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Use memcpy for stored blocks. 

This speeds up level 0 by about a factor of three, as compared to
the previous byte-at-a-time loop. We can do much better though. A
later commit avoids this copy for level 0 with large buffers,
instead copying directly from the input to the output. This commit
still speeds up storing incompressible data found when compressing
normally.
This commit is contained in:
Mark Adler 2016-10-30 09:25:32 -07:00
parent 03614c56ad
commit a456d898bb
1 changed files with 7 additions and 30 deletions
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37
trees.c
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@ -152,8 +152,6 @@ local int detect_data_type OF((deflate_state *s));
local unsigned bi_reverse OF((unsigned value, int length));
local void bi_windup OF((deflate_state *s));
local void bi_flush OF((deflate_state *s));
local void copy_block OF((deflate_state *s, charf *buf, unsigned len,
int header));
#ifdef GEN_TREES_H
local void gen_trees_header OF((void));
@ -869,11 +867,17 @@ void ZLIB_INTERNAL _tr_stored_block(s, buf, stored_len, last)
int last; /* one if this is the last block for a file */
{
send_bits(s, (STORED_BLOCK<<1)+last, 3); /* send block type */
bi_windup(s); /* align on byte boundary */
put_short(s, (ush)stored_len);
put_short(s, (ush)~stored_len);
zmemcpy(s->pending_buf + s->pending, buf, stored_len);
s->pending += stored_len;
#ifdef ZLIB_DEBUG
s->compressed_len = (s->compressed_len + 3 + 7) & (ulg)~7L;
s->compressed_len += (stored_len + 4) << 3;
s->bits_sent += 2*16;
s->bits_sent += stored_len<<3;
#endif
copy_block(s, buf, (unsigned)stored_len, 1); /* with header */
}
/* ===========================================================================
@ -1197,30 +1201,3 @@ local void bi_windup(s)
s->bits_sent = (s->bits_sent+7) & ~7;
#endif
}
/* ===========================================================================
* Copy a stored block, storing first the length and its
* one's complement if requested.
*/
local void copy_block(s, buf, len, header)
deflate_state *s;
charf *buf; /* the input data */
unsigned len; /* its length */
int header; /* true if block header must be written */
{
bi_windup(s); /* align on byte boundary */
if (header) {
put_short(s, (ush)len);
put_short(s, (ush)~len);
#ifdef ZLIB_DEBUG
s->bits_sent += 2*16;
#endif
}
#ifdef ZLIB_DEBUG
s->bits_sent += (ulg)len<<3;
#endif
while (len--) {
put_byte(s, *buf++);
}
}