xnu-2422.1.72.tar.gz

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

diff --git a/libsyscall/wrappers/string/memset.c b/libsyscall/wrappers/string/memset.c
new file mode 100644 (file)
index 0000000..3ae3c77
--- /dev/null
+++ b/libsyscall/wrappers/string/memset.c
@@ -0,0 +1,112 @@
+/*-
+ * Copyright (c) 1990, 1993
+ *     The Regents of the University of California.  All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * Mike Hibler and 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 "strings.h"
+#include <sys/types.h>
+
+#define        wsize   sizeof(u_int)
+#define        wmask   (wsize - 1)
+
+__attribute__((visibility("hidden")))
+void
+bzero(void *dst0, size_t length)
+{
+    return (void)memset(dst0, 0, length);
+}
+
+#define        RETURN  return (dst0)
+#define        VAL     c0
+#define        WIDEVAL c
+
+__attribute__((visibility("hidden")))
+void *
+memset(void *dst0, int c0, size_t length)
+{
+       size_t t;
+       u_int c;
+       u_char *dst;
+
+       dst = dst0;
+       /*
+        * If not enough words, just fill bytes.  A length >= 2 words
+        * guarantees that at least one of them is `complete' after
+        * any necessary alignment.  For instance:
+        *
+        *      |-----------|-----------|-----------|
+        *      |00|01|02|03|04|05|06|07|08|09|0A|00|
+        *                ^---------------------^
+        *               dst             dst+length-1
+        *
+        * but we use a minimum of 3 here since the overhead of the code
+        * to do word writes is substantial.
+        */
+       if (length < 3 * wsize) {
+               while (length != 0) {
+                       *dst++ = VAL;
+                       --length;
+               }
+               RETURN;
+       }
+
+       if ((c = (u_char)c0) != 0) {    /* Fill the word. */
+               c = (c << 8) | c;       /* u_int is 16 bits. */
+#if UINT_MAX > 0xffff
+               c = (c << 16) | c;      /* u_int is 32 bits. */
+#endif
+#if UINT_MAX > 0xffffffff
+               c = (c << 32) | c;      /* u_int is 64 bits. */
+#endif
+       }
+       /* Align destination by filling in bytes. */
+       if ((t = (long)dst & wmask) != 0) {
+               t = wsize - t;
+               length -= t;
+               do {
+                       *dst++ = VAL;
+               } while (--t != 0);
+       }
+
+       /* Fill words.  Length was >= 2*words so we know t >= 1 here. */
+       t = length / wsize;
+       do {
+               *(u_int *)dst = WIDEVAL;
+               dst += wsize;
+       } while (--t != 0);
+
+       /* Mop up trailing bytes, if any. */
+       t = length & wmask;
+       if (t != 0)
+               do {
+                       *dst++ = VAL;
+               } while (--t != 0);
+       RETURN;
+}