/*
 * Copyright 2009 Red Hat, Inc.
 *
 * Red Hat licenses this file to you under the Apache License, version 2.0
 * (the "License"); you may not use this file except in compliance with the
 * License.  You may obtain a copy of the License at:
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */
/*
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.
 */

package org.jboss.netty.util.internal.jzlib;

final class InfCodes {

    private static final int[] inflate_mask = { 0x00000000, 0x00000001,
            0x00000003, 0x00000007, 0x0000000f, 0x0000001f, 0x0000003f,
            0x0000007f, 0x000000ff, 0x000001ff, 0x000003ff, 0x000007ff,
            0x00000fff, 0x00001fff, 0x00003fff, 0x00007fff, 0x0000ffff };

    // waiting for "i:"=input,
    //             "o:"=output,
    //             "x:"=nothing
    private static final int START = 0;   // x: set up for LEN
    private static final int LEN = 1;     // i: get length/literal/eob next
    private static final int LENEXT = 2;  // i: getting length extra (have base)
    private static final int DIST = 3;    // i: get distance next
    private static final int DISTEXT = 4; // i: getting distance extra
    private static final int COPY = 5;    // o: copying bytes in window, waiting for space
    private static final int LIT = 6;     // o: got literal, waiting for output space
    private static final int WASH = 7;    // o: got eob, possibly still output waiting
    private static final int END = 8;     // x: got eob and all data flushed
    private static final int BADCODE = 9; // x: got error
    private int mode; // current inflate_codes mode
    // mode dependent information
    private int len;
    private int[] tree; // pointer into tree
    private int tree_index = 0;
    private int need; // bits needed
    private int lit;
    // if EXT or COPY, where and how much
    private int get; // bits to get for extra
    private int dist; // distance back to copy from
    private byte lbits; // ltree bits decoded per branch
    private byte dbits; // dtree bits decoder per branch
    private int[] ltree; // literal/length/eob tree
    private int ltree_index; // literal/length/eob tree
    private int[] dtree; // distance tree
    private int dtree_index; // distance tree

    InfCodes() {
        super();
    }

    void init(int bl, int bd, int[] tl, int tl_index, int[] td, int td_index) {
        mode = START;
        lbits = (byte) bl;
        dbits = (byte) bd;
        ltree = tl;
        ltree_index = tl_index;
        dtree = td;
        dtree_index = td_index;
        tree = null;
    }

    int proc(InfBlocks s, ZStream z, int r) {
        int j; // temporary storage
        int tindex; // temporary pointer
        int e; // extra bits or operation
        int b = 0; // bit buffer
        int k = 0; // bits in bit buffer
        int p = 0; // input data pointer
        int n; // bytes available there
        int q; // output window write pointer
        int m; // bytes to end of window or read pointer
        int f; // pointer to copy strings from

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

        // process input and output based on current state
        while (true) {
            switch (mode) {
            // waiting for "i:"=input, "o:"=output, "x:"=nothing
            case START: // x: set up for LEN
                if (m >= 258 && n >= 10) {

                    s.bitb = b;
                    s.bitk = k;
                    z.avail_in = n;
                    z.total_in += p - z.next_in_index;
                    z.next_in_index = p;
                    s.write = q;
                    r = inflate_fast(lbits, dbits, ltree, ltree_index, dtree,
                            dtree_index, s, z);

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

                    if (r != JZlib.Z_OK) {
                        mode = r == JZlib.Z_STREAM_END? WASH : BADCODE;
                        break;
                    }
                }
                need = lbits;
                tree = ltree;
                tree_index = ltree_index;

                mode = LEN;
            case LEN: // i: get length/literal/eob next
                j = need;

                while (k < j) {
                    if (n != 0) {
                        r = JZlib.Z_OK;
                    } else {

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

                tindex = (tree_index + (b & inflate_mask[j])) * 3;

                b >>>= tree[tindex + 1];
                k -= tree[tindex + 1];

                e = tree[tindex];

                if (e == 0) { // literal
                    lit = tree[tindex + 2];
                    mode = LIT;
                    break;
                }
                if ((e & 16) != 0) { // length
                    get = e & 15;
                    len = tree[tindex + 2];
                    mode = LENEXT;
                    break;
                }
                if ((e & 64) == 0) { // next table
                    need = e;
                    tree_index = tindex / 3 + tree[tindex + 2];
                    break;
                }
                if ((e & 32) != 0) { // end of block
                    mode = WASH;
                    break;
                }
                mode = BADCODE; // invalid code
                z.msg = "invalid literal/length code";
                r = JZlib.Z_DATA_ERROR;

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

            case LENEXT: // i: getting length extra (have base)
                j = get;

                while (k < j) {
                    if (n != 0) {
                        r = JZlib.Z_OK;
                    } else {

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

                len += b & inflate_mask[j];

                b >>= j;
                k -= j;

                need = dbits;
                tree = dtree;
                tree_index = dtree_index;
                mode = DIST;
            case DIST: // i: get distance next
                j = need;

                while (k < j) {
                    if (n != 0) {
                        r = JZlib.Z_OK;
                    } else {

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

                tindex = (tree_index + (b & inflate_mask[j])) * 3;

                b >>= tree[tindex + 1];
                k -= tree[tindex + 1];

                e = tree[tindex];
                if ((e & 16) != 0) { // distance
                    get = e & 15;
                    dist = tree[tindex + 2];
                    mode = DISTEXT;
                    break;
                }
                if ((e & 64) == 0) { // next table
                    need = e;
                    tree_index = tindex / 3 + tree[tindex + 2];
                    break;
                }
                mode = BADCODE; // invalid code
                z.msg = "invalid distance code";
                r = JZlib.Z_DATA_ERROR;

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

            case DISTEXT: // i: getting distance extra
                j = get;

                while (k < j) {
                    if (n != 0) {
                        r = JZlib.Z_OK;
                    } else {

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

                dist += b & inflate_mask[j];

                b >>= j;
                k -= j;

                mode = COPY;
            case COPY: // o: copying bytes in window, waiting for space
                f = q - dist;
                while (f < 0) { // modulo window size-"while" instead
                    f += s.end; // of "if" handles invalid distances
                }
                while (len != 0) {

                    if (m == 0) {
                        if (q == s.end && s.read != 0) {
                            q = 0;
                            m = q < s.read? s.read - q - 1 : s.end - q;
                        }
                        if (m == 0) {
                            s.write = q;
                            r = s.inflate_flush(z, r);
                            q = s.write;
                            m = q < s.read? s.read - q - 1 : s.end - q;

                            if (q == s.end && s.read != 0) {
                                q = 0;
                                m = q < s.read? s.read - q - 1 : s.end - q;
                            }

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

                    s.window[q ++] = s.window[f ++];
                    m --;

                    if (f == s.end) {
                        f = 0;
                    }
                    len --;
                }
                mode = START;
                break;
            case LIT: // o: got literal, waiting for output space
                if (m == 0) {
                    if (q == s.end && s.read != 0) {
                        q = 0;
                        m = q < s.read? s.read - q - 1 : s.end - q;
                    }
                    if (m == 0) {
                        s.write = q;
                        r = s.inflate_flush(z, r);
                        q = s.write;
                        m = q < s.read? s.read - q - 1 : s.end - q;

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

                s.window[q ++] = (byte) lit;
                m --;

                mode = START;
                break;
            case WASH: // o: got eob, possibly more output
                if (k > 7) { // return unused byte, if any
                    k -= 8;
                    n ++;
                    p --; // can always return one
                }

                s.write = q;
                r = s.inflate_flush(z, r);
                q = s.write;

                if (s.read != s.write) {
                    s.bitb = b;
                    s.bitk = k;
                    z.avail_in = n;
                    z.total_in += p - z.next_in_index;
                    z.next_in_index = p;
                    s.write = q;
                    return s.inflate_flush(z, r);
                }
                mode = END;
            case END:
                r = JZlib.Z_STREAM_END;
                s.bitb = b;
                s.bitk = k;
                z.avail_in = n;
                z.total_in += p - z.next_in_index;
                z.next_in_index = p;
                s.write = q;
                return s.inflate_flush(z, r);

            case BADCODE: // x: got error

                r = JZlib.Z_DATA_ERROR;

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

            default:
                r = JZlib.Z_STREAM_ERROR;

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

    // Called with number of bytes left to write in window at least 258
    // (the maximum string length) and number of input bytes available
    // at least ten.  The ten bytes are six bytes for the longest length/
    // distance pair plus four bytes for overloading the bit buffer.

    int inflate_fast(int bl, int bd, int[] tl, int tl_index, int[] td,
            int td_index, InfBlocks s, ZStream z) {
        int t; // temporary pointer
        int[] tp; // temporary pointer
        int tp_index; // temporary pointer
        int e; // extra bits or operation
        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
        int ml; // mask for literal/length tree
        int md; // mask for distance tree
        int c; // bytes to copy
        int d; // distance back to copy from
        int r; // copy source pointer

        int tp_index_t_3; // (tp_index+t)*3

        // load input, output, bit values
        p = z.next_in_index;
        n = z.avail_in;
        b = s.bitb;
        k = s.bitk;
        q = s.write;
        m = q < s.read? s.read - q - 1 : s.end - q;

        // initialize masks
        ml = inflate_mask[bl];
        md = inflate_mask[bd];

        // do until not enough input or output space for fast loop
        do { // assume called with m >= 258 && n >= 10
            // get literal/length code
            while (k < 20) { // max bits for literal/length code
                n --;
                b |= (z.next_in[p ++] & 0xff) << k;
                k += 8;
            }

            t = b & ml;
            tp = tl;
            tp_index = tl_index;
            tp_index_t_3 = (tp_index + t) * 3;
            if ((e = tp[tp_index_t_3]) == 0) {
                b >>= tp[tp_index_t_3 + 1];
                k -= tp[tp_index_t_3 + 1];

                s.window[q ++] = (byte) tp[tp_index_t_3 + 2];
                m --;
                continue;
            }
            do {

                b >>= tp[tp_index_t_3 + 1];
                k -= tp[tp_index_t_3 + 1];

                if ((e & 16) != 0) {
                    e &= 15;
                    c = tp[tp_index_t_3 + 2] + (b & inflate_mask[e]);

                    b >>= e;
                    k -= e;

                    // decode distance base of block to copy
                    while (k < 15) { // max bits for distance code
                        n --;
                        b |= (z.next_in[p ++] & 0xff) << k;
                        k += 8;
                    }

                    t = b & md;
                    tp = td;
                    tp_index = td_index;
                    tp_index_t_3 = (tp_index + t) * 3;
                    e = tp[tp_index_t_3];

                    do {

                        b >>= tp[tp_index_t_3 + 1];
                        k -= tp[tp_index_t_3 + 1];

                        if ((e & 16) != 0) {
                            // get extra bits to add to distance base
                            e &= 15;
                            while (k < e) { // get extra bits (up to 13)
                                n --;
                                b |= (z.next_in[p ++] & 0xff) << k;
                                k += 8;
                            }

                            d = tp[tp_index_t_3 + 2] + (b & inflate_mask[e]);

                            b >>= e;
                            k -= e;

                            // do the copy
                            m -= c;
                            if (q >= d) { // offset before dest
                                //  just copy
                                r = q - d;
                                if (q - r > 0 && 2 > q - r) {
                                    s.window[q ++] = s.window[r ++]; // minimum count is three,
                                    s.window[q ++] = s.window[r ++]; // so unroll loop a little
                                    c -= 2;
                                } else {
                                    System.arraycopy(s.window, r, s.window, q,
                                            2);
                                    q += 2;
                                    r += 2;
                                    c -= 2;
                                }
                            } else { // else offset after destination
                                r = q - d;
                                do {
                                    r += s.end; // force pointer in window
                                } while (r < 0); // covers invalid distances
                                e = s.end - r;
                                if (c > e) { // if source crosses,
                                    c -= e; // wrapped copy
                                    if (q - r > 0 && e > q - r) {
                                        do {
                                            s.window[q ++] = s.window[r ++];
                                        } while (-- e != 0);
                                    } else {
                                        System.arraycopy(s.window, r, s.window,
                                                q, e);
                                        q += e;
                                        r += e;
                                        e = 0;
                                    }
                                    r = 0; // copy rest from start of window
                                }

                            }

                            // copy all or what's left
                            if (q - r > 0 && c > q - r) {
                                do {
                                    s.window[q ++] = s.window[r ++];
                                } while (-- c != 0);
                            } else {
                                System.arraycopy(s.window, r, s.window, q, c);
                                q += c;
                                r += c;
                                c = 0;
                            }
                            break;
                        } else if ((e & 64) == 0) {
                            t += tp[tp_index_t_3 + 2];
                            t += b & inflate_mask[e];
                            tp_index_t_3 = (tp_index + t) * 3;
                            e = tp[tp_index_t_3];
                        } else {
                            z.msg = "invalid distance code";

                            c = z.avail_in - n;
                            c = k >> 3 < c? k >> 3 : c;
                            n += c;
                            p -= c;
                            k -= c << 3;

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

                            return JZlib.Z_DATA_ERROR;
                        }
                    } while (true);
                    break;
                }

                if ((e & 64) == 0) {
                    t += tp[tp_index_t_3 + 2];
                    t += b & inflate_mask[e];
                    tp_index_t_3 = (tp_index + t) * 3;
                    if ((e = tp[tp_index_t_3]) == 0) {

                        b >>= tp[tp_index_t_3 + 1];
                        k -= tp[tp_index_t_3 + 1];

                        s.window[q ++] = (byte) tp[tp_index_t_3 + 2];
                        m --;
                        break;
                    }
                } else if ((e & 32) != 0) {

                    c = z.avail_in - n;
                    c = k >> 3 < c? k >> 3 : c;
                    n += c;
                    p -= c;
                    k -= c << 3;

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

                    return JZlib.Z_STREAM_END;
                } else {
                    z.msg = "invalid literal/length code";

                    c = z.avail_in - n;
                    c = k >> 3 < c? k >> 3 : c;
                    n += c;
                    p -= c;
                    k -= c << 3;

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

                    return JZlib.Z_DATA_ERROR;
                }
            } while (true);
        } while (m >= 258 && n >= 10);

        // not enough input or output--restore pointers and return
        c = z.avail_in - n;
        c = k >> 3 < c? k >> 3 : c;
        n += c;
        p -= c;
        k -= c << 3;

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

        return JZlib.Z_OK;
    }
}
