sh: Optimised memset for SH4

Optimised version of memset for the SH4 which uses movca.l.

Signed-off-by: Stuart Menefy <stuart.menefy@st.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/lib/Makefile

@@ -2,7 +2,7 @@
 # Makefile for SuperH-specific library files..
 #
 
-lib-y  = delay.o memset.o memmove.o memchr.o \
+lib-y  = delay.o memmove.o memchr.o \
 	 checksum.o strlen.o div64.o div64-generic.o
 
 # Extracted from libgcc
@@ -23,8 +23,11 @@ obj-y				+= io.o
 memcpy-y			:= memcpy.o
 memcpy-$(CONFIG_CPU_SH4)	:= memcpy-sh4.o
 
+memset-y			:= memset.o
+memset-$(CONFIG_CPU_SH4)	:= memset-sh4.o
+
 lib-$(CONFIG_MMU)		+= copy_page.o __clear_user.o
 lib-$(CONFIG_MCOUNT)		+= mcount.o
-lib-y				+= $(memcpy-y) $(udivsi3-y)
+lib-y				+= $(memcpy-y) $(memset-y) $(udivsi3-y)
 
 EXTRA_CFLAGS += -Werror

arch/sh/lib/memset-sh4.S

@@ -0,0 +1,107 @@
+/*
+ * "memset" implementation for SH4
+ *
+ * Copyright (C) 1999  Niibe Yutaka
+ * Copyright (c) 2009  STMicroelectronics Limited
+ * Author: Stuart Menefy <stuart.menefy:st.com>
+ */
+
+/*
+ *            void *memset(void *s, int c, size_t n);
+ */
+
+#include <linux/linkage.h>
+
+ENTRY(memset)
+	mov	#12,r0
+	add	r6,r4
+	cmp/gt	r6,r0
+	bt/s	40f		! if it's too small, set a byte at once
+	 mov	r4,r0
+	and	#3,r0
+	cmp/eq	#0,r0
+	bt/s	2f		! It's aligned
+	 sub	r0,r6
+1:
+	dt	r0
+	bf/s	1b
+	 mov.b	r5,@-r4
+2:				! make VVVV
+	extu.b	r5,r5
+	swap.b	r5,r0		!   V0
+	or	r0,r5		!   VV
+	swap.w	r5,r0		! VV00
+	or	r0,r5		! VVVV
+
+	! Check if enough bytes need to be copied to be worth the big loop
+	mov	#0x40, r0	! (MT)
+	cmp/gt	r6,r0		! (MT)  64 > len => slow loop
+
+	bt/s	22f
+	 mov	r6,r0
+
+	! align the dst to the cache block size if necessary
+	mov	r4, r3
+	mov	#~(0x1f), r1
+
+	and	r3, r1
+	cmp/eq	r3, r1
+
+	bt/s	11f		! dst is already aligned
+	 sub	r1, r3		! r3-r1 -> r3
+	shlr2	r3		! number of loops
+
+10:	mov.l	r5,@-r4
+	dt	r3
+	bf/s	10b
+	 add	#-4, r6
+
+11:	! dst is 32byte aligned
+	mov	r6,r2
+	mov	#-5,r0
+	shld	r0,r2		! number of loops
+
+	add	#-32, r4
+	mov	r5, r0
+12:
+	movca.l	r0,@r4
+	mov.l	r5,@(4, r4)
+	mov.l	r5,@(8, r4)
+	mov.l	r5,@(12,r4)
+	mov.l	r5,@(16,r4)
+	mov.l	r5,@(20,r4)
+	add	#-0x20, r6
+	mov.l	r5,@(24,r4)
+	dt	r2
+	mov.l	r5,@(28,r4)
+	bf/s	12b
+	 add	#-32, r4
+
+	add	#32, r4
+	mov	#8, r0
+	cmp/ge	r0, r6
+	bf	40f
+
+	mov	r6,r0
+22:
+	shlr2	r0
+	shlr	r0		! r0 = r6 >> 3
+3:
+	dt	r0
+	mov.l	r5,@-r4		! set 8-byte at once
+	bf/s	3b
+	 mov.l	r5,@-r4
+	!
+	mov	#7,r0
+	and	r0,r6
+
+	! fill bytes (length may be zero)
+40:	tst	r6,r6
+	bt	5f
+4:
+	dt	r6
+	bf/s	4b
+	 mov.b	r5,@-r4
+5:
+	rts
+	 mov	r4,r0