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Diffstat (limited to 'newlib/libc/string/rawmemchr.c')
-rw-r--r--newlib/libc/string/rawmemchr.c121
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++;
+ }
+}