mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-10 07:10:06 +00:00
30c1dfde31
It follows the strategy:
- Align the destination on word boundary using byte operations.
- If source is also word aligned, read a word per time, check for
null (using has_zero from string-fzb.h), and write the remaining
bytes.
- If source is not word aligned, loop by aligning the source, and
merging the result of two reads. Similar to aligned case,
check for null with has_zero, and write the remaining bytes if
null is found.
Checked on x86_64-linux-gnu, i686-linux-gnu, powerpc64-linux-gnu,
and powerpc-linux-gnu by removing the arch-specific assembly
implementation and disabling multi-arch (it covers both LE and BE
for 64 and 32 bits).
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>
122 lines
3.1 KiB
C
122 lines
3.1 KiB
C
/* Copyright (C) 1992-2023 Free Software Foundation, Inc.
|
|
This file is part of the GNU C Library.
|
|
|
|
The GNU C Library is free software; you can redistribute it and/or
|
|
modify it under the terms of the GNU Lesser General Public
|
|
License as published by the Free Software Foundation; either
|
|
version 2.1 of the License, or (at your option) any later version.
|
|
|
|
The GNU C Library is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
Lesser General Public License for more details.
|
|
|
|
You should have received a copy of the GNU Lesser General Public
|
|
License along with the GNU C Library; if not, see
|
|
<https://www.gnu.org/licenses/>. */
|
|
|
|
#define NO_MEMPCPY_STPCPY_REDIRECT
|
|
#include <string.h>
|
|
#include <stdint.h>
|
|
#include <memcopy.h>
|
|
#include <string-fzb.h>
|
|
#include <string-misc.h>
|
|
|
|
#undef __stpcpy
|
|
#undef stpcpy
|
|
|
|
#ifndef STPCPY
|
|
# define STPCPY __stpcpy
|
|
#endif
|
|
|
|
static __always_inline char *
|
|
write_byte_from_word (op_t *dest, op_t word)
|
|
{
|
|
char *d = (char *) dest;
|
|
for (size_t i = 0; i < OPSIZ; i++, ++d)
|
|
{
|
|
char c = extractbyte (word, i);
|
|
*d = c;
|
|
if (c == '\0')
|
|
break;
|
|
}
|
|
return d;
|
|
}
|
|
|
|
static __always_inline char *
|
|
stpcpy_aligned_loop (op_t *restrict dst, const op_t *restrict src)
|
|
{
|
|
op_t word;
|
|
while (1)
|
|
{
|
|
word = *src++;
|
|
if (has_zero (word))
|
|
break;
|
|
*dst++ = word;
|
|
}
|
|
|
|
return write_byte_from_word (dst, word);
|
|
}
|
|
|
|
static __always_inline char *
|
|
stpcpy_unaligned_loop (op_t *restrict dst, const op_t *restrict src,
|
|
uintptr_t ofs)
|
|
{
|
|
op_t w2a = *src++;
|
|
uintptr_t sh_1 = ofs * CHAR_BIT;
|
|
uintptr_t sh_2 = OPSIZ * CHAR_BIT - sh_1;
|
|
|
|
op_t w2 = MERGE (w2a, sh_1, (op_t)-1, sh_2);
|
|
if (!has_zero (w2))
|
|
{
|
|
op_t w2b;
|
|
|
|
/* Unaligned loop. The invariant is that W2B, which is "ahead" of W1,
|
|
does not contain end-of-string. Therefore it is safe (and necessary)
|
|
to read another word from each while we do not have a difference. */
|
|
while (1)
|
|
{
|
|
w2b = *src++;
|
|
w2 = MERGE (w2a, sh_1, w2b, sh_2);
|
|
/* Check if there is zero on w2a. */
|
|
if (has_zero (w2))
|
|
goto out;
|
|
*dst++ = w2;
|
|
if (has_zero (w2b))
|
|
break;
|
|
w2a = w2b;
|
|
}
|
|
|
|
/* Align the final partial of P2. */
|
|
w2 = MERGE (w2b, sh_1, 0, sh_2);
|
|
}
|
|
|
|
out:
|
|
return write_byte_from_word (dst, w2);
|
|
}
|
|
|
|
|
|
/* Copy SRC to DEST, returning the address of the terminating '\0' in DEST. */
|
|
char *
|
|
STPCPY (char *dest, const char *src)
|
|
{
|
|
/* Copy just a few bytes to make DEST aligned. */
|
|
size_t len = (-(uintptr_t) dest) % OPSIZ;
|
|
for (; len != 0; len--, ++dest)
|
|
{
|
|
char c = *src++;
|
|
*dest = c;
|
|
if (c == '\0')
|
|
return dest;
|
|
}
|
|
|
|
/* DEST is now aligned to op_t, SRC may or may not be. */
|
|
uintptr_t ofs = (uintptr_t) src % OPSIZ;
|
|
return ofs == 0 ? stpcpy_aligned_loop ((op_t*) dest, (const op_t *) src)
|
|
: stpcpy_unaligned_loop ((op_t*) dest,
|
|
(const op_t *) (src - ofs) , ofs);
|
|
}
|
|
weak_alias (__stpcpy, stpcpy)
|
|
libc_hidden_def (__stpcpy)
|
|
libc_hidden_builtin_def (stpcpy)
|