// 
// Decompiled by Procyon v0.6.0
// 

package io.netty.handler.codec.quic;

import java.nio.ByteOrder;
import java.nio.ByteBuffer;
import io.netty.util.internal.ObjectUtil;

final class SipHash
{
    static final int SEED_LENGTH = 16;
    private final int compressionRounds;
    private final int finalizationRounds;
    private static final long INITIAL_STATE_V0 = 8317987319222330741L;
    private static final long INITIAL_STATE_V1 = 7237128888997146477L;
    private static final long INITIAL_STATE_V2 = 7816392313619706465L;
    private static final long INITIAL_STATE_V3 = 8387220255154660723L;
    private final long initialStateV0;
    private final long initialStateV1;
    private final long initialStateV2;
    private final long initialStateV3;
    private long v0;
    private long v1;
    private long v2;
    private long v3;
    
    SipHash(final int compressionRounds, final int finalizationRounds, final byte[] seed) {
        if (seed.length != 16) {
            throw new IllegalArgumentException("seed must be of length 16");
        }
        this.compressionRounds = ObjectUtil.checkPositive(compressionRounds, "compressionRounds");
        this.finalizationRounds = ObjectUtil.checkPositive(finalizationRounds, "finalizationRounds");
        final ByteBuffer keyBuffer = ByteBuffer.wrap(seed).order(ByteOrder.LITTLE_ENDIAN);
        final long k0 = keyBuffer.getLong();
        final long k2 = keyBuffer.getLong();
        this.initialStateV0 = (0x736F6D6570736575L ^ k0);
        this.initialStateV1 = (0x646F72616E646F6DL ^ k2);
        this.initialStateV2 = (0x6C7967656E657261L ^ k0);
        this.initialStateV3 = (0x7465646279746573L ^ k2);
    }
    
    long macHash(final ByteBuffer input) {
        this.v0 = this.initialStateV0;
        this.v1 = this.initialStateV1;
        this.v2 = this.initialStateV2;
        this.v3 = this.initialStateV3;
        final int remaining = input.remaining();
        final int position = input.position();
        final int len = remaining - remaining % 8;
        final boolean needsReverse = input.order() == ByteOrder.BIG_ENDIAN;
        for (int offset = position; offset < len; offset += 8) {
            long m = input.getLong(offset);
            if (needsReverse) {
                m = Long.reverseBytes(m);
            }
            this.v3 ^= m;
            for (int i = 0; i < this.compressionRounds; ++i) {
                this.sipround();
            }
            this.v0 ^= m;
        }
        final int left = remaining & 0x7;
        long b = (long)remaining << 56;
        assert left < 8;
        switch (left) {
            case 7: {
                b |= (long)input.get(position + len + 6) << 48;
            }
            case 6: {
                b |= (long)input.get(position + len + 5) << 40;
            }
            case 5: {
                b |= (long)input.get(position + len + 4) << 32;
            }
            case 4: {
                b |= (long)input.get(position + len + 3) << 24;
            }
            case 3: {
                b |= (long)input.get(position + len + 2) << 16;
            }
            case 2: {
                b |= (long)input.get(position + len + 1) << 8;
            }
            case 1: {
                b |= input.get(position + len);
                break;
            }
            case 0: {
                break;
            }
            default: {
                throw new IllegalStateException("Unexpected value: " + left);
            }
        }
        this.v3 ^= b;
        for (int i = 0; i < this.compressionRounds; ++i) {
            this.sipround();
        }
        this.v0 ^= b;
        this.v2 ^= 0xFFL;
        for (int i = 0; i < this.finalizationRounds; ++i) {
            this.sipround();
        }
        return this.v0 ^ this.v1 ^ this.v2 ^ this.v3;
    }
    
    private void sipround() {
        this.v0 += this.v1;
        this.v2 += this.v3;
        this.v1 = Long.rotateLeft(this.v1, 13);
        this.v3 = Long.rotateLeft(this.v3, 16);
        this.v1 ^= this.v0;
        this.v3 ^= this.v2;
        this.v0 = Long.rotateLeft(this.v0, 32);
        this.v2 += this.v1;
        this.v0 += this.v3;
        this.v1 = Long.rotateLeft(this.v1, 17);
        this.v3 = Long.rotateLeft(this.v3, 21);
        this.v1 ^= this.v2;
        this.v3 ^= this.v0;
        this.v2 = Long.rotateLeft(this.v2, 32);
    }
}