| /* |
| * 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(in, val) { \ |
| op_t tmp = ((val - mask_1) & ~val) & mask_128; \ |
| if (tmp) \ |
| return do_bytes(str, (const char *)(in), tmp); \ |
| } |
| #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(in, val) { \ |
| if (((val - mask_1) & ~val) & mask_128) { \ |
| return do_bytes(str, (const char *)(in)); \ |
| } \ |
| } |
| #endif |
| |
| size_t strnlen (const char *str, size_t n) { |
| if (n != 0) { |
| const char *p = (const char *) str; |
| const op_t *w; |
| op_t mask_1, mask_128; |
| |
| for (; n > 0 && ((size_t) p % op_size) != 0; --n, ++p) { |
| if (!(*p)) |
| return (p - str); |
| } |
| |
| w = (const op_t *) p; |
| |
| __asm__ volatile ( |
| "li %0, 0x01010101 \n\t" |
| : "=r" (mask_1) |
| ); |
| #if __mips64 |
| mask_1 |= mask_1 << 32; |
| #endif |
| mask_128 = mask_1 << 7; |
| |
| /* |
| * Check op_size byteswize after initial alignment |
| */ |
| while (n >= 4 * op_size) { |
| const op_t w0 = w[0]; |
| const op_t w1 = w[1]; |
| const op_t w2 = w[2]; |
| const op_t w3 = w[3]; |
| DO_WORD(w + 0, w0) |
| DO_WORD(w + 1, w1) |
| DO_WORD(w + 2, w2) |
| DO_WORD(w + 3, w3) |
| w += 4; |
| n -= 4 * op_size; |
| } |
| |
| while (n >= op_size) { |
| DO_WORD(w, w[0]); |
| w++; |
| n -= op_size; |
| } |
| |
| /* |
| * Check bytewize for remaining bytes |
| */ |
| p = (const char *) w; |
| for (; n > 0; --n, ++p) { |
| if (!(*p)) |
| return (p - str); |
| } |
| |
| return (p - str); |
| } |
| |
| return 0; |
| } |