kernel / pub / scm / linux / kernel / git / bwh / klibc / 1a6f222b01cead2ec48556203f0e200107eb4c2f / . / usr / gzip / trees.c

/* trees.c -- output deflated data using Huffman coding | |

* Copyright (C) 1992-1993 Jean-loup Gailly | |

* This is free software; you can redistribute it and/or modify it under the | |

* terms of the GNU General Public License, see the file COPYING. | |

*/ | |

/* | |

* PURPOSE | |

* | |

* Encode various sets of source values using variable-length | |

* binary code trees. | |

* | |

* DISCUSSION | |

* | |

* The PKZIP "deflation" process uses several Huffman trees. The more | |

* common source values are represented by shorter bit sequences. | |

* | |

* Each code tree is stored in the ZIP file in a compressed form | |

* which is itself a Huffman encoding of the lengths of | |

* all the code strings (in ascending order by source values). | |

* The actual code strings are reconstructed from the lengths in | |

* the UNZIP process, as described in the "application note" | |

* (APPNOTE.TXT) distributed as part of PKWARE's PKZIP program. | |

* | |

* REFERENCES | |

* | |

* Lynch, Thomas J. | |

* Data Compression: Techniques and Applications, pp. 53-55. | |

* Lifetime Learning Publications, 1985. ISBN 0-534-03418-7. | |

* | |

* Storer, James A. | |

* Data Compression: Methods and Theory, pp. 49-50. | |

* Computer Science Press, 1988. ISBN 0-7167-8156-5. | |

* | |

* Sedgewick, R. | |

* Algorithms, p290. | |

* Addison-Wesley, 1983. ISBN 0-201-06672-6. | |

* | |

* INTERFACE | |

* | |

* void ct_init (ush *attr, int *methodp) | |

* Allocate the match buffer, initialize the various tables and save | |

* the location of the internal file attribute (ascii/binary) and | |

* method (DEFLATE/STORE) | |

* | |

* void ct_tally (int dist, int lc); | |

* Save the match info and tally the frequency counts. | |

* | |

* long flush_block (char *buf, ulg stored_len, int eof) | |

* Determine the best encoding for the current block: dynamic trees, | |

* static trees or store, and output the encoded block to the zip | |

* file. Returns the total compressed length for the file so far. | |

* | |

*/ | |

#include <ctype.h> | |

#include "tailor.h" | |

#include "gzip.h" | |

#ifdef RCSID | |

static char rcsid[] = "$Id: trees.c,v 1.1 2002/08/18 00:59:21 hpa Exp $"; | |

#endif | |

/* =========================================================================== | |

* Constants | |

*/ | |

#define MAX_BITS 15 | |

/* All codes must not exceed MAX_BITS bits */ | |

#define MAX_BL_BITS 7 | |

/* Bit length codes must not exceed MAX_BL_BITS bits */ | |

#define LENGTH_CODES 29 | |

/* number of length codes, not counting the special END_BLOCK code */ | |

#define LITERALS 256 | |

/* number of literal bytes 0..255 */ | |

#define END_BLOCK 256 | |

/* end of block literal code */ | |

#define L_CODES (LITERALS+1+LENGTH_CODES) | |

/* number of Literal or Length codes, including the END_BLOCK code */ | |

#define D_CODES 30 | |

/* number of distance codes */ | |

#define BL_CODES 19 | |

/* number of codes used to transfer the bit lengths */ | |

local int extra_lbits[LENGTH_CODES] /* extra bits for each length code */ | |

= {0,0,0,0,0,0,0,0,1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4,5,5,5,5,0}; | |

local int extra_dbits[D_CODES] /* extra bits for each distance code */ | |

= {0,0,0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,13,13}; | |

local int extra_blbits[BL_CODES]/* extra bits for each bit length code */ | |

= {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2,3,7}; | |

#define STORED_BLOCK 0 | |

#define STATIC_TREES 1 | |

#define DYN_TREES 2 | |

/* The three kinds of block type */ | |

#ifndef LIT_BUFSIZE | |

# ifdef SMALL_MEM | |

# define LIT_BUFSIZE 0x2000 | |

# else | |

# ifdef MEDIUM_MEM | |

# define LIT_BUFSIZE 0x4000 | |

# else | |

# define LIT_BUFSIZE 0x8000 | |

# endif | |

# endif | |

#endif | |

#ifndef DIST_BUFSIZE | |

# define DIST_BUFSIZE LIT_BUFSIZE | |

#endif | |

/* Sizes of match buffers for literals/lengths and distances. There are | |

* 4 reasons for limiting LIT_BUFSIZE to 64K: | |

* - frequencies can be kept in 16 bit counters | |

* - if compression is not successful for the first block, all input data is | |

* still in the window so we can still emit a stored block even when input | |

* comes from standard input. (This can also be done for all blocks if | |

* LIT_BUFSIZE is not greater than 32K.) | |

* - if compression is not successful for a file smaller than 64K, we can | |

* even emit a stored file instead of a stored block (saving 5 bytes). | |

* - creating new Huffman trees less frequently may not provide fast | |

* adaptation to changes in the input data statistics. (Take for | |

* example a binary file with poorly compressible code followed by | |

* a highly compressible string table.) Smaller buffer sizes give | |

* fast adaptation but have of course the overhead of transmitting trees | |

* more frequently. | |

* - I can't count above 4 | |

* The current code is general and allows DIST_BUFSIZE < LIT_BUFSIZE (to save | |

* memory at the expense of compression). Some optimizations would be possible | |

* if we rely on DIST_BUFSIZE == LIT_BUFSIZE. | |

*/ | |

#if LIT_BUFSIZE > INBUFSIZ | |

error cannot overlay l_buf and inbuf | |

#endif | |

#define REP_3_6 16 | |

/* repeat previous bit length 3-6 times (2 bits of repeat count) */ | |

#define REPZ_3_10 17 | |

/* repeat a zero length 3-10 times (3 bits of repeat count) */ | |

#define REPZ_11_138 18 | |

/* repeat a zero length 11-138 times (7 bits of repeat count) */ | |

/* =========================================================================== | |

* Local data | |

*/ | |

/* Data structure describing a single value and its code string. */ | |

typedef struct ct_data { | |

union { | |

ush freq; /* frequency count */ | |

ush code; /* bit string */ | |

} fc; | |

union { | |

ush dad; /* father node in Huffman tree */ | |

ush len; /* length of bit string */ | |

} dl; | |

} ct_data; | |

#define Freq fc.freq | |

#define Code fc.code | |

#define Dad dl.dad | |

#define Len dl.len | |

#define HEAP_SIZE (2*L_CODES+1) | |

/* maximum heap size */ | |

local ct_data dyn_ltree[HEAP_SIZE]; /* literal and length tree */ | |

local ct_data dyn_dtree[2*D_CODES+1]; /* distance tree */ | |

local ct_data static_ltree[L_CODES+2]; | |

/* The static literal tree. Since the bit lengths are imposed, there is no | |

* need for the L_CODES extra codes used during heap construction. However | |

* The codes 286 and 287 are needed to build a canonical tree (see ct_init | |

* below). | |

*/ | |

local ct_data static_dtree[D_CODES]; | |

/* The static distance tree. (Actually a trivial tree since all codes use | |

* 5 bits.) | |

*/ | |

local ct_data bl_tree[2*BL_CODES+1]; | |

/* Huffman tree for the bit lengths */ | |

typedef struct tree_desc { | |

ct_data *dyn_tree; /* the dynamic tree */ | |

ct_data *static_tree; /* corresponding static tree or NULL */ | |

int *extra_bits; /* extra bits for each code or NULL */ | |

int extra_base; /* base index for extra_bits */ | |

int elems; /* max number of elements in the tree */ | |

int max_length; /* max bit length for the codes */ | |

int max_code; /* largest code with non zero frequency */ | |

} tree_desc; | |

local tree_desc l_desc = | |

{dyn_ltree, static_ltree, extra_lbits, LITERALS+1, L_CODES, MAX_BITS, 0}; | |

local tree_desc d_desc = | |

{dyn_dtree, static_dtree, extra_dbits, 0, D_CODES, MAX_BITS, 0}; | |

local tree_desc bl_desc = | |

{bl_tree, (ct_data *)0, extra_blbits, 0, BL_CODES, MAX_BL_BITS, 0}; | |

local ush bl_count[MAX_BITS+1]; | |

/* number of codes at each bit length for an optimal tree */ | |

local uch bl_order[BL_CODES] | |

= {16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15}; | |

/* The lengths of the bit length codes are sent in order of decreasing | |

* probability, to avoid transmitting the lengths for unused bit length codes. | |

*/ | |

local int heap[2*L_CODES+1]; /* heap used to build the Huffman trees */ | |

local int heap_len; /* number of elements in the heap */ | |

local int heap_max; /* element of largest frequency */ | |

/* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used. | |

* The same heap array is used to build all trees. | |

*/ | |

local uch depth[2*L_CODES+1]; | |

/* Depth of each subtree used as tie breaker for trees of equal frequency */ | |

local uch length_code[MAX_MATCH-MIN_MATCH+1]; | |

/* length code for each normalized match length (0 == MIN_MATCH) */ | |

local uch dist_code[512]; | |

/* distance codes. The first 256 values correspond to the distances | |

* 3 .. 258, the last 256 values correspond to the top 8 bits of | |

* the 15 bit distances. | |

*/ | |

local int base_length[LENGTH_CODES]; | |

/* First normalized length for each code (0 = MIN_MATCH) */ | |

local int base_dist[D_CODES]; | |

/* First normalized distance for each code (0 = distance of 1) */ | |

#define l_buf inbuf | |

/* DECLARE(uch, l_buf, LIT_BUFSIZE); buffer for literals or lengths */ | |

/* DECLARE(ush, d_buf, DIST_BUFSIZE); buffer for distances */ | |

local uch flag_buf[(LIT_BUFSIZE/8)]; | |

/* flag_buf is a bit array distinguishing literals from lengths in | |

* l_buf, thus indicating the presence or absence of a distance. | |

*/ | |

local unsigned last_lit; /* running index in l_buf */ | |

local unsigned last_dist; /* running index in d_buf */ | |

local unsigned last_flags; /* running index in flag_buf */ | |

local uch flags; /* current flags not yet saved in flag_buf */ | |

local uch flag_bit; /* current bit used in flags */ | |

/* bits are filled in flags starting at bit 0 (least significant). | |

* Note: these flags are overkill in the current code since we don't | |

* take advantage of DIST_BUFSIZE == LIT_BUFSIZE. | |

*/ | |

local ulg opt_len; /* bit length of current block with optimal trees */ | |

local ulg static_len; /* bit length of current block with static trees */ | |

local ulg compressed_len; /* total bit length of compressed file */ | |

local ulg input_len; /* total byte length of input file */ | |

/* input_len is for debugging only since we can get it by other means. */ | |

ush *file_type; /* pointer to UNKNOWN, BINARY or ASCII */ | |

int *file_method; /* pointer to DEFLATE or STORE */ | |

#ifdef DEBUG | |

extern ulg bits_sent; /* bit length of the compressed data */ | |

extern long isize; /* byte length of input file */ | |

#endif | |

extern long block_start; /* window offset of current block */ | |

extern unsigned strstart; /* window offset of current string */ | |

/* =========================================================================== | |

* Local (static) routines in this file. | |

*/ | |

local void init_block OF((void)); | |

local void pqdownheap OF((ct_data *tree, int k)); | |

local void gen_bitlen OF((tree_desc *desc)); | |

local void gen_codes OF((ct_data *tree, int max_code)); | |

local void build_tree OF((tree_desc *desc)); | |

local void scan_tree OF((ct_data *tree, int max_code)); | |

local void send_tree OF((ct_data *tree, int max_code)); | |

local int build_bl_tree OF((void)); | |

local void send_all_trees OF((int lcodes, int dcodes, int blcodes)); | |

local void compress_block OF((ct_data *ltree, ct_data *dtree)); | |

local void set_file_type OF((void)); | |

#ifndef DEBUG | |

# define send_code(c, tree) send_bits(tree[c].Code, tree[c].Len) | |

/* Send a code of the given tree. c and tree must not have side effects */ | |

#else /* DEBUG */ | |

# define send_code(c, tree) \ | |

{ if (verbose>1) fprintf(stderr,"\ncd %3d ",(c)); \ | |

send_bits(tree[c].Code, tree[c].Len); } | |

#endif | |

#define d_code(dist) \ | |

((dist) < 256 ? dist_code[dist] : dist_code[256+((dist)>>7)]) | |

/* Mapping from a distance to a distance code. dist is the distance - 1 and | |

* must not have side effects. dist_code[256] and dist_code[257] are never | |

* used. | |

*/ | |

#define MAX(a,b) (a >= b ? a : b) | |

/* the arguments must not have side effects */ | |

/* =========================================================================== | |

* Allocate the match buffer, initialize the various tables and save the | |

* location of the internal file attribute (ascii/binary) and method | |

* (DEFLATE/STORE). | |

*/ | |

void ct_init(attr, methodp) | |

ush *attr; /* pointer to internal file attribute */ | |

int *methodp; /* pointer to compression method */ | |

{ | |

int n; /* iterates over tree elements */ | |

int bits; /* bit counter */ | |

int length; /* length value */ | |

int code; /* code value */ | |

int dist; /* distance index */ | |

file_type = attr; | |

file_method = methodp; | |

compressed_len = input_len = 0L; | |

if (static_dtree[0].Len != 0) return; /* ct_init already called */ | |

/* Initialize the mapping length (0..255) -> length code (0..28) */ | |

length = 0; | |

for (code = 0; code < LENGTH_CODES-1; code++) { | |

base_length[code] = length; | |

for (n = 0; n < (1<<extra_lbits[code]); n++) { | |

length_code[length++] = (uch)code; | |

} | |

} | |

Assert (length == 256, "ct_init: length != 256"); | |

/* Note that the length 255 (match length 258) can be represented | |

* in two different ways: code 284 + 5 bits or code 285, so we | |

* overwrite length_code[255] to use the best encoding: | |

*/ | |

length_code[length-1] = (uch)code; | |

/* Initialize the mapping dist (0..32K) -> dist code (0..29) */ | |

dist = 0; | |

for (code = 0 ; code < 16; code++) { | |

base_dist[code] = dist; | |

for (n = 0; n < (1<<extra_dbits[code]); n++) { | |

dist_code[dist++] = (uch)code; | |

} | |

} | |

Assert (dist == 256, "ct_init: dist != 256"); | |

dist >>= 7; /* from now on, all distances are divided by 128 */ | |

for ( ; code < D_CODES; code++) { | |

base_dist[code] = dist << 7; | |

for (n = 0; n < (1<<(extra_dbits[code]-7)); n++) { | |

dist_code[256 + dist++] = (uch)code; | |

} | |

} | |

Assert (dist == 256, "ct_init: 256+dist != 512"); | |

/* Construct the codes of the static literal tree */ | |

for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0; | |

n = 0; | |

while (n <= 143) static_ltree[n++].Len = 8, bl_count[8]++; | |

while (n <= 255) static_ltree[n++].Len = 9, bl_count[9]++; | |

while (n <= 279) static_ltree[n++].Len = 7, bl_count[7]++; | |

while (n <= 287) static_ltree[n++].Len = 8, bl_count[8]++; | |

/* Codes 286 and 287 do not exist, but we must include them in the | |

* tree construction to get a canonical Huffman tree (longest code | |

* all ones) | |

*/ | |

gen_codes((ct_data *)static_ltree, L_CODES+1); | |

/* The static distance tree is trivial: */ | |

for (n = 0; n < D_CODES; n++) { | |

static_dtree[n].Len = 5; | |

static_dtree[n].Code = bi_reverse(n, 5); | |

} | |

/* Initialize the first block of the first file: */ | |

init_block(); | |

} | |

/* =========================================================================== | |

* Initialize a new block. | |

*/ | |

local void init_block() | |

{ | |

int n; /* iterates over tree elements */ | |

/* Initialize the trees. */ | |

for (n = 0; n < L_CODES; n++) dyn_ltree[n].Freq = 0; | |

for (n = 0; n < D_CODES; n++) dyn_dtree[n].Freq = 0; | |

for (n = 0; n < BL_CODES; n++) bl_tree[n].Freq = 0; | |

dyn_ltree[END_BLOCK].Freq = 1; | |

opt_len = static_len = 0L; | |

last_lit = last_dist = last_flags = 0; | |

flags = 0; flag_bit = 1; | |

} | |

#define SMALLEST 1 | |

/* Index within the heap array of least frequent node in the Huffman tree */ | |

/* =========================================================================== | |

* Remove the smallest element from the heap and recreate the heap with | |

* one less element. Updates heap and heap_len. | |

*/ | |

#define pqremove(tree, top) \ | |

{\ | |

top = heap[SMALLEST]; \ | |

heap[SMALLEST] = heap[heap_len--]; \ | |

pqdownheap(tree, SMALLEST); \ | |

} | |

/* =========================================================================== | |

* Compares to subtrees, using the tree depth as tie breaker when | |

* the subtrees have equal frequency. This minimizes the worst case length. | |

*/ | |

#define smaller(tree, n, m) \ | |

(tree[n].Freq < tree[m].Freq || \ | |

(tree[n].Freq == tree[m].Freq && depth[n] <= depth[m])) | |

/* =========================================================================== | |

* Restore the heap property by moving down the tree starting at node k, | |

* exchanging a node with the smallest of its two sons if necessary, stopping | |

* when the heap property is re-established (each father smaller than its | |

* two sons). | |

*/ | |

local void pqdownheap(tree, k) | |

ct_data *tree; /* the tree to restore */ | |

int k; /* node to move down */ | |

{ | |

int v = heap[k]; | |

int j = k << 1; /* left son of k */ | |

while (j <= heap_len) { | |

/* Set j to the smallest of the two sons: */ | |

if (j < heap_len && smaller(tree, heap[j+1], heap[j])) j++; | |

/* Exit if v is smaller than both sons */ | |

if (smaller(tree, v, heap[j])) break; | |

/* Exchange v with the smallest son */ | |

heap[k] = heap[j]; k = j; | |

/* And continue down the tree, setting j to the left son of k */ | |

j <<= 1; | |

} | |

heap[k] = v; | |

} | |

/* =========================================================================== | |

* Compute the optimal bit lengths for a tree and update the total bit length | |

* for the current block. | |

* IN assertion: the fields freq and dad are set, heap[heap_max] and | |

* above are the tree nodes sorted by increasing frequency. | |

* OUT assertions: the field len is set to the optimal bit length, the | |

* array bl_count contains the frequencies for each bit length. | |

* The length opt_len is updated; static_len is also updated if stree is | |

* not null. | |

*/ | |

local void gen_bitlen(desc) | |

tree_desc *desc; /* the tree descriptor */ | |

{ | |

ct_data *tree = desc->dyn_tree; | |

int *extra = desc->extra_bits; | |

int base = desc->extra_base; | |

int max_code = desc->max_code; | |

int max_length = desc->max_length; | |

ct_data *stree = desc->static_tree; | |

int h; /* heap index */ | |

int n, m; /* iterate over the tree elements */ | |

int bits; /* bit length */ | |

int xbits; /* extra bits */ | |

ush f; /* frequency */ | |

int overflow = 0; /* number of elements with bit length too large */ | |

for (bits = 0; bits <= MAX_BITS; bits++) bl_count[bits] = 0; | |

/* In a first pass, compute the optimal bit lengths (which may | |

* overflow in the case of the bit length tree). | |

*/ | |

tree[heap[heap_max]].Len = 0; /* root of the heap */ | |

for (h = heap_max+1; h < HEAP_SIZE; h++) { | |

n = heap[h]; | |

bits = tree[tree[n].Dad].Len + 1; | |

if (bits > max_length) bits = max_length, overflow++; | |

tree[n].Len = (ush)bits; | |

/* We overwrite tree[n].Dad which is no longer needed */ | |

if (n > max_code) continue; /* not a leaf node */ | |

bl_count[bits]++; | |

xbits = 0; | |

if (n >= base) xbits = extra[n-base]; | |

f = tree[n].Freq; | |

opt_len += (ulg)f * (bits + xbits); | |

if (stree) static_len += (ulg)f * (stree[n].Len + xbits); | |

} | |

if (overflow == 0) return; | |

Trace((stderr,"\nbit length overflow\n")); | |

/* This happens for example on obj2 and pic of the Calgary corpus */ | |

/* Find the first bit length which could increase: */ | |

do { | |

bits = max_length-1; | |

while (bl_count[bits] == 0) bits--; | |

bl_count[bits]--; /* move one leaf down the tree */ | |

bl_count[bits+1] += 2; /* move one overflow item as its brother */ | |

bl_count[max_length]--; | |

/* The brother of the overflow item also moves one step up, | |

* but this does not affect bl_count[max_length] | |

*/ | |

overflow -= 2; | |

} while (overflow > 0); | |

/* Now recompute all bit lengths, scanning in increasing frequency. | |

* h is still equal to HEAP_SIZE. (It is simpler to reconstruct all | |

* lengths instead of fixing only the wrong ones. This idea is taken | |

* from 'ar' written by Haruhiko Okumura.) | |

*/ | |

for (bits = max_length; bits != 0; bits--) { | |

n = bl_count[bits]; | |

while (n != 0) { | |

m = heap[--h]; | |

if (m > max_code) continue; | |

if (tree[m].Len != (unsigned) bits) { | |

Trace((stderr,"code %d bits %d->%d\n", m, tree[m].Len, bits)); | |

opt_len += ((long)bits-(long)tree[m].Len)*(long)tree[m].Freq; | |

tree[m].Len = (ush)bits; | |

} | |

n--; | |

} | |

} | |

} | |

/* =========================================================================== | |

* Generate the codes for a given tree and bit counts (which need not be | |

* optimal). | |

* IN assertion: the array bl_count contains the bit length statistics for | |

* the given tree and the field len is set for all tree elements. | |

* OUT assertion: the field code is set for all tree elements of non | |

* zero code length. | |

*/ | |

local void gen_codes (tree, max_code) | |

ct_data *tree; /* the tree to decorate */ | |

int max_code; /* largest code with non zero frequency */ | |

{ | |

ush next_code[MAX_BITS+1]; /* next code value for each bit length */ | |

ush code = 0; /* running code value */ | |

int bits; /* bit index */ | |

int n; /* code index */ | |

/* The distribution counts are first used to generate the code values | |

* without bit reversal. | |

*/ | |

for (bits = 1; bits <= MAX_BITS; bits++) { | |

next_code[bits] = code = (code + bl_count[bits-1]) << 1; | |

} | |

/* Check that the bit counts in bl_count are consistent. The last code | |

* must be all ones. | |

*/ | |

Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1, | |

"inconsistent bit counts"); | |

Tracev((stderr,"\ngen_codes: max_code %d ", max_code)); | |

for (n = 0; n <= max_code; n++) { | |

int len = tree[n].Len; | |

if (len == 0) continue; | |

/* Now reverse the bits */ | |

tree[n].Code = bi_reverse(next_code[len]++, len); | |

Tracec(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ", | |

n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len]-1)); | |

} | |

} | |

/* =========================================================================== | |

* Construct one Huffman tree and assigns the code bit strings and lengths. | |

* Update the total bit length for the current block. | |

* IN assertion: the field freq is set for all tree elements. | |

* OUT assertions: the fields len and code are set to the optimal bit length | |

* and corresponding code. The length opt_len is updated; static_len is | |

* also updated if stree is not null. The field max_code is set. | |

*/ | |

local void build_tree(desc) | |

tree_desc *desc; /* the tree descriptor */ | |

{ | |

ct_data *tree = desc->dyn_tree; | |

ct_data *stree = desc->static_tree; | |

int elems = desc->elems; | |

int n, m; /* iterate over heap elements */ | |

int max_code = -1; /* largest code with non zero frequency */ | |

int node = elems; /* next internal node of the tree */ | |

/* Construct the initial heap, with least frequent element in | |

* heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1]. | |

* heap[0] is not used. | |

*/ | |

heap_len = 0, heap_max = HEAP_SIZE; | |

for (n = 0; n < elems; n++) { | |

if (tree[n].Freq != 0) { | |

heap[++heap_len] = max_code = n; | |

depth[n] = 0; | |

} else { | |

tree[n].Len = 0; | |

} | |

} | |

/* The pkzip format requires that at least one distance code exists, | |

* and that at least one bit should be sent even if there is only one | |

* possible code. So to avoid special checks later on we force at least | |

* two codes of non zero frequency. | |

*/ | |

while (heap_len < 2) { | |

int new = heap[++heap_len] = (max_code < 2 ? ++max_code : 0); | |

tree[new].Freq = 1; | |

depth[new] = 0; | |

opt_len--; if (stree) static_len -= stree[new].Len; | |

/* new is 0 or 1 so it does not have extra bits */ | |

} | |

desc->max_code = max_code; | |

/* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree, | |

* establish sub-heaps of increasing lengths: | |

*/ | |

for (n = heap_len/2; n >= 1; n--) pqdownheap(tree, n); | |

/* Construct the Huffman tree by repeatedly combining the least two | |

* frequent nodes. | |

*/ | |

do { | |

pqremove(tree, n); /* n = node of least frequency */ | |

m = heap[SMALLEST]; /* m = node of next least frequency */ | |

heap[--heap_max] = n; /* keep the nodes sorted by frequency */ | |

heap[--heap_max] = m; | |

/* Create a new node father of n and m */ | |

tree[node].Freq = tree[n].Freq + tree[m].Freq; | |

depth[node] = (uch) (MAX(depth[n], depth[m]) + 1); | |

tree[n].Dad = tree[m].Dad = (ush)node; | |

#ifdef DUMP_BL_TREE | |

if (tree == bl_tree) { | |

fprintf(stderr,"\nnode %d(%d), sons %d(%d) %d(%d)", | |

node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq); | |

} | |

#endif | |

/* and insert the new node in the heap */ | |

heap[SMALLEST] = node++; | |

pqdownheap(tree, SMALLEST); | |

} while (heap_len >= 2); | |

heap[--heap_max] = heap[SMALLEST]; | |

/* At this point, the fields freq and dad are set. We can now | |

* generate the bit lengths. | |

*/ | |

gen_bitlen((tree_desc *)desc); | |

/* The field len is now set, we can generate the bit codes */ | |

gen_codes ((ct_data *)tree, max_code); | |

} | |

/* =========================================================================== | |

* Scan a literal or distance tree to determine the frequencies of the codes | |

* in the bit length tree. Updates opt_len to take into account the repeat | |

* counts. (The contribution of the bit length codes will be added later | |

* during the construction of bl_tree.) | |

*/ | |

local void scan_tree (tree, max_code) | |

ct_data *tree; /* the tree to be scanned */ | |

int max_code; /* and its largest code of non zero frequency */ | |

{ | |

int n; /* iterates over all tree elements */ | |

int prevlen = -1; /* last emitted length */ | |

int curlen; /* length of current code */ | |

int nextlen = tree[0].Len; /* length of next code */ | |

int count = 0; /* repeat count of the current code */ | |

int max_count = 7; /* max repeat count */ | |

int min_count = 4; /* min repeat count */ | |

if (nextlen == 0) max_count = 138, min_count = 3; | |

tree[max_code+1].Len = (ush)0xffff; /* guard */ | |

for (n = 0; n <= max_code; n++) { | |

curlen = nextlen; nextlen = tree[n+1].Len; | |

if (++count < max_count && curlen == nextlen) { | |

continue; | |

} else if (count < min_count) { | |

bl_tree[curlen].Freq += count; | |

} else if (curlen != 0) { | |

if (curlen != prevlen) bl_tree[curlen].Freq++; | |

bl_tree[REP_3_6].Freq++; | |

} else if (count <= 10) { | |

bl_tree[REPZ_3_10].Freq++; | |

} else { | |

bl_tree[REPZ_11_138].Freq++; | |

} | |

count = 0; prevlen = curlen; | |

if (nextlen == 0) { | |

max_count = 138, min_count = 3; | |

} else if (curlen == nextlen) { | |

max_count = 6, min_count = 3; | |

} else { | |

max_count = 7, min_count = 4; | |

} | |

} | |

} | |

/* =========================================================================== | |

* Send a literal or distance tree in compressed form, using the codes in | |

* bl_tree. | |

*/ | |

local void send_tree (tree, max_code) | |

ct_data *tree; /* the tree to be scanned */ | |

int max_code; /* and its largest code of non zero frequency */ | |

{ | |

int n; /* iterates over all tree elements */ | |

int prevlen = -1; /* last emitted length */ | |

int curlen; /* length of current code */ | |

int nextlen = tree[0].Len; /* length of next code */ | |

int count = 0; /* repeat count of the current code */ | |

int max_count = 7; /* max repeat count */ | |

int min_count = 4; /* min repeat count */ | |

/* tree[max_code+1].Len = -1; */ /* guard already set */ | |

if (nextlen == 0) max_count = 138, min_count = 3; | |

for (n = 0; n <= max_code; n++) { | |

curlen = nextlen; nextlen = tree[n+1].Len; | |

if (++count < max_count && curlen == nextlen) { | |

continue; | |

} else if (count < min_count) { | |

do { send_code(curlen, bl_tree); } while (--count != 0); | |

} else if (curlen != 0) { | |

if (curlen != prevlen) { | |

send_code(curlen, bl_tree); count--; | |

} | |

Assert(count >= 3 && count <= 6, " 3_6?"); | |

send_code(REP_3_6, bl_tree); send_bits(count-3, 2); | |

} else if (count <= 10) { | |

send_code(REPZ_3_10, bl_tree); send_bits(count-3, 3); | |

} else { | |

send_code(REPZ_11_138, bl_tree); send_bits(count-11, 7); | |

} | |

count = 0; prevlen = curlen; | |

if (nextlen == 0) { | |

max_count = 138, min_count = 3; | |

} else if (curlen == nextlen) { | |

max_count = 6, min_count = 3; | |

} else { | |

max_count = 7, min_count = 4; | |

} | |

} | |

} | |

/* =========================================================================== | |

* Construct the Huffman tree for the bit lengths and return the index in | |

* bl_order of the last bit length code to send. | |

*/ | |

local int build_bl_tree() | |

{ | |

int max_blindex; /* index of last bit length code of non zero freq */ | |

/* Determine the bit length frequencies for literal and distance trees */ | |

scan_tree((ct_data *)dyn_ltree, l_desc.max_code); | |

scan_tree((ct_data *)dyn_dtree, d_desc.max_code); | |

/* Build the bit length tree: */ | |

build_tree((tree_desc *)(&bl_desc)); | |

/* opt_len now includes the length of the tree representations, except | |

* the lengths of the bit lengths codes and the 5+5+4 bits for the counts. | |

*/ | |

/* Determine the number of bit length codes to send. The pkzip format | |

* requires that at least 4 bit length codes be sent. (appnote.txt says | |

* 3 but the actual value used is 4.) | |

*/ | |

for (max_blindex = BL_CODES-1; max_blindex >= 3; max_blindex--) { | |

if (bl_tree[bl_order[max_blindex]].Len != 0) break; | |

} | |

/* Update opt_len to include the bit length tree and counts */ | |

opt_len += 3*(max_blindex+1) + 5+5+4; | |

Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld", opt_len, static_len)); | |

return max_blindex; | |

} | |

/* =========================================================================== | |

* Send the header for a block using dynamic Huffman trees: the counts, the | |

* lengths of the bit length codes, the literal tree and the distance tree. | |

* IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4. | |

*/ | |

local void send_all_trees(lcodes, dcodes, blcodes) | |

int lcodes, dcodes, blcodes; /* number of codes for each tree */ | |

{ | |

int rank; /* index in bl_order */ | |

Assert (lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes"); | |

Assert (lcodes <= L_CODES && dcodes <= D_CODES && blcodes <= BL_CODES, | |

"too many codes"); | |

Tracev((stderr, "\nbl counts: ")); | |

send_bits(lcodes-257, 5); /* not +255 as stated in appnote.txt */ | |

send_bits(dcodes-1, 5); | |

send_bits(blcodes-4, 4); /* not -3 as stated in appnote.txt */ | |

for (rank = 0; rank < blcodes; rank++) { | |

Tracev((stderr, "\nbl code %2d ", bl_order[rank])); | |

send_bits(bl_tree[bl_order[rank]].Len, 3); | |

} | |

Tracev((stderr, "\nbl tree: sent %ld", bits_sent)); | |

send_tree((ct_data *)dyn_ltree, lcodes-1); /* send the literal tree */ | |

Tracev((stderr, "\nlit tree: sent %ld", bits_sent)); | |

send_tree((ct_data *)dyn_dtree, dcodes-1); /* send the distance tree */ | |

Tracev((stderr, "\ndist tree: sent %ld", bits_sent)); | |

} | |

/* =========================================================================== | |

* Determine the best encoding for the current block: dynamic trees, static | |

* trees or store, and output the encoded block to the zip file. This function | |

* returns the total compressed length for the file so far. | |

*/ | |

ulg flush_block(buf, stored_len, eof) | |

char *buf; /* input block, or NULL if too old */ | |

ulg stored_len; /* length of input block */ | |

int eof; /* true if this is the last block for a file */ | |

{ | |

ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */ | |

int max_blindex; /* index of last bit length code of non zero freq */ | |

flag_buf[last_flags] = flags; /* Save the flags for the last 8 items */ | |

/* Check if the file is ascii or binary */ | |

if (*file_type == (ush)UNKNOWN) set_file_type(); | |

/* Construct the literal and distance trees */ | |

build_tree((tree_desc *)(&l_desc)); | |

Tracev((stderr, "\nlit data: dyn %ld, stat %ld", opt_len, static_len)); | |

build_tree((tree_desc *)(&d_desc)); | |

Tracev((stderr, "\ndist data: dyn %ld, stat %ld", opt_len, static_len)); | |

/* At this point, opt_len and static_len are the total bit lengths of | |

* the compressed block data, excluding the tree representations. | |

*/ | |

/* Build the bit length tree for the above two trees, and get the index | |

* in bl_order of the last bit length code to send. | |

*/ | |

max_blindex = build_bl_tree(); | |

/* Determine the best encoding. Compute first the block length in bytes */ | |

opt_lenb = (opt_len+3+7)>>3; | |

static_lenb = (static_len+3+7)>>3; | |

input_len += stored_len; /* for debugging only */ | |

Trace((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u dist %u ", | |

opt_lenb, opt_len, static_lenb, static_len, stored_len, | |

last_lit, last_dist)); | |

if (static_lenb <= opt_lenb) opt_lenb = static_lenb; | |

/* If compression failed and this is the first and last block, | |

* and if the zip file can be seeked (to rewrite the local header), | |

* the whole file is transformed into a stored file: | |

*/ | |

#ifdef FORCE_METHOD | |

if (level == 1 && eof && compressed_len == 0L) { /* force stored file */ | |

#else | |

if (stored_len <= opt_lenb && eof && compressed_len == 0L && seekable()) { | |

#endif | |

/* Since LIT_BUFSIZE <= 2*WSIZE, the input data must be there: */ | |

if (buf == (char*)0) error ("block vanished"); | |

copy_block(buf, (unsigned)stored_len, 0); /* without header */ | |

compressed_len = stored_len << 3; | |

*file_method = STORED; | |

#ifdef FORCE_METHOD | |

} else if (level == 2 && buf != (char*)0) { /* force stored block */ | |

#else | |

} else if (stored_len+4 <= opt_lenb && buf != (char*)0) { | |

/* 4: two words for the lengths */ | |

#endif | |

/* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE. | |

* Otherwise we can't have processed more than WSIZE input bytes since | |

* the last block flush, because compression would have been | |

* successful. If LIT_BUFSIZE <= WSIZE, it is never too late to | |

* transform a block into a stored block. | |

*/ | |

send_bits((STORED_BLOCK<<1)+eof, 3); /* send block type */ | |

compressed_len = (compressed_len + 3 + 7) & ~7L; | |

compressed_len += (stored_len + 4) << 3; | |

copy_block(buf, (unsigned)stored_len, 1); /* with header */ | |

#ifdef FORCE_METHOD | |

} else if (level == 3) { /* force static trees */ | |

#else | |

} else if (static_lenb == opt_lenb) { | |

#endif | |

send_bits((STATIC_TREES<<1)+eof, 3); | |

compress_block((ct_data *)static_ltree, (ct_data *)static_dtree); | |

compressed_len += 3 + static_len; | |

} else { | |

send_bits((DYN_TREES<<1)+eof, 3); | |

send_all_trees(l_desc.max_code+1, d_desc.max_code+1, max_blindex+1); | |

compress_block((ct_data *)dyn_ltree, (ct_data *)dyn_dtree); | |

compressed_len += 3 + opt_len; | |

} | |

Assert (compressed_len == bits_sent, "bad compressed size"); | |

init_block(); | |

if (eof) { | |

Assert (input_len == isize, "bad input size"); | |

bi_windup(); | |

compressed_len += 7; /* align on byte boundary */ | |

} | |

Tracev((stderr,"\ncomprlen %lu(%lu) ", compressed_len>>3, | |

compressed_len-7*eof)); | |

return compressed_len >> 3; | |

} | |

/* =========================================================================== | |

* Save the match info and tally the frequency counts. Return true if | |

* the current block must be flushed. | |

*/ | |

int ct_tally (dist, lc) | |

int dist; /* distance of matched string */ | |

int lc; /* match length-MIN_MATCH or unmatched char (if dist==0) */ | |

{ | |

l_buf[last_lit++] = (uch)lc; | |

if (dist == 0) { | |

/* lc is the unmatched char */ | |

dyn_ltree[lc].Freq++; | |

} else { | |

/* Here, lc is the match length - MIN_MATCH */ | |

dist--; /* dist = match distance - 1 */ | |

Assert((ush)dist < (ush)MAX_DIST && | |

(ush)lc <= (ush)(MAX_MATCH-MIN_MATCH) && | |

(ush)d_code(dist) < (ush)D_CODES, "ct_tally: bad match"); | |

dyn_ltree[length_code[lc]+LITERALS+1].Freq++; | |

dyn_dtree[d_code(dist)].Freq++; | |

d_buf[last_dist++] = (ush)dist; | |

flags |= flag_bit; | |

} | |

flag_bit <<= 1; | |

/* Output the flags if they fill a byte: */ | |

if ((last_lit & 7) == 0) { | |

flag_buf[last_flags++] = flags; | |

flags = 0, flag_bit = 1; | |

} | |

/* Try to guess if it is profitable to stop the current block here */ | |

if (level > 2 && (last_lit & 0xfff) == 0) { | |

/* Compute an upper bound for the compressed length */ | |

ulg out_length = (ulg)last_lit*8L; | |

ulg in_length = (ulg)strstart-block_start; | |

int dcode; | |

for (dcode = 0; dcode < D_CODES; dcode++) { | |

out_length += (ulg)dyn_dtree[dcode].Freq*(5L+extra_dbits[dcode]); | |

} | |

out_length >>= 3; | |

Trace((stderr,"\nlast_lit %u, last_dist %u, in %ld, out ~%ld(%ld%%) ", | |

last_lit, last_dist, in_length, out_length, | |

100L - out_length*100L/in_length)); | |

if (last_dist < last_lit/2 && out_length < in_length/2) return 1; | |

} | |

return (last_lit == LIT_BUFSIZE-1 || last_dist == DIST_BUFSIZE); | |

/* We avoid equality with LIT_BUFSIZE because of wraparound at 64K | |

* on 16 bit machines and because stored blocks are restricted to | |

* 64K-1 bytes. | |

*/ | |

} | |

/* =========================================================================== | |

* Send the block data compressed using the given Huffman trees | |

*/ | |

local void compress_block(ltree, dtree) | |

ct_data *ltree; /* literal tree */ | |

ct_data *dtree; /* distance tree */ | |

{ | |

unsigned dist; /* distance of matched string */ | |

int lc; /* match length or unmatched char (if dist == 0) */ | |

unsigned lx = 0; /* running index in l_buf */ | |

unsigned dx = 0; /* running index in d_buf */ | |

unsigned fx = 0; /* running index in flag_buf */ | |

uch flag = 0; /* current flags */ | |

unsigned code; /* the code to send */ | |

int extra; /* number of extra bits to send */ | |

if (last_lit != 0) do { | |

if ((lx & 7) == 0) flag = flag_buf[fx++]; | |

lc = l_buf[lx++]; | |

if ((flag & 1) == 0) { | |

send_code(lc, ltree); /* send a literal byte */ | |

Tracecv(isgraph(lc), (stderr," '%c' ", lc)); | |

} else { | |

/* Here, lc is the match length - MIN_MATCH */ | |

code = length_code[lc]; | |

send_code(code+LITERALS+1, ltree); /* send the length code */ | |

extra = extra_lbits[code]; | |

if (extra != 0) { | |

lc -= base_length[code]; | |

send_bits(lc, extra); /* send the extra length bits */ | |

} | |

dist = d_buf[dx++]; | |

/* Here, dist is the match distance - 1 */ | |

code = d_code(dist); | |

Assert (code < D_CODES, "bad d_code"); | |

send_code(code, dtree); /* send the distance code */ | |

extra = extra_dbits[code]; | |

if (extra != 0) { | |

dist -= base_dist[code]; | |

send_bits(dist, extra); /* send the extra distance bits */ | |

} | |

} /* literal or match pair ? */ | |

flag >>= 1; | |

} while (lx < last_lit); | |

send_code(END_BLOCK, ltree); | |

} | |

/* =========================================================================== | |

* Set the file type to ASCII or BINARY, using a crude approximation: | |

* binary if more than 20% of the bytes are <= 6 or >= 128, ascii otherwise. | |

* IN assertion: the fields freq of dyn_ltree are set and the total of all | |

* frequencies does not exceed 64K (to fit in an int on 16 bit machines). | |

*/ | |

local void set_file_type() | |

{ | |

int n = 0; | |

unsigned ascii_freq = 0; | |

unsigned bin_freq = 0; | |

while (n < 7) bin_freq += dyn_ltree[n++].Freq; | |

while (n < 128) ascii_freq += dyn_ltree[n++].Freq; | |

while (n < LITERALS) bin_freq += dyn_ltree[n++].Freq; | |

*file_type = bin_freq > (ascii_freq >> 2) ? BINARY : ASCII; | |

if (*file_type == BINARY && translate_eol) { | |

warn("-l used on binary file", ""); | |

} | |

} |