import newlib-2000-02-17 snapshot

1 files changed, 111 insertions, 0 deletions

diff --git a/newlib/libc/string/memcpy.c b/newlib/libc/string/memcpy.c
new file mode 100644
index 000000000..5336f25a9
--- /dev/null
+++ b/newlib/libc/string/memcpy.c
@@ -0,0 +1,111 @@
+/*
+FUNCTION
+        <<memcpy>>---copy memory regions
+
+ANSI_SYNOPSIS
+        #include <string.h>
+        void* memcpy(void *<[out]>, const void *<[in]>, size_t <[n]>);
+
+TRAD_SYNOPSIS
+        void *memcpy(<[out]>, <[in]>, <[n]>
+        void *<[out]>;
+        void *<[in]>;
+        size_t <[n]>;
+
+DESCRIPTION
+        This function copies <[n]> bytes from the memory region
+        pointed to by <[in]> to the memory region pointed to by
+        <[out]>.
+
+        If the regions overlap, the behavior is undefined.
+
+RETURNS
+        <<memcpy>> returns a pointer to the first byte of the <[out]>
+        region.
+
+PORTABILITY
+<<memcpy>> is ANSI C.
+
+<<memcpy>> requires no supporting OS subroutines.
+
+QUICKREF
+        memcpy ansi pure
+	*/
+
+#include <_ansi.h>
+#include <stddef.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 4X unrolled loop.  */
+#define BIGBLOCKSIZE    (sizeof (long) << 2)
+
+/* 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) < BIGBLOCKSIZE)
+
+_PTR
+_DEFUN (memcpy, (dst0, src0, len0),
+	_PTR dst0 _AND
+	_CONST _PTR src0 _AND
+	size_t len0)
+{
+#if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__)
+  char *dst = (char *) dst0;
+  char *src = (char *) src0;
+
+  _PTR save = dst0;
+
+  while (len0--)
+    {
+      *dst++ = *src++;
+    }
+
+  return save;
+#else
+  char *dst = dst0;
+  _CONST char *src = src0;
+  long *aligned_dst;
+  _CONST long *aligned_src;
+  int   len =  len0;
+
+  /* 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(len) && !UNALIGNED (src, dst))
+    {
+      aligned_dst = (long*)dst;
+      aligned_src = (long*)src;
+
+      /* Copy 4X long words at a time if possible.  */
+      while (len >= BIGBLOCKSIZE)
+        {
+          *aligned_dst++ = *aligned_src++;
+          *aligned_dst++ = *aligned_src++;
+          *aligned_dst++ = *aligned_src++;
+          *aligned_dst++ = *aligned_src++;
+          len -= BIGBLOCKSIZE;
+        }
+
+      /* Copy one long word at a time if possible.  */
+      while (len >= LITTLEBLOCKSIZE)
+        {
+          *aligned_dst++ = *aligned_src++;
+          len -= LITTLEBLOCKSIZE;
+        }
+
+       /* Pick up any residual with a byte copier.  */
+      dst = (char*)aligned_dst;
+      src = (char*)aligned_src;
+    }
+
+  while (len--)
+    *dst++ = *src++;
+
+  return dst0;
+#endif /* not PREFER_SIZE_OVER_SPEED */
+}