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/memccpy.c

@@ -0,0 +1,144 @@
+/*
+FUNCTION
+        <<memccpy>>---copy memory regions with end-token check
+
+ANSI_SYNOPSIS
+        #include <string.h>
+        void* memccpy(void *restrict <[out]>, const void *restrict <[in]>, 
+                      int <[endchar]>, size_t <[n]>);
+
+TRAD_SYNOPSIS
+        void *memccpy(<[out]>, <[in]>, <[endchar]>, <[n]>
+        void *<[out]>;
+        void *<[in]>;
+	int <[endchar]>;
+        size_t <[n]>;
+
+DESCRIPTION
+        This function copies up to <[n]> bytes from the memory region
+        pointed to by <[in]> to the memory region pointed to by
+        <[out]>.  If a byte matching the <[endchar]> is encountered,
+	the byte is copied and copying stops.
+
+        If the regions overlap, the behavior is undefined.
+
+RETURNS
+        <<memccpy>> returns a pointer to the first byte following the
+	<[endchar]> in the <[out]> region.  If no byte matching
+	<[endchar]> was copied, then <<NULL>> is returned.
+
+PORTABILITY
+<<memccpy>> is a GNU extension.
+
+<<memccpy>> requires no supporting OS subroutines.
+
+	*/
+
+#include <_ansi.h>
+#include <stddef.h>
+#include <string.h>
+#include <limits.h>
+
+/* Nonzero if either X or Y is not aligned on a "long" boundary.  */
+#define UNALIGNED(X, Y) \
+  (((long)X & (sizeof (long) - 1)) | ((long)Y & (sizeof (long) - 1)))
+
+/* How many bytes are copied each iteration of the word copy loop.  */
+#define LITTLEBLOCKSIZE (sizeof (long))
+
+/* Threshhold for punting to the byte copier.  */
+#define TOO_SMALL(LEN)  ((LEN) < LITTLEBLOCKSIZE)
+
+/* Macros for detecting endchar */
+#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
+
+
+_PTR
+_DEFUN (memccpy, (dst0, src0, endchar, len0),
+	_PTR __restrict dst0 _AND
+	_CONST _PTR __restrict src0 _AND
+	int endchar0 _AND
+	size_t len0)
+{
+
+#if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__)
+  _PTR ptr = NULL;
+  char *dst = (char *) dst0;
+  char *src = (char *) src0;
+  char endchar = endchar0 & 0xff;
+
+  while (len0--)
+    {
+      if ((*dst++ = *src++) == endchar)
+        {
+          ptr = dst;
+          break;
+        }
+    }
+
+  return ptr;
+#else
+  _PTR ptr = NULL;
+  char *dst = dst0;
+  _CONST char *src = src0;
+  long *aligned_dst;
+  _CONST long *aligned_src;
+  char endchar = endchar0 & 0xff;
+
+  /* If the size is small, or either SRC or DST is unaligned,
+     then punt into the byte copy loop.  This should be rare.  */
+  if (!TOO_SMALL(len0) && !UNALIGNED (src, dst))
+    {
+      unsigned int i;
+      unsigned long mask = 0;
+
+      aligned_dst = (long*)dst;
+      aligned_src = (long*)src;
+
+      /* The fast code reads the ASCII 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 NULL in the
+         result.  */
+      for (i = 0; i < LITTLEBLOCKSIZE; i++)
+        mask = (mask << 8) + endchar;
+
+
+      /* Copy one long word at a time if possible.  */
+      while (len0 >= LITTLEBLOCKSIZE)
+        {
+          unsigned long buffer = (unsigned long)(*aligned_src);
+          buffer ^=  mask;
+          if (DETECTNULL (buffer))
+            break; /* endchar is found, go byte by byte from here */
+          *aligned_dst++ = *aligned_src++;
+          len0 -= LITTLEBLOCKSIZE;
+        }
+
+       /* Pick up any residual with a byte copier.  */
+      dst = (char*)aligned_dst;
+      src = (char*)aligned_src;
+    }
+
+  while (len0--)
+    {
+      if ((*dst++ = *src++) == endchar)
+        {
+          ptr = dst;
+          break;
+        }
+    }
+
+  return ptr;
+#endif /* not PREFER_SIZE_OVER_SPEED */
+}