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Simplify strncat.

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We rewrite strncat to use strnlen and malloc calls which simplifies code
an is faster as these functions are better optimized than original code.
This commit is contained in:
Ondřej Bílka 2014-12-19 23:09:40 +01:00
parent 0d4ba8be9c
commit 3eb38795db
2 changed files with 7 additions and 44 deletions
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4
ChangeLog
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@ -1,3 +1,7 @@
2014-12-19 Ondřej Bílka <neleai@seznam.cz>
* string/strncat.c (STRNCAT): Simplify implementation.
2014-12-19 David S. Miller <davem@davemloft.net>
* sysdeps/sparc/sparc32/soft-fp/q_neg.c (_Q_neg): Use a union to

47
string/strncat.c
View File

@ -17,10 +17,6 @@
#include <string.h>
#ifdef _LIBC
# include <memcopy.h>
#endif
#ifndef STRNCAT
# undef strncat
# define STRNCAT strncat
@ -29,52 +25,15 @@
char *
STRNCAT (char *s1, const char *s2, size_t n)
{
char c;
char *s = s1;
/* Find the end of S1. */
s1 += strlen (s1);
/* Make S1 point before next character, so we can increment
it while memory is read (wins on pipelined cpus). */
s1 -= 1;
size_t ss = __strnlen (s2, n);
if (n >= 4)
{
size_t n4 = n >> 2;
do
{
c = *s2++;
*++s1 = c;
if (c == '\0')
return s;
c = *s2++;
*++s1 = c;
if (c == '\0')
return s;
c = *s2++;
*++s1 = c;
if (c == '\0')
return s;
c = *s2++;
*++s1 = c;
if (c == '\0')
return s;
} while (--n4 > 0);
n &= 3;
}
while (n > 0)
{
c = *s2++;
*++s1 = c;
if (c == '\0')
return s;
n--;
}
if (c != '\0')
*++s1 = '\0';
s1[ss] = '\0';
memcpy (s1, s2, ss);
return s;
}