libgloss: msp430: split up crt0.S source

The build system compiles crt0.S many times to produce independent
object files by defining different -DLxxx symbols for each.  This
complicates the build, and has led to some bugs in the source and
build (see the previous cleanup commits in here).  The crt_bss.S
file has also been duplicated with crt0.S leading to confusion as
to which one is the "real" one.  The only reason to keep them in
one file is to make management of the section numbers when calling
START_CRT_FUNC a little easier, but that seems trivial to check
with a quick grep across all the files.

Considering how complicated the build is now, and the bugs we've
had as a result, split the crt0.S file up into multiple source
files so we don't have to compile it multiple times.  This will
also simplify merging it into the top-level Makefile.

1 files changed, 71 insertions, 0 deletions

diff --git a/libgloss/msp430/crt_move_highdata.S b/libgloss/msp430/crt_move_highdata.S
new file mode 100644
index 000000000..b96954962
--- /dev/null
+++ b/libgloss/msp430/crt_move_highdata.S
@@ -0,0 +1,71 @@
+/* Copyright (c) 2012-2015 Red Hat Incorporated.
+   All rights reserved.
+
+   Redistribution and use in source and binary forms, with or without
+   modification, are permitted provided that the following conditions
+   are met:
+
+     Redistributions of source code must retain the above copyright
+     notice, this list of conditions and the following disclaimer.
+
+     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.
+
+     The name of Red Hat Incorporated may not be used to endorse
+     or promote products derived from this software without specific
+     prior written permission.
+
+   This software is provided by the copyright holders 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 Red Hat
+   incorporated 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.  */
+
+#ifdef __MSP430X_LARGE__
+
+#include "memmodel.h"
+
+;; This function is responsible for making sure that the
+;; contents of the .upper.data section have their correct startup values.
+;; If a copy of the .upper.data section is stored in ROM then this means
+;; copying the contents into HIFRAM.  If a copy of .upper.data is stored in a
+;; shadow section in HIFRAM then this means copying from the shadow section
+;; into the real section.
+
+START_CRT_FUNC 0400 move_highdata
+	;;  __rom_highdatacopysize may be zero.  Test this first because
+	;; its value may come from the weak definitions above and we do
+	;; not want to access the memory at address 0 pointed to by the
+	;; weak definition of __upper_data_init.
+	mov.w	#__rom_highdatacopysize, R14
+	cmp.w	#0, R14
+	jeq	3f
+
+	/* Test our status word.  */
+	cmpx.w  #0, &__upper_data_init
+	jeq	1f
+	/* Status word is non-zero - copy from shadow into upper.  */
+	mov_	#__high_datastart, R12
+	mov_	#__rom_highdatastart, R13
+	jmp	2f
+
+1:	/* Status word is zero.  Copy from upper to shadow and change status word.  */
+	movx.w  #1, &__upper_data_init
+	mov_	#__rom_highdatastart, R12
+	mov_	#__high_datastart, R13
+
+2:	;; __rom_highdatacopysize may be zero.  memmove should cope.
+	mov.w	#__rom_highdatacopysize, R14
+
+	call_	#memmove
+3:
+END_CRT_FUNC	move_highdata
+
+#endif /* __MSP430X_LARGE__ */