newlib-2.4.0: wide character strings

git-svn-id: svn://kolibrios.org@6557 a494cfbc-eb01-0410-851d-a64ba20cac60

contrib/sdk/sources/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;
+  unsigned 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++;
+    }
+}