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/* Search character in UTF-8 string.
Copyright (C) 1999, 2002, 2006-2007, 2009-2024 Free Software Foundation,
Inc.
Written by Bruno Haible <bruno@clisp.org>, 2002.
This file is free software.
It is dual-licensed under "the GNU LGPLv3+ or the GNU GPLv2+".
You can redistribute it and/or modify it under either
- the terms of the GNU Lesser General Public License as published
by the Free Software Foundation, either version 3, or (at your
option) any later version, or
- the terms of the GNU General Public License as published by the
Free Software Foundation; either version 2, or (at your option)
any later version, or
- the same dual license "the GNU LGPLv3+ or the GNU GPLv2+".
This file is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License and the GNU General Public License
for more details.
You should have received a copy of the GNU Lesser General Public
License and of the GNU General Public License along with this
program. If not, see <https://www.gnu.org/licenses/>. */
#include <config.h>
/* Specification. */
#include "unistr.h"
#include <string.h>
uint8_t *
u8_strchr (const uint8_t *s, ucs4_t uc)
{
uint8_t c[6];
if (uc < 0x80)
{
uint8_t c0 = uc;
if (false)
{
/* Unoptimized code. */
for (;;)
{
uint8_t s0 = *s;
if (s0 == c0)
return (uint8_t *) s;
s++;
if (s0 == 0)
break;
}
}
else
{
/* Optimized code.
strchr() is often so well optimized, that it's worth the
added function call. */
return (uint8_t *) strchr ((const char *) s, c0);
}
}
else
/* Loops equivalent to strstr, optimized for a specific length (2, 3, 4)
of the needle. We use an algorithm similar to Boyer-Moore which
is documented in lib/unistr/u8-chr.c. There is additional
complication because we need to check after every byte for
a NUL byte, but the idea is the same. */
switch (u8_uctomb_aux (c, uc, 6))
{
case 2:
if (*s == 0 || s[1] == 0)
break;
{
uint8_t c0 = c[0];
uint8_t c1 = c[1];
/* Search for { c0, c1 }. */
uint8_t s1 = s[1];
for (;;)
{
/* Here s[0] != 0, s[1] != 0.
Test whether s[0..1] == { c0, c1 }. */
if (s1 == c1)
{
if (*s == c0)
return (uint8_t *) s;
else
/* Skip the search at s + 1, because s[1] = c1 < c0. */
goto case2_skip2;
}
else
{
if (s1 == c0)
goto case2_skip1;
else
/* Skip the search at s + 1, because s[1] != c0. */
goto case2_skip2;
}
case2_skip2:
s++;
s1 = s[1];
if (s[1] == 0)
break;
case2_skip1:
s++;
s1 = s[1];
if (s[1] == 0)
break;
}
}
break;
case 3:
if (*s == 0 || s[1] == 0 || s[2] == 0)
break;
{
uint8_t c0 = c[0];
uint8_t c1 = c[1];
uint8_t c2 = c[2];
/* Search for { c0, c1, c2 }. */
uint8_t s2 = s[2];
for (;;)
{
/* Here s[0] != 0, s[1] != 0, s[2] != 0.
Test whether s[0..2] == { c0, c1, c2 }. */
if (s2 == c2)
{
if (s[1] == c1 && *s == c0)
return (uint8_t *) s;
else
/* If c2 != c1:
Skip the search at s + 1, because s[2] == c2 != c1.
Skip the search at s + 2, because s[2] == c2 < c0. */
if (c2 == c1)
goto case3_skip1;
else
goto case3_skip3;
}
else
{
if (s2 == c1)
goto case3_skip1;
else if (s2 == c0)
/* Skip the search at s + 1, because s[2] != c1. */
goto case3_skip2;
else
/* Skip the search at s + 1, because s[2] != c1.
Skip the search at s + 2, because s[2] != c0. */
goto case3_skip3;
}
case3_skip3:
s++;
s2 = s[2];
if (s[2] == 0)
break;
case3_skip2:
s++;
s2 = s[2];
if (s[2] == 0)
break;
case3_skip1:
s++;
s2 = s[2];
if (s[2] == 0)
break;
}
}
break;
case 4:
if (*s == 0 || s[1] == 0 || s[2] == 0 || s[3] == 0)
break;
{
uint8_t c0 = c[0];
uint8_t c1 = c[1];
uint8_t c2 = c[2];
uint8_t c3 = c[3];
/* Search for { c0, c1, c2, c3 }. */
uint8_t s3 = s[3];
for (;;)
{
/* Here s[0] != 0, s[1] != 0, s[2] != 0, s[3] != 0.
Test whether s[0..3] == { c0, c1, c2, c3 }. */
if (s3 == c3)
{
if (s[2] == c2 && s[1] == c1 && *s == c0)
return (uint8_t *) s;
else
/* If c3 != c2:
Skip the search at s + 1, because s[3] == c3 != c2.
If c3 != c1:
Skip the search at s + 2, because s[3] == c3 != c1.
Skip the search at s + 3, because s[3] == c3 < c0. */
if (c3 == c2)
goto case4_skip1;
else if (c3 == c1)
goto case4_skip2;
else
goto case4_skip4;
}
else
{
if (s3 == c2)
goto case4_skip1;
else if (s3 == c1)
/* Skip the search at s + 1, because s[3] != c2. */
goto case4_skip2;
else if (s3 == c0)
/* Skip the search at s + 1, because s[3] != c2.
Skip the search at s + 2, because s[3] != c1. */
goto case4_skip3;
else
/* Skip the search at s + 1, because s[3] != c2.
Skip the search at s + 2, because s[3] != c1.
Skip the search at s + 3, because s[3] != c0. */
goto case4_skip4;
}
case4_skip4:
s++;
s3 = s[3];
if (s[3] == 0)
break;
case4_skip3:
s++;
s3 = s[3];
if (s[3] == 0)
break;
case4_skip2:
s++;
s3 = s[3];
if (s[3] == 0)
break;
case4_skip1:
s++;
s3 = s[3];
if (s[3] == 0)
break;
}
}
break;
}
return NULL;
}
|
