newlib-cygwin/newlib/libc/machine/microblaze/strlen.c

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/* Copyright (c) 2009 Xilinx, Inc. All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:
1. Redistributions source code must retain the above copyright notice,
this list of conditions and the following disclaimer.
2. 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.
3. Neither the name of Xilinx 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 HOLDER 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
HOLDER 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.
FUNCTION
<<strlen>>---character string length
INDEX
strlen
ANSI_SYNOPSIS
#include <string.h>
size_t strlen(const char *<[str]>);
TRAD_SYNOPSIS
#include <string.h>
size_t strlen(<[str]>)
char *<[src]>;
DESCRIPTION
The <<strlen>> function works out the length of the string
starting at <<*<[str]>>> by counting chararacters until it
reaches a <<NULL>> character.
RETURNS
<<strlen>> returns the character count.
PORTABILITY
<<strlen>> is ANSI C.
<<strlen>> requires no supporting OS subroutines.
QUICKREF
strlen ansi pure
*/
#include <_ansi.h>
#include <string.h>
#include <limits.h>
#define LBLOCKSIZE (sizeof (long))
#define UNALIGNED(X) ((long)X & (LBLOCKSIZE - 1))
#if LONG_MAX == 2147483647L
#define DETECTNULL(X) (((X) - 0x01010101) & ~(X) & 0x80808080)
#else
#if LONG_MAX == 9223372036854775807L
/* Nonzero if X (a long int) contains a NULL byte. */
#define DETECTNULL(X) (((X) - 0x0101010101010101) & ~(X) & 0x8080808080808080)
#else
#error long int is not a 32bit or 64bit type.
#endif
#endif
#ifndef DETECTNULL
#error long int is not a 32bit or 64bit byte
#endif
size_t
_DEFUN (strlen, (str),
_CONST char *str)
{
#ifndef HAVE_HW_PCMP
#if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__)
_CONST char *start = str;
while (*str)
str++;
return str - start;
#else
_CONST char *start = str;
unsigned long *aligned_addr;
if (!UNALIGNED (str))
{
/* If the string is word-aligned, we can check for the presence of
a null in each word-sized block. */
aligned_addr = (unsigned long*)str;
while (!DETECTNULL (*aligned_addr))
aligned_addr++;
/* Once a null is detected, we check each byte in that block for a
precise position of the null. */
str = (char*)aligned_addr;
}
while (*str)
str++;
return str - start;
#endif /* not PREFER_SIZE_OVER_SPEED */
#else
asm volatile (" \n\
or r9, r0, r0 /* Index register */ \n\
check_alignment: \n\
andi r3, r5, 3 \n\
bnei r3, align_arg \n\
len_loop: \n\
lw r3, r5, r9 \n\
pcmpbf r4, r3, r0 \n\
bnei r4, end_len \n\
brid len_loop \n\
addik r9, r9, 4 \n\
end_len: \n\
lbu r3, r5, r9 \n\
beqi r3, done_len \n\
brid end_len \n\
addik r9, r9, 1 \n\
done_len: \n\
rtsd r15, 8 \n\
or r3, r0, r9 /* Return len */ \n\
align_arg: \n\
rsubik r10, r3, 4 \n\
align_loop: \n\
lbu r3, r5, r9 \n\
beqid r3, done_len \n\
addik r10, r10, -1 \n\
bneid r10, align_loop \n\
addik r9, r9, 1 \n\
bri len_loop");
#endif /* ! HAVE_HW_PCMP */
}