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MINOR: buffers: simplify b_contig_space() 

This function is used a lot in block copies and is needlessly
complicated since it still uses pointer arithmetic. Let's fall
back to regular offsets and simplify it. This removed around
23 bytes from b_putblk() and it removed any conditional jump.
This commit is contained in:
Willy Tarreau 2018-07-20 16:07:42 +02:00
parent f495fc460e
commit ab322d4fd4
1 changed files with 16 additions and 9 deletions
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25
include/common/buf.h
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@ -300,21 +300,28 @@ static inline size_t b_contig_data(const struct buffer *b, size_t start)
}
/* b_contig_space() : returns the amount of bytes that can be appended to the
* buffer at once.
* buffer at once. We have 8 possible cases :
*
* [____________________] return size
* [______|_____________] return size - tail_ofs
* [XXXXXX|_____________] return size - tail_ofs
* [___|XXXXXX|_________] return size - tail_ofs
* [______________XXXXXX] return head_ofs
* [XXXX|___________|XXX] return head_ofs - tail_ofs
* [XXXXXXXXXX|XXXXXXXXX] return 0
* [XXXXXXXXXXXXXXXXXXXX] return 0
*/
static inline size_t b_contig_space(const struct buffer *b)
{
const char *left, *right;
size_t left, right;
right = b_head(b);
right = b_head_ofs(b);
left = right + b_data(b);
if (left >= b_wrap(b))
left -= b_size(b);
else
right = b_wrap(b);
return right - left;
left = b_size(b) - left;
if ((ssize_t)left <= 0)
left += right;
return left;
}
/* b_getblk() : gets one full block of data at once from a buffer, starting