contrib/infback9/inftree9.c

/* inftree9.c -- generate Huffman trees for efficient decoding
 * Copyright (C) 1995-2013 Mark Adler
 * For conditions of distribution and use, see copyright notice in zlib.h
 */

#include "zutil.h"
#include "inftree9.h"

#define MAXBITS 15

const char inflate9_copyright[] =
   " inflate9 1.2.8 Copyright 1995-2013 Mark Adler ";
/*
  If you use the zlib library in a product, an acknowledgment is welcome
  in the documentation of your product. If for some reason you cannot
  include such an acknowledgment, I would appreciate that you keep this
  copyright string in the executable of your product.
 */

/*
   Build a set of tables to decode the provided canonical Huffman code.
   The code lengths are lens[0..codes-1].  The result starts at *table,
   whose indices are 0..2^bits-1.  work is a writable array of at least
   lens shorts, which is used as a work area.  type is the type of code
   to be generated, CODES, LENS, or DISTS.  On return, zero is success,
   -1 is an invalid code, and +1 means that ENOUGH isn't enough.  table
   on return points to the next available entry's address.  bits is the
   requested root table index bits, and on return it is the actual root
   table index bits.  It will differ if the request is greater than the
   longest code or if it is less than the shortest code.
 */
int inflate_table9(type, lens, codes, table, bits, work)
codetype type;
unsigned short FAR *lens;
unsigned codes;
code FAR * FAR *table;
unsigned FAR *bits;
unsigned short FAR *work;
{
    unsigned len;               /* a code's length in bits */
    unsigned sym;               /* index of code symbols */
    unsigned min, max;          /* minimum and maximum code lengths */
    unsigned root;              /* number of index bits for root table */
    unsigned curr;              /* number of index bits for current table */
    unsigned drop;              /* code bits to drop for sub-table */
    int left;                   /* number of prefix codes available */
    unsigned used;              /* code entries in table used */
    unsigned huff;              /* Huffman code */
    unsigned incr;              /* for incrementing code, index */
    unsigned fill;              /* index for replicating entries */
    unsigned low;               /* low bits for current root entry */
    unsigned mask;              /* mask for low root bits */
    code this;                  /* table entry for duplication */
    code FAR *next;             /* next available space in table */
    const unsigned short FAR *base;     /* base value table to use */
    const unsigned short FAR *extra;    /* extra bits table to use */
    int end;                    /* use base and extra for symbol > end */
    unsigned short count[MAXBITS+1];    /* number of codes of each length */
    unsigned short offs[MAXBITS+1];     /* offsets in table for each length */
    static const unsigned short lbase[31] = { /* Length codes 257..285 base */
        3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17,
        19, 23, 27, 31, 35, 43, 51, 59, 67, 83, 99, 115,
        131, 163, 195, 227, 3, 0, 0};
    static const unsigned short lext[31] = { /* Length codes 257..285 extra */
        128, 128, 128, 128, 128, 128, 128, 128, 129, 129, 129, 129,
        130, 130, 130, 130, 131, 131, 131, 131, 132, 132, 132, 132,
        133, 133, 133, 133, 144, 72, 78};
    static const unsigned short dbase[32] = { /* Distance codes 0..31 base */
        1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49,
        65, 97, 129, 193, 257, 385, 513, 769, 1025, 1537, 2049, 3073,
        4097, 6145, 8193, 12289, 16385, 24577, 32769, 49153};
    static const unsigned short dext[32] = { /* Distance codes 0..31 extra */
        128, 128, 128, 128, 129, 129, 130, 130, 131, 131, 132, 132,
        133, 133, 134, 134, 135, 135, 136, 136, 137, 137, 138, 138,
        139, 139, 140, 140, 141, 141, 142, 142};

    /*
       Process a set of code lengths to create a canonical Huffman code.  The
       code lengths are lens[0..codes-1].  Each length corresponds to the
       symbols 0..codes-1.  The Huffman code is generated by first sorting the
       symbols by length from short to long, and retaining the symbol order
       for codes with equal lengths.  Then the code starts with all zero bits
       for the first code of the shortest length, and the codes are integer
       increments for the same length, and zeros are appended as the length
       increases.  For the deflate format, these bits are stored backwards
       from their more natural integer increment ordering, and so when the
       decoding tables are built in the large loop below, the integer codes
       are incremented backwards.

       This routine assumes, but does not check, that all of the entries in
       lens[] are in the range 0..MAXBITS.  The caller must assure this.
       1..MAXBITS is interpreted as that code length.  zero means that that
       symbol does not occur in this code.

       The codes are sorted by computing a count of codes for each length,
       creating from that a table of starting indices for each length in the
       sorted table, and then entering the symbols in order in the sorted
       table.  The sorted table is work[], with that space being provided by
       the caller.

       The length counts are used for other purposes as well, i.e. finding
       the minimum and maximum length codes, determining if there are any
       codes at all, checking for a valid set of lengths, and looking ahead
       at length counts to determine sub-table sizes when building the
       decoding tables.
     */

    /* accumulate lengths for codes (assumes lens[] all in 0..MAXBITS) */
    for (len = 0; len <= MAXBITS; len++)
        count[len] = 0;
    for (sym = 0; sym < codes; sym++)
        count[lens[sym]]++;

    /* bound code lengths, force root to be within code lengths */
    root = *bits;
    for (max = MAXBITS; max >= 1; max--)
        if (count[max] != 0) break;
    if (root > max) root = max;
    if (max == 0) return -1;            /* no codes! */
    for (min = 1; min <= MAXBITS; min++)
        if (count[min] != 0) break;
    if (root < min) root = min;

    /* check for an over-subscribed or incomplete set of lengths */
    left = 1;
    for (len = 1; len <= MAXBITS; len++) {
        left <<= 1;
        left -= count[len];
        if (left < 0) return -1;        /* over-subscribed */
    }
    if (left > 0 && (type == CODES || max != 1))
        return -1;                      /* incomplete set */

    /* generate offsets into symbol table for each length for sorting */
    offs[1] = 0;
    for (len = 1; len < MAXBITS; len++)
        offs[len + 1] = offs[len] + count[len];

    /* sort symbols by length, by symbol order within each length */
    for (sym = 0; sym < codes; sym++)
        if (lens[sym] != 0) work[offs[lens[sym]]++] = (unsigned short)sym;

    /*
       Create and fill in decoding tables.  In this loop, the table being
       filled is at next and has curr index bits.  The code being used is huff
       with length len.  That code is converted to an index by dropping drop
       bits off of the bottom.  For codes where len is less than drop + curr,
       those top drop + curr - len bits are incremented through all values to
       fill the table with replicated entries.

       root is the number of index bits for the root table.  When len exceeds
       root, sub-tables are created pointed to by the root entry with an index
       of the low root bits of huff.  This is saved in low to check for when a
       new sub-table should be started.  drop is zero when the root table is
       being filled, and drop is root when sub-tables are being filled.

       When a new sub-table is needed, it is necessary to look ahead in the
       code lengths to determine what size sub-table is needed.  The length
       counts are used for this, and so count[] is decremented as codes are
       entered in the tables.

       used keeps track of how many table entries have been allocated from the
       provided *table space.  It is checked for LENS and DIST tables against
       the constants ENOUGH_LENS and ENOUGH_DISTS to guard against changes in
       the initial root table size constants.  See the comments in inftree9.h
       for more information.

       sym increments through all symbols, and the loop terminates when
       all codes of length max, i.e. all codes, have been processed.  This
       routine permits incomplete codes, so another loop after this one fills
       in the rest of the decoding tables with invalid code markers.
     */

    /* set up for code type */
    switch (type) {
    case CODES:
        base = extra = work;    /* dummy value--not used */
        end = 19;
        break;
    case LENS:
        base = lbase;
        base -= 257;
        extra = lext;
        extra -= 257;
        end = 256;
        break;
    default:            /* DISTS */
        base = dbase;
        extra = dext;
        end = -1;
    }

    /* initialize state for loop */
    huff = 0;                   /* starting code */
    sym = 0;                    /* starting code symbol */
    len = min;                  /* starting code length */
    next = *table;              /* current table to fill in */
    curr = root;                /* current table index bits */
    drop = 0;                   /* current bits to drop from code for index */
    low = (unsigned)(-1);       /* trigger new sub-table when len > root */
    used = 1U << root;          /* use root table entries */
    mask = used - 1;            /* mask for comparing low */

    /* check available table space */
    if ((type == LENS && used >= ENOUGH_LENS) ||
        (type == DISTS && used >= ENOUGH_DISTS))
        return 1;

    /* process all codes and make table entries */
    for (;;) {
        /* create table entry */
        this.bits = (unsigned char)(len - drop);
        if ((int)(work[sym]) < end) {
            this.op = (unsigned char)0;
            this.val = work[sym];
        }
        else if ((int)(work[sym]) > end) {
            this.op = (unsigned char)(extra[work[sym]]);
            this.val = base[work[sym]];
        }
        else {
            this.op = (unsigned char)(32 + 64);         /* end of block */
            this.val = 0;
        }

        /* replicate for those indices with low len bits equal to huff */
        incr = 1U << (len - drop);
        fill = 1U << curr;
        do {
            fill -= incr;
            next[(huff >> drop) + fill] = this;
        } while (fill != 0);

        /* backwards increment the len-bit code huff */
        incr = 1U << (len - 1);
        while (huff & incr)
            incr >>= 1;
        if (incr != 0) {
            huff &= incr - 1;
            huff += incr;
        }
        else
            huff = 0;

        /* go to next symbol, update count, len */
        sym++;
        if (--(count[len]) == 0) {
            if (len == max) break;
            len = lens[work[sym]];
        }

        /* create new sub-table if needed */
        if (len > root && (huff & mask) != low) {
            /* if first time, transition to sub-tables */
            if (drop == 0)
                drop = root;

            /* increment past last table */
            next += 1U << curr;

            /* determine length of next table */
            curr = len - drop;
            left = (int)(1 << curr);
            while (curr + drop < max) {
                left -= count[curr + drop];
                if (left <= 0) break;
                curr++;
                left <<= 1;
            }

            /* check for enough space */
            used += 1U << curr;
            if ((type == LENS && used >= ENOUGH_LENS) ||
                (type == DISTS && used >= ENOUGH_DISTS))
                return 1;

            /* point entry in root table to sub-table */
            low = huff & mask;
            (*table)[low].op = (unsigned char)curr;
            (*table)[low].bits = (unsigned char)root;
            (*table)[low].val = (unsigned short)(next - *table);
        }
    }

    /*
       Fill in rest of table for incomplete codes.  This loop is similar to the
       loop above in incrementing huff for table indices.  It is assumed that
       len is equal to curr + drop, so there is no loop needed to increment
       through high index bits.  When the current sub-table is filled, the loop
       drops back to the root table to fill in any remaining entries there.
     */
    this.op = (unsigned char)64;                /* invalid code marker */
    this.bits = (unsigned char)(len - drop);
    this.val = (unsigned short)0;
    while (huff != 0) {
        /* when done with sub-table, drop back to root table */
        if (drop != 0 && (huff & mask) != low) {
            drop = 0;
            len = root;
            next = *table;
            curr = root;
            this.bits = (unsigned char)len;
        }

        /* put invalid code marker in table */
        next[huff >> drop] = this;

        /* backwards increment the len-bit code huff */
        incr = 1U << (len - 1);
        while (huff & incr)
            incr >>= 1;
        if (incr != 0) {
            huff &= incr - 1;
            huff += incr;
        }
        else
            huff = 0;
    }

    /* set return parameters */
    *table += used;
    *bits = root;
    return 0;
}
Revision:	1096
Committed:	Sat Dec 30 14:40:33 2017 UTC (7 years, 10 months ago) by s10k
Content type:	text/x-csrc
File size:	13404 byte(s)
Log Message:	Added zlib, quazip, basicxmlsyntaxhighlighter, conditionalsemaphore and linenumberdisplay libraries. zlib and quazip are pre-compiled, but you can compile them yourself, just delete the dll files (or equivalent binary files to your OS)
#	Content
1	/* inftree9.c -- generate Huffman trees for efficient decoding
2	* Copyright (C) 1995-2013 Mark Adler
3	* For conditions of distribution and use, see copyright notice in zlib.h
4	*/
5
6	#include "zutil.h"
7	#include "inftree9.h"
8
9	#define MAXBITS 15
10
11	const char inflate9_copyright[] =
12	" inflate9 1.2.8 Copyright 1995-2013 Mark Adler ";
13	/*
14	If you use the zlib library in a product, an acknowledgment is welcome
15	in the documentation of your product. If for some reason you cannot
16	include such an acknowledgment, I would appreciate that you keep this
17	copyright string in the executable of your product.
18	*/
19
20	/*
21	Build a set of tables to decode the provided canonical Huffman code.
22	The code lengths are lens[0..codes-1]. The result starts at *table,
23	whose indices are 0..2^bits-1. work is a writable array of at least
24	lens shorts, which is used as a work area. type is the type of code
25	to be generated, CODES, LENS, or DISTS. On return, zero is success,
26	-1 is an invalid code, and +1 means that ENOUGH isn't enough. table
27	on return points to the next available entry's address. bits is the
28	requested root table index bits, and on return it is the actual root
29	table index bits. It will differ if the request is greater than the
30	longest code or if it is less than the shortest code.
31	*/
32	int inflate_table9(type, lens, codes, table, bits, work)
33	codetype type;
34	unsigned short FAR *lens;
35	unsigned codes;
36	code FAR * FAR *table;
37	unsigned FAR *bits;
38	unsigned short FAR *work;
39	{
40	unsigned len; /* a code's length in bits */
41	unsigned sym; /* index of code symbols */
42	unsigned min, max; /* minimum and maximum code lengths */
43	unsigned root; /* number of index bits for root table */
44	unsigned curr; /* number of index bits for current table */
45	unsigned drop; /* code bits to drop for sub-table */
46	int left; /* number of prefix codes available */
47	unsigned used; /* code entries in table used */
48	unsigned huff; /* Huffman code */
49	unsigned incr; /* for incrementing code, index */
50	unsigned fill; /* index for replicating entries */
51	unsigned low; /* low bits for current root entry */
52	unsigned mask; /* mask for low root bits */
53	code this; /* table entry for duplication */
54	code FAR next; / next available space in table */
55	const unsigned short FAR base; / base value table to use */
56	const unsigned short FAR extra; / extra bits table to use */
57	int end; /* use base and extra for symbol > end */
58	unsigned short count[MAXBITS+1]; /* number of codes of each length */
59	unsigned short offs[MAXBITS+1]; /* offsets in table for each length */
60	static const unsigned short lbase[31] = { /* Length codes 257..285 base */
61	3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17,
62	19, 23, 27, 31, 35, 43, 51, 59, 67, 83, 99, 115,
63	131, 163, 195, 227, 3, 0, 0};
64	static const unsigned short lext[31] = { /* Length codes 257..285 extra */
65	128, 128, 128, 128, 128, 128, 128, 128, 129, 129, 129, 129,
66	130, 130, 130, 130, 131, 131, 131, 131, 132, 132, 132, 132,
67	133, 133, 133, 133, 144, 72, 78};
68	static const unsigned short dbase[32] = { /* Distance codes 0..31 base */
69	1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49,
70	65, 97, 129, 193, 257, 385, 513, 769, 1025, 1537, 2049, 3073,
71	4097, 6145, 8193, 12289, 16385, 24577, 32769, 49153};
72	static const unsigned short dext[32] = { /* Distance codes 0..31 extra */
73	128, 128, 128, 128, 129, 129, 130, 130, 131, 131, 132, 132,
74	133, 133, 134, 134, 135, 135, 136, 136, 137, 137, 138, 138,
75	139, 139, 140, 140, 141, 141, 142, 142};
76
77	/*
78	Process a set of code lengths to create a canonical Huffman code. The
79	code lengths are lens[0..codes-1]. Each length corresponds to the
80	symbols 0..codes-1. The Huffman code is generated by first sorting the
81	symbols by length from short to long, and retaining the symbol order
82	for codes with equal lengths. Then the code starts with all zero bits
83	for the first code of the shortest length, and the codes are integer
84	increments for the same length, and zeros are appended as the length
85	increases. For the deflate format, these bits are stored backwards
86	from their more natural integer increment ordering, and so when the
87	decoding tables are built in the large loop below, the integer codes
88	are incremented backwards.
89
90	This routine assumes, but does not check, that all of the entries in
91	lens[] are in the range 0..MAXBITS. The caller must assure this.
92	1..MAXBITS is interpreted as that code length. zero means that that
93	symbol does not occur in this code.
94
95	The codes are sorted by computing a count of codes for each length,
96	creating from that a table of starting indices for each length in the
97	sorted table, and then entering the symbols in order in the sorted
98	table. The sorted table is work[], with that space being provided by
99	the caller.
100
101	The length counts are used for other purposes as well, i.e. finding
102	the minimum and maximum length codes, determining if there are any
103	codes at all, checking for a valid set of lengths, and looking ahead
104	at length counts to determine sub-table sizes when building the
105	decoding tables.
106	*/
107
108	/* accumulate lengths for codes (assumes lens[] all in 0..MAXBITS) */
109	for (len = 0; len <= MAXBITS; len++)
110	count[len] = 0;
111	for (sym = 0; sym < codes; sym++)
112	count[lens[sym]]++;
113
114	/* bound code lengths, force root to be within code lengths */
115	root = *bits;
116	for (max = MAXBITS; max >= 1; max--)
117	if (count[max] != 0) break;
118	if (root > max) root = max;
119	if (max == 0) return -1; /* no codes! */
120	for (min = 1; min <= MAXBITS; min++)
121	if (count[min] != 0) break;
122	if (root < min) root = min;
123
124	/* check for an over-subscribed or incomplete set of lengths */
125	left = 1;
126	for (len = 1; len <= MAXBITS; len++) {
127	left <<= 1;
128	left -= count[len];
129	if (left < 0) return -1; /* over-subscribed */
130	}
131	if (left > 0 && (type == CODES \|\| max != 1))
132	return -1; /* incomplete set */
133
134	/* generate offsets into symbol table for each length for sorting */
135	offs[1] = 0;
136	for (len = 1; len < MAXBITS; len++)
137	offs[len + 1] = offs[len] + count[len];
138
139	/* sort symbols by length, by symbol order within each length */
140	for (sym = 0; sym < codes; sym++)
141	if (lens[sym] != 0) work[offs[lens[sym]]++] = (unsigned short)sym;
142
143	/*
144	Create and fill in decoding tables. In this loop, the table being
145	filled is at next and has curr index bits. The code being used is huff
146	with length len. That code is converted to an index by dropping drop
147	bits off of the bottom. For codes where len is less than drop + curr,
148	those top drop + curr - len bits are incremented through all values to
149	fill the table with replicated entries.
150
151	root is the number of index bits for the root table. When len exceeds
152	root, sub-tables are created pointed to by the root entry with an index
153	of the low root bits of huff. This is saved in low to check for when a
154	new sub-table should be started. drop is zero when the root table is
155	being filled, and drop is root when sub-tables are being filled.
156
157	When a new sub-table is needed, it is necessary to look ahead in the
158	code lengths to determine what size sub-table is needed. The length
159	counts are used for this, and so count[] is decremented as codes are
160	entered in the tables.
161
162	used keeps track of how many table entries have been allocated from the
163	provided *table space. It is checked for LENS and DIST tables against
164	the constants ENOUGH_LENS and ENOUGH_DISTS to guard against changes in
165	the initial root table size constants. See the comments in inftree9.h
166	for more information.
167
168	sym increments through all symbols, and the loop terminates when
169	all codes of length max, i.e. all codes, have been processed. This
170	routine permits incomplete codes, so another loop after this one fills
171	in the rest of the decoding tables with invalid code markers.
172	*/
173
174	/* set up for code type */
175	switch (type) {
176	case CODES:
177	base = extra = work; /* dummy value--not used */
178	end = 19;
179	break;
180	case LENS:
181	base = lbase;
182	base -= 257;
183	extra = lext;
184	extra -= 257;
185	end = 256;
186	break;
187	default: /* DISTS */
188	base = dbase;
189	extra = dext;
190	end = -1;
191	}
192
193	/* initialize state for loop */
194	huff = 0; /* starting code */
195	sym = 0; /* starting code symbol */
196	len = min; /* starting code length */
197	next = table; / current table to fill in */
198	curr = root; /* current table index bits */
199	drop = 0; /* current bits to drop from code for index */
200	low = (unsigned)(-1); /* trigger new sub-table when len > root */
201	used = 1U << root; /* use root table entries */
202	mask = used - 1; /* mask for comparing low */
203
204	/* check available table space */
205	if ((type == LENS && used >= ENOUGH_LENS) \|\|
206	(type == DISTS && used >= ENOUGH_DISTS))
207	return 1;
208
209	/* process all codes and make table entries */
210	for (;;) {
211	/* create table entry */
212	this.bits = (unsigned char)(len - drop);
213	if ((int)(work[sym]) < end) {
214	this.op = (unsigned char)0;
215	this.val = work[sym];
216	}
217	else if ((int)(work[sym]) > end) {
218	this.op = (unsigned char)(extra[work[sym]]);
219	this.val = base[work[sym]];
220	}
221	else {
222	this.op = (unsigned char)(32 + 64); /* end of block */
223	this.val = 0;
224	}
225
226	/* replicate for those indices with low len bits equal to huff */
227	incr = 1U << (len - drop);
228	fill = 1U << curr;
229	do {
230	fill -= incr;
231	next[(huff >> drop) + fill] = this;
232	} while (fill != 0);
233
234	/* backwards increment the len-bit code huff */
235	incr = 1U << (len - 1);
236	while (huff & incr)
237	incr >>= 1;
238	if (incr != 0) {
239	huff &= incr - 1;
240	huff += incr;
241	}
242	else
243	huff = 0;
244
245	/* go to next symbol, update count, len */
246	sym++;
247	if (--(count[len]) == 0) {
248	if (len == max) break;
249	len = lens[work[sym]];
250	}
251
252	/* create new sub-table if needed */
253	if (len > root && (huff & mask) != low) {
254	/* if first time, transition to sub-tables */
255	if (drop == 0)
256	drop = root;
257
258	/* increment past last table */
259	next += 1U << curr;
260
261	/* determine length of next table */
262	curr = len - drop;
263	left = (int)(1 << curr);
264	while (curr + drop < max) {
265	left -= count[curr + drop];
266	if (left <= 0) break;
267	curr++;
268	left <<= 1;
269	}
270
271	/* check for enough space */
272	used += 1U << curr;
273	if ((type == LENS && used >= ENOUGH_LENS) \|\|
274	(type == DISTS && used >= ENOUGH_DISTS))
275	return 1;
276
277	/* point entry in root table to sub-table */
278	low = huff & mask;
279	(*table)[low].op = (unsigned char)curr;
280	(*table)[low].bits = (unsigned char)root;
281	(table)[low].val = (unsigned short)(next - table);
282	}
283	}
284
285	/*
286	Fill in rest of table for incomplete codes. This loop is similar to the
287	loop above in incrementing huff for table indices. It is assumed that
288	len is equal to curr + drop, so there is no loop needed to increment
289	through high index bits. When the current sub-table is filled, the loop
290	drops back to the root table to fill in any remaining entries there.
291	*/
292	this.op = (unsigned char)64; /* invalid code marker */
293	this.bits = (unsigned char)(len - drop);
294	this.val = (unsigned short)0;
295	while (huff != 0) {
296	/* when done with sub-table, drop back to root table */
297	if (drop != 0 && (huff & mask) != low) {
298	drop = 0;
299	len = root;
300	next = *table;
301	curr = root;
302	this.bits = (unsigned char)len;
303	}
304
305	/* put invalid code marker in table */
306	next[huff >> drop] = this;
307
308	/* backwards increment the len-bit code huff */
309	incr = 1U << (len - 1);
310	while (huff & incr)
311	incr >>= 1;
312	if (incr != 0) {
313	huff &= incr - 1;
314	huff += incr;
315	}
316	else
317	huff = 0;
318	}
319
320	/* set return parameters */
321	*table += used;
322	*bits = root;
323	return 0;
324	}