From 104b81ea9a1a9c7b67e9e060fef4d0a97a547b7b Mon Sep 17 00:00:00 2001
From: Jens Arnold <amiconn@rockbox.org>
Date: Mon, 28 Nov 2005 23:40:57 +0000
Subject: Fixed self-extracting loader: (1) Proper startup code, ensuring the
 stack pointer is set to the desired location. (2) Code cleanup.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@8103 a1c6a512-1295-4272-9138-f99709370657
---
 firmware/decompressor/startup.S | 57 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 57 insertions(+)
 create mode 100755 firmware/decompressor/startup.S

(limited to 'firmware/decompressor/startup.S')

diff --git a/firmware/decompressor/startup.S b/firmware/decompressor/startup.S
new file mode 100755
index 0000000000..62efef9cc3
--- /dev/null
+++ b/firmware/decompressor/startup.S
@@ -0,0 +1,57 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ * $Id$
+ *
+ * Copyright (C) 2005 by Jens Arnold
+ * based on crt0.S by Linus Nielsen Feltzing
+ *
+ * All files in this archive are subject to the GNU General Public License.
+ * See the file COPYING in the source tree root for full license agreement.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ****************************************************************************/
+    .section  .start,"ax",@progbits
+    .global    _start
+_start:
+    /* copy the .iram section */
+    mov.l   .iramcopy_k,r0
+    mov.l   .iram_k,r1
+    mov.l   .iramend_k,r2
+    /* Note: We cannot put a PC relative load into the delay slot of a 'bra'
+       instruction (the offset would be wrong), but there is nothing else to
+       do before the loop, so the delay slot would be 'nop'. The cmp / bf
+       sequence is the same length, but more efficient. */
+    cmp/hi  r1,r2
+    bf      .noiramcopy
+.iramloop:
+    mov.l   @r0+,r3
+    mov.l   r3,@r1
+    add     #4,r1
+    cmp/hi  r1,r2
+    bt      .iramloop
+.noiramcopy:
+
+    /* call the mainline */
+    mov.l   .main_k,r0
+    mov.l   .stackend_k,r15
+    jmp     @r0
+    nop
+
+    .align  2
+.iramcopy_k:
+    .long   _iramcopy
+.iram_k:
+    .long   _iramstart
+.iramend_k:
+    .long   _iramend
+.stackend_k:
+    .long   _stackend
+.main_k:
+    .long   _main
-- 
cgit