sh: First support code of SuperH.

Signed-off-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
diff --git a/cpu/sh4/start.S b/cpu/sh4/start.S
new file mode 100644
index 0000000..d88b705
--- /dev/null
+++ b/cpu/sh4/start.S
@@ -0,0 +1,75 @@
+/*
+ * (C) Copyright 2007
+ * Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#include <config.h>
+#include <version.h>
+
+	.text
+	.align	2
+
+	.global	_start
+_start:
+	mov.l	._lowlevel_init, r0
+100:	bsrf	r0
+	nop
+
+	bsr	1f
+	nop
+1:	sts	pr, r5
+	mov.l	._reloc_dst, r4	
+	add	#(_start-1b), r5	
+	mov.l	._reloc_dst_end, r6	
+
+2:	mov.l	@r5+, r1
+	mov.l	r1, @r4
+	add	#4, r4
+	cmp/hs	r6, r4
+	bf	2b
+	
+	mov.l	._bss_start, r4	
+	mov.l	._bss_end, r5		
+	mov	#0, r1
+
+3:	mov.l	r1, @r4			/* bss clear */	
+	add	#4, r4
+	cmp/hs	r5, r4
+	bf	3b
+
+	mov.l	._gd_init, r13		/* global data */
+	mov.l	._stack_init, r15	/* stack */
+
+	mov.l	._sh_generic_init, r0
+	jsr	@r0			
+	nop				
+
+loop:
+	bra	loop
+
+	.align	2
+
+._lowlevel_init:	.long	(lowlevel_init - (100b + 4))
+._reloc_dst:		.long	reloc_dst
+._reloc_dst_end:	.long	reloc_dst_end
+._bss_start:		.long	bss_start
+._bss_end:		.long	bss_end
+._gd_init:		.long	(_start - CFG_GBL_DATA_SIZE)
+._stack_init:		.long	(_start - CFG_GBL_DATA_SIZE - CFG_MALLOC_LEN - 16)
+._sh_generic_init:	.long	sh_generic_init
+