summaryrefslogtreecommitdiffstats
path: root/firmware/crt0.S
blob: 339caadb569d2aca08435b4383d89a82043e944d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
/***************************************************************************
 *             __________               __   ___.
 *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
 *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
 *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
 *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
 *                     \/            \/     \/    \/            \/
 * $Id$
 *
 * Copyright (C) 2002 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 .init.text
	.global	start
start:
	/* We begin with some tricks. If we have built our code to be loaded
	 * via the standalone GDB stub, we will have out VBR at some other
	 * location than 0x9000000. We must copy the trap vectors for the
	 * GDB stub to our vector table.
	 * If, on the other hand, we are running standalone we will have
	 * the VBR at 0x9000000, and the copy will not do any harm.
	 */
	mov.l	vbr_k,r1	
	mov.l	orig_vbr_k,r2
	
	/* Move the invalid instruction vector (4) */
	mov	#4,r0
	shll2	r0
	mov.l	@(r0,r2),r3
	mov.l	r3,@(r0,r1)
	
	/* Move the invalid slot vector (6) */
	mov	#6,r0
	shll2	r0
	mov.l	@(r0,r2),r3
	mov.l	r3,@(r0,r1)
	
	/* Move the bus error vector (9) */
	mov	#9,r0
	shll2	r0
	mov.l	@(r0,r2),r3
	mov.l	r3,@(r0,r1)
	
	/* Move the DMA bus error vector (10) */
	mov	#10,r0
	shll2	r0
	mov.l	@(r0,r2),r3
	mov.l	r3,@(r0,r1)
	
	/* Move the NMI vector as well (11) */
	mov	#11,r0
	shll2	r0
	mov.l	@(r0,r2),r3
	mov.l	r3,@(r0,r1)
	
	/* Move the breakpoint trap vector (32) */
	mov	#32,r0
	shll2	r0
	mov.l	@(r0,r2),r3
	mov.l	r3,@(r0,r1)
	
	/* Move the IO trap vector (33) */
	mov	#33,r0
	shll2	r0
	mov.l	@(r0,r2),r3
	mov.l	r3,@(r0,r1)
	
	/* Move the serial Rx interrupt vector (105) */
	mov	#105,r0
	shll2	r0
	mov.l	@(r0,r2),r3
	mov.l	r3,@(r0,r1)

	/* Move the single step trap vector (127) */
	mov	#127,r0
	shll2	r0
	mov.l	@(r0,r2),r3
	mov.l	r3,@(r0,r1)
	
	ldc	r1,vbr

	/* Now let's get on with the normal business */
	mov.l	stack_k,r15

	/* zero out bss */
	mov.l	edata_k,r0
	mov.l	end_k,r1
	mov	#0,r2
start_l:
	mov.l	r2,@r0
	add	#4,r0
	cmp/ge	r0,r1
	bt	start_l
	nop

	! call the mainline	
	mov.l	main_k,r0
	jsr	@r0
	nop
.hoo:
    bra .hoo

	.align 2
stack_k:
	.long	_stack	
edata_k:
	.long	_edata
end_k:
	.long	_end
main_k:
	.long	_main
vbr_k:
	.long	vectors
orig_vbr_k:
	.long 0x9000000

#ifdef __ELF__
	.section .stack,"aw"
#else
	.section .stack
#endif

	.section .vectors
vectors:
	.long start
	.long _stack
	.long start
	.long _stack