@@ -1,10 +1,5 @@
/* Copyright (C) 1991-2015 Free Software Foundation, Inc.
This file is part of the GNU C Library.
- Based on strlen implementation by Torbjorn Granlund (tege@sics.se),
- with help from Dan Sahlin (dan@sics.se) and
- commentary by Jim Blandy (jimb@ai.mit.edu);
- adaptation to memchr suggested by Dick Karpinski (dick@cca.ucsf.edu),
- and implemented by Roland McGrath (roland@ai.mit.edu).
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
@@ -20,166 +15,23 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
-#ifdef HAVE_CONFIG_H
-#include <config.h>
-#endif
+#include <string.h>
+#include <stdlib.h>
-#undef __ptr_t
-#define __ptr_t void *
+#undef rawmemchr
+#undef __rawmemchr
-#if defined (_LIBC)
-# include <string.h>
-# include <memcopy.h>
-# include <stdlib.h>
-#endif
-#if defined (HAVE_LIMITS_H) || defined (_LIBC)
-# include <limits.h>
-#endif
+#include "string/common.h"
+#define EXPRESSION(p, c) (contains_zero (p ^ c))
+#include "string/skeleton.h"
-#define LONG_MAX_32_BITS 2147483647
-
-#ifndef LONG_MAX
-#define LONG_MAX LONG_MAX_32_BITS
-#endif
-
-#include <sys/types.h>
-
-#undef memchr
-
-#ifndef RAWMEMCHR
-# define RAWMEMCHR __rawmemchr
-#endif
-
-/* Find the first occurrence of C in S. */
-__ptr_t
-RAWMEMCHR (s, c_in)
- const __ptr_t s;
- int c_in;
+void *
+__rawmemchr (const void *s, int c)
{
- const unsigned char *char_ptr;
- const unsigned long int *longword_ptr;
- unsigned long int longword, magic_bits, charmask;
- unsigned char c;
-
- c = (unsigned char) c_in;
-
- /* Handle the first few characters by reading one character at a time.
- Do this until CHAR_PTR is aligned on a longword boundary. */
- for (char_ptr = (const unsigned char *) s;
- ((unsigned long int) char_ptr & (sizeof (longword) - 1)) != 0;
- ++char_ptr)
- if (*char_ptr == c)
- return (__ptr_t) char_ptr;
-
- /* All these elucidatory comments refer to 4-byte longwords,
- but the theory applies equally well to 8-byte longwords. */
-
- longword_ptr = (unsigned long int *) char_ptr;
-
- /* Bits 31, 24, 16, and 8 of this number are zero. Call these bits
- the "holes." Note that there is a hole just to the left of
- each byte, with an extra at the end:
-
- bits: 01111110 11111110 11111110 11111111
- bytes: AAAAAAAA BBBBBBBB CCCCCCCC DDDDDDDD
-
- The 1-bits make sure that carries propagate to the next 0-bit.
- The 0-bits provide holes for carries to fall into. */
-
- if (sizeof (longword) != 4 && sizeof (longword) != 8)
- abort ();
-
-#if LONG_MAX <= LONG_MAX_32_BITS
- magic_bits = 0x7efefeff;
-#else
- magic_bits = ((unsigned long int) 0x7efefefe << 32) | 0xfefefeff;
-#endif
-
- /* Set up a longword, each of whose bytes is C. */
- charmask = c | (c << 8);
- charmask |= charmask << 16;
-#if LONG_MAX > LONG_MAX_32_BITS
- charmask |= charmask << 32;
-#endif
-
- /* Instead of the traditional loop which tests each character,
- we will test a longword at a time. The tricky part is testing
- if *any of the four* bytes in the longword in question are zero. */
- while (1)
- {
- /* We tentatively exit the loop if adding MAGIC_BITS to
- LONGWORD fails to change any of the hole bits of LONGWORD.
-
- 1) Is this safe? Will it catch all the zero bytes?
- Suppose there is a byte with all zeros. Any carry bits
- propagating from its left will fall into the hole at its
- least significant bit and stop. Since there will be no
- carry from its most significant bit, the LSB of the
- byte to the left will be unchanged, and the zero will be
- detected.
-
- 2) Is this worthwhile? Will it ignore everything except
- zero bytes? Suppose every byte of LONGWORD has a bit set
- somewhere. There will be a carry into bit 8. If bit 8
- is set, this will carry into bit 16. If bit 8 is clear,
- one of bits 9-15 must be set, so there will be a carry
- into bit 16. Similarly, there will be a carry into bit
- 24. If one of bits 24-30 is set, there will be a carry
- into bit 31, so all of the hole bits will be changed.
-
- The one misfire occurs when bits 24-30 are clear and bit
- 31 is set; in this case, the hole at bit 31 is not
- changed. If we had access to the processor carry flag,
- we could close this loophole by putting the fourth hole
- at bit 32!
-
- So it ignores everything except 128's, when they're aligned
- properly.
-
- 3) But wait! Aren't we looking for C, not zero?
- Good point. So what we do is XOR LONGWORD with a longword,
- each of whose bytes is C. This turns each byte that is C
- into a zero. */
-
- longword = *longword_ptr++ ^ charmask;
-
- /* Add MAGIC_BITS to LONGWORD. */
- if ((((longword + magic_bits)
-
- /* Set those bits that were unchanged by the addition. */
- ^ ~longword)
-
- /* Look at only the hole bits. If any of the hole bits
- are unchanged, most likely one of the bytes was a
- zero. */
- & ~magic_bits) != 0)
- {
- /* Which of the bytes was C? If none of them were, it was
- a misfire; continue the search. */
-
- const unsigned char *cp = (const unsigned char *) (longword_ptr - 1);
-
- if (cp[0] == c)
- return (__ptr_t) cp;
- if (cp[1] == c)
- return (__ptr_t) &cp[1];
- if (cp[2] == c)
- return (__ptr_t) &cp[2];
- if (cp[3] == c)
- return (__ptr_t) &cp[3];
-#if LONG_MAX > 2147483647
- if (cp[4] == c)
- return (__ptr_t) &cp[4];
- if (cp[5] == c)
- return (__ptr_t) &cp[5];
- if (cp[6] == c)
- return (__ptr_t) &cp[6];
- if (cp[7] == c)
- return (__ptr_t) &cp[7];
-#endif
- }
- }
+ return (void *) string_skeleton (s, c, NULL);
}
+
libc_hidden_def (__rawmemchr)
weak_alias (__rawmemchr, rawmemchr)
+
@@ -1,8 +1,5 @@
/* Copyright (C) 1991-2015 Free Software Foundation, Inc.
This file is part of the GNU C Library.
- Written by Torbjorn Granlund (tege@sics.se),
- with help from Dan Sahlin (dan@sics.se);
- commentary by Jim Blandy (jimb@ai.mit.edu).
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
@@ -25,81 +22,15 @@
/* Return the length of the null-terminated string STR. Scan for
the null terminator quickly by testing four bytes at a time. */
+
+#include "string/common.h"
+#define EXPRESSION(p, c) (contains_zero (p))
+#include "string/skeleton.h"
+
size_t
strlen (const char *str)
{
- const char *char_ptr;
- const unsigned long int *longword_ptr;
- unsigned long int longword, himagic, lomagic;
-
- /* Handle the first few characters by reading one character at a time.
- Do this until CHAR_PTR is aligned on a longword boundary. */
- for (char_ptr = str; ((unsigned long int) char_ptr
- & (sizeof (longword) - 1)) != 0;
- ++char_ptr)
- if (*char_ptr == '\0')
- return char_ptr - str;
-
- /* All these elucidatory comments refer to 4-byte longwords,
- but the theory applies equally well to 8-byte longwords. */
-
- longword_ptr = (unsigned long int *) char_ptr;
-
- /* Bits 31, 24, 16, and 8 of this number are zero. Call these bits
- the "holes." Note that there is a hole just to the left of
- each byte, with an extra at the end:
-
- bits: 01111110 11111110 11111110 11111111
- bytes: AAAAAAAA BBBBBBBB CCCCCCCC DDDDDDDD
-
- The 1-bits make sure that carries propagate to the next 0-bit.
- The 0-bits provide holes for carries to fall into. */
- himagic = 0x80808080L;
- lomagic = 0x01010101L;
- if (sizeof (longword) > 4)
- {
- /* 64-bit version of the magic. */
- /* Do the shift in two steps to avoid a warning if long has 32 bits. */
- himagic = ((himagic << 16) << 16) | himagic;
- lomagic = ((lomagic << 16) << 16) | lomagic;
- }
- if (sizeof (longword) > 8)
- abort ();
-
- /* Instead of the traditional loop which tests each character,
- we will test a longword at a time. The tricky part is testing
- if *any of the four* bytes in the longword in question are zero. */
- for (;;)
- {
- longword = *longword_ptr++;
-
- if (((longword - lomagic) & ~longword & himagic) != 0)
- {
- /* Which of the bytes was the zero? If none of them were, it was
- a misfire; continue the search. */
-
- const char *cp = (const char *) (longword_ptr - 1);
-
- if (cp[0] == 0)
- return cp - str;
- if (cp[1] == 0)
- return cp - str + 1;
- if (cp[2] == 0)
- return cp - str + 2;
- if (cp[3] == 0)
- return cp - str + 3;
- if (sizeof (longword) > 4)
- {
- if (cp[4] == 0)
- return cp - str + 4;
- if (cp[5] == 0)
- return cp - str + 5;
- if (cp[6] == 0)
- return cp - str + 6;
- if (cp[7] == 0)
- return cp - str + 7;
- }
- }
- }
+ return string_skeleton (str, 0, 0) - str;
}
+
libc_hidden_builtin_def (strlen)