580 lines
16 KiB
C
580 lines
16 KiB
C
/* $OpenBSD: zopen.c,v 1.4 2017/01/22 01:55:08 krw Exp $ */
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/* $NetBSD: zopen.c,v 1.5 1995/03/26 09:44:53 glass Exp $ */
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/*-
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* Copyright (c) 1985, 1986, 1992, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Diomidis Spinellis and James A. Woods, derived from original
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* work by Spencer Thomas and Joseph Orost.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* From: @(#)zopen.c 8.1 (Berkeley) 6/27/93
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*/
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/*-
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* fcompress.c - File compression ala IEEE Computer, June 1984.
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*
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* Compress authors:
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* Spencer W. Thomas (decvax!utah-cs!thomas)
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* Jim McKie (decvax!mcvax!jim)
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* Steve Davies (decvax!vax135!petsd!peora!srd)
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* Ken Turkowski (decvax!decwrl!turtlevax!ken)
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* James A. Woods (decvax!ihnp4!ames!jaw)
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* Joe Orost (decvax!vax135!petsd!joe)
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*
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* Cleaned up and converted to library returning I/O streams by
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* Diomidis Spinellis <dds@doc.ic.ac.uk>.
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*
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* zopen(filename, mode, bits)
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* Returns a FILE * that can be used for read or write. The modes
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* supported are only "r" and "w". Seeking is not allowed. On
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* reading the file is decompressed, on writing it is compressed.
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* The output is compatible with compress(1) with 16 bit tables.
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* Any file produced by compress(1) can be read.
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*/
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#include <sys/stat.h>
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#include <ctype.h>
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#include <errno.h>
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#include <signal.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include "compress.h"
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#define MINIMUM(a, b) (((a) < (b)) ? (a) : (b))
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#define BITS 16 /* Default bits. */
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#define HSIZE 69001 /* 95% occupancy */
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#define ZBUFSIZ 8192 /* I/O buffer size */
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/* A code_int must be able to hold 2**BITS values of type int, and also -1. */
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typedef long code_int;
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typedef long count_int;
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static const u_char z_magic[] =
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{'\037', '\235'}; /* 1F 9D */
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#define BIT_MASK 0x1f /* Defines for third byte of header. */
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#define BLOCK_MASK 0x80
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/*
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* Masks 0x40 and 0x20 are free. I think 0x20 should mean that there is
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* a fourth header byte (for expansion).
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*/
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#define INIT_BITS 9 /* Initial number of bits/code. */
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#define MAXCODE(n_bits) ((1 << (n_bits)) - 1)
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struct s_zstate {
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int zs_fd; /* File stream for I/O */
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char zs_mode; /* r or w */
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enum {
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S_START, S_MAGIC, S_MIDDLE, S_EOF
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} zs_state; /* State of computation */
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int zs_n_bits; /* Number of bits/code. */
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int zs_maxbits; /* User settable max # bits/code. */
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code_int zs_maxcode; /* Maximum code, given n_bits. */
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code_int zs_maxmaxcode; /* Should NEVER generate this code. */
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count_int zs_htab[HSIZE];
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u_short zs_codetab[HSIZE];
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code_int zs_hsize; /* For dynamic table sizing. */
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code_int zs_free_ent; /* First unused entry. */
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/*
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* Block compression parameters -- after all codes are used up,
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* and compression rate changes, start over.
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*/
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int zs_block_compress;
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int zs_clear_flg;
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long zs_ratio;
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count_int zs_checkpoint;
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long zs_in_count; /* Length of input. */
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long zs_bytes_out; /* Length of output. */
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long zs_out_count; /* # of codes output (for debugging).*/
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u_char zs_buf[ZBUFSIZ]; /* I/O buffer */
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u_char *zs_bp; /* Current I/O window in the zs_buf */
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int zs_offset; /* Number of bits in the zs_buf */
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union {
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struct {
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long zs_fcode;
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code_int zs_ent;
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code_int zs_hsize_reg;
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int zs_hshift;
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} w; /* Write parameters */
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struct {
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u_char *zs_stackp, *zs_ebp;
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int zs_finchar;
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code_int zs_code, zs_oldcode, zs_incode;
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int zs_size;
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} r; /* Read parameters */
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} u;
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};
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/* Definitions to retain old variable names */
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#define zs_fcode u.w.zs_fcode
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#define zs_ent u.w.zs_ent
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#define zs_hsize_reg u.w.zs_hsize_reg
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#define zs_hshift u.w.zs_hshift
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#define zs_stackp u.r.zs_stackp
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#define zs_finchar u.r.zs_finchar
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#define zs_code u.r.zs_code
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#define zs_oldcode u.r.zs_oldcode
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#define zs_incode u.r.zs_incode
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#define zs_size u.r.zs_size
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#define zs_ebp u.r.zs_ebp
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/*
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* To save much memory, we overlay the table used by compress() with those
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* used by decompress(). The tab_prefix table is the same size and type as
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* the codetab. The tab_suffix table needs 2**BITS characters. We get this
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* from the beginning of htab. The output stack uses the rest of htab, and
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* contains characters. There is plenty of room for any possible stack
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* (stack used to be 8000 characters).
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*/
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#define htabof(i) zs->zs_htab[i]
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#define codetabof(i) zs->zs_codetab[i]
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#define tab_prefixof(i) codetabof(i)
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#define tab_suffixof(i) ((u_char *)(zs->zs_htab))[i]
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#define de_stack ((u_char *)&tab_suffixof(1 << BITS))
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#define CHECK_GAP 10000 /* Ratio check interval. */
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/*
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* the next two codes should not be changed lightly, as they must not
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* lie within the contiguous general code space.
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*/
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#define FIRST 257 /* First free entry. */
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#define CLEAR 256 /* Table clear output code. */
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static int cl_block(struct s_zstate *);
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static void cl_hash(struct s_zstate *, count_int);
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static int output(struct s_zstate *, code_int);
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/*-
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* Algorithm from "A Technique for High Performance Data Compression",
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* Terry A. Welch, IEEE Computer Vol 17, No 6 (June 1984), pp 8-19.
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*
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* Algorithm:
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* Modified Lempel-Ziv method (LZW). Basically finds common
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* substrings and replaces them with a variable size code. This is
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* deterministic, and can be done on the fly. Thus, the decompression
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* procedure needs no input table, but tracks the way the table was built.
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*/
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/*-
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* compress write
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*
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* Algorithm: use open addressing double hashing (no chaining) on the
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* prefix code / next character combination. We do a variant of Knuth's
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* algorithm D (vol. 3, sec. 6.4) along with G. Knott's relatively-prime
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* secondary probe. Here, the modular division first probe is gives way
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* to a faster exclusive-or manipulation. Also do block compression with
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* an adaptive reset, whereby the code table is cleared when the compression
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* ratio decreases, but after the table fills. The variable-length output
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* codes are re-sized at this point, and a special CLEAR code is generated
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* for the decompressor. Late addition: construct the table according to
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* file size for noticeable speed improvement on small files. Please direct
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* questions about this implementation to ames!jaw.
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*/
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int
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zwrite(void *cookie, const char *wbp, int num)
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{
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code_int i;
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int c, disp;
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struct s_zstate *zs;
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const u_char *bp;
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u_char tmp;
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int count;
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zs = cookie;
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count = num;
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bp = (u_char *)wbp;
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switch (zs->zs_state) {
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case S_MAGIC:
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return -1;
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case S_EOF:
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return 0;
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case S_START:
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zs->zs_state = S_MIDDLE;
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zs->zs_maxmaxcode = 1L << zs->zs_maxbits;
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if (write(zs->zs_fd, z_magic, sizeof(z_magic)) !=
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sizeof(z_magic))
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return (-1);
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tmp = (u_char)(zs->zs_maxbits | zs->zs_block_compress);
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if (write(zs->zs_fd, &tmp, sizeof(tmp)) != sizeof(tmp))
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return (-1);
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zs->zs_bp = zs->zs_buf;
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zs->zs_offset = 0;
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zs->zs_bytes_out = 3; /* Includes 3-byte header mojo. */
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zs->zs_out_count = 0;
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zs->zs_clear_flg = 0;
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zs->zs_ratio = 0;
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zs->zs_in_count = 1;
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zs->zs_checkpoint = CHECK_GAP;
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zs->zs_maxcode = MAXCODE(zs->zs_n_bits = INIT_BITS);
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zs->zs_free_ent = ((zs->zs_block_compress) ? FIRST : 256);
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zs->zs_ent = *bp++;
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--count;
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zs->zs_hshift = 0;
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for (zs->zs_fcode = (long)zs->zs_hsize; zs->zs_fcode < 65536L;
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zs->zs_fcode *= 2L)
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zs->zs_hshift++;
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/* Set hash code range bound. */
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zs->zs_hshift = 8 - zs->zs_hshift;
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zs->zs_hsize_reg = zs->zs_hsize;
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/* Clear hash table. */
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cl_hash(zs, (count_int)zs->zs_hsize_reg);
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case S_MIDDLE:
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for (i = 0; count-- > 0;) {
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c = *bp++;
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zs->zs_in_count++;
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zs->zs_fcode = (long)(((long)c << zs->zs_maxbits) +
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zs->zs_ent);
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/* Xor hashing. */
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i = ((c << zs->zs_hshift) ^ zs->zs_ent);
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if (htabof(i) == zs->zs_fcode) {
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zs->zs_ent = codetabof(i);
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continue;
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} else if ((long)htabof(i) < 0) /* Empty slot. */
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goto nomatch;
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/* Secondary hash (after G. Knott). */
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disp = zs->zs_hsize_reg - i;
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if (i == 0)
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disp = 1;
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probe: if ((i -= disp) < 0)
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i += zs->zs_hsize_reg;
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if (htabof(i) == zs->zs_fcode) {
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zs->zs_ent = codetabof(i);
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continue;
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}
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if ((long)htabof(i) >= 0)
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goto probe;
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nomatch: if (output(zs, (code_int) zs->zs_ent) == -1)
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return (-1);
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zs->zs_out_count++;
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zs->zs_ent = c;
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if (zs->zs_free_ent < zs->zs_maxmaxcode) {
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/* code -> hashtable */
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codetabof(i) = zs->zs_free_ent++;
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htabof(i) = zs->zs_fcode;
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} else if ((count_int)zs->zs_in_count >=
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zs->zs_checkpoint && zs->zs_block_compress) {
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if (cl_block(zs) == -1)
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return (-1);
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}
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}
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}
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return (num);
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}
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int
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z_close(void *cookie, struct z_info *info, const char *name, struct stat *sb)
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{
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struct s_zstate *zs;
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int rval;
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zs = cookie;
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if (zs->zs_mode == 'w') { /* Put out the final code. */
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if (output(zs, (code_int) zs->zs_ent) == -1) {
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(void)close(zs->zs_fd);
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free(zs);
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return (-1);
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}
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zs->zs_out_count++;
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if (output(zs, (code_int) - 1) == -1) {
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(void)close(zs->zs_fd);
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free(zs);
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return (-1);
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}
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}
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if (info != NULL) {
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info->mtime = 0;
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info->crc = (u_int32_t)-1;
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info->hlen = 0;
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info->total_in = (off_t)zs->zs_in_count;
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info->total_out = (off_t)zs->zs_bytes_out;
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}
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rval = close(zs->zs_fd);
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free(zs);
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return (rval);
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}
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static int
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zclose(void *cookie)
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{
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return z_close(cookie, NULL, NULL, NULL);
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}
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/*-
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* Output the given code.
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* Inputs:
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* code: A n_bits-bit integer. If == -1, then EOF. This assumes
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* that n_bits =< (long)wordsize - 1.
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* Outputs:
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* Outputs code to the file.
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* Assumptions:
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* Chars are 8 bits long.
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* Algorithm:
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* Maintain a BITS character long buffer (so that 8 codes will
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* fit in it exactly). Use the VAX insv instruction to insert each
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* code in turn. When the buffer fills up empty it and start over.
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*/
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static const u_char lmask[9] =
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{0xff, 0xfe, 0xfc, 0xf8, 0xf0, 0xe0, 0xc0, 0x80, 0x00};
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static const u_char rmask[9] =
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{0x00, 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x7f, 0xff};
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static int
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output(struct s_zstate *zs, code_int ocode)
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{
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int bits;
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if (ocode >= 0) {
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int r_off;
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u_char *bp;
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/* Get to the first byte. */
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bp = zs->zs_bp + (zs->zs_offset >> 3);
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r_off = zs->zs_offset & 7;
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bits = zs->zs_n_bits;
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/*
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* Since ocode is always >= 8 bits, only need to mask the first
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* hunk on the left.
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*/
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*bp = (*bp & rmask[r_off]) | ((ocode << r_off) & lmask[r_off]);
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bp++;
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bits -= (8 - r_off);
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ocode >>= 8 - r_off;
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/* Get any 8 bit parts in the middle (<=1 for up to 16 bits) */
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if (bits >= 8) {
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*bp++ = ocode;
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ocode >>= 8;
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bits -= 8;
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}
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/* Last bits. */
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if (bits)
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*bp = ocode;
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zs->zs_offset += zs->zs_n_bits;
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if (zs->zs_offset == (zs->zs_n_bits << 3)) {
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zs->zs_bp += zs->zs_n_bits;
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zs->zs_offset = 0;
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}
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/*
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* If the next entry is going to be too big for the ocode size,
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* then increase it, if possible.
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*/
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if (zs->zs_free_ent > zs->zs_maxcode ||
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(zs->zs_clear_flg > 0)) {
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/*
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* Write the whole buffer, because the input side won't
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* discover the size increase until after it has read it
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*/
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if (zs->zs_offset > 0) {
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zs->zs_bp += zs->zs_n_bits;
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zs->zs_offset = 0;
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}
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if (zs->zs_clear_flg) {
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zs->zs_maxcode =
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MAXCODE(zs->zs_n_bits = INIT_BITS);
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zs->zs_clear_flg = 0;
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} else {
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zs->zs_n_bits++;
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if (zs->zs_n_bits == zs->zs_maxbits)
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zs->zs_maxcode = zs->zs_maxmaxcode;
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else
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zs->zs_maxcode =
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MAXCODE(zs->zs_n_bits);
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}
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}
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if (zs->zs_bp + zs->zs_n_bits > &zs->zs_buf[ZBUFSIZ]) {
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bits = zs->zs_bp - zs->zs_buf;
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if (write(zs->zs_fd, zs->zs_buf, bits) != bits)
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return (-1);
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zs->zs_bytes_out += bits;
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if (zs->zs_offset > 0)
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fprintf (stderr, "zs_offset != 0\n");
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zs->zs_bp = zs->zs_buf;
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}
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} else {
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/* At EOF, write the rest of the buffer. */
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if (zs->zs_offset > 0)
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zs->zs_bp += (zs->zs_offset + 7) / 8;
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if (zs->zs_bp > zs->zs_buf) {
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bits = zs->zs_bp - zs->zs_buf;
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if (write(zs->zs_fd, zs->zs_buf, bits) != bits)
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return (-1);
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zs->zs_bytes_out += bits;
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}
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zs->zs_offset = 0;
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zs->zs_bp = zs->zs_buf;
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}
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return (0);
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}
|
|
|
|
/* Table clear for block compress. */
|
|
static int
|
|
cl_block(struct s_zstate *zs)
|
|
{
|
|
long rat;
|
|
|
|
zs->zs_checkpoint = zs->zs_in_count + CHECK_GAP;
|
|
|
|
if (zs->zs_in_count > 0x007fffff) { /* Shift will overflow. */
|
|
rat = zs->zs_bytes_out >> 8;
|
|
if (rat == 0) /* Don't divide by zero. */
|
|
rat = 0x7fffffff;
|
|
else
|
|
rat = zs->zs_in_count / rat;
|
|
} else {
|
|
/* 8 fractional bits. */
|
|
rat = (zs->zs_in_count << 8) / zs->zs_bytes_out;
|
|
}
|
|
if (rat > zs->zs_ratio)
|
|
zs->zs_ratio = rat;
|
|
else {
|
|
zs->zs_ratio = 0;
|
|
cl_hash(zs, (count_int) zs->zs_hsize);
|
|
zs->zs_free_ent = FIRST;
|
|
zs->zs_clear_flg = 1;
|
|
if (output(zs, (code_int) CLEAR) == -1)
|
|
return (-1);
|
|
}
|
|
return (0);
|
|
}
|
|
|
|
/* Reset code table. */
|
|
static void
|
|
cl_hash(struct s_zstate *zs, count_int cl_hsize)
|
|
{
|
|
count_int *htab_p;
|
|
long i, m1;
|
|
|
|
m1 = -1;
|
|
htab_p = zs->zs_htab + cl_hsize;
|
|
i = cl_hsize - 16;
|
|
do { /* Might use Sys V memset(3) here. */
|
|
*(htab_p - 16) = m1;
|
|
*(htab_p - 15) = m1;
|
|
*(htab_p - 14) = m1;
|
|
*(htab_p - 13) = m1;
|
|
*(htab_p - 12) = m1;
|
|
*(htab_p - 11) = m1;
|
|
*(htab_p - 10) = m1;
|
|
*(htab_p - 9) = m1;
|
|
*(htab_p - 8) = m1;
|
|
*(htab_p - 7) = m1;
|
|
*(htab_p - 6) = m1;
|
|
*(htab_p - 5) = m1;
|
|
*(htab_p - 4) = m1;
|
|
*(htab_p - 3) = m1;
|
|
*(htab_p - 2) = m1;
|
|
*(htab_p - 1) = m1;
|
|
htab_p -= 16;
|
|
} while ((i -= 16) >= 0);
|
|
for (i += 16; i > 0; i--)
|
|
*--htab_p = m1;
|
|
}
|
|
|
|
FILE *
|
|
zopen(const char *name, const char *mode, int bits)
|
|
{
|
|
FILE *fp;
|
|
int fd;
|
|
void *cookie;
|
|
if ((fd = open(name, (*mode=='r'? O_RDONLY:O_WRONLY|O_CREAT),
|
|
S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH)) == -1)
|
|
return NULL;
|
|
if ((cookie = z_open(fd, mode, NULL, bits, 0, 0)) == NULL) {
|
|
close(fd);
|
|
return NULL;
|
|
}
|
|
if ((fp = funopen(cookie, NULL,
|
|
(*mode == 'w'?zwrite:NULL), NULL, zclose)) == NULL) {
|
|
close(fd);
|
|
free(cookie);
|
|
return NULL;
|
|
}
|
|
return fp;
|
|
}
|
|
|
|
void *
|
|
z_open(int fd, const char *mode, char *name, int bits,
|
|
u_int32_t mtime, int gotmagic)
|
|
{
|
|
struct s_zstate *zs;
|
|
|
|
if ((mode[0] != 'r' && mode[0] != 'w') || mode[1] != '\0' ||
|
|
bits < 0 || bits > BITS) {
|
|
errno = EINVAL;
|
|
return (NULL);
|
|
}
|
|
|
|
if ((zs = calloc(1, sizeof(struct s_zstate))) == NULL)
|
|
return (NULL);
|
|
|
|
/* User settable max # bits/code. */
|
|
zs->zs_maxbits = bits ? bits : BITS;
|
|
/* Should NEVER generate this code. */
|
|
zs->zs_maxmaxcode = 1 << zs->zs_maxbits;
|
|
zs->zs_hsize = HSIZE; /* For dynamic table sizing. */
|
|
zs->zs_free_ent = 0; /* First unused entry. */
|
|
zs->zs_block_compress = BLOCK_MASK;
|
|
zs->zs_clear_flg = 0;
|
|
zs->zs_ratio = 0;
|
|
zs->zs_checkpoint = CHECK_GAP;
|
|
zs->zs_in_count = 0; /* Length of input. */
|
|
zs->zs_out_count = 0; /* # of codes output (for debugging).*/
|
|
zs->zs_state = gotmagic ? S_MAGIC : S_START;
|
|
zs->zs_offset = 0;
|
|
zs->zs_size = 0;
|
|
zs->zs_mode = mode[0];
|
|
zs->zs_bp = zs->zs_ebp = zs->zs_buf;
|
|
|
|
zs->zs_fd = fd;
|
|
return zs;
|
|
}
|