InfBlocks.cs

// Copyright (c) 2006, ComponentAce
// http://www.componentace.com
// All rights reserved.

// Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

// Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 
// Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. 
// Neither the name of ComponentAce nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission. 
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

/*
Copyright (c) 2000,2001,2002,2003 ymnk, JCraft,Inc. All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice,
this list of conditions and the following disclaimer.

2. Redistributions in binary form must reproduce the above copyright 
notice, this list of conditions and the following disclaimer in 
the documentation and/or other materials provided with the distribution.

3. The names of the authors may not be used to endorse or promote products
derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES,
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL JCRAFT,
INC. OR ANY CONTRIBUTORS TO THIS SOFTWARE BE LIABLE FOR ANY DIRECT, INDIRECT,
INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*
* This program is based on zlib-1.1.3, so all credit should go authors
* Jean-loup Gailly(jloup@gzip.org) and Mark Adler(madler@alumni.caltech.edu)
* and contributors of zlib.
*/
namespace ComponentAce.ZlibNet;

sealed class InfBlocks
{
    private const int MANY = 1440;

    // And'ing with mask[n] masks the lower n bits		
    private static readonly int[] inflate_mask = new int[] { 0x00000000, 0x00000001, 0x00000003, 0x00000007, 0x0000000f, 0x0000001f, 0x0000003f, 0x0000007f, 0x000000ff, 0x000001ff, 0x000003ff, 0x000007ff, 0x00000fff, 0x00001fff, 0x00003fff, 0x00007fff, 0x0000ffff };

    // Table for deflate from PKZIP's appnote.txt.		
    internal static readonly int[] border = new int[] { 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15 };

    private const int Z_OK = 0;
    private const int Z_STREAM_END = 1;
    private const int Z_NEED_DICT = 2;
    private const int Z_ERRNO = -1;
    private const int Z_STREAM_ERROR = -2;
    private const int Z_DATA_ERROR = -3;
    private const int Z_MEM_ERROR = -4;
    private const int Z_BUF_ERROR = -5;
    private const int Z_VERSION_ERROR = -6;

    private const int TYPE = 0; // get type bits (3, including end bit)
    private const int LENS = 1; // get lengths for stored
    private const int STORED = 2; // processing stored block
    private const int TABLE = 3; // get table lengths
    private const int BTREE = 4; // get bit lengths tree for a dynamic block
    private const int DTREE = 5; // get length, distance trees for a dynamic block
    private const int CODES = 6; // processing fixed or dynamic block
    private const int DRY = 7; // output remaining window bytes
    private const int DONE = 8; // finished last block, done
    private const int BAD = 9; // ot a data error--stuck here

    internal int mode; // current inflate_block mode 

    internal int left; // if STORED, bytes left to copy 

    internal int table; // table lengths (14 bits) 
    internal int index; // index into blens (or border) 
    internal int[] blens; // bit lengths of codes 
    internal int[] bb = new int[1]; // bit length tree depth 
    internal int[] tb = new int[1]; // bit length decoding tree 

    internal InfCodes codes; // if CODES, current state 

    internal int last; // true if this block is the last block 

    // mode independent information 
    internal int bitk; // bits in bit buffer 
    internal int bitb; // bit buffer 
    internal int[] hufts; // single malloc for tree space 
    internal byte[] window; // sliding window 
    internal int end; // one byte after sliding window 
    internal int read; // window read pointer 
    internal int write; // window write pointer 
    internal object checkfn; // check function 
    internal long check; // check on output 

    internal InfBlocks(ZStream z, object checkfn, int w)
    {
        hufts = new int[MANY * 3];
        window = new byte[w];
        end = w;
        this.checkfn = checkfn;
        mode = TYPE;
        reset(z, null);
    }

    internal void reset(ZStream z, long[] c)
    {
        if (c != null)
            c[0] = check;
        if (mode == BTREE || mode == DTREE)
        {
            blens = null;
        }
        if (mode == CODES)
        {
            codes.free(z);
        }
        mode = TYPE;
        bitk = 0;
        bitb = 0;
        read = write = 0;

        if (checkfn != null)
            z.adler = check = z._adler.adler32(0L, null, 0, 0);
    }

    internal int proc(ZStream z, int r)
    {
        int t; // temporary storage
        int b; // bit buffer
        int k; // bits in bit buffer
        int p; // input data pointer
        int n; // bytes available there
        int q; // output window write pointer
        int m; // bytes to end of window or read pointer

        // copy input/output information to locals (UPDATE macro restores)
        {
            p = z.next_in_index; n = z.avail_in; b = bitb; k = bitk;
        }
        {
            q = write; m = q < read ? read - q - 1 : end - q;
        }

        // process input based on current state
        while (true)
        {
            switch (mode)
            {

                case TYPE:

                    while (k < 3)
                    {
                        if (n != 0)
                        {
                            r = Z_OK;
                        }
                        else
                        {
                            bitb = b; bitk = k;
                            z.avail_in = n;
                            z.total_in += p - z.next_in_index; z.next_in_index = p;
                            write = q;
                            return inflate_flush(z, r);
                        }
                        ;
                        n--;
                        b |= (z.next_in[p++] & 0xff) << k;
                        k += 8;
                    }
                    t = b & 7;
                    last = t & 1;

                    switch (SupportClass.URShift(t, 1))
                    {

                        case 0:  // stored 
                            {
                                b = SupportClass.URShift(b, 3); k -= 3;
                            }
                            t = k & 7; // go to byte boundary

                            {
                                b = SupportClass.URShift(b, t); k -= t;
                            }
                            mode = LENS; // get length of stored block
                            break;

                        case 1:  // fixed
                            {
                                int[] bl = new int[1];
                                int[] bd = new int[1];
                                int[][] tl = new int[1][];
                                int[][] td = new int[1][];

                                InfTree.inflate_trees_fixed(bl, bd, tl, td, z);
                                codes = new InfCodes(bl[0], bd[0], tl[0], td[0], z);
                            }

                            {
                                b = SupportClass.URShift(b, 3); k -= 3;
                            }

                            mode = CODES;
                            break;

                        case 2:  // dynamic

                            {
                                b = SupportClass.URShift(b, 3); k -= 3;
                            }

                            mode = TABLE;
                            break;

                        case 3:  // illegal

                            {
                                b = SupportClass.URShift(b, 3); k -= 3;
                            }
                            mode = BAD;
                            z.msg = "invalid block type";
                            r = Z_DATA_ERROR;

                            bitb = b; bitk = k;
                            z.avail_in = n; z.total_in += p - z.next_in_index; z.next_in_index = p;
                            write = q;
                            return inflate_flush(z, r);
                    }
                    break;

                case LENS:

                    while (k < 32)
                    {
                        if (n != 0)
                        {
                            r = Z_OK;
                        }
                        else
                        {
                            bitb = b; bitk = k;
                            z.avail_in = n;
                            z.total_in += p - z.next_in_index; z.next_in_index = p;
                            write = q;
                            return inflate_flush(z, r);
                        }
                        ;
                        n--;
                        b |= (z.next_in[p++] & 0xff) << k;
                        k += 8;
                    }

                    if ((SupportClass.URShift(~b, 16) & 0xffff) != (b & 0xffff))
                    {
                        mode = BAD;
                        z.msg = "invalid stored block lengths";
                        r = Z_DATA_ERROR;

                        bitb = b; bitk = k;
                        z.avail_in = n; z.total_in += p - z.next_in_index; z.next_in_index = p;
                        write = q;
                        return inflate_flush(z, r);
                    }
                    left = b & 0xffff;
                    b = k = 0; // dump bits
                    mode = left != 0 ? STORED : last != 0 ? DRY : TYPE;
                    break;

                case STORED:
                    if (n == 0)
                    {
                        bitb = b; bitk = k;
                        z.avail_in = n; z.total_in += p - z.next_in_index; z.next_in_index = p;
                        write = q;
                        return inflate_flush(z, r);
                    }

                    if (m == 0)
                    {
                        if (q == end && read != 0)
                        {
                            q = 0; m = q < read ? read - q - 1 : end - q;
                        }
                        if (m == 0)
                        {
                            write = q;
                            r = inflate_flush(z, r);
                            q = write; m = q < read ? read - q - 1 : end - q;
                            if (q == end && read != 0)
                            {
                                q = 0; m = q < read ? read - q - 1 : end - q;
                            }
                            if (m == 0)
                            {
                                bitb = b; bitk = k;
                                z.avail_in = n; z.total_in += p - z.next_in_index; z.next_in_index = p;
                                write = q;
                                return inflate_flush(z, r);
                            }
                        }
                    }
                    r = Z_OK;

                    t = left;
                    if (t > n)
                        t = n;
                    if (t > m)
                        t = m;
                    Array.Copy(z.next_in, p, window, q, t);
                    p += t; n -= t;
                    q += t; m -= t;
                    if ((left -= t) != 0)
                        break;
                    mode = last != 0 ? DRY : TYPE;
                    break;

                case TABLE:

                    while (k < 14)
                    {
                        if (n != 0)
                        {
                            r = Z_OK;
                        }
                        else
                        {
                            bitb = b; bitk = k;
                            z.avail_in = n;
                            z.total_in += p - z.next_in_index; z.next_in_index = p;
                            write = q;
                            return inflate_flush(z, r);
                        }
                        ;
                        n--;
                        b |= (z.next_in[p++] & 0xff) << k;
                        k += 8;
                    }

                    table = t = b & 0x3fff;
                    if ((t & 0x1f) > 29 || (t >> 5 & 0x1f) > 29)
                    {
                        mode = BAD;
                        z.msg = "too many length or distance symbols";
                        r = Z_DATA_ERROR;

                        bitb = b; bitk = k;
                        z.avail_in = n; z.total_in += p - z.next_in_index; z.next_in_index = p;
                        write = q;
                        return inflate_flush(z, r);
                    }
                    t = 258 + (t & 0x1f) + (t >> 5 & 0x1f);
                    blens = new int[t];

                    {
                        b = SupportClass.URShift(b, 14); k -= 14;
                    }

                    index = 0;
                    mode = BTREE;
                    goto case BTREE;

                case BTREE:
                    while (index < 4 + SupportClass.URShift(table, 10))
                    {
                        while (k < 3)
                        {
                            if (n != 0)
                            {
                                r = Z_OK;
                            }
                            else
                            {
                                bitb = b; bitk = k;
                                z.avail_in = n;
                                z.total_in += p - z.next_in_index; z.next_in_index = p;
                                write = q;
                                return inflate_flush(z, r);
                            }
                            ;
                            n--;
                            b |= (z.next_in[p++] & 0xff) << k;
                            k += 8;
                        }

                        blens[border[index++]] = b & 7;

                        {
                            b = SupportClass.URShift(b, 3); k -= 3;
                        }
                    }

                    while (index < 19)
                    {
                        blens[border[index++]] = 0;
                    }

                    bb[0] = 7;
                    t = InfTree.inflate_trees_bits(blens, bb, tb, hufts, z);
                    if (t != Z_OK)
                    {
                        r = t;
                        if (r == Z_DATA_ERROR)
                        {
                            blens = null;
                            mode = BAD;
                        }

                        bitb = b; bitk = k;
                        z.avail_in = n; z.total_in += p - z.next_in_index; z.next_in_index = p;
                        write = q;
                        return inflate_flush(z, r);
                    }

                    index = 0;
                    mode = DTREE;
                    goto case DTREE;

                case DTREE:
                    while (true)
                    {
                        t = table;
                        if (!(index < 258 + (t & 0x1f) + (t >> 5 & 0x1f)))
                        {
                            break;
                        }


                        int i, j, c;

                        t = bb[0];

                        while (k < t)
                        {
                            if (n != 0)
                            {
                                r = Z_OK;
                            }
                            else
                            {
                                bitb = b; bitk = k;
                                z.avail_in = n;
                                z.total_in += p - z.next_in_index; z.next_in_index = p;
                                write = q;
                                return inflate_flush(z, r);
                            }
                            ;
                            n--;
                            b |= (z.next_in[p++] & 0xff) << k;
                            k += 8;
                        }

                        if (tb[0] == -1)
                        {
                            //System.err.println("null...");
                        }

                        t = hufts[(tb[0] + (b & inflate_mask[t])) * 3 + 1];
                        c = hufts[(tb[0] + (b & inflate_mask[t])) * 3 + 2];

                        if (c < 16)
                        {
                            b = SupportClass.URShift(b, t); k -= t;
                            blens[index++] = c;
                        }
                        else
                        {
                            // c == 16..18
                            i = c == 18 ? 7 : c - 14;
                            j = c == 18 ? 11 : 3;

                            while (k < t + i)
                            {
                                if (n != 0)
                                {
                                    r = Z_OK;
                                }
                                else
                                {
                                    bitb = b; bitk = k;
                                    z.avail_in = n;
                                    z.total_in += p - z.next_in_index; z.next_in_index = p;
                                    write = q;
                                    return inflate_flush(z, r);
                                }
                                ;
                                n--;
                                b |= (z.next_in[p++] & 0xff) << k;
                                k += 8;
                            }

                            b = SupportClass.URShift(b, t); k -= t;

                            j += b & inflate_mask[i];

                            b = SupportClass.URShift(b, i); k -= i;

                            i = index;
                            t = table;
                            if (i + j > 258 + (t & 0x1f) + (t >> 5 & 0x1f) || c == 16 && i < 1)
                            {
                                blens = null;
                                mode = BAD;
                                z.msg = "invalid bit length repeat";
                                r = Z_DATA_ERROR;

                                bitb = b; bitk = k;
                                z.avail_in = n; z.total_in += p - z.next_in_index; z.next_in_index = p;
                                write = q;
                                return inflate_flush(z, r);
                            }

                            c = c == 16 ? blens[i - 1] : 0;
                            do
                            {
                                blens[i++] = c;
                            }
                            while (--j != 0);
                            index = i;
                        }
                    }

                    tb[0] = -1;
                    {
                        int[] bl = new int[1];
                        int[] bd = new int[1];
                        int[] tl = new int[1];
                        int[] td = new int[1];


                        bl[0] = 9; // must be <= 9 for lookahead assumptions
                        bd[0] = 6; // must be <= 9 for lookahead assumptions
                        t = table;
                        t = InfTree.inflate_trees_dynamic(257 + (t & 0x1f), 1 + (t >> 5 & 0x1f), blens, bl, bd, tl, td, hufts, z);
                        if (t != Z_OK)
                        {
                            if (t == Z_DATA_ERROR)
                            {
                                blens = null;
                                mode = BAD;
                            }
                            r = t;

                            bitb = b; bitk = k;
                            z.avail_in = n; z.total_in += p - z.next_in_index; z.next_in_index = p;
                            write = q;
                            return inflate_flush(z, r);
                        }

                        codes = new InfCodes(bl[0], bd[0], hufts, tl[0], hufts, td[0], z);
                    }
                    blens = null;
                    mode = CODES;
                    goto case CODES;

                case CODES:
                    bitb = b; bitk = k;
                    z.avail_in = n; z.total_in += p - z.next_in_index; z.next_in_index = p;
                    write = q;

                    if ((r = codes.proc(this, z, r)) != Z_STREAM_END)
                    {
                        return inflate_flush(z, r);
                    }
                    r = Z_OK;
                    codes.free(z);

                    p = z.next_in_index; n = z.avail_in; b = bitb; k = bitk;
                    q = write; m = q < read ? read - q - 1 : end - q;

                    if (last == 0)
                    {
                        mode = TYPE;
                        break;
                    }
                    mode = DRY;
                    goto case DRY;

                case DRY:
                    write = q;
                    r = inflate_flush(z, r);
                    q = write; m = q < read ? read - q - 1 : end - q;
                    if (read != write)
                    {
                        bitb = b; bitk = k;
                        z.avail_in = n; z.total_in += p - z.next_in_index; z.next_in_index = p;
                        write = q;
                        return inflate_flush(z, r);
                    }
                    mode = DONE;
                    goto case DONE;

                case DONE:
                    r = Z_STREAM_END;

                    bitb = b; bitk = k;
                    z.avail_in = n; z.total_in += p - z.next_in_index; z.next_in_index = p;
                    write = q;
                    return inflate_flush(z, r);

                case BAD:
                    r = Z_DATA_ERROR;

                    bitb = b; bitk = k;
                    z.avail_in = n; z.total_in += p - z.next_in_index; z.next_in_index = p;
                    write = q;
                    return inflate_flush(z, r);


                default:
                    r = Z_STREAM_ERROR;

                    bitb = b; bitk = k;
                    z.avail_in = n; z.total_in += p - z.next_in_index; z.next_in_index = p;
                    write = q;
                    return inflate_flush(z, r);

            }
        }
    }

    internal void free(ZStream z)
    {
        reset(z, null);
        window = null;
        hufts = null;
        //ZFREE(z, s);
    }

    internal void set_dictionary(byte[] d, int start, int n)
    {
        Array.Copy(d, start, window, 0, n);
        read = write = n;
    }

    // Returns true if inflate is currently at the end of a block generated
    // by Z_SYNC_FLUSH or Z_FULL_FLUSH. 
    internal int sync_point()
    {
        return mode == LENS ? 1 : 0;
    }

    // copy as much as possible from the sliding window to the output area
    internal int inflate_flush(ZStream z, int r)
    {
        int n;
        int p;
        int q;

        // local copies of source and destination pointers
        p = z.next_out_index;
        q = read;

        // compute number of bytes to copy as far as end of window
        n = (q <= write ? write : end) - q;
        if (n > z.avail_out)
            n = z.avail_out;
        if (n != 0 && r == Z_BUF_ERROR)
            r = Z_OK;

        // update counters
        z.avail_out -= n;
        z.total_out += n;

        // update check information
        if (checkfn != null)
            z.adler = check = z._adler.adler32(check, window, q, n);

        // copy as far as end of window
        Array.Copy(window, q, z.next_out, p, n);
        p += n;
        q += n;

        // see if more to copy at beginning of window
        if (q == end)
        {
            // wrap pointers
            q = 0;
            if (write == end)
                write = 0;

            // compute bytes to copy
            n = write - q;
            if (n > z.avail_out)
                n = z.avail_out;
            if (n != 0 && r == Z_BUF_ERROR)
                r = Z_OK;

            // update counters
            z.avail_out -= n;
            z.total_out += n;

            // update check information
            if (checkfn != null)
                z.adler = check = z._adler.adler32(check, window, q, n);

            // copy
            Array.Copy(window, q, z.next_out, p, n);
            p += n;
            q += n;
        }

        // update pointers
        z.next_out_index = p;
        read = q;

        // done
        return r;
    }
}