ref: a1c990a6323d3834f876076edb098ddcd8a54098
dir: /src/lzw/zopen.c/
/* $NetBSD: zopen.c,v 1.8 2003/08/07 11:13:29 agc Exp $ */
/*-
* Copyright (c) 1985, 1986, 1992, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Diomidis Spinellis and James A. Woods, derived from original
* work by Spencer Thomas and Joseph Orost.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/*-
*
* Copyright (c) 2004, 2005
* Albert Chin-A-Young.
*
* Modified to work with FreeType's PCF driver.
*
*/
#if defined(LIBC_SCCS) && !defined(lint)
#if 0
static char sccsid[] = "@(#)zopen.c 8.1 (Berkeley) 6/27/93";
#else
static char rcsid[] = "$NetBSD: zopen.c,v 1.8 2003/08/07 11:13:29 agc Exp $";
#endif
#endif /* LIBC_SCCS and not lint */
/*-
* fcompress.c - File compression ala IEEE Computer, June 1984.
*
* Compress authors:
* Spencer W. Thomas (decvax!utah-cs!thomas)
* Jim McKie (decvax!mcvax!jim)
* Steve Davies (decvax!vax135!petsd!peora!srd)
* Ken Turkowski (decvax!decwrl!turtlevax!ken)
* James A. Woods (decvax!ihnp4!ames!jaw)
* Joe Orost (decvax!vax135!petsd!joe)
*
* Cleaned up and converted to library returning I/O streams by
* Diomidis Spinellis <[email protected]>.
*/
#include <ctype.h>
#if 0
#include <signal.h>
#endif
#include <stdlib.h>
#include <string.h>
#if 0
#include <unistd.h>
#endif
#if 0
static char_type magic_header[] =
{ 0x1f, 0x9d }; /* 1F 9D */
#endif
#define BIT_MASK 0x1f /* Defines for third byte of header. */
#define BLOCK_MASK 0x80
/*
* Masks 0x40 and 0x20 are free. I think 0x20 should mean that there is
* a fourth header byte (for expansion).
*/
#define INIT_BITS 9 /* Initial number of bits/code. */
#define MAXCODE(n_bits) ((1 << (n_bits)) - 1)
/* Definitions to retain old variable names */
#define fp zs->zs_fp
#define state zs->zs_state
#define n_bits zs->zs_n_bits
#define maxbits zs->zs_maxbits
#define maxcode zs->zs_maxcode
#define maxmaxcode zs->zs_maxmaxcode
#define htab zs->zs_htab
#define codetab zs->zs_codetab
#define hsize zs->zs_hsize
#define free_ent zs->zs_free_ent
#define block_compress zs->zs_block_compress
#define clear_flg zs->zs_clear_flg
#define offset zs->zs_offset
#define in_count zs->zs_in_count
#define buf_len zs->zs_buf_len
#define buf zs->zs_buf
#define stackp zs->u.r.zs_stackp
#define finchar zs->u.r.zs_finchar
#define code zs->u.r.zs_code
#define oldcode zs->u.r.zs_oldcode
#define incode zs->u.r.zs_incode
#define roffset zs->u.r.zs_roffset
#define size zs->u.r.zs_size
#define gbuf zs->u.r.zs_gbuf
/*
* To save much memory, we overlay the table used by compress() with those
* used by decompress(). The tab_prefix table is the same size and type as
* the codetab. The tab_suffix table needs 2**BITS characters. We get this
* from the beginning of htab. The output stack uses the rest of htab, and
* contains characters. There is plenty of room for any possible stack
* (stack used to be 8000 characters).
*/
#define htabof(i) htab[i]
#define codetabof(i) codetab[i]
#define tab_prefixof(i) codetabof(i)
#define tab_suffixof(i) ((char_type *)(htab))[i]
#define de_stack ((char_type *)&tab_suffixof(1 << BITS))
#define CHECK_GAP 10000 /* Ratio check interval. */
/*
* the next two codes should not be changed lightly, as they must not
* lie within the contiguous general code space.
*/
#define FIRST 257 /* First free entry. */
#define CLEAR 256 /* Table clear output code. */
/*-
* Algorithm from "A Technique for High Performance Data Compression",
* Terry A. Welch, IEEE Computer Vol 17, No 6 (June 1984), pp 8-19.
*
* Algorithm:
* Modified Lempel-Ziv method (LZW). Basically finds common
* substrings and replaces them with a variable size code. This is
* deterministic, and can be done on the fly. Thus, the decompression
* procedure needs no input table, but tracks the way the table was built.
*/
#if 0
static int
zclose(s_zstate_t *zs)
{
free(zs);
return (0);
}
#endif
/*-
* Output the given code.
* Inputs:
* code: A n_bits-bit integer. If == -1, then EOF. This assumes
* that n_bits =< (long)wordsize - 1.
* Outputs:
* Outputs code to the file.
* Assumptions:
* Chars are 8 bits long.
* Algorithm:
* Maintain a BITS character long buffer (so that 8 codes will
* fit in it exactly). Use the VAX insv instruction to insert each
* code in turn. When the buffer fills up empty it and start over.
*/
static const char_type rmask[9] =
{0x00, 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x7f, 0xff};
/*
* Decompress read. This routine adapts to the codes in the file building
* the "string" table on-the-fly; requiring no table to be stored in the
* compressed file. The tables used herein are shared with those of the
* compress() routine. See the definitions above.
*/
static int
zread(s_zstate_t *zs)
{
unsigned int count;
if (in_count == 0)
return -1;
if (zs->avail_out == 0)
return 0;
count = zs->avail_out;
switch (state) {
case S_START:
state = S_MIDDLE;
break;
case S_MIDDLE:
goto middle;
case S_EOF:
goto eof;
}
maxbits = *(zs->next_in); /* Set -b from file. */
zs->avail_in--;
zs->next_in++;
zs->total_in++;
in_count--;
block_compress = maxbits & BLOCK_MASK;
maxbits &= BIT_MASK;
maxmaxcode = 1L << maxbits;
if (maxbits > BITS) {
return -1;
}
/* As above, initialize the first 256 entries in the table. */
maxcode = MAXCODE(n_bits = INIT_BITS);
for (code = 255; code >= 0; code--) {
tab_prefixof(code) = 0;
tab_suffixof(code) = (char_type) code;
}
free_ent = block_compress ? FIRST : 256;
finchar = oldcode = getcode(zs);
if (oldcode == -1) /* EOF already? */
return 0; /* Get out of here */
/* First code must be 8 bits = char. */
*(zs->next_out)++ = (unsigned char)finchar;
zs->total_out++;
count--;
stackp = de_stack;
while ((code = getcode(zs)) > -1) {
if ((code == CLEAR) && block_compress) {
for (code = 255; code >= 0; code--)
tab_prefixof(code) = 0;
clear_flg = 1;
free_ent = FIRST - 1;
if ((code = getcode(zs)) == -1)
/* O, untimely death! */
break;
}
incode = code;
/* Special case for KwKwK string. */
if (code >= free_ent) {
*stackp++ = (unsigned char)finchar;
code = oldcode;
}
/* Generate output characters in reverse order. */
while (code >= 256) {
*stackp++ = tab_suffixof(code);
code = tab_prefixof(code);
}
*stackp++ = (unsigned char)(finchar = tab_suffixof(code));
/* And put them out in forward order. */
middle:
if (stackp == de_stack)
continue;
do {
if (count-- == 0) {
return zs->avail_out;
}
*(zs->next_out)++ = *--stackp;
zs->total_out++;
} while (stackp > de_stack);
/* Generate the new entry. */
if ((code = free_ent) < maxmaxcode) {
tab_prefixof(code) = (unsigned short)oldcode;
tab_suffixof(code) = (unsigned char)finchar;
free_ent = code + 1;
}
/* Remember previous code. */
oldcode = incode;
}
/* state = S_EOF; */
eof: return (zs->avail_out - count);
}
/*-
* Read one code from the standard input. If EOF, return -1.
* Inputs:
* stdin
* Outputs:
* code or -1 is returned.
*/
static code_int
getcode(s_zstate_t *zs)
{
code_int gcode;
int r_off, bits;
char_type *bp;
bp = gbuf;
if (clear_flg > 0 || roffset >= size || free_ent > maxcode) {
/*
* If the next entry will be too big for the current gcode
* size, then we must increase the size. This implies reading
* a new buffer full, too.
*/
if (free_ent > maxcode) {
n_bits++;
if (n_bits == maxbits) /* Won't get any bigger now. */
maxcode = maxmaxcode;
else
maxcode = MAXCODE(n_bits);
}
if (clear_flg > 0) {
maxcode = MAXCODE(n_bits = INIT_BITS);
clear_flg = 0;
}
if ( zs->avail_in < (unsigned int)n_bits && in_count > (long)n_bits ) {
memcpy (buf, zs->next_in, zs->avail_in);
buf_len = (unsigned char)zs->avail_in;
zs->avail_in = 0;
return -1;
}
if (buf_len) {
memcpy (gbuf, buf, buf_len);
memcpy (gbuf + buf_len, zs->next_in,
n_bits - buf_len);
zs->next_in += n_bits - buf_len;
zs->avail_in -= n_bits - buf_len;
buf_len = 0;
zs->total_in += n_bits;
size = n_bits;
in_count -= n_bits;
} else {
if (in_count > n_bits) {
memcpy (gbuf, zs->next_in, n_bits);
zs->next_in += n_bits;
zs->avail_in -= n_bits;
zs->total_in += n_bits;
size = n_bits;
in_count -= n_bits;
} else {
memcpy (gbuf, zs->next_in, in_count);
zs->next_in += in_count;
zs->avail_in -= in_count;
zs->total_in += in_count;
size = in_count;
in_count = 0;
}
}
roffset = 0;
/* Round size down to integral number of codes. */
size = (size << 3) - (n_bits - 1);
}
r_off = roffset;
bits = n_bits;
/* Get to the first byte. */
bp += (r_off >> 3);
r_off &= 7;
/* Get first part (low order bits). */
gcode = (*bp++ >> r_off);
bits -= (8 - r_off);
r_off = 8 - r_off; /* Now, roffset into gcode word. */
/* Get any 8 bit parts in the middle (<=1 for up to 16 bits). */
if (bits >= 8) {
gcode |= *bp++ << r_off;
r_off += 8;
bits -= 8;
}
/* High order bits. */
gcode |= (*bp & rmask[bits]) << r_off;
roffset += n_bits;
return (gcode);
}
static void
zinit(s_zstate_t *zs)
{
memset(zs, 0, sizeof (s_zstate_t));
maxbits = BITS; /* User settable max # bits/code. */
maxmaxcode = 1 << maxbits; /* Should NEVER generate this code. */
hsize = HSIZE; /* For dynamic table sizing. */
free_ent = 0; /* First unused entry. */
block_compress = BLOCK_MASK;
clear_flg = 0;
state = S_START;
roffset = 0;
size = 0;
}