1ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov/* inftrees.c -- generate Huffman trees for efficient decoding 2ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov * Copyright (C) 1995-2013 Mark Adler 3ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov * For conditions of distribution and use, see copyright notice in zlib.h 4ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov */ 5ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 6ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov#include "zutil.h" 7ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov#include "inftrees.h" 8ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 9ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov#define MAXBITS 15 10ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 11ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganovconst char inflate_copyright[] = 12ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov " inflate 1.2.8 Copyright 1995-2013 Mark Adler "; 13ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov/* 14ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov If you use the zlib library in a product, an acknowledgment is welcome 15ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov in the documentation of your product. If for some reason you cannot 16ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov include such an acknowledgment, I would appreciate that you keep this 17ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov copyright string in the executable of your product. 18ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov */ 19ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 20ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov/* 21ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov Build a set of tables to decode the provided canonical Huffman code. 22ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov The code lengths are lens[0..codes-1]. The result starts at *table, 23ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov whose indices are 0..2^bits-1. work is a writable array of at least 24ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov lens shorts, which is used as a work area. type is the type of code 25ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov to be generated, CODES, LENS, or DISTS. On return, zero is success, 26ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov -1 is an invalid code, and +1 means that ENOUGH isn't enough. table 27ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov on return points to the next available entry's address. bits is the 28ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov requested root table index bits, and on return it is the actual root 29ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov table index bits. It will differ if the request is greater than the 30ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov longest code or if it is less than the shortest code. 31ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov */ 32ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganovint ZLIB_INTERNAL inflate_table( 33ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganovcodetype type, 34ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganovunsigned short FAR *lens, 35ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganovunsigned codes, 36ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganovcode FAR * FAR *table, 37ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganovunsigned FAR *bits, 38ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganovunsigned short FAR *work) 39ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov{ 40ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov unsigned len; /* a code's length in bits */ 41ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov unsigned sym; /* index of code symbols */ 42ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov unsigned min, max; /* minimum and maximum code lengths */ 43ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov unsigned root; /* number of index bits for root table */ 44ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov unsigned curr; /* number of index bits for current table */ 45ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov unsigned drop; /* code bits to drop for sub-table */ 46ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov int left; /* number of prefix codes available */ 47ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov unsigned used; /* code entries in table used */ 48ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov unsigned huff; /* Huffman code */ 49ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov unsigned incr; /* for incrementing code, index */ 50ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov unsigned fill; /* index for replicating entries */ 51ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov unsigned low; /* low bits for current root entry */ 52ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov unsigned mask; /* mask for low root bits */ 53ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov code here; /* table entry for duplication */ 54ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov code FAR *next; /* next available space in table */ 55ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov const unsigned short FAR *base; /* base value table to use */ 56ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov const unsigned short FAR *extra; /* extra bits table to use */ 57ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov int end; /* use base and extra for symbol > end */ 58ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov unsigned short count[MAXBITS+1]; /* number of codes of each length */ 59ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov unsigned short offs[MAXBITS+1]; /* offsets in table for each length */ 60ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov static const unsigned short lbase[31] = { /* Length codes 257..285 base */ 61ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31, 62ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258, 0, 0}; 63ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov static const unsigned short lext[31] = { /* Length codes 257..285 extra */ 64ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 16, 16, 16, 16, 16, 16, 16, 16, 17, 17, 17, 17, 18, 18, 18, 18, 65ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 19, 19, 19, 19, 20, 20, 20, 20, 21, 21, 21, 21, 16, 72, 78}; 66ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov static const unsigned short dbase[32] = { /* Distance codes 0..29 base */ 67ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193, 68ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145, 69ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 8193, 12289, 16385, 24577, 0, 0}; 70ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov static const unsigned short dext[32] = { /* Distance codes 0..29 extra */ 71ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 16, 16, 16, 16, 17, 17, 18, 18, 19, 19, 20, 20, 21, 21, 22, 22, 72ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 23, 23, 24, 24, 25, 25, 26, 26, 27, 27, 73ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 28, 28, 29, 29, 64, 64}; 74ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 75ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov /* 76ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov Process a set of code lengths to create a canonical Huffman code. The 77ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov code lengths are lens[0..codes-1]. Each length corresponds to the 78ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov symbols 0..codes-1. The Huffman code is generated by first sorting the 79ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov symbols by length from short to long, and retaining the symbol order 80ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov for codes with equal lengths. Then the code starts with all zero bits 81ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov for the first code of the shortest length, and the codes are integer 82ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov increments for the same length, and zeros are appended as the length 83ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov increases. For the deflate format, these bits are stored backwards 84ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov from their more natural integer increment ordering, and so when the 85ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov decoding tables are built in the large loop below, the integer codes 86ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov are incremented backwards. 87ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 88ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov This routine assumes, but does not check, that all of the entries in 89ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov lens[] are in the range 0..MAXBITS. The caller must assure this. 90ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 1..MAXBITS is interpreted as that code length. zero means that that 91ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov symbol does not occur in this code. 92ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 93ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov The codes are sorted by computing a count of codes for each length, 94ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov creating from that a table of starting indices for each length in the 95ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov sorted table, and then entering the symbols in order in the sorted 96ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov table. The sorted table is work[], with that space being provided by 97ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov the caller. 98ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 99ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov The length counts are used for other purposes as well, i.e. finding 100ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov the minimum and maximum length codes, determining if there are any 101ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov codes at all, checking for a valid set of lengths, and looking ahead 102ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov at length counts to determine sub-table sizes when building the 103ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov decoding tables. 104ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov */ 105ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 106ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov /* accumulate lengths for codes (assumes lens[] all in 0..MAXBITS) */ 107ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov for (len = 0; len <= MAXBITS; len++) 108ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov count[len] = 0; 109ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov for (sym = 0; sym < codes; sym++) 110ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov count[lens[sym]]++; 111ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 112ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov /* bound code lengths, force root to be within code lengths */ 113ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov root = *bits; 114ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov for (max = MAXBITS; max >= 1; max--) 115ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov if (count[max] != 0) break; 116ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov if (root > max) root = max; 117ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov if (max == 0) { /* no symbols to code at all */ 118ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov here.op = (unsigned char)64; /* invalid code marker */ 119ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov here.bits = (unsigned char)1; 120ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov here.val = (unsigned short)0; 121ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov *(*table)++ = here; /* make a table to force an error */ 122ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov *(*table)++ = here; 123ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov *bits = 1; 124ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov return 0; /* no symbols, but wait for decoding to report error */ 125ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov } 126ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov for (min = 1; min < max; min++) 127ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov if (count[min] != 0) break; 128ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov if (root < min) root = min; 129ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 130ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov /* check for an over-subscribed or incomplete set of lengths */ 131ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov left = 1; 132ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov for (len = 1; len <= MAXBITS; len++) { 133ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov left <<= 1; 134ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov left -= count[len]; 135ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov if (left < 0) return -1; /* over-subscribed */ 136ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov } 137ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov if (left > 0 && (type == CODES || max != 1)) 138ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov return -1; /* incomplete set */ 139ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 140ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov /* generate offsets into symbol table for each length for sorting */ 141ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov offs[1] = 0; 142ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov for (len = 1; len < MAXBITS; len++) 143ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov offs[len + 1] = offs[len] + count[len]; 144ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 145ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov /* sort symbols by length, by symbol order within each length */ 146ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov for (sym = 0; sym < codes; sym++) 147ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov if (lens[sym] != 0) work[offs[lens[sym]]++] = (unsigned short)sym; 148ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 149ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov /* 150ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov Create and fill in decoding tables. In this loop, the table being 151ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov filled is at next and has curr index bits. The code being used is huff 152ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov with length len. That code is converted to an index by dropping drop 153ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov bits off of the bottom. For codes where len is less than drop + curr, 154ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov those top drop + curr - len bits are incremented through all values to 155ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov fill the table with replicated entries. 156ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 157ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov root is the number of index bits for the root table. When len exceeds 158ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov root, sub-tables are created pointed to by the root entry with an index 159ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov of the low root bits of huff. This is saved in low to check for when a 160ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov new sub-table should be started. drop is zero when the root table is 161ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov being filled, and drop is root when sub-tables are being filled. 162ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 163ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov When a new sub-table is needed, it is necessary to look ahead in the 164ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov code lengths to determine what size sub-table is needed. The length 165ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov counts are used for this, and so count[] is decremented as codes are 166ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov entered in the tables. 167ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 168ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov used keeps track of how many table entries have been allocated from the 169ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov provided *table space. It is checked for LENS and DIST tables against 170ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov the constants ENOUGH_LENS and ENOUGH_DISTS to guard against changes in 171ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov the initial root table size constants. See the comments in inftrees.h 172ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov for more information. 173ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 174ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov sym increments through all symbols, and the loop terminates when 175ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov all codes of length max, i.e. all codes, have been processed. This 176ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov routine permits incomplete codes, so another loop after this one fills 177ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov in the rest of the decoding tables with invalid code markers. 178ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov */ 179ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 180ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov /* set up for code type */ 181ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov switch (type) { 182ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov case CODES: 183ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov base = extra = work; /* dummy value--not used */ 184ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov end = 19; 185ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov break; 186ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov case LENS: 187ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov base = lbase; 188ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov base -= 257; 189ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov extra = lext; 190ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov extra -= 257; 191ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov end = 256; 192ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov break; 193ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov default: /* DISTS */ 194ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov base = dbase; 195ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov extra = dext; 196ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov end = -1; 197ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov } 198ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 199ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov /* initialize state for loop */ 200ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov huff = 0; /* starting code */ 201ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov sym = 0; /* starting code symbol */ 202ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov len = min; /* starting code length */ 203ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov next = *table; /* current table to fill in */ 204ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov curr = root; /* current table index bits */ 205ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov drop = 0; /* current bits to drop from code for index */ 206ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov low = (unsigned)(-1); /* trigger new sub-table when len > root */ 207ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov used = 1U << root; /* use root table entries */ 208ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov mask = used - 1; /* mask for comparing low */ 209ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 210ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov /* check available table space */ 211ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov if ((type == LENS && used > ENOUGH_LENS) || 212ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov (type == DISTS && used > ENOUGH_DISTS)) 213ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov return 1; 214ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 215ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov /* process all codes and make table entries */ 216ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov for (;;) { 217ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov /* create table entry */ 218ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov here.bits = (unsigned char)(len - drop); 219ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov if ((int)(work[sym]) < end) { 220ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov here.op = (unsigned char)0; 221ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov here.val = work[sym]; 222ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov } 223ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov else if ((int)(work[sym]) > end) { 224ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov here.op = (unsigned char)(extra[work[sym]]); 225ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov here.val = base[work[sym]]; 226ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov } 227ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov else { 228ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov here.op = (unsigned char)(32 + 64); /* end of block */ 229ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov here.val = 0; 230ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov } 231ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 232ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov /* replicate for those indices with low len bits equal to huff */ 233ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov incr = 1U << (len - drop); 234ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov fill = 1U << curr; 235ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov min = fill; /* save offset to next table */ 236ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov do { 237ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov fill -= incr; 238ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov next[(huff >> drop) + fill] = here; 239ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov } while (fill != 0); 240ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 241ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov /* backwards increment the len-bit code huff */ 242ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov incr = 1U << (len - 1); 243ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov while (huff & incr) 244ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov incr >>= 1; 245ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov if (incr != 0) { 246ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov huff &= incr - 1; 247ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov huff += incr; 248ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov } 249ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov else 250ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov huff = 0; 251ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 252ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov /* go to next symbol, update count, len */ 253ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov sym++; 254ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov if (--(count[len]) == 0) { 255ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov if (len == max) break; 256ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov len = lens[work[sym]]; 257ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov } 258ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 259ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov /* create new sub-table if needed */ 260ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov if (len > root && (huff & mask) != low) { 261ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov /* if first time, transition to sub-tables */ 262ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov if (drop == 0) 263ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov drop = root; 264ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 265ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov /* increment past last table */ 266ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov next += min; /* here min is 1 << curr */ 267ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 268ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov /* determine length of next table */ 269ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov curr = len - drop; 270ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov left = (int)(1 << curr); 271ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov while (curr + drop < max) { 272ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov left -= count[curr + drop]; 273ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov if (left <= 0) break; 274ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov curr++; 275ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov left <<= 1; 276ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov } 277ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 278ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov /* check for enough space */ 279ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov used += 1U << curr; 280ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov if ((type == LENS && used > ENOUGH_LENS) || 281ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov (type == DISTS && used > ENOUGH_DISTS)) 282ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov return 1; 283ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 284ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov /* point entry in root table to sub-table */ 285ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov low = huff & mask; 286ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov (*table)[low].op = (unsigned char)curr; 287ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov (*table)[low].bits = (unsigned char)root; 288ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov (*table)[low].val = (unsigned short)(next - *table); 289ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov } 290ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov } 291ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 292ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov /* fill in remaining table entry if code is incomplete (guaranteed to have 293ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov at most one remaining entry, since if the code is incomplete, the 294ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov maximum code length that was allowed to get this far is one bit) */ 295ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov if (huff != 0) { 296ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov here.op = (unsigned char)64; /* invalid code marker */ 297ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov here.bits = (unsigned char)(len - drop); 298ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov here.val = (unsigned short)0; 299ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov next[huff] = here; 300ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov } 301ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov 302ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov /* set return parameters */ 303ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov *table += used; 304ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov *bits = root; 305ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov return 0; 306ee451cb395940862dad63c85adfe8f2fd55e864cSvet Ganov} 307