summaryrefslogtreecommitdiffstats
path: root/gnu/usr.bin/gzip/unlzh.c
blob: 2c03d1fc315a4eee5767e6505c5288046d4e67e5 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
/* unlzh.c -- decompress files in SCO compress -H (LZH) format.
 * The code in this file is directly derived from the public domain 'ar002'
 * written by Haruhiko Okumura.
 */

#include <stdio.h>

#include "tailor.h"
#include "gzip.h"
#include "lzw.h" /* just for consistency checking */

/* decode.c */

local unsigned  decode  OF((unsigned count, uch buffer[]));
local void decode_start OF((void));

/* huf.c */
local void huf_decode_start OF((void));
local unsigned decode_c     OF((void));
local unsigned decode_p     OF((void));

/* io.c */
local void fillbuf      OF((int n));
local unsigned getbits  OF((int n));
local void init_getbits OF((void));

#define DICBIT    13    /* 12(-lh4-) or 13(-lh5-) */
#define DICSIZ ((unsigned) 1 << DICBIT)

#ifndef CHAR_BIT
#  define CHAR_BIT 8
#endif

#ifndef UCHAR_MAX
#  define UCHAR_MAX 255
#endif

#define BITBUFSIZ (CHAR_BIT * 2 * sizeof(char))
/* Do not use CHAR_BIT * sizeof(bitbuf), does not work on machines
 * for which short is not on 16 bits (Cray).
 */

/* encode.c and decode.c */

#define MAXMATCH 256    /* formerly F (not more than UCHAR_MAX + 1) */
#define THRESHOLD  3    /* choose optimal value */

/* huf.c */

#define NC (UCHAR_MAX + MAXMATCH + 2 - THRESHOLD)
	/* alphabet = {0, 1, 2, ..., NC - 1} */
#define CBIT 9  /* $\lfloor \log_2 NC \rfloor + 1$ */
#define CODE_BIT  16  /* codeword length */

#define NP (DICBIT + 1)
#define NT (CODE_BIT + 3)
#define PBIT 4  /* smallest integer such that (1U << PBIT) > NP */
#define TBIT 5  /* smallest integer such that (1U << TBIT) > NT */
#if NT > NP
# define NPT NT
#else
# define NPT NP
#endif

/* local ush left[2 * NC - 1]; */
/* local ush right[2 * NC - 1]; */
#define left  prev
#define right head
#if NC > 1<<(BITS-2)
    error cannot overlay left+right and prev
#endif

/* local uch c_len[NC]; */
#define c_len outbuf
#if NC > OUTBUFSIZ
    error cannot overlay c_len and outbuf
#endif

local uch pt_len[NPT];
local unsigned blocksize;
local ush pt_table[256];

/* local ush c_table[4096]; */
#define c_table d_buf
#if DIST_BUFSIZE < 4096
    error cannot overlay c_table and d_buf
#endif

local ush       bitbuf;
local unsigned  subbitbuf;
local int       bitcount;

local void fillbuf(n)  /* Shift bitbuf n bits left, read n bits */
    int n;
{
    bitbuf <<= n;
    while (n > bitcount) {
	bitbuf |= subbitbuf << (n -= bitcount);
	subbitbuf = (unsigned)try_byte();
	if ((int)subbitbuf == EOF) subbitbuf = 0;
	bitcount = CHAR_BIT;
    }
    bitbuf |= subbitbuf >> (bitcount -= n);
}

local unsigned getbits(n)
    int n;
{
    unsigned x;

    x = bitbuf >> (BITBUFSIZ - n);  fillbuf(n);
    return x;
}

local void init_getbits()
{
    bitbuf = 0;  subbitbuf = 0;  bitcount = 0;
    fillbuf(BITBUFSIZ);
}

/***********************************************************
	maketbl.c -- make table for decoding
***********************************************************/

local void make_table(nchar, bitlen, tablebits, table)
    int nchar;
    uch bitlen[];
    int tablebits;
    ush table[];
{
    ush count[17], weight[17], start[18], *p;
    unsigned i, k, len, ch, jutbits, avail, nextcode, mask;

    for (i = 1; i <= 16; i++) count[i] = 0;
    for (i = 0; i < nchar; i++) count[bitlen[i]]++;

    start[1] = 0;
    for (i = 1; i <= 16; i++)
	start[i + 1] = start[i] + (count[i] << (16 - i));
    if (start[17] != (ush)((unsigned) 1 << 16))
	error("Bad table\n");

    jutbits = 16 - tablebits;
    for (i = 1; i <= tablebits; i++) {
	start[i] >>= jutbits;
	weight[i] = (unsigned) 1 << (tablebits - i);
    }
    while (i <= 16) {
	weight[i] = (unsigned) 1 << (16 - i);
	i++;
    }

    i = start[tablebits + 1] >> jutbits;
    if (i != (ush)((unsigned) 1 << 16)) {
	k = 1 << tablebits;
	while (i != k) table[i++] = 0;
    }

    avail = nchar;
    mask = (unsigned) 1 << (15 - tablebits);
    for (ch = 0; ch < nchar; ch++) {
	if ((len = bitlen[ch]) == 0) continue;
	nextcode = start[len] + weight[len];
	if (len <= tablebits) {
	    for (i = start[len]; i < nextcode; i++) table[i] = ch;
	} else {
	    k = start[len];
	    p = &table[k >> jutbits];
	    i = len - tablebits;
	    while (i != 0) {
		if (*p == 0) {
		    right[avail] = left[avail] = 0;
		    *p = avail++;
		}
		if (k & mask) p = &right[*p];
		else          p = &left[*p];
		k <<= 1;  i--;
	    }
	    *p = ch;
	}
	start[len] = nextcode;
    }
}

/***********************************************************
        huf.c -- static Huffman
***********************************************************/

local void read_pt_len(nn, nbit, i_special)
    int nn;
    int nbit;
    int i_special;
{
    int i, c, n;
    unsigned mask;

    n = getbits(nbit);
    if (n == 0) {
	c = getbits(nbit);
	for (i = 0; i < nn; i++) pt_len[i] = 0;
	for (i = 0; i < 256; i++) pt_table[i] = c;
    } else {
	i = 0;
	while (i < n) {
	    c = bitbuf >> (BITBUFSIZ - 3);
	    if (c == 7) {
		mask = (unsigned) 1 << (BITBUFSIZ - 1 - 3);
		while (mask & bitbuf) {  mask >>= 1;  c++;  }
	    }
	    fillbuf((c < 7) ? 3 : c - 3);
	    pt_len[i++] = c;
	    if (i == i_special) {
		c = getbits(2);
		while (--c >= 0) pt_len[i++] = 0;
	    }
	}
	while (i < nn) pt_len[i++] = 0;
	make_table(nn, pt_len, 8, pt_table);
    }
}

local void read_c_len()
{
    int i, c, n;
    unsigned mask;

    n = getbits(CBIT);
    if (n == 0) {
	c = getbits(CBIT);
	for (i = 0; i < NC; i++) c_len[i] = 0;
	for (i = 0; i < 4096; i++) c_table[i] = c;
    } else {
	i = 0;
	while (i < n) {
	    c = pt_table[bitbuf >> (BITBUFSIZ - 8)];
	    if (c >= NT) {
		mask = (unsigned) 1 << (BITBUFSIZ - 1 - 8);
		do {
		    if (bitbuf & mask) c = right[c];
		    else               c = left [c];
		    mask >>= 1;
		} while (c >= NT);
	    }
	    fillbuf((int) pt_len[c]);
	    if (c <= 2) {
		if      (c == 0) c = 1;
		else if (c == 1) c = getbits(4) + 3;
		else             c = getbits(CBIT) + 20;
		while (--c >= 0) c_len[i++] = 0;
	    } else c_len[i++] = c - 2;
	}
	while (i < NC) c_len[i++] = 0;
	make_table(NC, c_len, 12, c_table);
    }
}

local unsigned decode_c()
{
    unsigned j, mask;

    if (blocksize == 0) {
	blocksize = getbits(16);
	if (blocksize == 0) {
	    return NC; /* end of file */
	}
	read_pt_len(NT, TBIT, 3);
	read_c_len();
	read_pt_len(NP, PBIT, -1);
    }
    blocksize--;
    j = c_table[bitbuf >> (BITBUFSIZ - 12)];
    if (j >= NC) {
	mask = (unsigned) 1 << (BITBUFSIZ - 1 - 12);
	do {
	    if (bitbuf & mask) j = right[j];
	    else               j = left [j];
	    mask >>= 1;
	} while (j >= NC);
    }
    fillbuf((int) c_len[j]);
    return j;
}

local unsigned decode_p()
{
    unsigned j, mask;

    j = pt_table[bitbuf >> (BITBUFSIZ - 8)];
    if (j >= NP) {
	mask = (unsigned) 1 << (BITBUFSIZ - 1 - 8);
	do {
	    if (bitbuf & mask) j = right[j];
	    else               j = left [j];
	    mask >>= 1;
	} while (j >= NP);
    }
    fillbuf((int) pt_len[j]);
    if (j != 0) j = ((unsigned) 1 << (j - 1)) + getbits((int) (j - 1));
    return j;
}

local void huf_decode_start()
{
    init_getbits();  blocksize = 0;
}

/***********************************************************
        decode.c
***********************************************************/

local int j;    /* remaining bytes to copy */
local int done; /* set at end of input */

local void decode_start()
{
    huf_decode_start();
    j = 0;
    done = 0;
}

/* Decode the input and return the number of decoded bytes put in buffer
 */
local unsigned decode(count, buffer)
    unsigned count;
    uch buffer[];
    /* The calling function must keep the number of
       bytes to be processed.  This function decodes
       either 'count' bytes or 'DICSIZ' bytes, whichever
       is smaller, into the array 'buffer[]' of size
       'DICSIZ' or more.
       Call decode_start() once for each new file
       before calling this function.
     */
{
    local unsigned i;
    unsigned r, c;

    r = 0;
    while (--j >= 0) {
	buffer[r] = buffer[i];
	i = (i + 1) & (DICSIZ - 1);
	if (++r == count) return r;
    }
    for ( ; ; ) {
	c = decode_c();
	if (c == NC) {
	    done = 1;
	    return r;
	}
	if (c <= UCHAR_MAX) {
	    buffer[r] = c;
	    if (++r == count) return r;
	} else {
	    j = c - (UCHAR_MAX + 1 - THRESHOLD);
	    i = (r - decode_p() - 1) & (DICSIZ - 1);
	    while (--j >= 0) {
		buffer[r] = buffer[i];
		i = (i + 1) & (DICSIZ - 1);
		if (++r == count) return r;
	    }
	}
    }
}


/* ===========================================================================
 * Unlzh in to out. Return OK or ERROR.
 */
int unlzh(in, out)
    int in;
    int out;
{
    unsigned n;
    ifd = in;
    ofd = out;

    decode_start();
    while (!done) {
	n = decode((unsigned) DICSIZ, window);
	if (!test && n > 0) {
	    write_buf(out, (char*)window, n);
	}
    }
    return OK;
}
OpenPOWER on IntegriCloud