980 lines
41 KiB
C++
980 lines
41 KiB
C++
/* DEC/CMS REPLACEMENT HISTORY, Element INFLATE.C */
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/* *1 14-NOV-1996 10:26:23 ANIGBOGU "[113914]Data decompression functions using the inflate algorithm" */
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/* DEC/CMS REPLACEMENT HISTORY, Element INFLATE.C */
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/* PRIVATE FILE
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******************************************************************************
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**
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** (c) Copyright Schlumberger Technology Corp., unpublished work, created 1996.
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**
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** This computer program includes Confidential, Proprietary Information and is
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** a Trade Secret of Schlumberger Tehnology Corp. All use, disclosure, and/or
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** reproduction is prohibited unless authorized in writing by Schlumberger.
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** All Rights Reserved.
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**
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******************************************************************************
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**
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** compress/inflate.c
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**
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** PURPOSE
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**
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**
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**
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** Inflate deflated (PKZIP's method 8 compressed) data. The compression
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** method searches for as much of the current string of bytes (up to a
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** length of 258) in the previous 32K bytes If it doesn't find any
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** matches (of at least length 3), it codes the next byte. Otherwise, it
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** codes the length of the matched string and its distance backwards from
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** the current position. There is a single Huffman code that codes both
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** single bytes (called "literals") and match lengths. A second Huffman
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** code codes the distance information, which follows a length code. Each
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** length or distance code actually represents a base value and a number
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** of "extra" (sometime zero) bits to get to add to the base value. At
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** the end of each deflated block is a special end-of-block (EOB) literal/
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** length code. The decoding process is basically: get a literal/length
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** code; if EOB then done; if a literal, emit the decoded byte; if a
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** length then get the distance and emit the referred-to bytes from the
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** sliding window of previously emitted data.
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**
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** There are (currently) three kinds of inflate blocks: stored, fixed, and
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** dynamic. The compressor deals with some chunk of data at a time, and
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** decides which method to use on a chunk-by-chunk basis. A chunk might
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** typically be 32K or 64K. If the chunk is uncompressible, then the
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** "stored" method is used. In this case, the bytes are simply stored as
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** is, eight bits per byte, with none of the above coding. The bytes are
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** preceded by a count, since there is no longer an EOB code.
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**
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** If the data is compressible, then either the fixed or dynamic methods
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** are used. I the dynamic method, the compressed data is preceded by
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** an encoding of the literal/length and distance Huffman codes that are
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** to be used to decode this block. The representation is itself Huffman
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** coded, and so is preceded by a description of that code. These code
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** descriptions take up a little space, and so for small blocks, there is
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** a predefined set of codes, called the fixed codes. The fixed method is
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** used if the block codes up smaller that way (usually for quite small
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** chunks), otherwise the dynamic method is used. In the latter case, the
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** codes are customized to the probabilities in the current block, and so
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** can code it much better than the pre-determined fixed codes.
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**
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** The Huffman codes themselves are decoded using a multi-level table
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** lookup, in order to maximize the speed of decoding plus the speed of
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** building the decoding tables. See the comments below that precede the
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** LBits and DBits tuning parameters.
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**
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** SPECIALREQUIREMENTS & NOTES
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**
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** AUTHOR
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**
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** J. C. Anigbogu
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** Austin Systems Center
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** Nov 1996
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**
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******************************************************************************
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*/
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/*
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Notes beyond the 193a appnote.txt:
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1. Distance pointers never point before the beginning of the output
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stream.
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2. Distance pointers can point back across blocks, up to 32k away.
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3. There is an implied maximum of 7 bits for the bit length table and
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15 bits for the actual data.
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4. If only one code exists, then it is encoded using one bit. (Zero
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would be more efficient, but perhaps a little confusing.) If two
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codes exist, they are coded using one bit each (0 and 1).
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5. There is no way of sending zero distance codes--a dummy must be
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sent if there are none. (History: a pre 2.0 version of PKZIP would
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store blocks with no distance codes, but this was discovered to be
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too harsh a criterion.) Valid only for 1.93a. 2.04c does allow
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zero distance codes, which is sent as one code of zero bits in
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length.
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6. There are up to 286 literal/length codes. Code 256 represents the
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end-of-block. Note however that the static length tree defines
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288 codes just to fill out the Huffman codes. Codes 286 and 287
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cannot be used though, since there is no length base or extra bits
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defined for them. Similarly, there are up to 30 distance codes.
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However, static trees define 32 codes (all 5 bits) to fill out the
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Huffman codes, but the last two had better not show up in the data.
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7. Unzip can check dynamic Huffman blocks for complete code sets.
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The exception is that a single code would not be complete (see #4).
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8. The five bits following the block type is really the number of
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literal codes sent minus 257.
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9. Length codes 8,16,16 are interpreted as 13 length codes of 8 bits
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(1+6+6). Therefore, to output three times the length, you output
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three codes (1+1+1), wheras to output four times the same length,
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you only need two codes (1+3). Hmm.
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10. In the tree reconstruction algorithm, Code = Code + Increment
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only if BitLength(i) is not zero. (Pretty obvious.)
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11. Correction: 4 Bits: # of Bit Length codes - 4 (4 - 19)
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12. Note: length code 284 can represent 227-258, but length code 285
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really is 258. The last length deserves its own, short code
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since it gets used a lot in very redundant files. The length
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. 258 is special since 258 - 3 (the min match length) is 255.
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13. The literal/length and distance code bit lengths are read as a
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single stream of lengths. It is possible (and advantageous) for
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a repeat code (16, 17, or 18) to go across the boundary between
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the two sets of lengths.
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*/
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#include "comppriv.h"
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/* Huffman code lookup table entry--this entry is four bytes for machines
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that have 16-bit pointers (e.g. PC's in the small or medium model).
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Valid extra bits are 0..13. Extra == 15 is EOB (end of block), Extra == 16
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means that HuftUnion is a literal, 16 < Extra < 32 means that HuftUnion is
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a pointer to the next table, which codes Extra - 16 bits, and lastly
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Extra == 99 indicates an unused code. If a code with Extra == 99 is looked
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up, this implies an error in the data.
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*/
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typedef struct HuffmanTree
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{
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unsigned char Extra; /* number of extra bits or operation */
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unsigned char Bits; /* number of bits in this code or subcode */
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union
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{
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unsigned short LBase; /* literal, length base, or distance base */
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struct HuffmanTree *next; /* pointer to next level of table */
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} HuftUnion;
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} HuffmanTree_t;
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/* Function prototypes */
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int BuildHuffmanTree(unsigned int *, unsigned int, unsigned int,
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unsigned short *, unsigned short *,
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HuffmanTree_t **, int *);
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void FreeHuffmanTree(HuffmanTree_t *);
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CompressStatus_t InflateCodes(HuffmanTree_t *, HuffmanTree_t *, int, int,
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CompParam_t *Comp);
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CompressStatus_t InflateStored(CompParam_t *Comp);
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int InflateFixed(CompParam_t *Comp);
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CompressStatus_t InflateDynamic(CompParam_t *Comp);
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CompressStatus_t InflateBlock(int *, CompParam_t *Comp);
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/* The inflate algorithm uses a sliding 32K byte window on the uncompressed
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stream to find repeated byte strings. This is implemented here as a
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circular buffer. The index is updated simply by incrementing and then
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and'ing with 0x7fff (32K-1). */
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/* It is left to other modules to supply the 32K area. It is assumed
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to be usable as if it were declared "unsigned char slide[32768];" or as just
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"unsigned char *slide;" and then malloc'ed in the latter case. */
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/* unsigned c->OutBytes; current position in slide */
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#define FlushOutput(w,c) (c->OutBytes = (w),FlushWindow(c))
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/* Tables for deflate from PKZIP's appnote.txt. */
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static unsigned int Border[] =
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{ /* Order of the bit length code lengths */
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16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15
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};
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static unsigned short CopyLengths[] =
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{ /* Copy lengths for literal codes 257..285 */
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3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31,
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35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258, 0, 0
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};
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/* note: see note #13 above about the 258 in this list. */
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static unsigned short CopyExtraBits[] =
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{ /* Extra bits for literal codes 257..285 */
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0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2,
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3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0, 99, 99
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}; /* 99==invalid */
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static unsigned short CopyDistOffset[] =
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{ /* Copy offsets for distance codes 0..29 */
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1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193,
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257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145,
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8193, 12289, 16385, 24577
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};
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static unsigned short CopyDistExtra[] =
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{ /* Extra bits for distance codes */
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0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6,
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7, 7, 8, 8, 9, 9, 10, 10, 11, 11,
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12, 12, 13, 13
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};
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/* Macros for Inflate() bit peeking and grabbing.
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The usage is:
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NEEDBITS(j,comp)
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x = b & MaskBits[j];
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DUMPBITS(j)
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where NEEDBITS makes sure that b has at least j bits in it, and
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DUMPBITS removes the bits from b. The macros use the variable k
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for the number of bits in b. Normally, b and k are register
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variables for speed, and are initialized at the beginning of a
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routine that uses these macros from a global bit buffer and count.
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If we assume that EOB will be the longest code, then we will never
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ask for bits with NEEDBITS that are beyond the end of the stream.
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So, NEEDBITS should not read any more bytes than are needed to
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meet the request. Then no bytes need to be "returned" to the buffer
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at the end of the last block.
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However, this assumption is not true for fixed blocks--the EOB code
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is 7 bits, but the other literal/length codes can be 8 or 9 bits.
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(The EOB code is shorter than other codes because fixed blocks are
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generally short. So, while a block always has an EOB, many other
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literal/length codes have a significantly lower probability of
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showing up at all.) However, by making the first table have a
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lookup of seven bits, the EOB code will be found in that first
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lookup, and so will not require tat too many bits be pulled from
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the stream.
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*/
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unsigned short MaskBits[] =
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{
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0x0000,
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0x0001, 0x0003, 0x0007, 0x000f, 0x001f, 0x003f, 0x007f, 0x00ff,
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0x01ff, 0x03ff, 0x07ff, 0x0fff, 0x1fff, 0x3fff, 0x7fff, 0xffff
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};
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#define NEXTBYTE(c) (unsigned char)GetByte(c)
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#define NEEDBITS(n,c) {while (LocalBitBufferSize < (n)) \
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{ LocalBitBuffer |= ((unsigned long)NEXTBYTE(c))<< LocalBitBufferSize; \
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LocalBitBufferSize += 8; }}
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#define DUMPBITS(n) {LocalBitBuffer >>= (n); LocalBitBufferSize -= (n);}
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/*
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Huffmancode decoding is performed using a multi-level table lookup.
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The fastest way to decode is to simply build a lookup table whose
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size is determined by the longest code. However, the time it takes
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to build this table can also be a factor if the data being decoded
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is not very long. The most common codes are necessarily the
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shortest codes, so those codes dominate the decoding time, and hence
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the speed. The idea is you can have a shorter table that decodes the
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shorter, more probabl codes, and then point to subsidiary tables for
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the longer codes. The time it costs to decode the longer codes is
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then traded against the time it takes to make longer tables.
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The results of this trade are in the variables LBits and DBits
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below. LBits is the number of bits the first level table for literal/
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length codes can decode in one step, and DBits is the same thing for
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the distance codes. Subsequent tables are also less than or equal to
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those sizes. These values may b adjusted either when all of the
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codes are shorter than that, in which case the longest code length in
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bits is used, or when the shortest code is *longer* than the requested
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table size, in which case the length of the shortest code in bits is
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used.
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There are two different values for the two tables, since they code a
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different number of possibilities each. The literal/length table
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codes 286 possible values, or in a flat code, a little over eight
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bits. The distance table codes 30 possible values, or a little less
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than five bits, flat. The optimum values for speed end up being
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about one bit more than those, so LBits is 8+1 and DBits is 5+1.
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The optimum values may differ though from machine to machine, and
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possibly even between compilers. Your mileage may vary.
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*/
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int LBits = 9; /* bits in base literal/length lookup table */
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int DBits = 6; /* bits in base distance lookup table */
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/* If BMAX needs to be larger than 16, then h and x[] should be unsigned long. */
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#define BMAX 16 /* maximum bit length of any code (16 for explode) */
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#define N_MAX 288 /* maximum number of codes in any set */
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unsigned int HuftMemory; /* track memory usage */
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int
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BuildHuffmanTree(
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unsigned int *CodeLengths, /* code lengths in bits (all assumed <= BMAX) */
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unsigned int Codes, /* number of codes (assumed <= N_MAX) */
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unsigned int SimpleCodes, /* number of simple-valued codes (0..s-1) */
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unsigned short *BaseValues, /* list of base values for non-simple codes */
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unsigned short *ExtraBits, /* list of extra bits for non-simple codes */
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HuffmanTree_t **StartTable, /* result: starting table */
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int *MaxBits /* maximum lookup bits, returns actual */
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)
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/* Given a list of code lengths and a maximum table size, make a set of
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tables to decode that set of codes. Return zero on success, one if
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the given code set is incomplete (the tables are still built in this
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case), two if the input is invalid (all zero length codes or an
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oversubscribed set of lengths), and three if not enough memory. */
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{
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unsigned int CodeCounter; /* counter for codes of length k */
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unsigned int CurrentCount; /* counter, current code */
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unsigned int LengthTable[BMAX+1]; /* bit length count table */
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unsigned int CurrentTotal; /* CurrentCount repeats in table every CurrentTotal entries*/
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unsigned int MaxCodeLength; /* maximum code length */
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int TableLevel;
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unsigned int Counter;
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unsigned int CurrentBitCount; /* number of bits in current code */
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unsigned int BitsPerTable; /* bits per table (returned in MaxBits) */
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unsigned int *Pointer; /* pointer into LengthTable[], CodeLengths[], or BitValues[] */
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HuffmanTree_t *CurrentPointer; /* points to current table */
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HuffmanTree_t TableEntry; /* table entry for structure assignment */
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HuffmanTree_t *TableStack[BMAX]; /* table stack */
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unsigned int BitValues[N_MAX]; /* values in order of bit length */
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int BitsBeforeTable; /* bits before this table == (BitsPerTable * TableLevel) */
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unsigned int BitOffsets[BMAX+1]; /* bit offsets, then code stack */
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unsigned int *BitOffsetsPointer; /* pointer into BitOffsets */
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int DummyCodes; /* number of dummy codes added */
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unsigned int TableSize; /* number of entries in current table */
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unsigned int TmpDummyCodes; /* unsigned DummyCodes */
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CompressStatus_t Status;
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/* Generate counts for each bit length */
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memzero(LengthTable, sizeof(LengthTable));
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Pointer = CodeLengths;
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CurrentCount = Codes;
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do
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{
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LengthTable[*Pointer]++; /* assume all entries <= BMAX */
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Pointer++; /* Can't combine with above line (Solaris bug) */
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} while (--CurrentCount);
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if (LengthTable[0] == Codes) /* null input--all zero length codes */
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{
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*StartTable = (HuffmanTree_t *)NULL;
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*MaxBits = 0;
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return COMPRESS_OK;
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}
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/* Find minimum and maximum length, bound *MaxBits by those */
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BitsPerTable = (unsigned int)*MaxBits;
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for (Counter = 1; Counter <= BMAX; Counter++)
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if (LengthTable[Counter])
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break;
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CurrentBitCount = Counter; /* minimum code length */
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if (BitsPerTable < Counter)
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BitsPerTable = Counter;
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for (CurrentCount = BMAX; CurrentCount; CurrentCount--)
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if(LengthTable[CurrentCount])
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break;
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MaxCodeLength = CurrentCount; /* maximum code length */
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if ((unsigned int)BitsPerTable > CurrentCount)
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BitsPerTable = CurrentCount;
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*MaxBits = (int)BitsPerTable;
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/* Adjust last length count to fill out codes, if needed */
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for (TmpDummyCodes = 1 << Counter; Counter < CurrentCount; Counter++, TmpDummyCodes <<= 1)
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{
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DummyCodes = (int)TmpDummyCodes;
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if ((DummyCodes -= (int)LengthTable[Counter]) < 0)
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return BAD_INPUT; /* bad input: more codes than bits */
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TmpDummyCodes = (unsigned int)DummyCodes;
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}
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DummyCodes = (int)TmpDummyCodes;
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if ((DummyCodes -= (int)LengthTable[CurrentCount]) < 0)
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return BAD_INPUT;
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LengthTable[CurrentCount] += (unsigned int)DummyCodes;
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/* Generate starting offsets into the value table for each length */
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BitOffsets[1] = Counter = 0;
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Pointer = LengthTable + 1;
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BitOffsetsPointer = BitOffsets + 2;
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while (--CurrentCount)
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{ /* note that CurrentCount == MaxCodeLength from above */
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*BitOffsetsPointer++ = (Counter += *Pointer++);
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}
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/* Make a table of values in order of bit lengths */
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Pointer = CodeLengths;
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CurrentCount = 0;
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do
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{
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if ((Counter = *Pointer++) != 0)
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BitValues[BitOffsets[Counter]++] = CurrentCount;
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} while (++CurrentCount < Codes);
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/* Generate the Huffman codes and for each, make the table entries */
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BitOffsets[0] = CurrentCount = 0; /* first Huffman code is zero */
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Pointer = BitValues; /* grab values in bit order */
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TableLevel = -1; /* no tables yet--level -1 */
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BitsBeforeTable = -(int)BitsPerTable; /* bits decoded == (BitsPerTable * TableLevel) */
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TableStack[0] = (HuffmanTree_t *)NULL; /* just to keep compilers happy */
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CurrentPointer = (HuffmanTree_t *)NULL;/* ditto */
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TableSize = 0; /* ditto */
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/* go through the bit lengths (CurrentBitCount already is bits in shortest code) */
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for (; CurrentBitCount <= MaxCodeLength; CurrentBitCount++)
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{
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CodeCounter = LengthTable[CurrentBitCount];
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while (CodeCounter--)
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{
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/* here MaxCodeLength is the Huffman code of length CurrentBitCount bits */
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/* for value *p. make tables up to required level */
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while (CurrentBitCount > (unsigned int)BitsBeforeTable + BitsPerTable)
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{
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TableLevel++;
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BitsBeforeTable += (int)BitsPerTable; /* previous table always BitsPerTable bits */
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/* compute minimum size table less than or equal to BitsPerTable bits */
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TableSize = (TableSize = MaxCodeLength - (unsigned int)BitsBeforeTable) >
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(unsigned int)BitsPerTable ? BitsPerTable : TableSize;
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/* upper limit on table size */
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if ((CurrentTotal = 1 << (Counter = CurrentBitCount -
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(unsigned int)BitsBeforeTable)) > CodeCounter + 1)
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/* try a CurrentBitCount-BitsBeforeTable bit table */
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{ /* too few codes for CurrentBitCount-BitsBeforeTable bit table */
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CurrentTotal -= CodeCounter + 1; /* deduct codes from patterns left */
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BitOffsetsPointer = LengthTable + CurrentBitCount;
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while (++Counter < TableSize) /* try smaller tables up to TableSize bits */
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{
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if ((CurrentTotal <<= 1) <= *++BitOffsetsPointer)
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break; /* enough codes to use up j bits */
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CurrentTotal -= *BitOffsetsPointer; /* else deduct codes from patterns */
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}
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}
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TableSize = 1 << Counter; /* table entries for Counter-bit table */
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/* allocate and link in new table */
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if ((CurrentPointer = (HuffmanTree_t *)CompressMalloc((TableSize + 1)*sizeof(HuffmanTree_t),
|
|
&Status)) == (HuffmanTree_t *)NULL)
|
|
{
|
|
if (TableLevel)
|
|
FreeHuffmanTree(TableStack[0]);
|
|
return INSUFFICIENT_MEMORY; /* not enough memory */
|
|
}
|
|
HuftMemory += TableSize + 1; /* track memory usage */
|
|
*StartTable = CurrentPointer + 1; /* link to list for FreeHuffmanTree() */
|
|
*(StartTable = &(CurrentPointer->HuftUnion.next)) = (HuffmanTree_t *)NULL;
|
|
TableStack[TableLevel] = ++CurrentPointer; /* table starts after link */
|
|
|
|
/* connect to last table, if there is one */
|
|
if (TableLevel)
|
|
{
|
|
BitOffsets[TableLevel] = CurrentCount; /* save pattern for backing up */
|
|
TableEntry.Bits = (unsigned char)BitsPerTable; /* bits to dump before this table */
|
|
TableEntry.Extra = (unsigned char)(16 + Counter); /* bits in this table */
|
|
TableEntry.HuftUnion.next = CurrentPointer; /* pointer to this table */
|
|
Counter = CurrentCount >> ((unsigned int)BitsBeforeTable - BitsPerTable);
|
|
TableStack[TableLevel-1][Counter] = TableEntry; /* connect to last table */
|
|
}
|
|
}
|
|
|
|
/* set up table entry in r */
|
|
TableEntry.Bits = (unsigned char)(CurrentBitCount - (unsigned int)BitsBeforeTable);
|
|
if (Pointer >= BitValues + Codes)
|
|
TableEntry.Extra = 99; /* out of values--invalid code */
|
|
else if (*Pointer < SimpleCodes)
|
|
{
|
|
TableEntry.Extra = (unsigned char)(*Pointer < 256 ? 16 : 15); /* 256 is end-of-block code */
|
|
TableEntry.HuftUnion.LBase = (unsigned short)(*Pointer); /* simple code is just the value */
|
|
Pointer++; /* one compiler does not like *Pointer++ */
|
|
}
|
|
else
|
|
{
|
|
/* non-simple--look up in lists */
|
|
TableEntry.Extra = (unsigned char)ExtraBits[*Pointer - SimpleCodes];
|
|
TableEntry.HuftUnion.LBase = BaseValues[*Pointer++ - SimpleCodes];
|
|
}
|
|
|
|
/* fill code-like entries with TableEntry */
|
|
CurrentTotal = 1 << (CurrentBitCount - (unsigned int)BitsBeforeTable);
|
|
for (Counter = CurrentCount >> BitsBeforeTable; Counter < TableSize; Counter += CurrentTotal)
|
|
CurrentPointer[Counter] = TableEntry;
|
|
|
|
/* backwards increment the CurrentBitCount - bit code i */
|
|
for (Counter = 1 << (CurrentBitCount - 1); CurrentCount & Counter; Counter >>= 1)
|
|
CurrentCount ^= Counter;
|
|
CurrentCount ^= Counter;
|
|
|
|
/* backup over finished tables */
|
|
while ((CurrentCount & ((1 << BitsBeforeTable) - 1)) != BitOffsets[TableLevel])
|
|
{
|
|
TableLevel--; /* don't need to update CurrentPointer */
|
|
BitsBeforeTable -= (int)BitsPerTable;
|
|
}
|
|
}
|
|
}
|
|
|
|
/* Return true (1) if we were given an incomplete table */
|
|
return DummyCodes != 0 && MaxCodeLength != 1;
|
|
}
|
|
|
|
void
|
|
FreeHuffmanTree(
|
|
HuffmanTree_t *Table /* table to free */
|
|
)
|
|
/* Free the malloc'ed tables built by BuildHuffmanTree(), which makes a linked
|
|
list of the tables it made, with the links in a dummy first entry of
|
|
each table. */
|
|
{
|
|
HuffmanTree_t *Pointer, *CurrentPointer;
|
|
|
|
/* Go through linked list, freeing from the malloc'd (t[-1]) address. */
|
|
Pointer = Table;
|
|
while (Pointer != (HuffmanTree_t *)NULL)
|
|
{
|
|
CurrentPointer = (--Pointer)->HuftUnion.next;
|
|
CompressFree((char *)Pointer);
|
|
Pointer = CurrentPointer;
|
|
}
|
|
}
|
|
|
|
CompressStatus_t
|
|
InflateCodes(
|
|
HuffmanTree_t *LitLengthTable,
|
|
HuffmanTree_t *DistCodeTable, /* literal/length and dist. decoder tables */
|
|
int LLTLookup,
|
|
int DCTLookup, /* number of bits decoded by LitLengthTable[] and DistCodeTable[] */
|
|
CompParam_t *Comp
|
|
)
|
|
/* inflate (decompress) the codes in a deflated (compressed) block.
|
|
Return an error code or zero if it all goes ok. */
|
|
{
|
|
unsigned int ExtraBits; /* table entry flag/number of extra bits */
|
|
unsigned int Length, Index; /* length and index for copy */
|
|
unsigned int WindowPosition; /* current window position */
|
|
HuffmanTree_t *TableEntry; /* pointer to table entry */
|
|
unsigned int LLTLookupMask, DCTLookupMask; /* masks for LLT and DCT bits */
|
|
unsigned long LocalBitBuffer; /* bit buffer */
|
|
unsigned int LocalBitBufferSize; /* number of bits in bit buffer */
|
|
|
|
/* make local copies of globals */
|
|
LocalBitBuffer = Comp->BitBuffer; /* initialize bit buffer */
|
|
LocalBitBufferSize = Comp->BitsInBitBuffer;
|
|
WindowPosition = Comp->OutBytes; /* initialize window position */
|
|
|
|
/* inflate the coded data */
|
|
LLTLookupMask = MaskBits[LLTLookup]; /* precompute masks for speed */
|
|
DCTLookupMask = MaskBits[DCTLookup];
|
|
for (;;) /* do until end of block */
|
|
{
|
|
NEEDBITS((unsigned int)LLTLookup, Comp)
|
|
if ((ExtraBits = (TableEntry = LitLengthTable +
|
|
((unsigned int)LocalBitBuffer & LLTLookupMask))->Extra) > 16)
|
|
do
|
|
{
|
|
if (ExtraBits == 99)
|
|
return EXTRA_BITS;
|
|
DUMPBITS(TableEntry->Bits)
|
|
ExtraBits -= 16;
|
|
NEEDBITS(ExtraBits, Comp)
|
|
} while ((ExtraBits = (TableEntry = TableEntry->HuftUnion.next +
|
|
((unsigned int)LocalBitBuffer & MaskBits[ExtraBits]))->Extra) > 16);
|
|
DUMPBITS(TableEntry->Bits)
|
|
if (ExtraBits == 16) /* then it's a literal */
|
|
{
|
|
Comp->Window[WindowPosition++] = (unsigned char)TableEntry->HuftUnion.LBase;
|
|
if (WindowPosition == WSIZE)
|
|
{
|
|
CompressStatus_t Status;
|
|
Status = FlushOutput(WindowPosition, Comp);
|
|
if (COMPRESS_OK != Status)
|
|
return Status;
|
|
|
|
WindowPosition = 0;
|
|
}
|
|
}
|
|
else /* it's an EOF or a length */
|
|
{
|
|
/* exit if end of block */
|
|
if (ExtraBits == 15)
|
|
break;
|
|
|
|
/* get length of block tocopy */
|
|
NEEDBITS(ExtraBits, Comp)
|
|
Length = TableEntry->HuftUnion.LBase +
|
|
((unsigned int)LocalBitBuffer & MaskBits[ExtraBits]);
|
|
DUMPBITS(ExtraBits)
|
|
|
|
/* decode distance of block to copy */
|
|
NEEDBITS((unsigned int)DCTLookup, Comp)
|
|
if ((ExtraBits = (TableEntry = DistCodeTable +
|
|
((unsigned int)LocalBitBuffer & DCTLookupMask))->Extra) > 16)
|
|
do
|
|
{
|
|
if (ExtraBits == 99)
|
|
return EXTRA_BITS;
|
|
DUMPBITS(TableEntry->Bits)
|
|
ExtraBits -= 16;
|
|
NEEDBITS(ExtraBits, Comp)
|
|
} while ((ExtraBits = (TableEntry = TableEntry->HuftUnion.next +
|
|
((unsigned int)LocalBitBuffer & MaskBits[ExtraBits]))->Extra) > 16);
|
|
DUMPBITS(TableEntry->Bits)
|
|
NEEDBITS(ExtraBits, Comp)
|
|
Index = WindowPosition - TableEntry->HuftUnion.LBase -
|
|
((unsigned int)LocalBitBuffer & MaskBits[ExtraBits]);
|
|
DUMPBITS(ExtraBits)
|
|
|
|
/* do the copy */
|
|
do
|
|
{
|
|
Length -= (ExtraBits = (ExtraBits = WSIZE - ((Index &= WSIZE-1) >
|
|
WindowPosition ? Index : WindowPosition)) > Length ? Length : ExtraBits);
|
|
|
|
if (WindowPosition - Index >= ExtraBits) /* (this test assumes unsigned comparison) */
|
|
{
|
|
memcpy((char *)Comp->Window + WindowPosition,
|
|
(char *)Comp->Window + Index, (int)ExtraBits);
|
|
WindowPosition += ExtraBits;
|
|
Index += ExtraBits;
|
|
}
|
|
else /* do it slow to avoid memcpy() overlap */
|
|
do
|
|
{
|
|
Comp->Window[WindowPosition++] = Comp->Window[Index++];
|
|
} while (--ExtraBits);
|
|
if (WindowPosition == WSIZE)
|
|
{
|
|
CompressStatus_t Status;
|
|
Status = FlushOutput(WindowPosition, Comp);
|
|
if (COMPRESS_OK != Status)
|
|
return Status;
|
|
|
|
WindowPosition = 0;
|
|
}
|
|
} while (Length);
|
|
}
|
|
}
|
|
|
|
|
|
/* restore the globals from the locals */
|
|
Comp->OutBytes = WindowPosition; /* restore global window pointer */
|
|
Comp->BitBuffer = LocalBitBuffer; /* restore global bit buffer */
|
|
Comp->BitsInBitBuffer = LocalBitBufferSize;
|
|
|
|
/* done */
|
|
return COMPRESS_OK;
|
|
}
|
|
|
|
CompressStatus_t
|
|
InflateStored(
|
|
CompParam_t *Comp
|
|
)
|
|
/* "decompress" an inflated type 0 (stored) block. */
|
|
{
|
|
unsigned int BytesInBlock; /* number of bytes in block */
|
|
unsigned int WindowPosition; /* current window position */
|
|
unsigned long LocalBitBuffer; /* bit buffer */
|
|
unsigned int LocalBitBufferSize; /* number of bits in bit buffer */
|
|
|
|
/* make local copies of globals */
|
|
LocalBitBuffer = Comp->BitBuffer; /* initialize bit buffer */
|
|
LocalBitBufferSize = Comp->BitsInBitBuffer;
|
|
WindowPosition = Comp->OutBytes; /* initialize window position */
|
|
|
|
|
|
/* go to byte boundary */
|
|
BytesInBlock = LocalBitBufferSize & 7;
|
|
DUMPBITS(BytesInBlock)
|
|
|
|
|
|
/* get the length and its complement */
|
|
NEEDBITS(16, Comp)
|
|
BytesInBlock = ((unsigned int)LocalBitBuffer & 0xffff);
|
|
DUMPBITS(16)
|
|
NEEDBITS(16, Comp)
|
|
if (BytesInBlock != (unsigned int)((~LocalBitBuffer) & 0xffff))
|
|
return BAD_COMPRESSED_DATA; /* error in compressed data */
|
|
DUMPBITS(16)
|
|
|
|
/* read and output the compressed data */
|
|
while (BytesInBlock--)
|
|
{
|
|
NEEDBITS(8, Comp)
|
|
Comp->Window[WindowPosition++] = (unsigned char)LocalBitBuffer;
|
|
if (WindowPosition == WSIZE)
|
|
{
|
|
CompressStatus_t Status;
|
|
Status = FlushOutput(WindowPosition, Comp);
|
|
if (COMPRESS_OK != Status)
|
|
return Status;
|
|
|
|
WindowPosition = 0;
|
|
}
|
|
DUMPBITS(8)
|
|
}
|
|
|
|
/* restore the globals from the locals */
|
|
Comp->OutBytes = WindowPosition; /* restore global window pointer */
|
|
Comp->BitBuffer = LocalBitBuffer; /* restore global bit buffer */
|
|
Comp->BitsInBitBuffer = LocalBitBufferSize;
|
|
return COMPRESS_OK;
|
|
}
|
|
|
|
int
|
|
InflateFixed(
|
|
CompParam_t *Comp
|
|
)
|
|
/* decompress an inflated type 1 (fixed Huffman codes) block. We should
|
|
either replace this with a custom decoder, or at least precompute the
|
|
Huffman tables. */
|
|
{
|
|
int Index; /* temporary variable */
|
|
HuffmanTree_t *LitLengthTable; /* literal/length code table */
|
|
HuffmanTree_t *DistCodeTable; /* distance code table */
|
|
int LLTLookup; /* lookup bits for LitLengthTable */
|
|
int DCTLookup; /* lookup bits for DistCodeTable */
|
|
unsigned int Length[288]; /* length list for BuildHuffmanTree */
|
|
|
|
/* set up literal table */
|
|
for (Index = 0; Index < 144; Index++)
|
|
Length[Index] = 8;
|
|
for (; Index < 256; Index++)
|
|
Length[Index] = 9;
|
|
for (; Index < 280; Index++)
|
|
Length[Index] = 7;
|
|
for (; Index < 288; Index++) /* make a complete, but wrong code set */
|
|
Length[Index] = 8;
|
|
LLTLookup = 7;
|
|
|
|
if ((Index = BuildHuffmanTree(Length, 288, 257, CopyLengths,
|
|
CopyExtraBits, &LitLengthTable, &LLTLookup)) != 0)
|
|
return Index;
|
|
|
|
/* set up distance table */
|
|
for (Index = 0; Index < 30; Index++) /* make an incomplete code set */
|
|
Length[Index] = 5;
|
|
DCTLookup = 5;
|
|
if ((Index = BuildHuffmanTree(Length, 30, 0, CopyDistOffset, CopyDistExtra,
|
|
&DistCodeTable, &DCTLookup)) > 1)
|
|
{
|
|
FreeHuffmanTree(LitLengthTable);
|
|
return Index;
|
|
}
|
|
|
|
/* decompress until an end-of-block code */
|
|
if (InflateCodes(LitLengthTable, DistCodeTable, LLTLookup, DCTLookup, Comp))
|
|
return END_OF_BLOCK;
|
|
|
|
/* free the decoding tables, return */
|
|
FreeHuffmanTree(LitLengthTable);
|
|
FreeHuffmanTree(DistCodeTable);
|
|
return static_cast<int>(COMPRESS_OK);
|
|
}
|
|
|
|
CompressStatus_t
|
|
InflateDynamic(
|
|
CompParam_t *Comp
|
|
)
|
|
/* decompress an inflated type 2 (dynamic Huffman codes) block. */
|
|
{
|
|
int TmpVar1; /* temporary variables */
|
|
unsigned int TmpVar2;
|
|
unsigned int LastLength; /* last length */
|
|
unsigned int TableMask; /* mask for bit lengths table */
|
|
unsigned int Lengths; /* number of lengths to get */
|
|
HuffmanTree_t *LitLengthTable; /* literal/length code table */
|
|
HuffmanTree_t *DistCodeTable; /* distance code table */
|
|
int LLTLookup; /* lookup bits for LitLengthTable */
|
|
int DCTLookup; /* lookup bits for DistCodeTable */
|
|
unsigned int BitCodes; /* number of bit length codes */
|
|
unsigned int LitLenCodes; /* number of literal/length codes */
|
|
unsigned int DistCodes; /* number of distance codes */
|
|
unsigned int CodeLength[286+30]; /* literal/length and distance code lengths */
|
|
unsigned long LocalBitBuffer; /* bit buffer */
|
|
unsigned int LocalBitBufferSize; /* number of bits in bit buffer */
|
|
|
|
/* make local bit buffer */
|
|
LocalBitBuffer = Comp->BitBuffer;
|
|
LocalBitBufferSize = Comp->BitsInBitBuffer;
|
|
|
|
/* read in table lengths */
|
|
NEEDBITS(5, Comp)
|
|
LitLenCodes = 257 + ((unsigned int)LocalBitBuffer & 0x1f); /* number of literal/length codes */
|
|
DUMPBITS(5)
|
|
NEEDBITS(5, Comp)
|
|
DistCodes = 1 + ((unsigned int)LocalBitBuffer & 0x1f); /* number of distance codes */
|
|
DUMPBITS(5)
|
|
NEEDBITS(4, Comp)
|
|
BitCodes = 4 + ((unsigned int)LocalBitBuffer & 0xf); /* number of bit length codes */
|
|
DUMPBITS(4)
|
|
if (LitLenCodes > 286 || DistCodes > 30)
|
|
return BAD_CODE_LENGTHS; /* bad lengths */
|
|
|
|
/* read in bit-length-code lengths */
|
|
for (TmpVar2 = 0; TmpVar2 < BitCodes; TmpVar2++)
|
|
{
|
|
NEEDBITS(3, Comp)
|
|
CodeLength[Border[TmpVar2]] = (unsigned int)LocalBitBuffer & 7;
|
|
DUMPBITS(3)
|
|
}
|
|
|
|
for (; TmpVar2 < 19; TmpVar2++)
|
|
CodeLength[Border[TmpVar2]] = 0;
|
|
|
|
/* build decoding table for trees--single level, 7 bit lookup */
|
|
LLTLookup = 7;
|
|
if ((TmpVar1 = BuildHuffmanTree(CodeLength, 19, 19, NULL, NULL,
|
|
&LitLengthTable, &LLTLookup)) != 0)
|
|
{
|
|
if (TmpVar1 == 1)
|
|
FreeHuffmanTree(LitLengthTable);
|
|
return INCOMPLETE_CODE_SET; /* incomplete code set */
|
|
}
|
|
|
|
/* read in literal and distance code lengths */
|
|
Lengths = LitLenCodes + DistCodes;
|
|
TableMask = MaskBits[LLTLookup];
|
|
TmpVar1 = LastLength = 0;
|
|
while ((unsigned int)TmpVar1 < Lengths)
|
|
{
|
|
NEEDBITS((unsigned int)LLTLookup, Comp)
|
|
TmpVar2 = (DistCodeTable = LitLengthTable +
|
|
((unsigned int)LocalBitBuffer & TableMask))->Bits;
|
|
DUMPBITS(TmpVar2)
|
|
TmpVar2 = DistCodeTable->HuftUnion.LBase;
|
|
if (TmpVar2 < 16) /* length of code in bits (0..15) */
|
|
CodeLength[TmpVar1++] = LastLength = TmpVar2; /* save last length in l */
|
|
else if (TmpVar2 == 16) /* repeat last length 3 to 6 times */
|
|
{
|
|
NEEDBITS(2, Comp)
|
|
TmpVar2 = 3 + ((unsigned int)LocalBitBuffer & 3);
|
|
DUMPBITS(2)
|
|
if ((unsigned int)TmpVar1 + TmpVar2 > Lengths)
|
|
return EXTRA_BITS;
|
|
while (TmpVar2--)
|
|
CodeLength[TmpVar1++] = LastLength;
|
|
}
|
|
else if (TmpVar2 == 17) /* 3 to 10 zero length codes */
|
|
{
|
|
NEEDBITS(3, Comp)
|
|
TmpVar2 = 3 + ((unsigned int)LocalBitBuffer & 7);
|
|
DUMPBITS(3)
|
|
if ((unsigned int)TmpVar1 + TmpVar2 > Lengths)
|
|
return INCOMPLETE_CODE_SET;
|
|
while (TmpVar2--)
|
|
CodeLength[TmpVar1++] = 0;
|
|
LastLength = 0;
|
|
}
|
|
else /* TmpVar2 == 18: 11 to 138 zero length codes */
|
|
{
|
|
NEEDBITS(7, Comp)
|
|
TmpVar2 = 11 + ((unsigned int)LocalBitBuffer & 0x7f);
|
|
DUMPBITS(7)
|
|
if ((unsigned int)TmpVar1 + TmpVar2 > Lengths)
|
|
return INCOMPLETE_CODE_SET;
|
|
while (TmpVar2--)
|
|
CodeLength[TmpVar1++] = 0;
|
|
LastLength = 0;
|
|
}
|
|
}
|
|
|
|
/* free decoding table for trees */
|
|
FreeHuffmanTree(LitLengthTable);
|
|
|
|
/* restore the global bit buffer */
|
|
Comp->BitBuffer = LocalBitBuffer;
|
|
Comp->BitsInBitBuffer = LocalBitBufferSize;
|
|
|
|
/* build the decoding tables for literal/length and distance codes */
|
|
LLTLookup = LBits;
|
|
if ((TmpVar1 = BuildHuffmanTree(CodeLength, LitLenCodes, 257,
|
|
CopyLengths, CopyExtraBits, &LitLengthTable, &LLTLookup)) != 0)
|
|
{
|
|
if (TmpVar1 == 1)
|
|
{
|
|
fprintf(stderr, " incomplete literal tree\n");
|
|
FreeHuffmanTree(LitLengthTable);
|
|
}
|
|
return INCOMPLETE_CODE_SET; /* incomplete code set */
|
|
}
|
|
DCTLookup = DBits;
|
|
if ((TmpVar1 = BuildHuffmanTree(CodeLength + LitLenCodes, DistCodes, 0,
|
|
CopyDistOffset, CopyDistExtra, &DistCodeTable, &DCTLookup)) != 0)
|
|
{
|
|
if (TmpVar1 == 1)
|
|
{
|
|
fprintf(stderr, " incomplete distance tree\n");
|
|
FreeHuffmanTree(DistCodeTable);
|
|
}
|
|
FreeHuffmanTree(LitLengthTable);
|
|
return INCOMPLETE_CODE_SET; /* incomplete code set */
|
|
}
|
|
|
|
/* decompress until an end-of-block code */
|
|
if (InflateCodes(LitLengthTable, DistCodeTable, LLTLookup, DCTLookup, Comp))
|
|
return END_OF_BLOCK;
|
|
|
|
/* free the decoding tables, return */
|
|
FreeHuffmanTree(LitLengthTable);
|
|
FreeHuffmanTree(DistCodeTable);
|
|
return COMPRESS_OK;
|
|
}
|
|
|
|
CompressStatus_t
|
|
InflateBlock(
|
|
int *LastBlock, /* last block flag */
|
|
CompParam_t *Comp
|
|
)
|
|
/* decompress an inflated block */
|
|
{
|
|
unsigned int BlockType; /* block type */
|
|
unsigned long LocalBitBuffer; /* bit buffer */
|
|
unsigned int LocalBitBufferSize; /* number of bits in bit buffer */
|
|
|
|
|
|
/* make local bit buffer */
|
|
LocalBitBuffer = Comp->BitBuffer;
|
|
LocalBitBufferSize = Comp->BitsInBitBuffer;
|
|
|
|
/* read in last block bit */
|
|
NEEDBITS(1, Comp)
|
|
*LastBlock = (int)LocalBitBuffer & 1;
|
|
DUMPBITS(1)
|
|
|
|
|
|
/* read in block type */
|
|
NEEDBITS(2, Comp)
|
|
BlockType = (unsigned)LocalBitBuffer & 3;
|
|
DUMPBITS(2)
|
|
|
|
|
|
/* restore the global bit buffer */
|
|
Comp->BitBuffer = LocalBitBuffer;
|
|
Comp->BitsInBitBuffer = LocalBitBufferSize;
|
|
|
|
|
|
/* inflate that block type */
|
|
if (BlockType == DYN_TREES)
|
|
return InflateDynamic(Comp);
|
|
if (BlockType == STORED_BLOCK)
|
|
return InflateStored(Comp);
|
|
if (BlockType == STATIC_TREES)
|
|
return static_cast<CompressStatus_t>(InflateFixed(Comp));
|
|
// this is an
|
|
// anomaly cast but
|
|
// don't know what
|
|
// else to do.
|
|
|
|
/* bad block type */
|
|
return BAD_BLOCK_TYPE;
|
|
}
|
|
|
|
CompressStatus_t
|
|
Inflate(
|
|
CompParam_t *Comp
|
|
)
|
|
/* decompress an inflated entry */
|
|
{
|
|
int LastBlock; /* last block flag */
|
|
CompressStatus_t Status; /* result code */
|
|
unsigned int MaxHuft; /* maximum struct huft's malloc'ed */
|
|
|
|
/* initialize window, bit buffer */
|
|
Comp->OutBytes = 0;
|
|
Comp->BitsInBitBuffer = 0;
|
|
Comp->BitBuffer = 0;
|
|
|
|
/* decompress until the last block */
|
|
MaxHuft = 0;
|
|
do
|
|
{
|
|
HuftMemory = 0;
|
|
if ((Status = InflateBlock(&LastBlock, Comp)) != COMPRESS_OK)
|
|
return Status;
|
|
if (HuftMemory > MaxHuft)
|
|
MaxHuft = HuftMemory;
|
|
} while (!LastBlock);
|
|
|
|
/* Undo too much lookahead. The next read will be byte aligned so we
|
|
* can discard unused bits in the last meaningful byte.
|
|
*/
|
|
while (Comp->BitsInBitBuffer >= 8)
|
|
{
|
|
Comp->BitsInBitBuffer -= 8;
|
|
Comp->Index--;
|
|
}
|
|
|
|
/* flush out slide */
|
|
return FlushOutput(Comp->OutBytes, Comp);
|
|
}
|