/*
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* Copyright (c) 2017 Imagination Technologies.
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*
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer
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* in the documentation and/or other materials provided with
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* the distribution.
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* * Neither the name of Imagination Technologies nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <string.h>
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#define op_t unsigned long int
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#define op_size sizeof (op_t)
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#if __mips64 || __mips_isa_rev >= 2
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static inline size_t __attribute__ ((always_inline))
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do_bytes (const char *base, const char *p, op_t inval)
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{
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op_t outval = 0;
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#if __mips64
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__asm__ volatile (
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"dsbh %1, %0 \n\t"
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"dshd %0, %1 \n\t"
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"dclz %1, %0 \n\t"
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: "+r" (inval), "+r" (outval)
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);
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#else
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__asm__ volatile (
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"wsbh %1, %0 \n\t"
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"rotr %0, %1, 16 \n\t"
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"clz %1, %0 \n\t"
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: "+r" (inval), "+r" (outval)
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);
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#endif
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p += (outval >> 3);
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return (size_t) (p - base);
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}
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#define DO_WORD(in, val) { \
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op_t tmp = ((val - mask_1) & ~val) & mask_128; \
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if (tmp) \
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return do_bytes(str, (const char *)(in), tmp); \
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}
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#else
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static inline size_t __attribute__ ((always_inline))
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do_bytes (const char *base, const char *p)
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{
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for (; *p; ++p);
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return (size_t) (p - base);
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}
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#define DO_WORD(in, val) { \
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if (((val - mask_1) & ~val) & mask_128) { \
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return do_bytes(str, (const char *)(in)); \
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} \
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}
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#endif
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size_t strnlen (const char *str, size_t n) {
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if (n != 0) {
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const char *p = (const char *) str;
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const op_t *w;
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op_t mask_1, mask_128;
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for (; n > 0 && ((size_t) p % op_size) != 0; --n, ++p) {
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if (!(*p))
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return (p - str);
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}
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w = (const op_t *) p;
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__asm__ volatile (
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"li %0, 0x01010101 \n\t"
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: "=r" (mask_1)
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);
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#if __mips64
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mask_1 |= mask_1 << 32;
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#endif
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mask_128 = mask_1 << 7;
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/*
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* Check op_size byteswize after initial alignment
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*/
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while (n >= 4 * op_size) {
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const op_t w0 = w[0];
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const op_t w1 = w[1];
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const op_t w2 = w[2];
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const op_t w3 = w[3];
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DO_WORD(w + 0, w0)
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DO_WORD(w + 1, w1)
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DO_WORD(w + 2, w2)
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DO_WORD(w + 3, w3)
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w += 4;
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n -= 4 * op_size;
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}
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while (n >= op_size) {
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DO_WORD(w, w[0]);
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w++;
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n -= op_size;
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}
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/*
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* Check bytewize for remaining bytes
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*/
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p = (const char *) w;
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for (; n > 0; --n, ++p) {
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if (!(*p))
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return (p - str);
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}
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return (p - str);
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}
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return 0;
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}
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