From: Corinna Vinschen <vinschen@redhat.com>
To: James Tirta Halim <tirtajames45@gmail.com>
Cc: newlib@sourceware.org
Subject: Re: [PATCH] strchr, strchrnul: implement strchr() as strchrnul()
Date: Tue, 5 Dec 2023 16:23:17 +0100 [thread overview]
Message-ID: <ZW9AZIEEMWoGQTqA@calimero.vinschen.de> (raw)
In-Reply-To: <20231205145839.474295-1-tirtajames45@gmail.com>
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
next prev parent reply other threads:[~2023-12-05 15:24 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-05 14:58 James Tirta Halim
2023-12-05 15:23 ` Corinna Vinschen [this message]
2023-12-05 15:52 ` James
2023-12-05 16:39 ` Richard Earnshaw
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=ZW9AZIEEMWoGQTqA@calimero.vinschen.de \
--to=vinschen@redhat.com \
--cc=newlib@sourceware.org \
--cc=tirtajames45@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).