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author | Yaakov Selkowitz <yselkowi@redhat.com> | 2013-06-24 15:11:24 +0000 |
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committer | Yaakov Selkowitz <yselkowi@redhat.com> | 2013-06-24 15:11:24 +0000 |
commit | e3928ce48c90d51a78a0dbee416979fdf38b0f44 (patch) | |
tree | 408e7388ce3e2740dbae98d6911d0f0fc2bdba96 /newlib/libc/string/rawmemchr.c | |
parent | 837a83bf1c0ea8315825b903075ba279997e5e8c (diff) | |
download | cygnal-e3928ce48c90d51a78a0dbee416979fdf38b0f44.tar.gz cygnal-e3928ce48c90d51a78a0dbee416979fdf38b0f44.tar.bz2 cygnal-e3928ce48c90d51a78a0dbee416979fdf38b0f44.zip |
* libc/include/string.h (rawmemchr): Declare.
* libc/string/Makefile.am (ELIX_4_SOURCES): Add rawmemchr.c.
(CHEWOUT_FILES): Add rawmemchr.def.
* libc/string/Makefile.in: Regenerate.
* libc/string/rawmemchr.c: New file.
Diffstat (limited to 'newlib/libc/string/rawmemchr.c')
-rw-r--r-- | newlib/libc/string/rawmemchr.c | 121 |
1 files changed, 121 insertions, 0 deletions
diff --git a/newlib/libc/string/rawmemchr.c b/newlib/libc/string/rawmemchr.c new file mode 100644 index 000000000..a9e2acd85 --- /dev/null +++ b/newlib/libc/string/rawmemchr.c @@ -0,0 +1,121 @@ +/* +FUNCTION + <<rawmemchr>>---find character in memory + +INDEX + rawmemchr + +ANSI_SYNOPSIS + #include <string.h> + void *rawmemchr(const void *<[src]>, int <[c]>); + +TRAD_SYNOPSIS + #include <string.h> + void *rawmemchr(<[src]>, <[c]>) + void *<[src]>; + void *<[c]>; + +DESCRIPTION + This function searches memory starting at <<*<[src]>>> for the + character <[c]>. The search only ends with the first occurrence + of <[c]>; in particular, <<NUL>> does not terminate the search. + No bounds checking is performed, so this function should only + be used when it is certain that the character <[c]> will be found. + +RETURNS + A pointer to the first occurance of character <[c]>. + +PORTABILITY +<<rawmemchr>> is a GNU extension. + +<<rawmemchr>> requires no supporting OS subroutines. + +QUICKREF + rawmemchr +*/ + +#include <_ansi.h> +#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)) + +/* Threshhold for punting to the bytewise iterator. */ +#define TOO_SMALL(LEN) ((LEN) < LBLOCKSIZE) + +#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 + +#ifndef DETECTNULL +#error long int is not a 32bit or 64bit byte +#endif + +/* DETECTCHAR returns nonzero if (long)X contains the byte used + to fill (long)MASK. */ +#define DETECTCHAR(X,MASK) (DETECTNULL(X ^ MASK)) + +_PTR +_DEFUN (rawmemchr, (src_void, c), + _CONST _PTR src_void _AND + int c) +{ + _CONST unsigned char *src = (_CONST unsigned char *) src_void; + unsigned char d = c; + +#if !defined(PREFER_SIZE_OVER_SPEED) && !defined(__OPTIMIZE_SIZE__) + unsigned long *asrc; + unsigned long mask; + int i; + + while (UNALIGNED (src)) + { + if (*src == d) + return (void *) src; + src++; + } + + /* If we get this far, we know that src is word-aligned. */ + /* The fast code reads the source one word at a time and only + performs the bytewise search on word-sized segments if they + contain the search character, which is detected by XORing + the word-sized segment with a word-sized block of the search + character and then detecting for the presence of NUL in the + result. */ + asrc = (unsigned long *) src; + mask = d << 8 | d; + mask = mask << 16 | mask; + for (i = 32; i < LBLOCKSIZE * 8; i <<= 1) + mask = (mask << i) | mask; + + while (1) + { + if (DETECTCHAR (*asrc, mask)) + break; + asrc++; + } + + /* We have the matching word, now we resort to a bytewise loop. */ + + src = (unsigned char *) asrc; + +#endif // !PREFER_SIZE_OVER_SPEED && !__OPTIMIZE_SIZE__ + + while (1) + { + if (*src == d) + return (void *) src; + src++; + } +} |