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/** @file
A brief file description
@section license License
Licensed to the Apache Software Foundation (ASF) under one
or more contributor license agreements. See the NOTICE file
distributed with this work for additional information
regarding copyright ownership. The ASF licenses this file
to you under the Apache License, Version 2.0 (the
"License"); you may not use this file except in compliance
with the License. You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
#include <stdio.h>
//
// fast memchr
//
void *
ink_memchr(const void *as, int ac, size_t an)
{
unsigned char c = (unsigned char) ac;
unsigned char *s = (unsigned char *) as;
// initial segment
int i_len = (int)(((uintptr_t) 8 - (uintptr_t) as) & 7);
// too short to concern us
if ((int) an < i_len) {
for (int i = 0; i < (int) an; i++)
if (s[i] == c)
return &s[i];
return 0;
}
// bytes 0-3
switch (i_len & 3) {
case 3:
if (*s++ == c)
return s - 1;
case 2:
if (*s++ == c)
return s - 1;
case 1:
if (*s++ == c)
return s - 1;
case 0:
break;
}
// bytes 4-8
unsigned int ib = c;
ib |= (ib << 8);
ib |= (ib << 16);
unsigned int im = 0x7efefeff;
if (i_len & 4) {
unsigned int ibp = *(unsigned int *) s;
unsigned int ibb = ibp ^ ib;
ibb = ((ibb + im) ^ ~ibb) & ~im;
if (ibb) {
if (s[0] == c)
return &s[0];
if (s[1] == c)
return &s[1];
if (s[2] == c)
return &s[2];
if (s[3] == c)
return &s[3];
}
s += 4;
}
// next 8x bytes
uint64_t m = 0x7efefefefefefeffLL;
uint64_t b = ((uint64_t) ib);
b |= (b << 32);
uint64_t *p = (uint64_t *) s;
unsigned int n = (((unsigned int) an) - (s - (unsigned char *) as)) >> 3;
uint64_t *end = p + n;
while (p < end) {
uint64_t bp = *p;
uint64_t bb = bp ^ b;
bb = ((bb + m) ^ ~bb) & ~m;
if (bb) {
s = (unsigned char *) p;
if (s[0] == c)
return &s[0];
if (s[1] == c)
return &s[1];
if (s[2] == c)
return &s[2];
if (s[3] == c)
return &s[3];
if (s[4] == c)
return &s[4];
if (s[5] == c)
return &s[5];
if (s[6] == c)
return &s[6];
if (s[7] == c)
return &s[7];
}
p++;
}
// terminal segement
i_len = an - (((unsigned char *) p) - ((unsigned char *) as));
s = (unsigned char *) p;
// n-(4..8)..n bytes
if (i_len & 4) {
unsigned int ibp = *(unsigned int *) s;
unsigned int ibb = ibp ^ ib;
ibb = ((ibb + im) ^ ~ibb) & ~im;
if (ibb) {
if (s[0] == c)
return &s[0];
if (s[1] == c)
return &s[1];
if (s[2] == c)
return &s[2];
if (s[3] == c)
return &s[3];
}
s += 4;
}
// n-(0..3)..n bytes
switch (i_len & 3) {
case 3:
if (*s++ == c)
return s - 1;
case 2:
if (*s++ == c)
return s - 1;
case 1:
if (*s++ == c)
return s - 1;
case 0:
break;
}
return 0;
}
#define MEMCHR(_s,_c) ink_memchr(_s,_c,strlen(_s))?:""
main()
{
int i = 0;
printf("%d %s\n", i++, MEMCHR("a;ldkfjoiwenalkdufla asdfj3i", ' '));
printf("%d %s\n", i++, MEMCHR("a;ldkfjoiwenalkdufla asdfj3i", '3'));
printf("%d %s\n", i++, MEMCHR("a;ldkfjoiwenalkdufla asdfj3i", '\n'));
printf("%d %s\n", i++, MEMCHR("a;ldkfjoiwenalk$uflaE$$dfj3i", '$'));
printf("%d %s\n", i++, MEMCHR("a;ldkfjoiwenalkd#####asdfj3i", '#'));
printf("%d %s\n", i++, MEMCHR("a;ldkfjoiwenalkdufla a^^sdfj3i", '^'));
printf("%d %s\n", i++, MEMCHR("a;ldkfjoiwenalkdufla asd*************fj3i", '*'));
}
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