source: trunk/libs/newlib/src/libgloss/m68k/sim-crt0.S @ 546

Last change on this file since 546 was 444, checked in by satin@…, 6 years ago

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

File size: 2.7 KB
Line 
1/*
2 * crt0.S -- startup file for m68k-coff
3 *
4 * Copyright (c) 1995, 1996, 1998, 2001 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 (atexit)
42        .extern SYM(__do_global_dtors)
43
44/*
45 * These values are set in the linker script, so they must be
46 * explicitly named here without SYM.
47 */
48        .extern __stack
49        .extern __bss_start
50        .extern _end
51
52/*
53 * set things up so the application will run. This *must* be called start.
54 */
55        .global SYM (start)
56
57SYM (start):
58        /* See if user supplied their own stack (__stack != 0).  If not, then
59         * default to using the value of %sp as set by the ROM monitor.
60         */
61        movel   IMM(__stack), a0
62        cmpl    IMM(0), a0
63        jbeq    1f
64        movel   a0, sp
651:
66        /* set up initial stack frame */
67        link    a6, IMM(-8)
68
69/*
70 * zero out the bss section.
71 */
72        movel   IMM(__bss_start), d1
73        movel   IMM(_end), d0
74        cmpl    d0, d1
75        jbeq    3f
76        movl    d1, a0
77        subl    d1, d0
78        subql   IMM(1), d0
792:
80        clrb    (a0)+
81#if !defined(__mcoldfire__) && !defined(__mcf5200__)
82        dbra    d0, 2b
83        clrw    d0
84        subql   IMM(1), d0
85        jbcc    2b
86#else
87        subql   IMM(1), d0
88        jbpl    2b
89#endif
90       
913:
92
93/*
94 * call the main routine from the application to get it going.
95 * main (argc, argv, environ)
96 * we pass argv as a pointer to NULL.
97 */
98
99#ifdef ADD_DTORS
100        /* put __do_global_dtors in the atexit list so the destructors get run */
101        movel   IMM (SYM(__do_global_dtors)),(sp)
102        PICCALL SYM (atexit)
103#endif
104        movel   IMM (__FINI_SECTION__),(sp)
105        PICCALL SYM (atexit)
106
107        PICCALL __INIT_SECTION__
108
109        pea     0
110        PICPEA  SYM (environ),a0
111        pea     sp@(4)
112        pea     0
113        PICCALL SYM (main)
114        movel   d0, sp@-
115
116/*
117 * drop down into exit incase the user doesn't. This should drop
118 * control back to the ROM monitor, if there is one. This calls the
119 * exit() from the C library so the C++ tables get cleaned up right.
120 */
121        PICCALL SYM (exit)
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