infutil.h

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/* infutil.h -- types and macros common to blocks and codes
 * Copyright (C) 1995-1998 Mark Adler
 * For conditions of distribution and use, see copyright notice in zlib.h 
 */

/* WARNING: this file should *not* be used by applications. It is
   part of the implementation of the compression library and is
   subject to change. Applications should only use zlib.h.
 */

#ifndef _INFUTIL_H
#define _INFUTIL_H

#include "zconf.h"
#include "inftrees.h"
#include "infcodes.h"

typedef enum {
      TYPE,     /* get type bits (3, including end bit) */
      LENS,     /* get lengths for stored */
      STORED,   /* processing stored block */
      TABLE,    /* get table lengths */
      BTREE,    /* get bit lengths tree for a dynamic block */
      DTREE,    /* get length, distance trees for a dynamic block */
      CODES,    /* processing fixed or dynamic block */
      DRY,      /* output remaining window bytes */
      B_DONE,   /* finished last block, done */
      B_BAD}    /* got a data error--stuck here */
inflate_block_mode;

/* inflate blocks semi-private state */
struct inflate_blocks_state {

  /* mode */
  inflate_block_mode  mode;     /* current inflate_block mode */

  /* mode dependent information */
  union {
    uInt left;          /* if STORED, bytes left to copy */
    struct {
      uInt table;               /* table lengths (14 bits) */
      uInt index;               /* index into blens (or border) */
      uIntf *blens;             /* bit lengths of codes */
      uInt bb;                  /* bit length tree depth */
      inflate_huft *tb;         /* bit length decoding tree */
    } trees;            /* if DTREE, decoding info for trees */
    struct {
      inflate_codes_statef 
         *codes;
    } decode;           /* if CODES, current state */
  } sub;                /* submode */
  uInt last;            /* true if this block is the last block */

  /* mode independent information */
  uInt bitk;            /* bits in bit buffer */
  uLong bitb;           /* bit buffer */
  inflate_huft *hufts;  /* single malloc for tree space */
  Bytef *window;        /* sliding window */
  Bytef *end;           /* one byte after sliding window */
  Bytef *read;          /* window read pointer */
  Bytef *write;         /* window write pointer */
  check_func checkfn;   /* check function */
  uLong check;          /* check on output */

};


/* defines for inflate input/output */
/*   update pointers and return */
#define UPDBITS {s->bitb=b;s->bitk=k;}
#define UPDIN {z->avail_in=n;z->total_in+=p-z->next_in;z->next_in=p;}
#define UPDOUT {s->write=q;}
#define UPDATE {UPDBITS UPDIN UPDOUT}
#define LEAVE {UPDATE return zlib_fs_inflate_flush(s,z,r);}
/*   get bytes and bits */
#define LOADIN {p=z->next_in;n=z->avail_in;b=s->bitb;k=s->bitk;}
#define NEEDBYTE {if(n)r=Z_OK;else LEAVE}
#define NEXTBYTE (n--,*p++)
#define NEEDBITS(j) {while(k<(j)){NEEDBYTE;b|=((uLong)NEXTBYTE)<<k;k+=8;}}
#define DUMPBITS(j) {b>>=(j);k-=(j);}
/*   output bytes */
#define WAVAIL (uInt)(q<s->read?s->read-q-1:s->end-q)
#define LOADOUT {q=s->write;m=(uInt)WAVAIL;}
#define WRAP {if(q==s->end&&s->read!=s->window){q=s->window;m=(uInt)WAVAIL;}}
#define FLUSH {UPDOUT r=zlib_fs_inflate_flush(s,z,r); LOADOUT}
#define NEEDOUT {if(m==0){WRAP if(m==0){FLUSH WRAP if(m==0) LEAVE}}r=Z_OK;}
#define OUTBYTE(a) {*q++=(Byte)(a);m--;}
/*   load local pointers */
#define LOAD {LOADIN LOADOUT}

/* masks for lower bits (size given to avoid silly warnings with Visual C++) */
extern uInt zlib_fs_inflate_mask[17];

/* copy as much as possible from the sliding window to the output area */
extern int zlib_fs_inflate_flush OF((
    inflate_blocks_statef *,
    z_streamp ,
    int));

/* inflate private state */
typedef enum {
      METHOD,   /* waiting for method byte */
      FLAG,     /* waiting for flag byte */
      DICT4,    /* four dictionary check bytes to go */
      DICT3,    /* three dictionary check bytes to go */
      DICT2,    /* two dictionary check bytes to go */
      DICT1,    /* one dictionary check byte to go */
      DICT0,    /* waiting for inflateSetDictionary */
      BLOCKS,   /* decompressing blocks */
      CHECK4,   /* four check bytes to go */
      CHECK3,   /* three check bytes to go */
      CHECK2,   /* two check bytes to go */
      CHECK1,   /* one check byte to go */
      I_DONE,   /* finished check, done */
      I_BAD}    /* got an error--stay here */
inflate_mode;

struct internal_state {

  /* mode */
  inflate_mode  mode;   /* current inflate mode */

  /* mode dependent information */
  union {
    uInt method;        /* if FLAGS, method byte */
    struct {
      uLong was;                /* computed check value */
      uLong need;               /* stream check value */
    } check;            /* if CHECK, check values to compare */
    uInt marker;        /* if BAD, inflateSync's marker bytes count */
  } sub;        /* submode */

  /* mode independent information */
  int  nowrap;          /* flag for no wrapper */
  uInt wbits;           /* log2(window size)  (8..15, defaults to 15) */
  inflate_blocks_statef 
    *blocks;            /* current inflate_blocks state */

};

/* inflate codes private state */
typedef enum {        /* waiting for "i:"=input, "o:"=output, "x:"=nothing */
      START,    /* x: set up for LEN */
      LEN,      /* i: get length/literal/eob next */
      LENEXT,   /* i: getting length extra (have base) */
      DIST,     /* i: get distance next */
      DISTEXT,  /* i: getting distance extra */
      COPY,     /* o: copying bytes in window, waiting for space */
      LIT,      /* o: got literal, waiting for output space */
      WASH,     /* o: got eob, possibly still output waiting */
      END,      /* x: got eob and all data flushed */
      BADCODE}  /* x: got error */
inflate_codes_mode;

struct inflate_codes_state {

  /* mode */
  inflate_codes_mode mode;      /* current inflate_codes mode */

  /* mode dependent information */
  uInt len;
  union {
    struct {
      inflate_huft *tree;       /* pointer into tree */
      uInt need;                /* bits needed */
    } code;             /* if LEN or DIST, where in tree */
    uInt lit;           /* if LIT, literal */
    struct {
      uInt get;                 /* bits to get for extra */
      uInt dist;                /* distance back to copy from */
    } copy;             /* if EXT or COPY, where and how much */
  } sub;                /* submode */

  /* mode independent information */
  Byte lbits;           /* ltree bits decoded per branch */
  Byte dbits;           /* dtree bits decoder per branch */
  inflate_huft *ltree;          /* literal/length/eob tree */
  inflate_huft *dtree;          /* distance tree */

};

/* memory allocation for inflation */

struct inflate_workspace {
	inflate_codes_statef working_state;
	struct inflate_blocks_state working_blocks_state;
	struct internal_state internal_state;
	unsigned int tree_work_area_1[19];
	unsigned int tree_work_area_2[288];
	unsigned working_blens[258 + 0x1f + 0x1f];
	inflate_huft working_hufts[MANY];
	unsigned char working_window[1 << MAX_WBITS];
};

#define WS(z) ((struct inflate_workspace *)(z->workspace))

#endif