MIPS specific optimizations.

1 files changed, 83 insertions, 0 deletions

diff --git a/sysdeps/mips/memset.S b/sysdeps/mips/memset.S
new file mode 100644
index 0000000000..7e3f129af9
--- /dev/null
+++ b/sysdeps/mips/memset.S
@@ -0,0 +1,83 @@
+/* Copyright (C) 2002 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Hartvig Ekner <hartvige@mips.com>, 2002.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#include <sysdep.h>
+#include <endian.h>
+
+
+/* void *memset(void *s, int c, size_t n).
+
+   This routine could be optimized further for MIPS64, but this is left
+   as an exercise for the future. When it is done, the file should be kept
+   as a sisterfile to this one, and placed in the sysdeps/mips/mips64 
+   directory.  */
+
+#if __BYTE_ORDER == __BIG_ENDIAN
+# define SWHI	swl		/* high part is left in big-endian	*/
+#else
+# define SWHI	swr		/* high part is right in little-endian	*/
+#endif
+
+ENTRY (memset)
+	.set	noreorder
+
+	slti	t1, a2, 8		# Less than 8?
+	bne	t1, zero, $last8
+	move	v0, a0			# Setup exit value before too late
+
+	beq	a1, zero, $ueven	# If zero pattern, no need to extend
+	andi	a1, 0xff		# Avoid problems with bogus arguments
+	sll	t0, a1, 8
+	or	a1, t0
+	sll	t0, a1, 16
+	or	a1, t0			# a1 is now pattern in full word
+
+$ueven:	subu	t0, zero, a0		# Unaligned address?
+	andi	t0, 0x3
+	beq	t0, zero, $chkw
+	subu	a2, t0
+	SWHI	a1, 0(a0)		# Yes, handle first unaligned part
+	addu	a0, t0			# Now both a0 and a2 are updated
+
+$chkw:	andi	t0, a2, 0x7		# Enough left for one loop iteration?
+	beq	t0, a2, $chkl
+	subu	a3, a2, t0
+	addu	a3, a0			# a3 is last loop address +1
+	move	a2, t0			# a2 is now # of bytes left after loop
+$loopw:	addiu	a0, 8			# Handle 2 words pr. iteration
+	sw	a1, -8(a0)
+	bne	a0, a3, $loopw
+	sw	a1, -4(a0)
+
+$chkl:	andi	t0, a2, 0x4		# Check if there is at least a full
+	beq	t0, zero, $last8	#  word remaining after the loop
+	subu	a2, t0
+	sw	a1, 0(a0)		# Yes...
+	addiu	a0, 4
+
+$last8:	blez	a2, $exit		# Handle last 8 bytes (if cnt>0)
+	addu	a3, a2, a0		# a3 is last address +1
+$lst8l:	addiu	a0, 1
+	bne	a0, a3, $lst8l
+	sb	a1, -1(a0)
+$exit:	j	ra			# Bye, bye
+	nop
+
+	.set	reorder
+END (memset)