Descent3/unzip/infutil.c

/*
* Descent 3 
* Copyright (C) 2024 Parallax Software
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

/*
 * $Logfile: $
 * $Revision: $
 * $Date: $
 * $Author:  $
 *
 * <insert description of file here>
 *
 * $Log:  $
 *
 * $NoKeywords: $
 */

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

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

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

/* And'ing with mask[n] masks the lower n bits */
uInt inflate_mask[17] = {0x0000, 0x0001, 0x0003, 0x0007, 0x000f, 0x001f, 0x003f, 0x007f, 0x00ff,
                         0x01ff, 0x03ff, 0x07ff, 0x0fff, 0x1fff, 0x3fff, 0x7fff, 0xffff};

/* copy as much as possible from the sliding window to the output area */
int inflate_flush(inflate_blocks_statef *s, z_streamp z, int r) {
  uInt n;
  Bytef *p;
  Bytef *q;

  /* local copies of source and destination pointers */
  p = z->next_out;
  q = s->read;

  /* compute number of bytes to copy as far as end of window */
  n = (uInt)((q <= s->write ? s->write : s->end) - q);
  if (n > z->avail_out)
    n = z->avail_out;
  if (n && r == Z_BUF_ERROR)
    r = Z_OK;

  /* update counters */
  z->avail_out -= n;
  z->total_out += n;

  /* update check information */
  if (s->checkfn != Z_NULL)
    z->adler = s->check = (*s->checkfn)(s->check, q, n);

  /* copy as far as end of window */
  zmemcpy(p, q, n);
  p += n;
  q += n;

  /* see if more to copy at beginning of window */
  if (q == s->end) {
    /* wrap pointers */
    q = s->window;
    if (s->write == s->end)
      s->write = s->window;

    /* compute bytes to copy */
    n = (uInt)(s->write - q);
    if (n > z->avail_out)
      n = z->avail_out;
    if (n && r == Z_BUF_ERROR)
      r = Z_OK;

    /* update counters */
    z->avail_out -= n;
    z->total_out += n;

    /* update check information */
    if (s->checkfn != Z_NULL)
      z->adler = s->check = (*s->checkfn)(s->check, q, n);

    /* copy */
    zmemcpy(p, q, n);
    p += n;
    q += n;
  }

  /* update pointers */
  z->next_out = p;
  s->read = q;

  /* done */
  return r;
}