source: trunk/libs/newlib/src/libgloss/mt/crt0-16-003.S @ 532

Last change on this file since 532 was 444, checked in by satin@…, 6 years ago

add newlib,libalmos-mkh, restructure shared_syscalls.h and mini-libc

File size: 2.8 KB
Line 
1; crt0.s - Startup code for the mrisc1. This code initializes the C
2;              run-time model.
3;
4;
5; Copyright 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
6;
7;  The authors hereby grant permission to use, copy, modify, distribute,
8;  and license this software and its documentation for any purpose, provided
9;  that existing copyright notices are retained in all copies and that this
10;  notice is included verbatim in any distributions. No written agreement,
11;  license, or royalty fee is required for any of the authorized uses.
12;  Modifications to this software may be copyrighted by their authors
13;  and need not follow the licensing terms described here, provided that
14;  the new terms are clearly indicated on the first page of each file where
15;  they apply.
16;
17
18        ; Create a label for the start of the eh_frame section.
19        .section .eh_frame
20__eh_frame_begin:
21
22        .text
23        .global _start
24_start:
25        ;; Initialize the stack pointer
26        ldui    sp, #%hi16(__stack)
27        addui   sp, sp, #%lo16(__stack)
28        or      fp, sp, sp
29        ;; Zero the bss space
30        ldui    r9, #%hi16(__bss_start)
31        addui   r9, r9, #%lo16(__bss_start)
32        ldui    r10, #%hi16(__bss_end)
33        addui   r10, r10, #%lo16(__bss_end)
34        or      r0, r0, r0
35        brle    r10, r9, .Lnext1
36        or      r0, r0, r0
37.Lcpy0:
38        stw     r0, r9, #0
39        addi    r9, r9, #4
40        or      r0, r0, r0      ; nop
41        brle    r9, r10, .Lcpy0
42        or      r0, r0, r0      ; nop
43
44.Lnext1:
45        ;; Copy data from ROM to Frame Buffer (on-chip memory)
46        ldui    r9, #%hi16(_fbdata_start)
47        ori     r9, r9, #%lo16(_fbdata_start)
48        ldui    r10, #%hi16(_fbdata_end)
49        ori     r10, r10, #%lo16(_fbdata_end)
50        ldui    r11, #%hi16(_fbdata_vma)
51        brle    r10, r9, .Lnext2
52        ori     r11, r11, #%lo16(_fbdata_vma)
53.Lcpy1:
54        ldw     r5, r9, #$0
55        addi    r9, r9, #$4
56        stw     r5, r11, #$0
57        brlt    r9, r10, .Lcpy1
58        addi    r11, r11, #$4
59
60.Lnext2:
61        ;; Zero the frame buffer bss section
62        ldui    r9, #%hi16(_fbbss_start)
63        ori     r9, r9, #%lo16(_fbbss_start)
64        ldui    r10, #%hi16(_fbbss_end)
65        ori     r10, r10, #%lo16(_fbbss_end)
66        or      r0, r0, r0
67        brle    r10, r9, .Lnext3
68        or      r0, r0, r0
69.Lcpy2:
70        stw     r0, r9, #$0
71        addi    r9, r9, #$4
72        or      r0, r0, r0
73        brle    r9, r10, .Lcpy2
74        or      r0, r0, r0
75
76.Lnext3:
77        ;; Call global and static constructors
78        ldui    r10, #%hi16(_init)
79        ori     r10, r10, #%lo16(_init)
80        or      r0, r0, r0      ; nop
81        jal     r14, r10
82        or      r0, r0, r0      ; nop
83
84        ;; Call main
85        ldui    r10, #%hi16(main)
86        ori     r10, r10, #%lo16(main)
87        or      r0, r0, r0      ; nop
88        jal     r14, r10
89        or      r0, r0, r0      ; nop
90
91        ;; DJK - Added 12Nov01. Pass main's return value to exit.
92        or      r1, r11, r0
93
94        ;; Jump to exit
95        ldui    r10, #%hi16(exit)
96        ori     r10, r10, #%lo16(exit)
97        or      r0, r0, r0      ; nop
98        jal     r14, r10
99        or      r0, r0, r0      ; nop
100
101        ;; Exit does not return, however, this code is to catch an
102        ;;   error if it does. Set the processor into sleep mode.
103        ori     r1, r0, #$1
104        stw     r1, r0, #%lo16(_DEBUG_HALT_REG)
105        or      r0, r0, r0
106        or      r0, r0, r0
107        or      r0, r0, r0
108        or      r0, r0, r0
109        or      r0, r0, r0
110.Lend:
111        jmp .Lend
112        or      r0, r0, r0
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