strm->total_in = strm->total_out = 0;
    strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */
    strm->data_type = Z_UNKNOWN;

    s = (deflate_state *)strm->state;
    s->pending = 0;
    s->pending_out = s->pending_buf;

    if (s->noheader < 0) {
        s->noheader = 0; /* was set to -1 by deflate(..., Z_FINISH); */
    }
    s->status = s->noheader ? BUSY_STATE : INIT_STATE;
    strm->adler = 1;
    s->last_flush = Z_NO_FLUSH;

    _tr_init(s);
    lm_init(s);

    return Z_OK;
}

/* ========================================================================= */
int ZEXPORT deflateParams(strm, level, strategy)
    z_streamp strm;
    int level;
    int strategy;
{
    deflate_state *s;
    compress_func func;
    int err = Z_OK;

    if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
    s = strm->state;

    if (level == Z_DEFAULT_COMPRESSION) {
	level = 6;
    }
    if (level < 0 || level > 9 || strategy < 0 || strategy > Z_HUFFMAN_ONLY) {
	return Z_STREAM_ERROR;
    }
    func = configuration_table[s->level].func;

    if (func != configuration_table[level].func && strm->total_in != 0) {
	/* Flush the last buffer: */
	err = deflate(strm, Z_PARTIAL_FLUSH);
    }
    if (s->level != level) {
	s->level = level;
	s->max_lazy_match   = configuration_table[level].max_lazy;
	s->good_match       = configuration_table[level].good_length;
	s->nice_match       = configuration_table[level].nice_length;
	s->max_chain_length = configuration_table[level].max_chain;
    }
    s->strategy = strategy;
    return err;
}

/* =========================================================================
 * Put a short in the pending buffer. The 16-bit value is put in MSB order.
 * IN assertion: the stream state is correct and there is enough room in
 * pending_buf.
 */
local void putShortMSB (s, b)
    deflate_state *s;
    uInt b;
{
    put_byte(s, (Byte)(b >> 8));
    put_byte(s, (Byte)(b & 0xff));
}   

/* =========================================================================
 * Flush as much pending output as possible. All deflate() output goes
 * through this function so some applications may wish to modify it
 * to avoid allocating a large strm->next_out buffer and copying into it.
 * (See also read_buf()).
 */
local void flush_pending(strm)
    z_streamp strm;
{
    unsigned len = strm->state->pending;

    if (len > strm->avail_out) len = strm->avail_out;
    if (len == 0) return;

    zmemcpy(strm->next_out, strm->state->pending_out, len);
    strm->next_out  += len;
    strm->state->pending_out  += len;
    strm->total_out += len;
    strm->avail_out  -= len;
    strm->state->pending -= len;
    if (strm->state->pending == 0) {
        strm->state->pending_out = strm->state->pending_buf;
    }
}

/* ========================================================================= */
int ZEXPORT deflate (strm, flush)
    z_streamp strm;
    int flush;
{
    int old_flush; /* value of flush param for previous deflate call */
    deflate_state *s;

    if (strm == Z_NULL || strm->state == Z_NULL ||
	flush > Z_FINISH || flush < 0) {
        return Z_STREAM_ERROR;
    }
    s = strm->state;

    if (strm->next_out == Z_NULL ||
        (strm->next_in == Z_NULL && strm->avail_in != 0) ||
	(s->status == FINISH_STATE && flush != Z_FINISH)) {
        ERR_RETURN(strm, Z_STREAM_ERROR);
    }
    if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR);

    s->strm = strm; /* just in case */
    old_flush = s->last_flush;
    s->last_flush = flush;

    /* Write the zlib header */
    if (s->status == INIT_STATE) {

        uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8;
        uInt level_flags = (s->level-1) >> 1;

        if (level_flags > 3) level_flags = 3;
        header |= (level_flags << 6);
	if (s->strstart != 0) header |= PRESET_DICT;
        header += 31 - (header % 31);

        s->status = BUSY_STATE;
        putShortMSB(s, header);

	/* Save the adler32 of the preset dictionary: */
	if (s->strstart != 0) {
	    putShortMSB(s, (uInt)(strm->adler >> 16));
	    putShortMSB(s, (uInt)(strm->adler & 0xffff));
	}
	strm->adler = 1L;
    }

    /* Flush as much pending output as possible */
    if (s->pending != 0) {
        flush_pending(strm);
        if (strm->avail_out == 0) {
	    /* Since avail_out is 0, deflate will be called again with
	     * more output space, but possibly with both pending and
	     * avail_in equal to zero. There won't be anything to do,
	     * but this is not an error situation so make sure we
	     * return OK instead of BUF_ERROR at next call of deflate:
             */
	    s->last_flush = -1;
	    return Z_OK;
	}

    /* Make sure there is something to do and avoid duplicate consecutive
     * flushes. For repeated and useless calls with Z_FINISH, we keep
     * returning Z_STREAM_END instead of Z_BUFF_ERROR.
     */
    } else if (strm->avail_in == 0 && flush <= old_flush &&
	       flush != Z_FINISH) {
        ERR_RETURN(strm, Z_BUF_ERROR);
    }

    /* User must not provide more input after the first FINISH: */
    if (s->status == FINISH_STATE && strm->avail_in != 0) {
        ERR_RETURN(strm, Z_BUF_ERROR);
    }

    /* Start a new block or continue the current one.
     */
    if (strm->avail_in != 0 || s->lookahead != 0 ||
        (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) {
        block_state bstate;

	bstate = (*(configuration_table[s->level].func))(s, flush);

        if (bstate == finish_started || bstate == finish_done) {
            s->status = FINISH_STATE;
        }
        if (bstate == need_more || bstate == finish_started) {
	    if (strm->avail_out == 0) {
	        s->last_flush = -1; /* avoid BUF_ERROR next call, see above */
	    }
	    return Z_OK;
	    /* If flush != Z_NO_FLUSH && avail_out == 0, the next call
	     * of deflate should use the same flush parameter to make sure
	     * that the flush is complete. So we don't have to output an
	     * empty block here, this will be done at next call. This also
	     * ensures that for a very small output buffer, we emit at most
	     * one empty block.
	     */
	}
        if (bstate == block_done) {
            if (flush == Z_PARTIAL_FLUSH) {
                _tr_align(s);
            } else { /* FULL_FLUSH or SYNC_FLUSH */
                _tr_stored_block(s, (char*)0, 0L, 0);
                /* For a full flush, this empty block will be recognized
                 * as a special marker by inflate_sync().
                 */
                if (flush == Z_FULL_FLUSH) {
                    CLEAR_HASH(s);             /* forget history */
                }
            }
            flush_pending(strm);
	    if (strm->avail_out == 0) {
	      s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */
	      return Z_OK;
	    }
        }
    }
    Assert(strm->avail_out > 0, "bug2");

    if (flush != Z_FINISH) return Z_OK;
    if (s->noheader) return Z_STREAM_END;

    /* Write the zlib trailer (adler32) */
    putShortMSB(s, (uInt)(strm->adler >> 16));
    putShortMSB(s, (uInt)(strm->adler & 0xffff));
    flush_pending(strm);
    /* If avail_out is zero, the application will call deflate again
     * to flush the rest.
     */
    s->noheader = -1; /* write the trailer only once! */
    return s->pending != 0 ? Z_OK : Z_STREAM_END;
}

/* ========================================================================= */
int ZEXPORT deflateEnd (strm)
    z_streamp strm;
{
    int status;

    if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;

    status = strm->state->status;
    if (status != INIT_STATE && status != BUSY_STATE &&
	status != FINISH_STATE) {
      return Z_STREAM_ERROR;
    }

    /* Deallocate in reverse order of allocations: */
    TRY_FREE(strm, strm->state->pending_buf);
    TRY_FREE(strm, strm->state->head);
    TRY_FREE(strm, strm->state->prev);
    TRY_FREE(strm, strm->state->window);

    ZFREE(strm, strm->state);
    strm->state = Z_NULL;

    return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK;
}

/* =========================================================================
 * Copy the source state to the destination state.
 * To simplify the source, this is not supported for 16-bit MSDOS (which
 * doesn't have enough memory anyway to duplicate compression states).
 */
int ZEXPORT deflateCopy (dest, source)
    z_streamp dest;
    z_streamp source;
{
#ifdef MAXSEG_64K
    return Z_STREAM_ERROR;
#else
    deflate_state *ds;
    deflate_state *ss;
    ushf *overlay;


    if (source == Z_NULL || dest == Z_NULL || source->state == Z_NULL) {
        return Z_STREAM_ERROR;
    }

    ss = source->state;

    *dest = *source;

    ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state));
    if (ds == Z_NULL) return Z_MEM_ERROR;
    dest->state = (struct internal_state FAR *) ds;
    *ds = *ss;
    ds->strm = dest;

    ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte));
    ds->prev   = (Posf *)  ZALLOC(dest, ds->w_size, sizeof(Pos));
    ds->head   = (Posf *)  ZALLOC(dest, ds->hash_size, sizeof(Pos));
    overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2);
    ds->pending_buf = (uchf *) overlay;

    if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL ||
        ds->pending_buf == Z_NULL) {
        deflateEnd (dest);
        return Z_MEM_ERROR;
    }
    /* following zmemcpy do not work for 16-bit MSDOS */
    zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte));
    zmemcpy(ds->prev, ss->prev, ds->w_size * sizeof(Pos));
    zmemcpy(ds->head, ss->head, ds->hash_size * sizeof(Pos));
    zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size);

    ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf);
    ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush);
    ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize;

    ds->l_desc.dyn_tree = ds->dyn_ltree;
    ds->d_desc.dyn_tree = ds->dyn_dtree;
    ds->bl_desc.dyn_tree = ds->bl_tree;

    return Z_OK;
#endif
}

/* ===========================================================================
 * Read a new buffer from the current input stream, update the adler32
 * and total number of bytes read.  All deflate() input goes through
 * this function so some applications may wish to modify it to avoid
 * allocating a large strm->next_in buffer and copying from it.
 * (See also flush_pending()).
 */
local int read_buf(strm, buf, size)
    z_streamp strm;
    Bytef *buf;
    unsigned size;
{
    unsigned len = strm->avail_in;

    if (len > size) len = size;
    if (len == 0) return 0;

    strm->avail_in  -= len;

    if (!strm->state->noheader) {
        strm->adler = adler32(strm->adler, strm->next_in, len);
    }
    zmemcpy(buf, strm->next_in, len);
    strm->next_in  += len;