InfCodes.cs

// Copyright (c) 2006, ComponentAce
// http:https://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.
*/
using System;
namespace ComponentAce.Compression.Libs.zlib
{
	internal sealed class InfCodes
	{
				
		private static readonly int[] inflate_mask = {0x00000000, 0x00000001, 0x00000003, 0x00000007, 0x0000000f, 0x0000001f, 0x0000003f, 0x0000007f, 0x000000ff, 0x000001ff, 0x000003ff, 0x000007ff, 0x00000fff, 0x00001fff, 0x00003fff, 0x00007fff, 0x0000ffff};
		
		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;
		
		// waiting for "i:"=input,
		//             "o:"=output,
		//             "x:"=nothing
		private const int START = 0; // x: set up for LEN
		private const int LEN = 1; // i: get length/literal/eob next
		private const int LENEXT = 2; // i: getting length extra (have base)
		private const int DIST = 3; // i: get distance next
		private const int DISTEXT = 4; // i: getting distance extra
		private const int COPY = 5; // o: copying bytes in window, waiting for space
		private const int LIT = 6; // o: got literal, waiting for output space
		private const int WASH = 7; // o: got eob, possibly still output waiting
		private const int END = 8; // x: got eob and all data flushed
		private const int BADCODE = 9; // x: got error
		
		internal int mode; // current inflate_codes mode
		
		// mode dependent information
		internal int len;
		
		internal int[] tree; // pointer into tree
		internal int tree_index = 0;
		internal int need; // bits needed
		
		internal int lit;
		
		// if EXT or COPY, where and how much
		internal int get_Renamed; // bits to get for extra
		internal int dist; // distance back to copy from
		
		internal byte lbits; // ltree bits decoded per branch
		internal byte dbits; // dtree bits decoder per branch
		internal int[] ltree; // literal/length/eob tree
		internal int ltree_index; // literal/length/eob tree
		internal int[] dtree; // distance tree
		internal int dtree_index; // distance tree
		
		internal InfCodes(int bl, int bd, int[] tl, int tl_index, int[] td, int td_index, ZStream z)
		{
			mode = START;
			lbits = (byte) bl;
			dbits = (byte) bd;
			ltree = tl;
			ltree_index = tl_index;
			dtree = td;
			dtree_index = td_index;
		}
		
		internal InfCodes(int bl, int bd, int[] tl, int[] td, ZStream z)
		{
			mode = START;
			lbits = (byte) bl;
			dbits = (byte) bd;
			ltree = tl;
			ltree_index = 0;
			dtree = td;
			dtree_index = 0;
		}
		
		internal int proc(InfBlocks s, ZStream z, int r)
		{
			int j; // temporary storage
			 //int[] t; // temporary pointer
			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 != Z_OK)
							{
								mode = r == Z_STREAM_END?WASH:BADCODE;
								break;
							}
						}
						need = lbits;
						tree = ltree;
						tree_index = ltree_index;
						
						mode = LEN;
						goto case LEN;
					
					case LEN:  // i: get length/literal/eob next
						j = need;
						
						while (k < (j))
						{
							if (n != 0)
								r = 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 = SupportClass.URShift(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_Renamed = 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 = 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_Renamed;
						
						while (k < (j))
						{
							if (n != 0)
								r = 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;
						goto case DIST;
					
					case DIST:  // i: get distance next
						j = need;
						
						while (k < (j))
						{
							if (n != 0)
								r = 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_Renamed = 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 = 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_Renamed;
						
						while (k < (j))
						{
							if (n != 0)
								r = 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;
						goto case 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 = 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; m = q < s.read?s.read - q - 1:s.end - q;
						
						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;
						goto case END;
					
					case END: 
						r = 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 = 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 = 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);
					
				}
			}
		}
		
		// *TODO: What is going on here?
		internal void free(ZStream z)
		{
			//  ZFREE(z, c);
		}
		
		// 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.
		
		internal static 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
			
			// 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;
				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;
						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++]; c--; // minimum count is three,
										s.window[q++] = s.window[r++]; c--; // so unroll loop a little
									}
									else
									{
										Array.Copy(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
										{
											Array.Copy(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
								{
									Array.Copy(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]);
								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 Z_DATA_ERROR;
							}
						}
						while (true);
						break;
					}
					
					if ((e & 64) == 0)
					{
						t += tp[(tp_index + t) * 3 + 2];
						t += (b & inflate_mask[e]);
						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 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 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 Z_OK;
		}
	}
}