Click here to Skip to main content
15,885,278 members
Articles / Containers / Virtual Machine

TOOL

Rate me:
Please Sign up or sign in to vote.
4.98/5 (52 votes)
23 Oct 200676 min read 230.2K   5.4K   147  
TOOL (Tiny Object Oriented Language) is an easily-embedded, object-oriented, C++-like-language interpreter. The purpose of this article is to introduce the TOOL interpreter and language from the perspective of a person who has a desire to include a scripting solution as part of his project.
/* inffast.c -- process literals and length/distance pairs fast
 * Copyright (C) 1995-2002 Mark Adler
 * For conditions of distribution and use, see copyright notice in zlib.h 
 */

#include "zutil.h"
#include "inftrees.h"
#include "infblock.h"
#include "infcodes.h"
#include "infutil.h"
#include "inffast.h"

struct inflate_codes_state {int dummy;}; /* for buggy compilers */

/* simplify the use of the inflate_huft type with some defines */
#define exop word.what.Exop
#define bits word.what.Bits

/* macros for bit input with no checking and for returning unused bytes */
#define GRABBITS(j) {while(k<(j)){b|=((uLong)NEXTBYTE)<<k;k+=8;}}
#define UNGRAB {c=z->avail_in-n;c=(k>>3)<c?k>>3:c;n+=c;p-=c;k-=c<<3;}

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

int inflate_fast(bl, bd, tl, td, s, z)
uInt bl, bd;
inflate_huft *tl;
inflate_huft *td; /* need separate declaration for Borland C++ */
inflate_blocks_statef *s;
z_streamp z;
{
  inflate_huft *t;      /* temporary pointer */
  uInt e;               /* extra bits or operation */
  uLong b;              /* bit buffer */
  uInt k;               /* bits in bit buffer */
  Bytef *p;             /* input data pointer */
  uInt n;               /* bytes available there */
  Bytef *q;             /* output window write pointer */
  uInt m;               /* bytes to end of window or read pointer */
  uInt ml;              /* mask for literal/length tree */
  uInt md;              /* mask for distance tree */
  uInt c;               /* bytes to copy */
  uInt d;               /* distance back to copy from */
  Bytef *r;             /* copy source pointer */

  /* load input, output, bit values */
  LOAD

  /* 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 */
    GRABBITS(20)                /* max bits for literal/length code */
    if ((e = (t = tl + ((uInt)b & ml))->exop) == 0)
    {
      DUMPBITS(t->bits)
      Tracevv((stderr, t->base >= 0x20 && t->base < 0x7f ?
                "inflate:         * literal '%c'\n" :
                "inflate:         * literal 0x%02x\n", t->base));
      *q++ = (Byte)t->base;
      m--;
      continue;
    }
    do {
      DUMPBITS(t->bits)
      if (e & 16)
      {
        /* get extra bits for length */
        e &= 15;
        c = t->base + ((uInt)b & inflate_mask[e]);
        DUMPBITS(e)
        Tracevv((stderr, "inflate:         * length %u\n", c));

        /* decode distance base of block to copy */
        GRABBITS(15);           /* max bits for distance code */
        e = (t = td + ((uInt)b & md))->exop;
        do {
          DUMPBITS(t->bits)
          if (e & 16)
          {
            /* get extra bits to add to distance base */
            e &= 15;
            GRABBITS(e)         /* get extra bits (up to 13) */
            d = t->base + ((uInt)b & inflate_mask[e]);
            DUMPBITS(e)
            Tracevv((stderr, "inflate:         * distance %u\n", d));

            /* do the copy */
            m -= c;
            r = q - d;
            if (r < s->window)                  /* wrap if needed */
            {
              do {
                r += s->end - s->window;        /* force pointer in window */
              } while (r < s->window);          /* covers invalid distances */
              e = s->end - r;
              if (c > e)
              {
                c -= e;                         /* wrapped copy */
                do {
                    *q++ = *r++;
                } while (--e);
                r = s->window;
                do {
                    *q++ = *r++;
                } while (--c);
              }
              else                              /* normal copy */
              {
                *q++ = *r++;  c--;
                *q++ = *r++;  c--;
                do {
                    *q++ = *r++;
                } while (--c);
              }
            }
            else                                /* normal copy */
            {
              *q++ = *r++;  c--;
              *q++ = *r++;  c--;
              do {
                *q++ = *r++;
              } while (--c);
            }
            break;
          }
          else if ((e & 64) == 0)
          {
            t += t->base;
            e = (t += ((uInt)b & inflate_mask[e]))->exop;
          }
          else
          {
            z->msg = (char*)"invalid distance code";
            UNGRAB
            UPDATE
            return Z_DATA_ERROR;
          }
        } while (1);
        break;
      }
      if ((e & 64) == 0)
      {
        t += t->base;
        if ((e = (t += ((uInt)b & inflate_mask[e]))->exop) == 0)
        {
          DUMPBITS(t->bits)
          Tracevv((stderr, t->base >= 0x20 && t->base < 0x7f ?
                    "inflate:         * literal '%c'\n" :
                    "inflate:         * literal 0x%02x\n", t->base));
          *q++ = (Byte)t->base;
          m--;
          break;
        }
      }
      else if (e & 32)
      {
        Tracevv((stderr, "inflate:         * end of block\n"));
        UNGRAB
        UPDATE
        return Z_STREAM_END;
      }
      else
      {
        z->msg = (char*)"invalid literal/length code";
        UNGRAB
        UPDATE
        return Z_DATA_ERROR;
      }
    } while (1);
  } while (m >= 258 && n >= 10);

  /* not enough input or output--restore pointers and return */
  UNGRAB
  UPDATE
  return Z_OK;
}

By viewing downloads associated with this article you agree to the Terms of Service and the article's licence.

If a file you wish to view isn't highlighted, and is a text file (not binary), please let us know and we'll add colourisation support for it.

License

This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here


Written By
Web Developer
United States United States
This member has not yet provided a Biography. Assume it's interesting and varied, and probably something to do with programming.

Comments and Discussions