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/*
* Mach Operating System
* Copyright (c) 1993 Carnegie Mellon University
* All Rights Reserved.
*
* Permission to use, copy, modify and distribute this software and its
* documentation is hereby granted, provided that both the copyright
* notice and this permission notice appear in all copies of the
* software, derivative works or modified versions, and any portions
* thereof, and that both notices appear in supporting documentation.
*
* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
* ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
*
* Carnegie Mellon requests users of this software to return to
*
* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
* School of Computer Science
* Carnegie Mellon University
* Pittsburgh PA 15213-3890
*
* any improvements or extensions that they make and grant Carnegie Mellon
* the rights to redistribute these changes.
*/
/*
* File: strings.c
* Author: Robert V. Baron, Carnegie Mellon University
* Date: ??/92
*
* String functions.
*/
#include <kern/strings.h> /* make sure we sell the truth */
#ifdef strcpy
#undef strcmp
#undef strncmp
#undef strcpy
#undef strncpy
#undef strlen
#endif
/*
* Abstract:
* strcmp (s1, s2) compares the strings "s1" and "s2".
* It returns 0 if the strings are identical. It returns
* > 0 if the first character that differs in the two strings
* is larger in s1 than in s2 or if s1 is longer than s2 and
* the contents are identical up to the length of s2.
* It returns < 0 if the first differing character is smaller
* in s1 than in s2 or if s1 is shorter than s2 and the
* contents are identical upto the length of s1.
*/
int
strcmp(
register const char *s1,
register const char *s2)
{
register unsigned int a, b;
do {
a = *s1++;
b = *s2++;
if (a != b)
return a-b; /* includes case when
'a' is zero and 'b' is not zero
or vice versa */
} while (a != '\0');
return 0; /* both are zero */
}
/*
* Abstract:
* strncmp (s1, s2, n) compares the strings "s1" and "s2"
* in exactly the same way as strcmp does. Except the
* comparison runs for at most "n" characters.
*/
int
strncmp(
register const char *s1,
register const char *s2,
unsigned long n)
{
register unsigned int a, b;
while (n != 0) {
a = *s1++;
b = *s2++;
if (a != b)
return a-b; /* includes case when
'a' is zero and 'b' is not zero
or vice versa */
if (a == '\0')
return 0; /* both are zero */
n--;
}
return 0;
}
/*
* Abstract:
* strcpy copies the contents of the string "from" including
* the null terminator to the string "to". A pointer to "to"
* is returned.
*/
char *
strcpy(
register char *to,
register const char *from)
{
register char *ret = to;
while ((*to++ = *from++) != '\0')
continue;
return ret;
}
/*
* Abstract:
* strncpy copies "count" characters from the "from" string to
* the "to" string. If "from" contains less than "count" characters
* "to" will be padded with null characters until exactly "count"
* characters have been written. The return value is a pointer
* to the "to" string.
*/
char *
strncpy(
register char *to,
register const char *from,
register unsigned long count)
{
register char *ret = to;
while (count != 0) {
count--;
if ((*to++ = *from++) == '\0')
break;
}
while (count != 0) {
*to++ = '\0';
count--;
}
return ret;
}
/*
* Abstract:
* strlen returns the number of characters in "string" preceeding
* the terminating null character.
*/
unsigned long
strlen(
register const char *string)
{
register const char *ret = string;
while (*string++ != '\0')
continue;
return string - 1 - ret;
}
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