL,

0x456cac67L, 0xb7072f64L, 0xa457dc90L, 0x563c5f93L,

0x082f63b7L, 0xfa44e0b4L, 0xe9141340L, 0x1b7f9043L,

0xcfb5f4a8L, 0x3dde77abL, 0x2e8e845fL, 0xdce5075cL,

0x92a8fc17L, 0x60c37f14L, 0x73938ce0L, 0x81f80fe3L,

0x55326b08L, 0xa759e80bL, 0xb4091bffL, 0x466298fcL,

0x1871a4d8L, 0xea1a27dbL, 0xf94ad42fL, 0x0b21572cL,

0xdfeb33c7L, 0x2d80b0c4L, 0x3ed04330L, 0xccbbc033L,

0xa24bb5a6L, 0x502036a5L, 0x4370c551L, 0xb11b4652L,

0x65d122b9L, 0x97baa1baL, 0x84ea524eL, 0x7681d14dL,

0x2892ed69L, 0xdaf96e6aL, 0xc9a99d9eL, 0x3bc21e9dL,

0xef087a76L, 0x1d63f975L, 0x0e330a81L, 0xfc588982L,

0xb21572c9L, 0x407ef1caL, 0x532e023eL, 0xa145813dL,

0x758fe5d6L, 0x87e466d5L, 0x94b49521L, 0x66df1622L,

0x38cc2a06L, 0xcaa7a905L, 0xd9f75af1L, 0x2b9cd9f2L,

0xff56bd19L, 0x0d3d3e1aL, 0x1e6dcdeeL, 0xec064eedL,

0xc38d26c4L, 0x31e6a5c7L, 0x22b65633L, 0xd0ddd530L,

0x0417b1dbL, 0xf67c32d8L, 0xe52cc12cL, 0x1747422fL,

0x49547e0bL, 0xbb3ffd08L, 0xa86f0efcL, 0x5a048dffL,

0x8ecee914L, 0x7ca56a17L, 0x6ff599e3L, 0x9d9e1ae0L,

0xd3d3e1abL, 0x21b862a8L, 0x32e8915cL, 0xc083125fL,

0x144976b4L, 0xe622f5b7L, 0xf5720643L, 0x07198540L,

0x590ab964L, 0xab613a67L, 0xb831c993L, 0x4a5a4a90L,

0x9e902e7bL, 0x6cfbad78L, 0x7fab5e8cL, 0x8dc0dd8fL,

0xe330a81aL, 0x115b2b19L, 0x020bd8edL, 0xf0605beeL,

0x24aa3f05L, 0xd6c1bc06L, 0xc5914ff2L, 0x37faccf1L,

0x69e9f0d5L, 0x9b8273d6L, 0x88d28022L, 0x7ab90321L,

0xae7367caL, 0x5c18e4c9L, 0x4f48173dL, 0xbd23943eL,

0xf36e6f75L, 0x0105ec76L, 0x12551f82L, 0xe03e9c81L,

0x34f4f86aL, 0xc69f7b69L, 0xd5cf889dL, 0x27a40b9eL,

0x79b737baL, 0x8bdcb4b9L, 0x988c474dL, 0x6ae7c44eL,

0xbe2da0a5L, 0x4c4623a6L, 0x5f16d052L, 0xad7d5351L

};

private static final long LONG_MASK = 0xffffffffL;

private static final long BYTE_MASK = 0xffL;

private void updateSoftware(byte[] bArray, int off, int len) {

long newCrc = crc ^ LONG_MASK;

int end = off + len;

// Process 8 bytes at a time for better performance

int fastEnd = end - 7;

int i = off;

while (i < fastEnd) {

newCrc = updateByte(bArray[i], newCrc);

newCrc = updateByte(bArray[i + 1], newCrc);

newCrc = updateByte(bArray[i + 2], newCrc);

newCrc = updateByte(bArray[i + 3], newCrc);

newCrc = updateByte(bArray[i + 4], newCrc);

newCrc = updateByte(bArray[i + 5], newCrc);

newCrc = updateByte(bArray[i + 6], newCrc);

newCrc = updateByte(bArray[i + 7], newCrc);

i += 8;

}

// Process remaining bytes

while (i < end) {

newCrc = updateByte(bArray[i], newCrc);

i++;

}

crc = newCrc ^ LONG_MASK;

}

private static long updateByte(byte newByte, long crc) {

int index = (int) ((crc ^ newByte) & BYTE_MASK);

return (CRC_TABLE[index] ^ (crc >>> 8)) & LONG_MASK;

}

zlib-tiny/src-java/CRC32C.java at master · source-c/zlib-tiny · GitHub

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