int wrap = 1;
static const char my_version[] = PREFIX2(VERSION);
- uint16_t *overlay;
- /* We overlay pending_buf and d_buf+l_buf. This works since the average
- * output size for (length,distance) codes is <= 24 bits.
- */
-
#ifdef X86_CPUID
x86_check_features();
#endif
s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */
- overlay = (uint16_t *) ZALLOC(strm, s->lit_bufsize, sizeof(uint16_t)+2);
- s->pending_buf = (unsigned char *) overlay;
- s->pending_buf_size = (unsigned long)s->lit_bufsize * (sizeof(uint16_t)+2L);
+ /* We overlay pending_buf and sym_buf. This works since the average size
+ * for length/distance pairs over any compressed block is assured to be 31
+ * bits or less.
+ *
+ * Analysis: The longest fixed codes are a length code of 8 bits plus 5
+ * extra bits, for lengths 131 to 257. The longest fixed distance codes are
+ * 5 bits plus 13 extra bits, for distances 16385 to 32768. The longest
+ * possible fixed-codes length/distance pair is then 31 bits total.
+ *
+ * sym_buf starts one-fourth of the way into pending_buf. So there are
+ * three bytes in sym_buf for every four bytes in pending_buf. Each symbol
+ * in sym_buf is three bytes -- two for the distance and one for the
+ * literal/length. As each symbol is consumed, the pointer to the next
+ * sym_buf value to read moves forward three bytes. From that symbol, up to
+ * 31 bits are written to pending_buf. The closest the written pending_buf
+ * bits gets to the next sym_buf symbol to read is just before the last
+ * code is written. At that time, 31*(n-2) bits have been written, just
+ * after 24*(n-2) bits have been consumed from sym_buf. sym_buf starts at
+ * 8*n bits into pending_buf. (Note that the symbol buffer fills when n-1
+ * symbols are written.) The closest the writing gets to what is unread is
+ * then n+14 bits. Here n is lit_bufsize, which is 16384 by default, and
+ * can range from 128 to 32768.
+ *
+ * Therefore, at a minimum, there are 142 bits of space between what is
+ * written and what is read in the overlain buffers, so the symbols cannot
+ * be overwritten by the compressed data. That space is actually 139 bits,
+ * due to the three-bit fixed-code block header.
+ *
+ * That covers the case where either Z_FIXED is specified, forcing fixed
+ * codes, or when the use of fixed codes is chosen, because that choice
+ * results in a smaller compressed block than dynamic codes. That latter
+ * condition then assures that the above analysis also covers all dynamic
+ * blocks. A dynamic-code block will only be chosen to be emitted if it has
+ * fewer bits than a fixed-code block would for the same set of symbols.
+ * Therefore its average symbol length is assured to be less than 31. So
+ * the compressed data for a dynamic block also cannot overwrite the
+ * symbols from which it is being constructed.
+ */
+
+ s->pending_buf = (unsigned char *) ZALLOC(strm, s->lit_bufsize, 4);
+ s->pending_buf_size = (unsigned long)s->lit_bufsize * 4;
if (s->window == NULL || s->prev == NULL || s->head == NULL ||
s->pending_buf == NULL) {
PREFIX(deflateEnd)(strm);
return Z_MEM_ERROR;
}
- s->d_buf = overlay + s->lit_bufsize/sizeof(uint16_t);
- s->l_buf = s->pending_buf + (1+sizeof(uint16_t))*s->lit_bufsize;
+ s->sym_buf = s->pending_buf + s->lit_bufsize;
+ s->sym_end = (s->lit_bufsize - 1) * 3;
+ /* We avoid equality with lit_bufsize*3 because of wraparound at 64K
+ * on 16 bit machines and because stored blocks are restricted to
+ * 64K-1 bytes.
+ */
s->level = level;
s->strategy = strategy;
if (deflateStateCheck(strm))
return Z_STREAM_ERROR;
s = strm->state;
- if ((unsigned char *)(s->d_buf) < s->pending_out + ((Buf_size + 7) >> 3))
+ if (s->sym_buf < s->pending_out + ((Buf_size + 7) >> 3))
return Z_BUF_ERROR;
do {
put = Buf_size - s->bi_valid;
int ZEXPORT PREFIX(deflateCopy)(PREFIX3(stream) *dest, PREFIX3(stream) *source) {
deflate_state *ds;
deflate_state *ss;
- uint16_t *overlay;
if (deflateStateCheck(source) || dest == NULL) {
return Z_STREAM_ERROR;
ds->window = (unsigned char *) ZALLOC(dest, ds->w_size, 2*sizeof(unsigned char));
ds->prev = (Pos *) ZALLOC(dest, ds->w_size, sizeof(Pos));
ds->head = (Pos *) ZALLOC(dest, ds->hash_size, sizeof(Pos));
- overlay = (uint16_t *) ZALLOC(dest, ds->lit_bufsize, sizeof(uint16_t)+2);
- ds->pending_buf = (unsigned char *) overlay;
+ ds->pending_buf = (unsigned char *) ZALLOC(dest, ds->lit_bufsize, 4);
if (ds->window == NULL || ds->prev == NULL || ds->head == NULL || ds->pending_buf == NULL) {
PREFIX(deflateEnd)(dest);
memcpy(ds->pending_buf, ss->pending_buf, (unsigned int)ds->pending_buf_size);
ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf);
- ds->d_buf = overlay + ds->lit_bufsize/sizeof(uint16_t);
- ds->l_buf = ds->pending_buf + (1+sizeof(uint16_t))*ds->lit_bufsize;
+ ds->sym_buf = ds->pending_buf + ds->lit_bufsize;
ds->l_desc.dyn_tree = ds->dyn_ltree;
ds->d_desc.dyn_tree = ds->dyn_dtree;
FLUSH_BLOCK(s, 1);
return finish_done;
}
- if (s->last_lit)
+ if (s->sym_next)
FLUSH_BLOCK(s, 0);
return block_done;
}
FLUSH_BLOCK(s, 1);
return finish_done;
}
- if (s->last_lit)
+ if (s->sym_next)
FLUSH_BLOCK(s, 0);
return block_done;
}
/* Depth of each subtree used as tie breaker for trees of equal frequency
*/
- unsigned char *l_buf; /* buffer for literals or lengths */
+ unsigned char *sym_buf; /* buffer for distances and literals/lengths */
unsigned int lit_bufsize;
/* Size of match buffer for literals/lengths. There are 4 reasons for
* - I can't count above 4
*/
- unsigned int last_lit; /* running index in l_buf */
-
- uint16_t *d_buf;
- /* Buffer for distances. To simplify the code, d_buf and l_buf have
- * the same number of elements. To use different lengths, an extra flag
- * array would be necessary.
- */
+ unsigned int sym_next; /* running index in sym_buf */
+ unsigned int sym_end; /* symbol table full when sym_next reaches this */
unsigned long opt_len; /* bit length of current block with optimal trees */
unsigned long static_len; /* bit length of current block with static trees */
# define _tr_tally_lit(s, c, flush) \
{ unsigned char cc = (c); \
- s->d_buf[s->last_lit] = 0; \
- s->l_buf[s->last_lit++] = cc; \
+ s->sym_buf[s->sym_next++] = 0; \
+ s->sym_buf[s->sym_next++] = 0; \
+ s->sym_buf[s->sym_next++] = cc; \
s->dyn_ltree[cc].Freq++; \
- flush = (s->last_lit == s->lit_bufsize-1); \
+ flush = (s->sym_next == s->sym_end); \
}
# define _tr_tally_dist(s, distance, length, flush) \
{ unsigned char len = (unsigned char)(length); \
uint16_t dist = (uint16_t)(distance); \
- s->d_buf[s->last_lit] = dist; \
- s->l_buf[s->last_lit++] = len; \
+ s->sym_buf[s->sym_next++] = dist; \
+ s->sym_buf[s->sym_next++] = dist >> 8; \
+ s->sym_buf[s->sym_next++] = len; \
dist--; \
s->dyn_ltree[_length_code[len]+LITERALS+1].Freq++; \
s->dyn_dtree[d_code(dist)].Freq++; \
- flush = (s->last_lit == s->lit_bufsize-1); \
+ flush = (s->sym_next == s->sym_end); \
}
#else
# define _tr_tally_lit(s, c, flush) flush = _tr_tally(s, 0, c)
FLUSH_BLOCK(s, 1);
return finish_done;
}
- if (s->last_lit)
+ if (s->sym_next)
FLUSH_BLOCK(s, 0);
return block_done;
}
FLUSH_BLOCK(s, 1);
return finish_done;
}
- if (s->last_lit)
+ if (s->sym_next)
FLUSH_BLOCK(s, 0);
return block_done;
FLUSH_BLOCK(s, 1);
return finish_done;
}
- if (s->last_lit)
+ if (s->sym_next)
FLUSH_BLOCK(s, 0);
return block_done;
}
s->dyn_ltree[END_BLOCK].Freq = 1;
s->opt_len = s->static_len = 0L;
- s->last_lit = s->matches = 0;
+ s->sym_next = s->matches = 0;
}
#define SMALLEST 1
static_lenb = (s->static_len+3+7) >> 3;
Tracev((stderr, "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u ",
- opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len, s->last_lit));
+ opt_lenb, s->opt_len, static_lenb, s->static_len, stored_len,
+ s->sym_next / 3));
if (static_lenb <= opt_lenb)
opt_lenb = static_lenb;
int ZLIB_INTERNAL _tr_tally(deflate_state *s, unsigned dist, unsigned lc) {
/* dist: distance of matched string */
/* lc: match length-MIN_MATCH or unmatched char (if dist==0) */
- s->d_buf[s->last_lit] = (uint16_t)dist;
- s->l_buf[s->last_lit++] = (unsigned char)lc;
+ s->sym_buf[s->sym_next++] = dist;
+ s->sym_buf[s->sym_next++] = dist >> 8;
+ s->sym_buf[s->sym_next++] = lc;
if (dist == 0) {
/* lc is the unmatched char */
s->dyn_ltree[lc].Freq++;
s->dyn_ltree[_length_code[lc]+LITERALS+1].Freq++;
s->dyn_dtree[d_code(dist)].Freq++;
}
-
-#ifdef TRUNCATE_BLOCK
- /* Try to guess if it is profitable to stop the current block here */
- if ((s->last_lit & 0x1fff) == 0 && s->level > 2) {
- /* Compute an upper bound for the compressed length */
- unsigned long out_length = (unsigned long)s->last_lit*8L;
- unsigned long in_length = (unsigned long)((long)s->strstart - s->block_start);
- int dcode;
- for (dcode = 0; dcode < D_CODES; dcode++) {
- out_length += (unsigned long)s->dyn_dtree[dcode].Freq * (5L+extra_dbits[dcode]);
- }
- out_length >>= 3;
- Tracev((stderr, "\nlast_lit %u, in %ld, out ~%ld(%ld%%) ",
- s->last_lit, in_length, out_length, 100L - out_length*100L/in_length));
- if (s->matches < s->last_lit/2 && out_length < in_length/2)
- return 1;
- }
-#endif
- return (s->last_lit == s->lit_bufsize-1);
- /* 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.
- */
+ return (s->sym_next == s->sym_end);
}
/* ===========================================================================
/* 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 sx = 0; /* running index in sym_buf */
int code; /* the code to send */
int extra; /* number of extra bits to send */
- if (s->last_lit != 0) {
+ if (s->sym_next != 0) {
do {
- dist = s->d_buf[lx];
- lc = s->l_buf[lx++];
+ dist = s->sym_buf[sx++] & 0xff;
+ dist += (unsigned)(s->sym_buf[sx++] & 0xff) << 8;
+ lc = s->sym_buf[sx++];
if (dist == 0) {
send_code(s, lc, ltree); /* send a literal byte */
Tracecv(isgraph(lc), (stderr, " '%c' ", lc));
}
} /* literal or match pair ? */
- /* Check that the overlay between pending_buf and d_buf+l_buf is ok: */
- Assert((unsigned int)(s->pending) < s->lit_bufsize + 2*lx, "pendingBuf overflow");
- } while (lx < s->last_lit);
+ /* Check that the overlay between pending_buf and sym_buf is ok: */
+ Assert(s->pending < s->lit_bufsize + sx, "pendingBuf overflow");
+ } while (sx < s->sym_next);
}
send_code(s, END_BLOCK, ltree);
projects / thirdparty / zlib-ng.git / commitdiff
