6 * published by the Free Software Foundation. Oracle designates this 7 * particular file as subject to the "Classpath" exception as provided 8 * by Oracle in the LICENSE file that accompanied this code. 9 * 10 * This code is distributed in the hope that it will be useful, but WITHOUT 11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 13 * version 2 for more details (a copy is included in the LICENSE file that 14 * accompanied this code). 15 * 16 * You should have received a copy of the GNU General Public License version 17 * 2 along with this work; if not, write to the Free Software Foundation, 18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 19 * 20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 21 * or visit www.oracle.com if you need additional information or have any 22 * questions. 23 */ 24 25 /* inftrees.c -- generate Huffman trees for efficient decoding 26 * Copyright (C) 1995-2022 Mark Adler 27 * For conditions of distribution and use, see copyright notice in zlib.h 28 */ 29 30 #include "zutil.h" 31 #include "inftrees.h" 32 33 #define MAXBITS 15 34 35 const char inflate_copyright[] = 36 " inflate 1.2.13 Copyright 1995-2022 Mark Adler "; 37 /* 38 If you use the zlib library in a product, an acknowledgment is welcome 39 in the documentation of your product. If for some reason you cannot 40 include such an acknowledgment, I would appreciate that you keep this 41 copyright string in the executable of your product. 42 */ 43 44 /* 45 Build a set of tables to decode the provided canonical Huffman code. 46 The code lengths are lens[0..codes-1]. The result starts at *table, 47 whose indices are 0..2^bits-1. work is a writable array of at least 48 lens shorts, which is used as a work area. type is the type of code 49 to be generated, CODES, LENS, or DISTS. On return, zero is success, 50 -1 is an invalid code, and +1 means that ENOUGH isn't enough. table 51 on return points to the next available entry's address. bits is the 52 requested root table index bits, and on return it is the actual root 53 table index bits. It will differ if the request is greater than the 54 longest code or if it is less than the shortest code. 55 */ 56 int ZLIB_INTERNAL inflate_table(type, lens, codes, table, bits, work) 57 codetype type; 58 unsigned short FAR *lens; 59 unsigned codes; 60 code FAR * FAR *table; 61 unsigned FAR *bits; 62 unsigned short FAR *work; 63 { 64 unsigned len; /* a code's length in bits */ 65 unsigned sym; /* index of code symbols */ 66 unsigned min, max; /* minimum and maximum code lengths */ 67 unsigned root; /* number of index bits for root table */ 68 unsigned curr; /* number of index bits for current table */ 69 unsigned drop; /* code bits to drop for sub-table */ 70 int left; /* number of prefix codes available */ 71 unsigned used; /* code entries in table used */ 72 unsigned huff; /* Huffman code */ 73 unsigned incr; /* for incrementing code, index */ 74 unsigned fill; /* index for replicating entries */ 75 unsigned low; /* low bits for current root entry */ 76 unsigned mask; /* mask for low root bits */ 77 code here; /* table entry for duplication */ 78 code FAR *next; /* next available space in table */ 79 const unsigned short FAR *base; /* base value table to use */ 80 const unsigned short FAR *extra; /* extra bits table to use */ 81 unsigned match; /* use base and extra for symbol >= match */ 82 unsigned short count[MAXBITS+1]; /* number of codes of each length */ 83 unsigned short offs[MAXBITS+1]; /* offsets in table for each length */ 84 static const unsigned short lbase[31] = { /* Length codes 257..285 base */ 85 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31, 86 35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258, 0, 0}; 87 static const unsigned short lext[31] = { /* Length codes 257..285 extra */ 88 16, 16, 16, 16, 16, 16, 16, 16, 17, 17, 17, 17, 18, 18, 18, 18, 89 19, 19, 19, 19, 20, 20, 20, 20, 21, 21, 21, 21, 16, 194, 65}; 90 static const unsigned short dbase[32] = { /* Distance codes 0..29 base */ 91 1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193, 92 257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145, 93 8193, 12289, 16385, 24577, 0, 0}; 94 static const unsigned short dext[32] = { /* Distance codes 0..29 extra */ 95 16, 16, 16, 16, 17, 17, 18, 18, 19, 19, 20, 20, 21, 21, 22, 22, 96 23, 23, 24, 24, 25, 25, 26, 26, 27, 27, 97 28, 28, 29, 29, 64, 64}; 98 99 /* 100 Process a set of code lengths to create a canonical Huffman code. The 101 code lengths are lens[0..codes-1]. Each length corresponds to the 102 symbols 0..codes-1. The Huffman code is generated by first sorting the 103 symbols by length from short to long, and retaining the symbol order 104 for codes with equal lengths. Then the code starts with all zero bits 105 for the first code of the shortest length, and the codes are integer 106 increments for the same length, and zeros are appended as the length 107 increases. For the deflate format, these bits are stored backwards 108 from their more natural integer increment ordering, and so when the 109 decoding tables are built in the large loop below, the integer codes |
6 * published by the Free Software Foundation. Oracle designates this 7 * particular file as subject to the "Classpath" exception as provided 8 * by Oracle in the LICENSE file that accompanied this code. 9 * 10 * This code is distributed in the hope that it will be useful, but WITHOUT 11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 13 * version 2 for more details (a copy is included in the LICENSE file that 14 * accompanied this code). 15 * 16 * You should have received a copy of the GNU General Public License version 17 * 2 along with this work; if not, write to the Free Software Foundation, 18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 19 * 20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 21 * or visit www.oracle.com if you need additional information or have any 22 * questions. 23 */ 24 25 /* inftrees.c -- generate Huffman trees for efficient decoding 26 * Copyright (C) 1995-2024 Mark Adler 27 * For conditions of distribution and use, see copyright notice in zlib.h 28 */ 29 30 #include "zutil.h" 31 #include "inftrees.h" 32 33 #define MAXBITS 15 34 35 const char inflate_copyright[] = 36 " inflate 1.3.1 Copyright 1995-2024 Mark Adler "; 37 /* 38 If you use the zlib library in a product, an acknowledgment is welcome 39 in the documentation of your product. If for some reason you cannot 40 include such an acknowledgment, I would appreciate that you keep this 41 copyright string in the executable of your product. 42 */ 43 44 /* 45 Build a set of tables to decode the provided canonical Huffman code. 46 The code lengths are lens[0..codes-1]. The result starts at *table, 47 whose indices are 0..2^bits-1. work is a writable array of at least 48 lens shorts, which is used as a work area. type is the type of code 49 to be generated, CODES, LENS, or DISTS. On return, zero is success, 50 -1 is an invalid code, and +1 means that ENOUGH isn't enough. table 51 on return points to the next available entry's address. bits is the 52 requested root table index bits, and on return it is the actual root 53 table index bits. It will differ if the request is greater than the 54 longest code or if it is less than the shortest code. 55 */ 56 int ZLIB_INTERNAL inflate_table(codetype type, unsigned short FAR *lens, 57 unsigned codes, code FAR * FAR *table, 58 unsigned FAR *bits, unsigned short FAR *work) { 59 unsigned len; /* a code's length in bits */ 60 unsigned sym; /* index of code symbols */ 61 unsigned min, max; /* minimum and maximum code lengths */ 62 unsigned root; /* number of index bits for root table */ 63 unsigned curr; /* number of index bits for current table */ 64 unsigned drop; /* code bits to drop for sub-table */ 65 int left; /* number of prefix codes available */ 66 unsigned used; /* code entries in table used */ 67 unsigned huff; /* Huffman code */ 68 unsigned incr; /* for incrementing code, index */ 69 unsigned fill; /* index for replicating entries */ 70 unsigned low; /* low bits for current root entry */ 71 unsigned mask; /* mask for low root bits */ 72 code here; /* table entry for duplication */ 73 code FAR *next; /* next available space in table */ 74 const unsigned short FAR *base; /* base value table to use */ 75 const unsigned short FAR *extra; /* extra bits table to use */ 76 unsigned match; /* use base and extra for symbol >= match */ 77 unsigned short count[MAXBITS+1]; /* number of codes of each length */ 78 unsigned short offs[MAXBITS+1]; /* offsets in table for each length */ 79 static const unsigned short lbase[31] = { /* Length codes 257..285 base */ 80 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31, 81 35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258, 0, 0}; 82 static const unsigned short lext[31] = { /* Length codes 257..285 extra */ 83 16, 16, 16, 16, 16, 16, 16, 16, 17, 17, 17, 17, 18, 18, 18, 18, 84 19, 19, 19, 19, 20, 20, 20, 20, 21, 21, 21, 21, 16, 203, 77}; 85 static const unsigned short dbase[32] = { /* Distance codes 0..29 base */ 86 1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193, 87 257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145, 88 8193, 12289, 16385, 24577, 0, 0}; 89 static const unsigned short dext[32] = { /* Distance codes 0..29 extra */ 90 16, 16, 16, 16, 17, 17, 18, 18, 19, 19, 20, 20, 21, 21, 22, 22, 91 23, 23, 24, 24, 25, 25, 26, 26, 27, 27, 92 28, 28, 29, 29, 64, 64}; 93 94 /* 95 Process a set of code lengths to create a canonical Huffman code. The 96 code lengths are lens[0..codes-1]. Each length corresponds to the 97 symbols 0..codes-1. The Huffman code is generated by first sorting the 98 symbols by length from short to long, and retaining the symbol order 99 for codes with equal lengths. Then the code starts with all zero bits 100 for the first code of the shortest length, and the codes are integer 101 increments for the same length, and zeros are appended as the length 102 increases. For the deflate format, these bits are stored backwards 103 from their more natural integer increment ordering, and so when the 104 decoding tables are built in the large loop below, the integer codes |