source: trunk/libs/newlib/src/libgloss/m68k/crt0.S @ 679

Last change on this file since 679 was 444, checked in by satin@…, 6 years ago

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

File size: 3.3 KB
Line 
1/*
2 * crt0.S -- startup file for m68k-coff
3 *
4 * Copyright (c) 1995, 1996, 1998 Cygnus Support
5 *
6 * The authors hereby grant permission to use, copy, modify, distribute,
7 * and license this software and its documentation for any purpose, provided
8 * that existing copyright notices are retained in all copies and that this
9 * notice is included verbatim in any distributions. No written agreement,
10 * license, or royalty fee is required for any of the authorized uses.
11 * Modifications to this software may be copyrighted by their authors
12 * and need not follow the licensing terms described here, provided that
13 * the new terms are clearly indicated on the first page of each file where
14 * they apply.
15 */
16
17#include "asm.h"
18
19        .title "crt0.S for m68k-coff"
20#define STACKSIZE       0x4000
21
22/*
23 * Define an empty environment.
24 */
25        .data
26        .align 2
27SYM (environ):
28        .long 0
29
30        .align  2
31        .text
32
33/*
34 * These symbols are defined in C code, so they need to always be
35 * named with SYM because of the difference between object file formats.
36 */
37
38/* These are defined in C code. */
39        .extern SYM (main)
40        .extern SYM (exit)
41        .extern SYM (hardware_init_hook)
42        .extern SYM (software_init_hook)
43        .extern SYM (atexit)
44        .extern SYM(__do_global_dtors)
45
46/*
47 * These values are set in the linker script, so they must be
48 * explicitly named here without SYM.
49 */
50        .extern __stack
51        .extern __bss_start
52        .extern _end
53
54/*
55 * Set things up so the application will run. For historical reasons
56 * this is called 'start'.  We set things up to provide '_start'
57 * as with other systems, but also provide a weak alias called
58 * 'start' for compatibility with existing linker scripts.
59 */
60        .global SYM (start)
61        .weak SYM (start)
62        .set SYM (start),SYM(_start)
63
64        .global SYM (_start)
65SYM (_start):
66        /*
67         * put any hardware init code here
68         */
69
70        /* See if user supplied their own stack (__stack != 0).  If not, then
71         * default to using the value of %sp as set by the ROM monitor.
72         */
73        movel   IMM(__stack), a0
74        cmpl    IMM(0), a0
75        jbeq    1f
76        movel   a0, sp
771:
78        /* set up initial stack frame */
79        link    a6, IMM(-8)
80
81/*
82 * zero out the bss section.
83 */
84        movel   IMM(__bss_start), d1
85        movel   IMM(_end), d0
86        cmpl    d0, d1
87        jbeq    3f
88        movl    d1, a0
89        subl    d1, d0
90        subql   IMM(1), d0
912:
92        clrb    (a0)+
93#if !defined(__mcoldfire__)
94        dbra    d0, 2b
95        clrw    d0
96        subql   IMM(1), d0
97        jbcc    2b
98#else
99        subql   IMM(1), d0
100        jbpl    2b
101#endif
102       
1033:
104
105/*
106 * initialize target specific stuff. Only execute these
107 * functions it they exist.
108 */
109        PICLEA  SYM (hardware_init_hook), a0
110        cmpl    IMM(0),a0
111        jbeq    4f
112        jsr     (a0)
1134:
114
115        PICLEA  SYM (software_init_hook), a0
116        cmpl    IMM(0),a0
117        jbeq    5f
118        jsr     (a0)
1195:
120
121/*
122 * call the main routine from the application to get it going.
123 * main (argc, argv, environ)
124 * we pass argv as a pointer to NULL.
125 */
126
127#ifdef ADD_DTORS
128        /* put __do_global_dtors in the atexit list so the destructors get run */
129        movel   IMM (SYM(__do_global_dtors)),(sp)
130        PICCALL SYM (atexit)
131#endif
132        movel   IMM (__FINI_SECTION__),(sp)
133        PICCALL SYM (atexit)
134
135        PICCALL __INIT_SECTION__
136
137        pea     0
138        PICPEA  SYM (environ),a0
139        pea     sp@(4)
140        pea     0
141        PICCALL SYM (main)
142        movel   d0, sp@-
143
144/*
145 * drop down into exit incase the user doesn't. This should drop
146 * control back to the ROM monitor, if there is one. This calls the
147 * exit() from the C library so the C++ tables get cleaned up right.
148 */
149        PICCALL SYM (exit)
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