157 lines
5.3 KiB
C
157 lines
5.3 KiB
C
/* Copyright (c) 2009 Xilinx, Inc. All rights reserved.
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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 are
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met:
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1. Redistributions source code must retain the above copyright notice,
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this list of conditions and the following disclaimer.
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2. Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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3. Neither the name of Xilinx nor the names of its contributors may be
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used to endorse or promote products derived from this software without
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specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER AND CONTRIBUTORS "AS
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IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
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PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
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TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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FUNCTION
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<<strlen>>---character string length
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INDEX
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strlen
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ANSI_SYNOPSIS
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#include <string.h>
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size_t strlen(const char *<[str]>);
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TRAD_SYNOPSIS
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#include <string.h>
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size_t strlen(<[str]>)
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char *<[src]>;
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DESCRIPTION
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The <<strlen>> function works out the length of the string
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starting at <<*<[str]>>> by counting chararacters until it
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reaches a <<NULL>> character.
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RETURNS
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<<strlen>> returns the character count.
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PORTABILITY
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<<strlen>> is ANSI C.
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<<strlen>> requires no supporting OS subroutines.
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QUICKREF
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strlen ansi pure
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*/
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#include <_ansi.h>
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#include <string.h>
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#include <limits.h>
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#define LBLOCKSIZE (sizeof (long))
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#define UNALIGNED(X) ((long)X & (LBLOCKSIZE - 1))
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#if LONG_MAX == 2147483647L
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#define DETECTNULL(X) (((X) - 0x01010101) & ~(X) & 0x80808080)
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#else
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#if LONG_MAX == 9223372036854775807L
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/* Nonzero if X (a long int) contains a NULL byte. */
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#define DETECTNULL(X) (((X) - 0x0101010101010101) & ~(X) & 0x8080808080808080)
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#else
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#error long int is not a 32bit or 64bit type.
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#endif
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#endif
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#ifndef DETECTNULL
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#error long int is not a 32bit or 64bit byte
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#endif
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size_t
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_DEFUN (strlen, (str),
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_CONST char *str)
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{
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#ifndef HAVE_HW_PCMP
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#if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__)
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_CONST char *start = str;
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while (*str)
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str++;
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return str - start;
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#else
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_CONST char *start = str;
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unsigned long *aligned_addr;
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if (!UNALIGNED (str))
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{
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/* If the string is word-aligned, we can check for the presence of
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a null in each word-sized block. */
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aligned_addr = (unsigned long*)str;
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while (!DETECTNULL (*aligned_addr))
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aligned_addr++;
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/* Once a null is detected, we check each byte in that block for a
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precise position of the null. */
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str = (char*)aligned_addr;
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}
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while (*str)
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str++;
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return str - start;
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#endif /* not PREFER_SIZE_OVER_SPEED */
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#else
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#include "mb_endian.h"
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asm volatile (" \n\
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or r9, r0, r0 /* Index register */ \n\
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check_alignment: \n\
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andi r3, r5, 3 \n\
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bnei r3, align_arg \n\
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len_loop: \n"
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LOAD4BYTES("r3", "r5", "r9")
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" \n\
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pcmpbf r4, r3, r0 \n\
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bnei r4, end_len \n\
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brid len_loop \n\
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addik r9, r9, 4 \n\
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end_len: \n\
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lbu r3, r5, r9 \n\
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beqi r3, done_len \n\
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brid end_len \n\
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addik r9, r9, 1 \n\
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done_len: \n\
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rtsd r15, 8 \n\
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or r3, r0, r9 /* Return len */ \n\
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align_arg: \n\
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rsubik r10, r3, 4 \n\
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align_loop: \n\
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lbu r3, r5, r9 \n\
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beqid r3, done_len \n\
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addik r10, r10, -1 \n\
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bneid r10, align_loop \n\
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addik r9, r9, 1 \n\
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bri len_loop");
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#endif /* ! HAVE_HW_PCMP */
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}
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