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gzip cleanup part #6

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This commit is contained in:
Denis Vlasenko 2007-01-07 19:39:34 +00:00
parent da31fbc1b1
commit 1a03c21adf
1 changed files with 45 additions and 33 deletions
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78
archival/gzip.c
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@ -1476,7 +1476,7 @@ static void ct_init(ush * attr, int *methodp)
for (code = 0; code < 16; code++) {
base_dist[code] = dist;
for (n = 0; n < (1 << extra_dbits[code]); n++) {
dist_code[dist++] = (uch) code;
dist_code[dist++] = code;
}
}
Assert(dist == 256, "ct_init: dist != 256");
@ -1492,15 +1492,24 @@ static void ct_init(ush * attr, int *methodp)
/* 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]++;
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)
@ -1684,10 +1693,8 @@ static void gen_bitlen(tree_desc * desc)
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;
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--;
@ -1846,8 +1853,10 @@ static void scan_tree(ct_data * tree, int max_code)
int max_count = 7; /* max repeat count */
int min_count = 4; /* min repeat count */
if (nextlen == 0)
max_count = 138, min_count = 3;
if (nextlen == 0) {
max_count = 138;
min_count = 3;
}
tree[max_code + 1].Len = (ush) 0xffff; /* guard */
for (n = 0; n <= max_code; n++) {
@ -1869,11 +1878,14 @@ static void scan_tree(ct_data * tree, int max_code)
count = 0;
prevlen = curlen;
if (nextlen == 0) {
max_count = 138, min_count = 3;
max_count = 138;
min_count = 3;
} else if (curlen == nextlen) {
max_count = 6, min_count = 3;
max_count = 6;
min_count = 3;
} else {
max_count = 7, min_count = 4;
max_count = 7;
min_count = 4;
}
}
}
@ -1904,8 +1916,7 @@ static void send_tree(ct_data * tree, int max_code)
} else if (count < min_count) {
do {
send_code(curlen, bl_tree);
} while (--count != 0);
} while (--count);
} else if (curlen != 0) {
if (curlen != prevlen) {
send_code(curlen, bl_tree);
@ -1914,11 +1925,9 @@ static void send_tree(ct_data * tree, int max_code)
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);
@ -1926,11 +1935,14 @@ static void send_tree(ct_data * tree, int max_code)
count = 0;
prevlen = curlen;
if (nextlen == 0) {
max_count = 138, min_count = 3;
max_count = 138;
min_count = 3;
} else if (curlen == nextlen) {
max_count = 6, min_count = 3;
max_count = 6;
min_count = 3;
} else {
max_count = 7, min_count = 4;
max_count = 7;
min_count = 4;
}
}
}
@ -2046,7 +2058,7 @@ static ulg flush_block(char *buf, ulg stored_len, int eof)
*/
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)
if (buf == NULL)
bb_error_msg("block vanished");
copy_block(buf, (unsigned) stored_len, 0); /* without header */
@ -2104,14 +2116,15 @@ static int ct_tally(int dist, int lc)
} 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");
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;
d_buf[last_dist++] = dist;
flags |= flag_bit;
}
flag_bit <<= 1;
@ -2124,13 +2137,12 @@ static int ct_tally(int dist, int lc)
/* Try to guess if it is profitable to stop the current block here */
if ((last_lit & 0xfff) == 0) {
/* Compute an upper bound for the compressed length */
ulg out_length = (ulg) last_lit * 8L;
ulg out_length = 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 += dyn_dtree[dcode].Freq * (5L + extra_dbits[dcode]);
}
out_length >>= 3;
Trace((stderr,