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MDEV-17534 Implement fast path for ASCII range in strnxfrm_onelevel_internal()

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Alexander Barkov 2018-10-24 15:12:38 +04:00
parent 88cfde26e8
commit 4272eec050
1 changed files with 39 additions and 0 deletions
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39
strings/ctype-uca.ic
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@ -559,6 +559,45 @@ MY_FUNCTION_NAME(strnxfrm_onelevel_internal)(CHARSET_INFO *cs,
DBUG_ASSERT(src || !srclen);
#if MY_UCA_ASCII_OPTIMIZE && !MY_UCA_COMPILE_CONTRACTIONS
/*
Fast path for the ASCII range with no contractions.
*/
{
const uchar *de2= de - 1; /* Last position where 2 bytes fit */
const uint16 *weights0= level->weights[0];
uint lengths0= level->lengths[0];
for ( ; ; src++, srclen--)
{
const uint16 *weight;
if (!srclen || !*nweights)
return dst; /* Done */
if (*src > 0x7F)
break; /* Non-ASCII */
weight= weights0 + (((uint) *src) * lengths0);
if (!(s_res= *weight))
continue; /* Ignorable */
if (weight[1]) /* Expansion (e.g. in a user defined collation */
break;
/* Here we have a character with extactly one 2-byte UCA weight */
if (dst < de2) /* Most typical case is when both bytes fit */
{
*dst++= s_res >> 8;
*dst++= s_res & 0xFF;
(*nweights)--;
continue;
}
if (dst >= de) /* No space left in "dst" */
return dst;
*dst++= s_res >> 8; /* There is space only for one byte */
(*nweights)--;
return dst;
}
}
#endif
my_uca_scanner_init_any(&scanner, cs, level, src, srclen);
for (; dst < de && *nweights &&
(s_res= MY_FUNCTION_NAME(scanner_next)(&scanner)) > 0 ; (*nweights)--)