inflate.c

ADS下的bios工程

/* inflate.c -- Not copyrighted 1992 by Mark Adler
   version c10p1, 10 January 1993 */

/* 
 * Adapted for booting Linux by Hannu Savolainen 1993
 * based on gzip-1.0.3 
 */

/*
   Inflate deflated (PKZIP's method 8 compressed) data.  The compression
   method searches for as mu8 of the current string of bytes (up to a
   length of 258) in the previous 32 K bytes.  If it doesn't find any
   matches (of at least length 3), it codes the next byte.  Otherwise, it
   codes the length of the matched string and its distance backwards from
   the current position.  There is a single Huffman code that codes both
   single bytes (called "literals") and match lengths.  A second Huffman
   code codes the distance information, which follows a length code.  Each
   length or distance code actually represents a base value and a number
   of "extra" (sometimes zero) bits to get to add to the base value.  At
   the end of each deflated block is a special end-of-block (EOB) literal/
   length code.  The decoding process is basically: get a literal/length
   code; if EOB then done; if a literal, emit the decoded byte; if a
   length then get the distance and emit the referred-to bytes from the
   sliding window of previously emitted data.

   There are (currently) three kinds of inflate blocks: stored, fixed, and
   dynamic.  The compressor deals with some chunk of data at a time, and
   decides which method to use on a chunk-by-chunk basis.  A chunk might
   typically be 32 K or 64 K.  If the chunk is incompressible, then the
   "stored" method is used.  In this case, the bytes are simply stored as
   is, eight bits per byte, with none of the above coding.  The bytes are
   preceded by a count, since there is no longer an EOB code.

   If the data is compressible, then either the fixed or dynamic methods
   are used.  In the dynamic method, the compressed data is preceded by
   an encoding of the literal/length and distance Huffman codes that are
   to be used to decode this block.  The representation is itself Huffman
   coded, and so is preceded by a description of that code.  These code
   descriptions take up a little space, and so for small blocks, there is
   a predefined set of codes, called the fixed codes.  The fixed method is
   used if the block codes up smaller that way (usually for quite small
   chunks), otherwise the dynamic method is used.  In the latter case, the
   codes are customized to the probabilities in the current block, and so
   can code it mu8 better than the pre-determined fixed codes.
 
   The Huffman codes themselves are decoded using a multi-level table
   lookup, in order to maximize the speed of decoding plus the speed of
   building the decoding tables.  See the comments below that precede the
   lbits and dbits tuning parameters.
 */


/*
   Notes beyond the 1.93a appnote.txt:

   1. Distance pointers never point before the beginning of the output
      stream.
   2. Distance pointers can point back across blocks, up to 32k away.
   3. There is an implied maximum of 7 bits for the bit length table and
      15 bits for the actual data.
   4. If only one code exists, then it is encoded using one bit.  (Zero
      would be more efficient, but perhaps a little confusing.)  If two
      codes exist, they are coded using one bit each (0 and 1).
   5. There is no way of sending zero distance codes--a dummy must be
      sent if there are none.  (History: a pre 2.0 version of PKZIP would
      store blocks with no distance codes, but this was discovered to be
      too harsh a criterion.)  Valid only for 1.93a.  2.04c does allow
      zero distance codes, which is sent as one code of zero bits in
      length.
   6. There are up to 286 literal/length codes.  Code 256 represents the
      end-of-block.  Note however that the static length tree defines
      288 codes just to fill out the Huffman codes.  Codes 286 and 287
      cannot be used though, since there is no length base or extra bits
      defined for them.  Similarly, there are up to 30 distance codes.
      However, static trees define 32 codes (all 5 bits) to fill out the
      Huffman codes, but the last two had better not show up in the data.
   7. Unzip can check dynamic Huffman blocks for complete code sets.
      The exception is that a single code would not be complete (see #4).
   8. The five bits following the block type is really the number of
      literal codes sent minus 257.
   9. Length codes 8,16,16 are interpreted as 13 length codes of 8 bits
      (1+6+6).  Therefore, to output three times the length, you output
      three codes (1+1+1), whereas to output four times the same length,
      you only need two codes (1+3).  Hmm.
  10. In the tree reconstruction algorithm, Code = Code + Increment
      only if BitLength(i) is not zero.  (Pretty obvious.)
  11. Correction: 4 Bits: # of Bit Length codes - 4     (4 - 19)
  12. Note: length code 284 can represent 227-258, but length code 285
      really is 258.  The last length deserves its own, short code
      since it gets used a lot in very redundant files.  The length
      258 is special since 258 - 3 (the min match length) is 255.
  13. The literal/length and distance code bit lengths are read as a
      single stream of lengths.  It is possible (and advantageous) for
      a repeat code (16, 17, or 18) to go across the boundary between
      the two sets of lengths.
 */
#include  <bios/gzip.h> 
#include <bios/stdio.h>
#include <bios/types.h>
#include <bios/string.h>
#include <bios/malloc.h>
	
#define slide window

#undef DEBUG
#ifdef DEBUG
#define DEBUG_ZIP(args...) printf(args)
#else
#define DEBUG_ZIP(args...)
#endif

/*
 * gzip delarations
 */
#define OF(args)  args
#define STATIC static

static u8 *inbuf;              /* input buffer */
static u8 window[WSIZE];       /* Sliding window buffer */

//static unsigned long insize;         /* valid bytes in inbuf */
static unsigned long inptr;          /* index of next byte to be processed in inbuf */
static u32 crc_32_tab[256];
static u32 crc; /* shift register contents */
#define CRC_VALUE (crc ^ 0xffffffffL)

static unsigned outcnt;         /* bytes in output buffer */
void flush_window(void);

static u8 *output_data;
static u32 output_ptr;
static u32 bytes_out;

#define __ptr_t void *
static u32 free_mem_ptr;
static u32 free_mem_ptr_end;
static void *xmalloc(int size);
void error(char *x);

/****************************************************************************/
/* FUNCTION                                                                 */
/*                                                                          */
/*    xmalloc                                                               */
/*                                                                          */
/* DESCRIPTION                                                              */
/*             Semi-safe malloc -- never returns NULL.                      */
/*                                                                          */
/* CALLED BY                                                                */
/*                                                                          */
/* CALLS                                                                    */
/*                                                                          */
/* INPUTS                                                                   */
/*                                                                          */
/*                                                                          */
/* OUTPUTS                                                                  */
/*                                                                          */
/*    STATUS                                                                */
/*                                                                          */
/* HISTORY                                                                  */
/*                                                                          */
/*       NAME                 DATE            REMARKS                       */
/*                                                                          */
/*       yskim              20-06-2000    Created initial version 1.0       */
/*                                                                          */
/****************************************************************************/
static void *xmalloc(int size)
{
	void *cp;
	cp = (void *)malloc (size);

	DEBUG_ZIP("\np = xmalloc(size): size = %d, p = 0x%x\n", size, (int)cp); 
    
	if (cp == NULL) error("out of memory");
	return cp;
}


/****************************************************************************/
/* FUNCTION                                                                 */
/*                                                                          */
/*    flush_window                                                          */
/*                                                                          */
/* DESCRIPTION                                                              */
/*             Write the output window window[0..outcnt-1] and update crc   */
/* and bytes_out. (used for the decompressed data only.)                    */
/*                                                                          */
/* CALLED BY                                                                */
/*                                                                          */
/* CALLS                                                                    */
/*                                                                          */
/* INPUTS                                                                   */
/*                                                                          */
/*                                                                          */
/* OUTPUTS                                                                  */
/*                                                                          */
/*    STATUS                                                                */
/*                                                                          */
/* HISTORY                                                                  */
/*                                                                          */
/*       NAME                 DATE            REMARKS                       */
/*                                                                          */
/*       yskim              20-06-2000    Created initial version 1.0       */
/*                                                                          */
/****************************************************************************/
void flush_window(void)
{
        u32 c;
        unsigned n;
        u8 *in, *out, ch;

        c = crc;
        in = window;
        out = &output_data[output_ptr];
        for (n = 0; n < outcnt; n++) {
                ch = *out++ = *in++;
                c = crc_32_tab[((int)c ^ ch) & 0xff] ^ (c >> 8);
        }
        crc = c;
        bytes_out += (u32)outcnt;
        output_ptr += (u32)outcnt;
        outcnt = 0;
        printf(".");
}


/****************************************************************************/
/* FUNCTION                                                                 */
/*                                                                          */
/*    error                                                                 */
/*                                                                          */
/* DESCRIPTION                                                              */
/*                                                                          */
/* CALLED BY                                                                */
/*                                                                          */
/* CALLS                                                                    */
/*                                                                          */
/* INPUTS                                                                   */
/*                                                                          */
/*                                                                          */
/* OUTPUTS                                                                  */
/*                                                                          */
/*    STATUS                                                                */
/*                                                                          */
/* HISTORY                                                                  */
/*                                                                          */
/*       NAME                 DATE            REMARKS                       */
/*                                                                          */
/*       yskim              20-06-2000    Created initial version 1.0       */
/*                                                                          */
/****************************************************************************/
void error(char *x)
{
        printf("\n\n");
        printf(x);
        printf("\n\n -- System halted");

        while(1);       /* Halt */
}


/* Huffman code lookup table entry--this entry is four bytes for machines
   that have 16-bit pointers (e.g. PC's in the small or medium model).
   Valid extra bits are 0..13.  e == 15 is EOB (end of block), e == 16
   means that v is a literal, 16 < e < 32 means that v is a pointer to
   the next table, which codes e - 16 bits, and lastly e == 99 indicates
   an unused code.  If a code with e == 99 is looked up, this implies an
   error in the data. */

struct huft {
  u8 e;                /* number of extra bits or operation */
  u8 b;                /* number of bits in this code or subcode */
  union {
    u16 n;              /* literal, length base, or distance base */
    struct huft *t;     /* pointer to next level of table */
  } v;
};


/* Function prototypes */
static int huft_build OF((unsigned *, unsigned, unsigned, u16 *, u16 *,
                   struct huft **, int *));
static int huft_free OF((struct huft *));
static int inflate_codes OF((struct huft *, struct huft *, int, int));
static int inflate_stored OF((void));
static int inflate_fixed OF((void));
static int inflate_dynamic OF((void));
static int inflate_block OF((int *));
static int inflate OF((void));


/* The inflate algorithm uses a sliding 32 K byte window on the uncompressed
   stream to find repeated byte strings.  This is implemented here as a
   circular buffer.  The index is updated simply by incrementing and then
   ANDing with 0x7fff (32K-1). */
/* It is left to other modules to supply the 32 K area.  It is assumed
   to be usable as if it were declared "u8 slide[32768];" or as just
   "u8 *slide;" and then malloc'ed in the latter case.  The definition
   must be in unzip.h, included above. */
/* unsigned wp;             current position in slide */

#define wp outcnt
#define flush_output(w) (wp=(w),flush_window())

/* Tables for deflate from PKZIP's appnote.txt. */
static unsigned border[] = {    /* Order of the bit length code lengths */
        16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15};
static u16 cplens[] = {         /* Copy lengths for literal codes 257..285 */
        3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31,
        35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258, 0, 0};
        /* note: see note #13 above about the 258 in this list. */
static u16 cplext[] = {         /* Extra bits for literal codes 257..285 */
        0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2,
        3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0, 99, 99}; /* 99==invalid */
static u16 cpdist[] = {         /* Copy offsets for distance codes 0..29 */
        1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193,