xnu-2422.1.72.tar.gz

[apple/xnu.git] / libsyscall / wrappers / string / memcpy.c

diff --git a/libsyscall/wrappers/string/memcpy.c b/libsyscall/wrappers/string/memcpy.c
new file mode 100644 (file)
index 0000000..ef30a90
--- /dev/null
+++ b/libsyscall/wrappers/string/memcpy.c
@@ -0,0 +1,128 @@
+/*-
+ * Copyright (c) 1990, 1993
+ *     The Regents of the University of California.  All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * Chris Torek.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 4. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include "string.h"
+
+/*
+ * sizeof(word) MUST BE A POWER OF TWO
+ * SO THAT wmask BELOW IS ALL ONES
+ */
+typedef        int word;               /* "word" used for optimal copy speed */
+
+#define        wsize   sizeof(word)
+#define        wmask   (wsize - 1)
+
+/*
+ * Copy a block of memory, handling overlap.
+ * This is the routine that actually implements
+ * (the portable versions of) bcopy, memcpy, and memmove.
+ */
+
+__attribute__((visibility("hidden")))
+void * memcpy(void *dst0, const void *src0, size_t length)
+{
+       char *dst = dst0;
+       const char *src = src0;
+       size_t t;
+       
+       if (length == 0 || dst == src)          /* nothing to do */
+               goto done;
+       
+       /*
+        * Macros: loop-t-times; and loop-t-times, t>0
+        */
+#define        TLOOP(s) if (t) TLOOP1(s)
+#define        TLOOP1(s) do { s; } while (--t)
+       
+       if ((unsigned long)dst < (unsigned long)src) {
+               /*
+                * Copy forward.
+                */
+               t = (uintptr_t)src;     /* only need low bits */
+               if ((t | (uintptr_t)dst) & wmask) {
+                       /*
+                        * Try to align operands.  This cannot be done
+                        * unless the low bits match.
+                        */
+                       if ((t ^ (uintptr_t)dst) & wmask || length < wsize)
+                               t = length;
+                       else
+                               t = wsize - (t & wmask);
+                       length -= t;
+                       TLOOP1(*dst++ = *src++);
+               }
+               /*
+                * Copy whole words, then mop up any trailing bytes.
+                */
+               t = length / wsize;
+               TLOOP(*(word *)dst = *(word *)src; src += wsize; dst += wsize);
+               t = length & wmask;
+               TLOOP(*dst++ = *src++);
+       } else {
+               /*
+                * Copy backwards.  Otherwise essentially the same.
+                * Alignment works as before, except that it takes
+                * (t&wmask) bytes to align, not wsize-(t&wmask).
+                */
+               src += length;
+               dst += length;
+               t = (uintptr_t)src;
+               if ((t | (uintptr_t)dst) & wmask) {
+                       if ((t ^ (uintptr_t)dst) & wmask || length <= wsize)
+                               t = length;
+                       else
+                               t &= wmask;
+                       length -= t;
+                       TLOOP1(*--dst = *--src);
+               }
+               t = length / wsize;
+               TLOOP(src -= wsize; dst -= wsize; *(word *)dst = *(word *)src);
+               t = length & wmask;
+               TLOOP(*--dst = *--src);
+       }
+done:
+       return (dst0);
+}
+
+__attribute__((visibility("hidden")))
+void *
+memmove(void *s1, const void *s2, size_t n)
+{
+       return memcpy(s1, s2, n);
+}
+
+__attribute__((visibility("hidden")))
+void
+bcopy(const void *s1, void *s2, size_t n)
+{
+       memcpy(s2, s1, n);
+}