mirror of
https://github.com/autc04/Retro68.git
synced 2024-11-27 14:50:23 +00:00
124 lines
2.8 KiB
C
124 lines
2.8 KiB
C
/*
|
|
FUNCTION
|
|
<<strchr>>---search for character in string
|
|
|
|
INDEX
|
|
strchr
|
|
|
|
ANSI_SYNOPSIS
|
|
#include <string.h>
|
|
char * strchr(const char *<[string]>, int <[c]>);
|
|
|
|
TRAD_SYNOPSIS
|
|
#include <string.h>
|
|
char * strchr(<[string]>, <[c]>);
|
|
const char *<[string]>;
|
|
int <[c]>;
|
|
|
|
DESCRIPTION
|
|
This function finds the first occurence of <[c]> (converted to
|
|
a char) in the string pointed to by <[string]> (including the
|
|
terminating null character).
|
|
|
|
RETURNS
|
|
Returns a pointer to the located character, or a null pointer
|
|
if <[c]> does not occur in <[string]>.
|
|
|
|
PORTABILITY
|
|
<<strchr>> is ANSI C.
|
|
|
|
<<strchr>> requires no supporting OS subroutines.
|
|
|
|
QUICKREF
|
|
strchr ansi pure
|
|
*/
|
|
|
|
#include <string.h>
|
|
#include <limits.h>
|
|
|
|
/* Nonzero if X is not aligned on a "long" boundary. */
|
|
#define UNALIGNED(X) ((long)X & (sizeof (long) - 1))
|
|
|
|
/* How many bytes are loaded each iteration of the word copy loop. */
|
|
#define LBLOCKSIZE (sizeof (long))
|
|
|
|
#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
|
|
|
|
/* DETECTCHAR returns nonzero if (long)X contains the byte used
|
|
to fill (long)MASK. */
|
|
#define DETECTCHAR(X,MASK) (DETECTNULL(X ^ MASK))
|
|
|
|
char *
|
|
_DEFUN (strchr, (s1, i),
|
|
_CONST char *s1 _AND
|
|
int i)
|
|
{
|
|
_CONST unsigned char *s = (_CONST unsigned char *)s1;
|
|
unsigned char c = i;
|
|
|
|
#if !defined(PREFER_SIZE_OVER_SPEED) && !defined(__OPTIMIZE_SIZE__)
|
|
unsigned long mask,j;
|
|
unsigned long *aligned_addr;
|
|
|
|
/* Special case for finding 0. */
|
|
if (!c)
|
|
{
|
|
while (UNALIGNED (s))
|
|
{
|
|
if (!*s)
|
|
return (char *) s;
|
|
s++;
|
|
}
|
|
/* Operate a word at a time. */
|
|
aligned_addr = (unsigned long *) s;
|
|
while (!DETECTNULL (*aligned_addr))
|
|
aligned_addr++;
|
|
/* Found the end of string. */
|
|
s = (const unsigned char *) aligned_addr;
|
|
while (*s)
|
|
s++;
|
|
return (char *) s;
|
|
}
|
|
|
|
/* All other bytes. Align the pointer, then search a long at a time. */
|
|
while (UNALIGNED (s))
|
|
{
|
|
if (!*s)
|
|
return NULL;
|
|
if (*s == c)
|
|
return (char *) s;
|
|
s++;
|
|
}
|
|
|
|
mask = c;
|
|
for (j = 8; j < LBLOCKSIZE * 8; j <<= 1)
|
|
mask = (mask << j) | mask;
|
|
|
|
aligned_addr = (unsigned long *) s;
|
|
while (!DETECTNULL (*aligned_addr) && !DETECTCHAR (*aligned_addr, mask))
|
|
aligned_addr++;
|
|
|
|
/* The block of bytes currently pointed to by aligned_addr
|
|
contains either a null or the target char, or both. We
|
|
catch it using the bytewise search. */
|
|
|
|
s = (unsigned char *) aligned_addr;
|
|
|
|
#endif /* not PREFER_SIZE_OVER_SPEED */
|
|
|
|
while (*s && *s != c)
|
|
s++;
|
|
if (*s == c)
|
|
return (char *)s;
|
|
return NULL;
|
|
}
|