source: trunk/libs/newlib/src/libgloss/mn10300/crt0_cygmon.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: 2.6 KB
Line 
1/*
2 * crt0_cygmon.S -- Minimal startup file for MN10300 targets running Cygmon.
3 *
4 * Copyright (c) 1995, 1996, 1997, 2000 Red Hat, Inc.
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/*
18 * This file contains the minimal startup code necessary.
19 * This will not do any hardware initialization.  It is assumed that we are talking to Cygmon
20 * and therefore the hardware will be initialized properly.
21 */
22
23/*
24 * Set up some room for a stack. We just grab a chunk of memory.
25 */
26#define STACK_SIZE  0x4000
27#define GLOBAL_SIZE 0x2000
28
29#define STARTUP_STACK_SIZE      0x0100
30
31        .comm   __memsize, 12
32        .comm   __lstack, STARTUP_STACK_SIZE
33        .comm   __stackbase,4
34
35        .section .text
36        .global _start
37_start:
38        /*
39         * Setup a small stack so we can run some C code,
40         * and get the usable memory size.
41         */
42        mov     __lstack,a0
43        add     STARTUP_STACK_SIZE-4,a0
44        mov     a0,sp
45
46        /*
47         * zero out the bss section.
48         */
49        .global __memsize
50        .global _get_mem_info
51zerobss:
52        mov     __bss_start, a0                         # These variables are defined in the linker script
53        mov     _end, a1
54
55        cmp     a0, a1                                  # If no bss, then do nothing
56        beq     7f
57
58        clr     d0
593:
60        movbu   d0,(a0)                                 # Clear a byte and bump pointer
61        inc     a0
62        cmp     a0, a1
63        bne     3b
64
657:
66        /*
67         * Setup the stack pointer --
68         *    get_mem_info returns the top of memory, so just use that In
69         *    addition, we must subtract 24 bytes for the 3 8 byte
70         *    arguments to main, in case main wants to write them back to
71         *    the stack.  The caller is supposed to allocate stack space
72         *    for parameters in registers in the old MIPS ABIs.  We must
73         *    do this even though we aren't passing arguments, because
74         *    main might be declared to have them.
75         *    Some ports need a larger alignment for the stack, so we
76         *    subtract 32, which satisifes the stack for the arguments and
77         *    keeps the stack pointer better aligned.
78         */
79        mov     __memsize, d0
80        call    _get_mem_info,[],0
81
82        sub     32, a0
83        mov     a0, sp
84
85        mov     __stackbase, a1
86        mov     a0, (a1)                                # keep this for future ref
87
88        call    ___main,[],0                            # Call __main to run ctors/dtors
89        clr     d0
90        clr     d1
91        mov     d0, (4,sp)
92        call    _main,[],0                              # Call main program
93        call    _exit,[],0
94       
95/* EOF crt0_cygmon.S */
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