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/*
* Copyright (c) 2017 Imagination Technologies.
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with
* the distribution.
* * Neither the name of Imagination Technologies nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <string.h>
#define op_t unsigned long int
#define op_size sizeof (op_t)
#if __mips64 || __mips_isa_rev >= 2
static inline size_t __attribute__ ((always_inline))
do_bytes (const char *base, const char *p, op_t inval)
{
op_t outval = 0;
#if __mips64
__asm__ volatile (
"dsbh %1, %0 \n\t"
"dshd %0, %1 \n\t"
"dclz %1, %0 \n\t"
: "+r" (inval), "+r" (outval)
);
#else
__asm__ volatile (
"wsbh %1, %0 \n\t"
"rotr %0, %1, 16 \n\t"
"clz %1, %0 \n\t"
: "+r" (inval), "+r" (outval)
);
#endif
p += (outval >> 3);
return (size_t) (p - base);
}
#define DO_WORD(w, cnt) { \
op_t val = ((w[cnt] - mask_1) & ~w[cnt]) & mask_128; \
if (val) \
return do_bytes(str, (const char *)(w + cnt), val); \
}
#else
static inline size_t __attribute__ ((always_inline))
do_bytes (const char *base, const char *p)
{
for (; *p; ++p);
return (size_t) (p - base);
}
#define DO_WORD(w, cnt) { \
if (((w[cnt] - mask_1) & ~w[cnt]) & mask_128) \
return do_bytes(str, (const char *)(w + cnt)); \
}
#endif
size_t
strlen (const char *str)
{
if (*str) {
const char *p = (const char *) str;
const op_t *w;
op_t mask_1, mask_128;
while ((size_t) p % sizeof (op_t)) {
if (!(*p))
return (p - str);
p++;
}
__asm__ volatile (
"li %0, 0x01010101 \n\t"
: "=r" (mask_1)
);
#if __mips64
mask_1 |= mask_1 << 32;
#endif
mask_128 = mask_1 << 7;
w = (const op_t *) p;
while (1) {
DO_WORD(w, 0);
DO_WORD(w, 1);
DO_WORD(w, 2);
DO_WORD(w, 3);
w += 4;
}
}
return 0;
}
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