source: rtems/c/src/lib/libbsp/powerpc/psim/start/start.S @ 24fced7

Last change on this file since 24fced7 was 15c48f4c, checked in by Joel Sherrill <joel.sherrill@…>, on 08/02/00 at 16:30:57

Properly pass argc, argc, and environp to boot_card.
  • Property mode set to 100644
File size: 2.9 KB
Line 
1/*
2 * This is based on the mvme-crt0.S file from libgloss/rs6000.
3 * crt0.S -- startup file for PowerPC systems.
4 *
5 * Copyright (c) 1995 Cygnus Support
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 *  $Id$
18 */
19
20#include "ppc-asm.h"
21
22        .file   "startsim.s"
23        .section ".got2","aw"
24        .align  2
25
26.LCTOC1 = .+32768
27
28        .extern FUNC_NAME(atexit)
29        .globl  FUNC_NAME(__atexit)
30        .section ".sdata","aw"
31        .align  2
32FUNC_NAME(__atexit):                    /* tell C's eabi-ctor's we have an atexit function */
33        .long   FUNC_NAME(atexit)@fixup /* and that it is to register __do_global_dtors */
34
35        .section ".fixup","aw"
36        .align  2
37        .long   FUNC_NAME(__atexit)
38
39        .section ".got2","aw"
40.Ltable = .-.LCTOC1
41        .long   .LCTOC1                 /* address we think .LCTOC1 is loaded at */
42
43.Lbss_start = .-.LCTOC1
44        .long   __bss_start
45
46.Lend = .-.LCTOC1
47        .long   _end
48
49.Lstack = .-.LCTOC1                     /* stack address if set by user */
50        .long   __stack
51
52        .text
53.Lptr:
54        .long .LCTOC1-.Laddr
55
56        .globl  _start
57        .type   _start,@function
58_start:
59        bl      .Laddr                  /* get current address */
60.Laddr:
61        mflr    r4                      /* real address of .Laddr */
62        lwz     r5,(.Lptr-.Laddr)(r4)   /* linker generated address of .LCTOC1 */
63        add     r5,r5,r4                /* correct to real pointer */
64        lwz     r4,.Ltable(r5)          /* get linker's idea of where .Laddr is */
65        subf    r4,r4,r5                /* calculate difference between where linked and current */
66
67        /* clear bss */
68        lwz     r6,.Lbss_start(r5)      /* calculate beginning of the BSS */
69        lwz     r7,.Lend(r5)            /* calculate end of the BSS */
70        add     r6,r6,r4                /* adjust pointers */
71        add     r7,r7,r4
72
73        cmplw   1,r6,r7
74        bc      4,4,.Ldone
75
76        subf    r8,r6,r7                /* number of bytes to zero */
77        srwi    r9,r8,2                 /* number of words to zero */
78        mtctr   r9
79        li      r0,0                    /* zero to clear memory */
80        addi    r6,r6,-4                /* adjust so we can use stwu */
81.Lloop:
82        stwu    r0,4(r6)                /* zero bss */
83        bdnz    .Lloop
84
85.Ldone:
86
87        lwz     r0,.Lstack(r5)          /* stack address or 0 */
88        cmplwi  1,r0,0                  /* equal to 0? */
89        bc      12,6,.Lnostack          /* use default stack if == 0 */
90        mr      sp,r0                   /* use user defined stack */
91
92.Lnostack:
93        /* set up initial stack frame */
94        addi    sp,sp,-4                /* make sure we don't overwrite debug mem */
95        lis     r0,0
96        stw     r0,0(sp)                /* clear back chain */
97        stwu    sp,-56(sp)              /* push another stack frame */
98
99        lis     r5,environ@ha
100        la      r5,environ@l(r5)        /* environp */
101        li      r4, 0                   /* argv */
102        li      r3, 0                   /* argc */
103        /* Let her rip */
104        bl      FUNC_NAME(boot_card)
105
106        /* return value from boot_card is argument to exit */
107        bl      FUNC_NAME(exit)
108        trap
109.Lstart:
110        .size   _start,.Lstart-_start
111
112        .comm   environ,4,4
113
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