11da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds/* inftrees.c -- generate Huffman trees for efficient decoding 24f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie * Copyright (C) 1995-2005 Mark Adler 34f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie * For conditions of distribution and use, see copyright notice in zlib.h 41da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds */ 51da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds 61da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds#include <linux/zutil.h> 71da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds#include "inftrees.h" 81da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds 94f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie#define MAXBITS 15 104f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie 111da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds/* 124f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie Build a set of tables to decode the provided canonical Huffman code. 134f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie The code lengths are lens[0..codes-1]. The result starts at *table, 144f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie whose indices are 0..2^bits-1. work is a writable array of at least 154f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie lens shorts, which is used as a work area. type is the type of code 164f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie to be generated, CODES, LENS, or DISTS. On return, zero is success, 174f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie -1 is an invalid code, and +1 means that ENOUGH isn't enough. table 184f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie on return points to the next available entry's address. bits is the 194f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie requested root table index bits, and on return it is the actual root 204f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie table index bits. It will differ if the request is greater than the 214f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie longest code or if it is less than the shortest code. 221da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds */ 23b762450e84e20a179ee5993b065caaad99a65fbfRandy Dunlapint zlib_inflate_table(codetype type, unsigned short *lens, unsigned codes, 24b762450e84e20a179ee5993b065caaad99a65fbfRandy Dunlap code **table, unsigned *bits, unsigned short *work) 251da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds{ 264f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie unsigned len; /* a code's length in bits */ 274f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie unsigned sym; /* index of code symbols */ 284f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie unsigned min, max; /* minimum and maximum code lengths */ 294f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie unsigned root; /* number of index bits for root table */ 304f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie unsigned curr; /* number of index bits for current table */ 314f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie unsigned drop; /* code bits to drop for sub-table */ 324f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie int left; /* number of prefix codes available */ 334f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie unsigned used; /* code entries in table used */ 344f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie unsigned huff; /* Huffman code */ 354f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie unsigned incr; /* for incrementing code, index */ 364f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie unsigned fill; /* index for replicating entries */ 374f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie unsigned low; /* low bits for current root entry */ 384f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie unsigned mask; /* mask for low root bits */ 394f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie code this; /* table entry for duplication */ 404f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie code *next; /* next available space in table */ 414f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie const unsigned short *base; /* base value table to use */ 424f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie const unsigned short *extra; /* extra bits table to use */ 434f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie int end; /* use base and extra for symbol > end */ 444f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie unsigned short count[MAXBITS+1]; /* number of codes of each length */ 454f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie unsigned short offs[MAXBITS+1]; /* offsets in table for each length */ 464f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie static const unsigned short lbase[31] = { /* Length codes 257..285 base */ 474f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31, 484f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie 35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258, 0, 0}; 494f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie static const unsigned short lext[31] = { /* Length codes 257..285 extra */ 504f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie 16, 16, 16, 16, 16, 16, 16, 16, 17, 17, 17, 17, 18, 18, 18, 18, 514f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie 19, 19, 19, 19, 20, 20, 20, 20, 21, 21, 21, 21, 16, 201, 196}; 524f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie static const unsigned short dbase[32] = { /* Distance codes 0..29 base */ 534f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie 1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193, 544f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie 257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145, 554f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie 8193, 12289, 16385, 24577, 0, 0}; 564f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie static const unsigned short dext[32] = { /* Distance codes 0..29 extra */ 574f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie 16, 16, 16, 16, 17, 17, 18, 18, 19, 19, 20, 20, 21, 21, 22, 22, 584f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie 23, 23, 24, 24, 25, 25, 26, 26, 27, 27, 594f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie 28, 28, 29, 29, 64, 64}; 604f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie 614f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie /* 624f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie Process a set of code lengths to create a canonical Huffman code. The 634f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie code lengths are lens[0..codes-1]. Each length corresponds to the 644f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie symbols 0..codes-1. The Huffman code is generated by first sorting the 654f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie symbols by length from short to long, and retaining the symbol order 664f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie for codes with equal lengths. Then the code starts with all zero bits 674f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie for the first code of the shortest length, and the codes are integer 684f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie increments for the same length, and zeros are appended as the length 694f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie increases. For the deflate format, these bits are stored backwards 704f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie from their more natural integer increment ordering, and so when the 714f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie decoding tables are built in the large loop below, the integer codes 724f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie are incremented backwards. 734f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie 744f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie This routine assumes, but does not check, that all of the entries in 754f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie lens[] are in the range 0..MAXBITS. The caller must assure this. 764f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie 1..MAXBITS is interpreted as that code length. zero means that that 774f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie symbol does not occur in this code. 784f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie 794f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie The codes are sorted by computing a count of codes for each length, 804f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie creating from that a table of starting indices for each length in the 814f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie sorted table, and then entering the symbols in order in the sorted 824f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie table. The sorted table is work[], with that space being provided by 834f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie the caller. 844f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie 854f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie The length counts are used for other purposes as well, i.e. finding 864f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie the minimum and maximum length codes, determining if there are any 874f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie codes at all, checking for a valid set of lengths, and looking ahead 884f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie at length counts to determine sub-table sizes when building the 894f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie decoding tables. 904f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie */ 914f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie 924f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie /* accumulate lengths for codes (assumes lens[] all in 0..MAXBITS) */ 934f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie for (len = 0; len <= MAXBITS; len++) 944f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie count[len] = 0; 954f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie for (sym = 0; sym < codes; sym++) 964f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie count[lens[sym]]++; 974f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie 984f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie /* bound code lengths, force root to be within code lengths */ 994f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie root = *bits; 1004f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie for (max = MAXBITS; max >= 1; max--) 1014f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie if (count[max] != 0) break; 1024f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie if (root > max) root = max; 1034f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie if (max == 0) { /* no symbols to code at all */ 1044f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie this.op = (unsigned char)64; /* invalid code marker */ 1054f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie this.bits = (unsigned char)1; 1064f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie this.val = (unsigned short)0; 1074f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie *(*table)++ = this; /* make a table to force an error */ 1084f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie *(*table)++ = this; 1094f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie *bits = 1; 1104f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie return 0; /* no symbols, but wait for decoding to report error */ 1114f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie } 1124f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie for (min = 1; min <= MAXBITS; min++) 1134f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie if (count[min] != 0) break; 1144f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie if (root < min) root = min; 1154f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie 1164f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie /* check for an over-subscribed or incomplete set of lengths */ 1174f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie left = 1; 1184f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie for (len = 1; len <= MAXBITS; len++) { 1194f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie left <<= 1; 1204f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie left -= count[len]; 1214f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie if (left < 0) return -1; /* over-subscribed */ 1224f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie } 1234f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie if (left > 0 && (type == CODES || max != 1)) 1244f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie return -1; /* incomplete set */ 1254f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie 1264f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie /* generate offsets into symbol table for each length for sorting */ 1274f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie offs[1] = 0; 1284f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie for (len = 1; len < MAXBITS; len++) 1294f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie offs[len + 1] = offs[len] + count[len]; 1304f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie 1314f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie /* sort symbols by length, by symbol order within each length */ 1324f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie for (sym = 0; sym < codes; sym++) 1334f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie if (lens[sym] != 0) work[offs[lens[sym]]++] = (unsigned short)sym; 1344f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie 1354f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie /* 1364f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie Create and fill in decoding tables. In this loop, the table being 1374f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie filled is at next and has curr index bits. The code being used is huff 1384f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie with length len. That code is converted to an index by dropping drop 1394f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie bits off of the bottom. For codes where len is less than drop + curr, 1404f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie those top drop + curr - len bits are incremented through all values to 1414f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie fill the table with replicated entries. 1424f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie 1434f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie root is the number of index bits for the root table. When len exceeds 1444f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie root, sub-tables are created pointed to by the root entry with an index 1454f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie of the low root bits of huff. This is saved in low to check for when a 1464f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie new sub-table should be started. drop is zero when the root table is 1474f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie being filled, and drop is root when sub-tables are being filled. 1484f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie 1494f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie When a new sub-table is needed, it is necessary to look ahead in the 1504f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie code lengths to determine what size sub-table is needed. The length 1514f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie counts are used for this, and so count[] is decremented as codes are 1524f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie entered in the tables. 1534f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie 1544f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie used keeps track of how many table entries have been allocated from the 1554f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie provided *table space. It is checked when a LENS table is being made 1564f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie against the space in *table, ENOUGH, minus the maximum space needed by 1574f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie the worst case distance code, MAXD. This should never happen, but the 1584f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie sufficiency of ENOUGH has not been proven exhaustively, hence the check. 1594f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie This assumes that when type == LENS, bits == 9. 1604f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie 1614f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie sym increments through all symbols, and the loop terminates when 1624f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie all codes of length max, i.e. all codes, have been processed. This 1634f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie routine permits incomplete codes, so another loop after this one fills 1644f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie in the rest of the decoding tables with invalid code markers. 1654f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie */ 1664f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie 1674f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie /* set up for code type */ 1684f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie switch (type) { 1694f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie case CODES: 1704f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie base = extra = work; /* dummy value--not used */ 1714f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie end = 19; 1724f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie break; 1734f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie case LENS: 1744f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie base = lbase; 1754f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie base -= 257; 1764f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie extra = lext; 1774f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie extra -= 257; 1784f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie end = 256; 1794f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie break; 1804f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie default: /* DISTS */ 1814f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie base = dbase; 1824f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie extra = dext; 1834f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie end = -1; 1844f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie } 1851da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds 1864f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie /* initialize state for loop */ 1874f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie huff = 0; /* starting code */ 1884f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie sym = 0; /* starting code symbol */ 1894f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie len = min; /* starting code length */ 1904f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie next = *table; /* current table to fill in */ 1914f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie curr = root; /* current table index bits */ 1924f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie drop = 0; /* current bits to drop from code for index */ 1934f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie low = (unsigned)(-1); /* trigger new sub-table when len > root */ 1944f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie used = 1U << root; /* use root table entries */ 1954f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie mask = used - 1; /* mask for comparing low */ 1964f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie 1974f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie /* check available table space */ 1984f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie if (type == LENS && used >= ENOUGH - MAXD) 1994f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie return 1; 2004f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie 2014f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie /* process all codes and make table entries */ 2024f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie for (;;) { 2034f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie /* create table entry */ 2044f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie this.bits = (unsigned char)(len - drop); 2054f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie if ((int)(work[sym]) < end) { 2064f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie this.op = (unsigned char)0; 2074f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie this.val = work[sym]; 2081da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds } 2094f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie else if ((int)(work[sym]) > end) { 2104f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie this.op = (unsigned char)(extra[work[sym]]); 2114f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie this.val = base[work[sym]]; 2124f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie } 2134f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie else { 2144f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie this.op = (unsigned char)(32 + 64); /* end of block */ 2154f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie this.val = 0; 2161da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds } 2171da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds 2184f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie /* replicate for those indices with low len bits equal to huff */ 2194f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie incr = 1U << (len - drop); 2204f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie fill = 1U << curr; 2214f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie min = fill; /* save offset to next table */ 2224f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie do { 2234f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie fill -= incr; 2244f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie next[(huff >> drop) + fill] = this; 2254f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie } while (fill != 0); 2264f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie 2274f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie /* backwards increment the len-bit code huff */ 2284f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie incr = 1U << (len - 1); 2294f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie while (huff & incr) 2304f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie incr >>= 1; 2314f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie if (incr != 0) { 2324f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie huff &= incr - 1; 2334f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie huff += incr; 2344f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie } 2354f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie else 2364f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie huff = 0; 2371da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds 2384f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie /* go to next symbol, update count, len */ 2394f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie sym++; 2404f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie if (--(count[len]) == 0) { 2414f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie if (len == max) break; 2424f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie len = lens[work[sym]]; 2434f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie } 2441da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds 2454f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie /* create new sub-table if needed */ 2464f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie if (len > root && (huff & mask) != low) { 2474f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie /* if first time, transition to sub-tables */ 2484f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie if (drop == 0) 2494f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie drop = root; 2504f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie 2514f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie /* increment past last table */ 2524f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie next += min; /* here min is 1 << curr */ 2534f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie 2544f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie /* determine length of next table */ 2554f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie curr = len - drop; 2564f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie left = (int)(1 << curr); 2574f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie while (curr + drop < max) { 2584f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie left -= count[curr + drop]; 2594f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie if (left <= 0) break; 2604f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie curr++; 2614f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie left <<= 1; 2624f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie } 2631da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds 2644f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie /* check for enough space */ 2654f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie used += 1U << curr; 2664f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie if (type == LENS && used >= ENOUGH - MAXD) 2674f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie return 1; 2681da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds 2694f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie /* point entry in root table to sub-table */ 2704f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie low = huff & mask; 2714f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie (*table)[low].op = (unsigned char)curr; 2724f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie (*table)[low].bits = (unsigned char)root; 2734f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie (*table)[low].val = (unsigned short)(next - *table); 2744f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie } 2751da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds } 2761da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds 2774f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie /* 2784f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie Fill in rest of table for incomplete codes. This loop is similar to the 2794f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie loop above in incrementing huff for table indices. It is assumed that 2804f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie len is equal to curr + drop, so there is no loop needed to increment 2814f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie through high index bits. When the current sub-table is filled, the loop 2824f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie drops back to the root table to fill in any remaining entries there. 2834f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie */ 2844f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie this.op = (unsigned char)64; /* invalid code marker */ 2854f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie this.bits = (unsigned char)(len - drop); 2864f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie this.val = (unsigned short)0; 2874f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie while (huff != 0) { 2884f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie /* when done with sub-table, drop back to root table */ 2894f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie if (drop != 0 && (huff & mask) != low) { 2904f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie drop = 0; 2914f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie len = root; 2924f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie next = *table; 2934f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie this.bits = (unsigned char)len; 2944f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie } 2951da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds 2964f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie /* put invalid code marker in table */ 2974f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie next[huff >> drop] = this; 2981da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds 2994f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie /* backwards increment the len-bit code huff */ 3004f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie incr = 1U << (len - 1); 3014f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie while (huff & incr) 3024f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie incr >>= 1; 3034f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie if (incr != 0) { 3044f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie huff &= incr - 1; 3054f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie huff += incr; 3064f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie } 3074f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie else 3084f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie huff = 0; 3094f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie } 3104f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie 3114f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie /* set return parameters */ 3124f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie *table += used; 3134f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie *bits = root; 3144f3865fb57a04db7cca068fed1c15badc064a302Richard Purdie return 0; 3151da177e4c3f41524e886b7f1b8a0c1fc7321cacLinus Torvalds} 316