Initial. Don't... just don't ask.

2011-02-24 00:22:00 -08:00 · 2011-02-24 00:22:00 -08:00 · 00bae13bba
commit 00bae13bba
586 changed files with 129057 additions and 0 deletions
--- a/demos/memset.c
+++ b/demos/memset.c
@ -0,0 +1,91 @@
+/* Set a block of memory to some byte value.
+   For Intel 80x86, x>=3.
+   Copyright (C) 1991, 1992, 1993, 1997, 1998 Free Software Foundation, Inc.
+   Contributed by Torbjorn Granlund (tege@sics.se).
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Library General Public License as
+   published by the Free Software Foundation; either version 2 of the
+   License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Library General Public License for more details.
+
+   You should have received a copy of the GNU Library General Public
+   License along with the GNU C Library; see the file COPYING.LIB.  If not,
+   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+   Boston, MA 02111-1307, USA.  */
+
+#include <string.h>
+
+#ifdef __i386__
+
+#if defined(__GNUC__) 
+
+#undef memset
+
+#define op_t unsigned int
+#define OPSIZ 4
+
+
+void *
+memset (void *dstpp, int c, size_t len)
+{
+  int d0;
+  unsigned long int dstp = (unsigned long int) dstpp;
+
+  /* This explicit register allocation
+     improves code very much indeed.  */
+  register op_t x asm("ax");
+
+  x = (unsigned char) c;
+
+  /* Clear the direction flag, so filling will move forward.  */
+  asm volatile("cld");
+
+  /* This threshold value is optimal.  */
+  if (len >= 12)
+    {
+      /* Fill X with four copies of the char we want to fill with.  */
+      x |= (x << 8);
+      x |= (x << 16);
+
+      /* Adjust LEN for the bytes handled in the first loop.  */
+      len -= (-dstp) % OPSIZ;
+
+      /* There are at least some bytes to set.
+	 No need to test for LEN == 0 in this alignment loop.  */
+
+      /* Fill bytes until DSTP is aligned on a longword boundary.  */
+      asm volatile("rep\n"
+		   "stosb" /* %0, %2, %3 */ :
+		   "=D" (dstp), "=c" (d0) :
+		   "0" (dstp), "1" ((-dstp) % OPSIZ), "a" (x) :
+		   "memory");
+
+      /* Fill longwords.  */
+      asm volatile("rep\n"
+		   "stosl" /* %0, %2, %3 */ :
+		   "=D" (dstp), "=c" (d0) :
+		   "0" (dstp), "1" (len / OPSIZ), "a" (x) :
+		   "memory");
+      len %= OPSIZ;
+    }
+
+  /* Write the last few bytes.  */
+  asm volatile("rep\n"
+	       "stosb" /* %0, %2, %3 */ :
+	       "=D" (dstp), "=c" (d0) :
+	       "0" (dstp), "1" (len), "a" (x) :
+	       "memory");
+
+  return dstpp;
+}
+
+#else /* __GNUC__ */
+#include <sysdeps/generic/memset.c>
+#endif
+
+#endif /* __i386__ */