Paper/src/main/java/net/minecraft/server/ChunkSection.java

package net.minecraft.server;

public class ChunkSection {

    private int a;
    private int b;
    private int c;
    private byte[] d;
    private NibbleArray e;
    private NibbleArray f;
    private NibbleArray g;
    private NibbleArray h;

    public ChunkSection(int i) {
        this.a = i;
        this.d = new byte[4096];
        this.f = new NibbleArray(this.d.length, 4);
        this.h = new NibbleArray(this.d.length, 4);
        this.g = new NibbleArray(this.d.length, 4);
    }

    // CraftBukkit start
    public ChunkSection(int y, byte[] blkData, byte[] extBlkData) {
        this.a = y;
        this.d = blkData;
        if (extBlkData != null) {
            this.e = new NibbleArray(extBlkData, 4);
        }
        this.f = new NibbleArray(this.d.length, 4);
        this.h = new NibbleArray(this.d.length, 4);
        this.g = new NibbleArray(this.d.length, 4);
        this.e();
    }
    // CraftBukkit end

    public int a(int i, int j, int k) {
        int l = this.d[j << 8 | k << 4 | i] & 255;

        return this.e != null ? this.e.a(i, j, k) << 8 | l : l;
    }

    public void a(int i, int j, int k, int l) {
        int i1 = this.d[j << 8 | k << 4 | i] & 255;

        if (this.e != null) {
            i1 |= this.e.a(i, j, k) << 8;
        }

        if (i1 == 0 && l != 0) {
            ++this.b;
            if (Block.byId[l] != null && Block.byId[l].r()) {
                ++this.c;
            }
        } else if (i1 != 0 && l == 0) {
            --this.b;
            if (Block.byId[i1] != null && Block.byId[i1].r()) {
                --this.c;
            }
        } else if (Block.byId[i1] != null && Block.byId[i1].r() && (Block.byId[l] == null || !Block.byId[l].r())) {
            --this.c;
        } else if ((Block.byId[i1] == null || !Block.byId[i1].r()) && Block.byId[l] != null && Block.byId[l].r()) {
            ++this.c;
        }

        this.d[j << 8 | k << 4 | i] = (byte) (l & 255);
        if (l > 255) {
            if (this.e == null) {
                this.e = new NibbleArray(this.d.length, 4);
            }

            this.e.a(i, j, k, (l & 3840) >> 8);
        } else if (this.e != null) {
            this.e.a(i, j, k, 0);
        }
    }

    public int b(int i, int j, int k) {
        return this.f.a(i, j, k);
    }

    public void b(int i, int j, int k, int l) {
        this.f.a(i, j, k, l);
    }

    public boolean a() {
        return this.b == 0;
    }

    public boolean b() {
        return this.c > 0;
    }

    public int d() {
        return this.a;
    }

    public void c(int i, int j, int k, int l) {
        this.h.a(i, j, k, l);
    }

    public int c(int i, int j, int k) {
        return this.h.a(i, j, k);
    }

    public void d(int i, int j, int k, int l) {
        this.g.a(i, j, k, l);
    }

    public int d(int i, int j, int k) {
        return this.g.a(i, j, k);
    }

    public void e() {
        // CraftBukkit start - optimize for speed
        byte[] dd = this.d;
        int cntb = 0;
        int cntc = 0;
        if (this.e == null) { // No extended block IDs?  Don't waste time messing with them
            for (int off = 0; off < dd.length; off++) {
                int l = dd[off] & 0xFF;
                if (l > 0) {
                    if (Block.byId[l] == null) {
                        dd[off] = 0;
                    } else {
                        ++cntb;
                        if (Block.byId[l].r()) {
                            ++cntc;
                        }
                    }
                }
            }
        } else {
            byte[] ext = this.e.a;
            for (int off = 0, off2 = 0; off < dd.length;) {
                byte extid = ext[off2];
                int l = (dd[off] & 0xFF) | ((extid & 0xF) << 8); // Even data
                if (l > 0) {
                    if (Block.byId[l] == null) {
                        dd[off] = 0;
                        ext[off2] &= 0xF0;
                    } else {
                        ++cntb;
                        if (Block.byId[l].r()) {
                            ++cntc;
                        }
                    }
                }
                off++;
                l = (dd[off] & 0xFF) | ((extid & 0xF0) << 4); // Odd data
                if (l > 0) {
                    if (Block.byId[l] == null) {
                        dd[off] = 0;
                        ext[off2] &= 0x0F;
                    } else {
                        ++cntb;
                        if (Block.byId[l].r()) {
                            ++cntc;
                        }
                    }
                }
                off++;
                off2++;
            }
        }
        this.b = cntb;
        this.c = cntc;
    }
    
    private void old_e() {
        // CraftBukkit end
        this.b = 0;
        this.c = 0;

        for (int i = 0; i < 16; ++i) {
            for (int j = 0; j < 16; ++j) {
                for (int k = 0; k < 16; ++k) {
                    int l = this.a(i, j, k);

                    if (l > 0) {
                        if (Block.byId[l] == null) {
                            this.d[j << 8 | k << 4 | i] = 0;
                            if (this.e != null) {
                                this.e.a(i, j, k, 0);
                            }
                        } else {
                            ++this.b;
                            if (Block.byId[l].r()) {
                                ++this.c;
                            }
                        }
                    }
                }
            }
        }
    }

    public byte[] g() {
        return this.d;
    }

    public NibbleArray i() {
        return this.e;
    }

    public NibbleArray j() {
        return this.f;
    }

    public NibbleArray k() {
        return this.g;
    }

    public NibbleArray l() {
        return this.h;
    }

    public void a(byte[] abyte) {
        this.d = abyte;
    }

    public void a(NibbleArray nibblearray) {
        this.e = nibblearray;
    }

    public void b(NibbleArray nibblearray) {
        this.f = nibblearray;
    }

    public void c(NibbleArray nibblearray) {
        this.g = nibblearray;
    }

    public void d(NibbleArray nibblearray) {
        this.h = nibblearray;
    }
}