/* 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.
* Encode various sets of source values using variable-length
* 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.
* Data Compression: Techniques and Applications, pp. 53-55.
* Lifetime Learning Publications, 1985. ISBN 0-534-03418-7.
* Data Compression: Methods and Theory, pp. 49-50.
* Computer Science Press, 1988. ISBN 0-7167-8156-5.
* Addison-Wesley, 1983. ISBN 0-201-06672-6.
* 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
* 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.
static char rcsid
[] = "$Id: trees.c,v 0.12 1993/06/10 13:27:54 jloup Exp $";
/* ===========================================================================
/* All codes must not exceed MAX_BITS bits */
/* Bit length codes must not exceed MAX_BL_BITS bits */
/* number of length codes, not counting the special END_BLOCK code */
/* number of literal bytes 0..255 */
/* end of block literal code */
#define L_CODES (LITERALS+1+LENGTH_CODES)
/* number of Literal or Length codes, including the END_BLOCK code */
/* number of distance codes */
/* number of codes used to transfer the bit lengths */
local
int near 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 near 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 near 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};
/* The three kinds of block type */
# define LIT_BUFSIZE 0x2000
# define LIT_BUFSIZE 0x4000
# define LIT_BUFSIZE 0x8000
# define DIST_BUFSIZE LIT_BUFSIZE
/* 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
* - 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
/* repeat previous bit length 3-6 times (2 bits of repeat count) */
/* repeat a zero length 3-10 times (3 bits of repeat count) */
/* repeat a zero length 11-138 times (7 bits of repeat count) */
/* ===========================================================================
/* Data structure describing a single value and its code string. */
ush freq
; /* frequency count */
ush code
; /* bit string */
ush dad
; /* father node in Huffman tree */
ush len
; /* length of bit string */
#define HEAP_SIZE (2*L_CODES+1)
local ct_data near dyn_ltree
[HEAP_SIZE
]; /* literal and length tree */
local ct_data near dyn_dtree
[2*D_CODES
+1]; /* distance tree */
local ct_data near 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
local ct_data near static_dtree
[D_CODES
];
/* The static distance tree. (Actually a trivial tree since all codes use
local ct_data near bl_tree
[2*BL_CODES
+1];
/* Huffman tree for the bit lengths */
typedef struct tree_desc
{
ct_data near
*dyn_tree
; /* the dynamic tree */
ct_data near
*static_tree
; /* corresponding static tree or NULL */
int near
*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 */
local tree_desc near l_desc
=
{dyn_ltree
, static_ltree
, extra_lbits
, LITERALS
+1, L_CODES
, MAX_BITS
, 0};
local tree_desc near d_desc
=
{dyn_dtree
, static_dtree
, extra_dbits
, 0, D_CODES
, MAX_BITS
, 0};
local tree_desc near bl_desc
=
{bl_tree
, (ct_data near
*)0, extra_blbits
, 0, BL_CODES
, MAX_BL_BITS
, 0};
local ush near bl_count
[MAX_BITS
+1];
/* number of codes at each bit length for an optimal tree */
local uch near 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 near 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 near 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
local
int near base_length
[LENGTH_CODES
];
/* First normalized length for each code (0 = MIN_MATCH) */
local
int near base_dist
[D_CODES
];
/* First normalized distance for each code (0 = distance of 1) */
/* DECLARE(uch, l_buf, LIT_BUFSIZE); buffer for literals or lengths */
/* DECLARE(ush, d_buf, DIST_BUFSIZE); buffer for distances */
local uch near 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 */
extern ulg bits_sent
; /* bit length of the compressed data */
extern long isize
; /* byte length of input file */
extern long block_start
; /* window offset of current block */
extern unsigned near strstart
; /* window offset of current string */
/* ===========================================================================
* Local (static) routines in this file.
local
void init_block
OF((void));
local
void pqdownheap
OF((ct_data near
*tree
, int k
));
local
void gen_bitlen
OF((tree_desc near
*desc
));
local
void gen_codes
OF((ct_data near
*tree
, int max_code
));
local
void build_tree
OF((tree_desc near
*desc
));
local
void scan_tree
OF((ct_data near
*tree
, int max_code
));
local
void send_tree
OF((ct_data near
*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 near
*ltree
, ct_data near
*dtree
));
local
void set_file_type
OF((void));
# 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 */
# define send_code(c, tree) \
{ if (verbose>1) fprintf(stderr,"\ncd %3d ",(c)); \
send_bits(tree[c].Code, tree[c].Len); }
((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
#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
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 */
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) */
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) */
for (code
= 0 ; code
< 16; code
++) {
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;
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
gen_codes((ct_data near
*)static_ltree
, L_CODES
+1);
/* The static distance tree is trivial: */
for (n
= 0; n
< D_CODES
; n
++) {
static_dtree
[n
].Code
= bi_reverse(n
, 5);
/* Initialize the first block of the first file: */
/* ===========================================================================
* Initialize a new 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;
/* 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) \
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
local
void pqdownheap(tree
, k
)
ct_data near
*tree
; /* the tree to restore */
int k
; /* node to move down */
int j
= k
<< 1; /* left son of k */
/* 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 */
/* ===========================================================================
* Compute the optimal bit lengths for a tree and update the total bit length
* 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
local
void gen_bitlen(desc
)
tree_desc near
*desc
; /* the tree descriptor */
ct_data near
*tree
= desc
->dyn_tree
;
int near
*extra
= desc
->extra_bits
;
int base
= desc
->extra_base
;
int max_code
= desc
->max_code
;
int max_length
= desc
->max_length
;
ct_data near
*stree
= desc
->static_tree
;
int n
, m
; /* iterate over the tree elements */
int bits
; /* bit length */
int xbits
; /* extra bits */
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
++) {
bits
= tree
[tree
[n
].Dad
].Len
+ 1;
if (bits
> max_length
) bits
= max_length
, overflow
++;
/* We overwrite tree[n].Dad which is no longer needed */
if (n
> max_code
) continue; /* not a leaf node */
if (n
>= base
) xbits
= extra
[n
-base
];
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: */
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 */
/* The brother of the overflow item also moves one step up,
* but this does not affect bl_count[max_length]
/* 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
--) {
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
;
/* ===========================================================================
* Generate the codes for a given tree and bit counts (which need not be
* 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
local
void gen_codes (tree
, max_code
)
ct_data near
*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 */
/* The distribution counts are first used to generate the code values
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
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
++) {
/* 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 near
*desc
; /* the tree descriptor */
ct_data near
*tree
= desc
->dyn_tree
;
ct_data near
*stree
= desc
->static_tree
;
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_len
= 0, heap_max
= HEAP_SIZE
;
for (n
= 0; n
< elems
; n
++) {
heap
[++heap_len
] = max_code
= n
;
/* 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.
int new = heap
[++heap_len
] = (max_code
< 2 ? ++max_code
: 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
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 */
/* 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
;
fprintf(stderr
,"\nnode %d(%d), sons %d(%d) %d(%d)",
node
, tree
[node
].Freq
, n
, tree
[n
].Freq
, m
, tree
[m
].Freq
);
/* and insert the new node in the heap */
pqdownheap(tree
, SMALLEST
);
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 near
*)desc
);
/* The field len is now set, we can generate the bit codes */
gen_codes ((ct_data near
*)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 near
*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
) {
} else if (count
< min_count
) {
bl_tree
[curlen
].Freq
+= count
;
} else if (curlen
!= 0) {
if (curlen
!= prevlen
) bl_tree
[curlen
].Freq
++;
} else if (count
<= 10) {
bl_tree
[REPZ_3_10
].Freq
++;
bl_tree
[REPZ_11_138
].Freq
++;
count
= 0; prevlen
= curlen
;
max_count
= 138, min_count
= 3;
} else if (curlen
== nextlen
) {
max_count
= 6, min_count
= 3;
max_count
= 7, min_count
= 4;
/* ===========================================================================
* Send a literal or distance tree in compressed form, using the codes in
local
void send_tree (tree
, max_code
)
ct_data near
*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
) {
} else if (count
< min_count
) {
do { send_code(curlen
, bl_tree
); } while (--count
!= 0);
} else if (curlen
!= 0) {
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);
send_code(REPZ_11_138
, bl_tree
); send_bits(count
-11, 7);
count
= 0; prevlen
= curlen
;
max_count
= 138, min_count
= 3;
} else if (curlen
== nextlen
) {
max_count
= 6, min_count
= 3;
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 near
*)dyn_ltree
, l_desc
.max_code
);
scan_tree((ct_data near
*)dyn_dtree
, d_desc
.max_code
);
/* Build the bit length tree: */
build_tree((tree_desc near
*)(&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
));
/* ===========================================================================
* 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
,
Tracev((stderr
, "\nbl counts: "));
send_bits(lcodes
-257, 5); /* not +255 as stated in appnote.txt */
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 near
*)dyn_ltree
, lcodes
-1); /* send the literal tree */
Tracev((stderr
, "\nlit tree: sent %ld", bits_sent
));
send_tree((ct_data near
*)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 near
*)(&l_desc
));
Tracev((stderr
, "\nlit data: dyn %ld, stat %ld", opt_len
, static_len
));
build_tree((tree_desc near
*)(&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
,
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:
if (level
== 1 && eof
&& compressed_len
== 0L) { /* force stored file */
if (stored_len
<= opt_lenb
&& eof
&& compressed_len
== 0L && seekable()) {
/* 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;
} else if (level
== 2 && buf
!= (char*)0) { /* force stored block */
} else if (stored_len
+4 <= opt_lenb
&& buf
!= (char*)0) {
/* 4: two words for the lengths */
/* 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 */
} else if (level
== 3) { /* force static trees */
} else if (static_lenb
== opt_lenb
) {
send_bits((STATIC_TREES
<<1)+eof
, 3);
compress_block((ct_data near
*)static_ltree
, (ct_data near
*)static_dtree
);
compressed_len
+= 3 + static_len
;
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 near
*)dyn_ltree
, (ct_data near
*)dyn_dtree
);
compressed_len
+= 3 + opt_len
;
Assert (compressed_len
== bits_sent
, "bad compressed size");
Assert (input_len
== isize
, "bad input size");
compressed_len
+= 7; /* align on byte boundary */
Tracev((stderr
,"\ncomprlen %lu(%lu) ", compressed_len
>>3,
return compressed_len
>> 3;
/* ===========================================================================
* Save the match info and tally the frequency counts. Return true if
* the current block must be flushed.
int dist
; /* distance of matched string */
int lc
; /* match length-MIN_MATCH or unmatched char (if dist==0) */
l_buf
[last_lit
++] = (uch
)lc
;
/* lc is the unmatched char */
/* 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
;
/* Output the flags if they fill a byte: */
if ((last_lit
& 7) == 0) {
flag_buf
[last_flags
++] = flags
;
/* 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
;
for (dcode
= 0; dcode
< D_CODES
; dcode
++) {
out_length
+= (ulg
)dyn_dtree
[dcode
].Freq
*(5L+extra_dbits
[dcode
]);
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
/* ===========================================================================
* Send the block data compressed using the given Huffman trees
local
void compress_block(ltree
, dtree
)
ct_data near
*ltree
; /* literal tree */
ct_data near
*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 ((lx
& 7) == 0) flag
= flag_buf
[fx
++];
send_code(lc
, ltree
); /* send a literal byte */
Tracecv(isgraph(lc
), (stderr
," '%c' ", lc
));
/* Here, lc is the match length - MIN_MATCH */
send_code(code
+LITERALS
+1, ltree
); /* send the length code */
extra
= extra_lbits
[code
];
send_bits(lc
, extra
); /* send the extra length bits */
/* Here, dist is the match distance - 1 */
Assert (code
< D_CODES
, "bad d_code");
send_code(code
, dtree
); /* send the distance code */
extra
= extra_dbits
[code
];
send_bits(dist
, extra
); /* send the extra distance bits */
} /* literal or match pair ? */
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()
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", "");