Re: [PATCH] strchr, strchrnul: implement strchr() as strchrnul()

Why?

Please add a descriptive commit message with the reasoning and the
desired result for this change.


Thanks,
Corinna

On Dec  5 21:58, James Tirta Halim wrote:
> ---
>  newlib/libc/string/strchr.c    | 81 +---------------------------------
>  newlib/libc/string/strchrnul.c | 77 +++++++++++++++++++++++++++++++-
>  2 files changed, 77 insertions(+), 81 deletions(-)
> 
> diff --git a/newlib/libc/string/strchr.c b/newlib/libc/string/strchr.c
> index 96f30be04..382275b1d 100644
> --- a/newlib/libc/string/strchr.c
> +++ b/newlib/libc/string/strchr.c
> @@ -30,87 +30,10 @@ QUICKREF
>  #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 *
>  strchr (const char *s1,
>  	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;
> +  s1 = strchrnul(s1, i);
> +  return s1 && *s1 ? (char *) s1 : NULL;
>  }
> diff --git a/newlib/libc/string/strchrnul.c b/newlib/libc/string/strchrnul.c
> index f5c3eb25d..69f66db63 100644
> --- a/newlib/libc/string/strchrnul.c
> +++ b/newlib/libc/string/strchrnul.c
> @@ -29,12 +29,85 @@ QUICKREF
>  */
>  
>  #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 *
>  strchrnul (const char *s1,
>  	int i)
>  {
> -  char *s = strchr(s1, 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 || *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 */
>  
> -  return s ? s : (char *)s1 + strlen(s1);
> +  while (*s && *s != c)
> +    s++;
> +  return (char *) s;
>  }
> -- 
> 2.43.0