| 1 | /* |
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| 2 | * crt0.S -- startup file for m68k-coff |
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| 3 | * |
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| 4 | * Copyright (c) 1995, 1996, 1998 Cygnus Support |
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| 5 | * |
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| 6 | * The authors hereby grant permission to use, copy, modify, distribute, |
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| 7 | * and license this software and its documentation for any purpose, provided |
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| 8 | * that existing copyright notices are retained in all copies and that this |
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| 9 | * notice is included verbatim in any distributions. No written agreement, |
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| 10 | * license, or royalty fee is required for any of the authorized uses. |
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| 11 | * Modifications to this software may be copyrighted by their authors |
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| 12 | * and need not follow the licensing terms described here, provided that |
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| 13 | * the new terms are clearly indicated on the first page of each file where |
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| 14 | * they apply. |
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| 15 | */ |
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| 16 | |
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| 17 | #include "asm.h" |
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| 18 | |
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| 19 | .title "crt0.S for m68k-coff" |
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| 20 | #define STACKSIZE 0x4000 |
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| 21 | |
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| 22 | /* |
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| 23 | * Define an empty environment. |
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| 24 | */ |
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| 25 | .data |
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| 26 | .align 2 |
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| 27 | SYM (environ): |
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| 28 | .long 0 |
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| 29 | |
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| 30 | .align 2 |
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| 31 | .text |
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| 32 | |
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| 33 | /* |
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| 34 | * These symbols are defined in C code, so they need to always be |
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| 35 | * named with SYM because of the difference between object file formats. |
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| 36 | */ |
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| 37 | |
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| 38 | /* These are defined in C code. */ |
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| 39 | .extern SYM (main) |
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| 40 | .extern SYM (exit) |
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| 41 | .extern SYM (hardware_init_hook) |
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| 42 | .extern SYM (software_init_hook) |
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| 43 | .extern SYM (atexit) |
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| 44 | .extern SYM(__do_global_dtors) |
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| 45 | |
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| 46 | /* |
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| 47 | * These values are set in the linker script, so they must be |
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| 48 | * explicitly named here without SYM. |
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| 49 | */ |
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| 50 | .extern __stack |
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| 51 | .extern __bss_start |
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| 52 | .extern _end |
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| 53 | |
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| 54 | /* |
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| 55 | * Set things up so the application will run. For historical reasons |
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| 56 | * this is called 'start'. We set things up to provide '_start' |
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| 57 | * as with other systems, but also provide a weak alias called |
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| 58 | * 'start' for compatibility with existing linker scripts. |
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| 59 | */ |
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| 60 | .global SYM (start) |
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| 61 | .weak SYM (start) |
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| 62 | .set SYM (start),SYM(_start) |
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| 63 | |
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| 64 | .global SYM (_start) |
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| 65 | SYM (_start): |
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| 66 | /* |
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| 67 | * put any hardware init code here |
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| 68 | */ |
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| 69 | |
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| 70 | /* See if user supplied their own stack (__stack != 0). If not, then |
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| 71 | * default to using the value of %sp as set by the ROM monitor. |
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| 72 | */ |
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| 73 | movel IMM(__stack), a0 |
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| 74 | cmpl IMM(0), a0 |
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| 75 | jbeq 1f |
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| 76 | movel a0, sp |
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| 77 | 1: |
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| 78 | /* set up initial stack frame */ |
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| 79 | link a6, IMM(-8) |
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| 80 | |
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| 81 | /* |
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| 82 | * zero out the bss section. |
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| 83 | */ |
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| 84 | movel IMM(__bss_start), d1 |
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| 85 | movel IMM(_end), d0 |
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| 86 | cmpl d0, d1 |
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| 87 | jbeq 3f |
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| 88 | movl d1, a0 |
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| 89 | subl d1, d0 |
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| 90 | subql IMM(1), d0 |
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| 91 | 2: |
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| 92 | clrb (a0)+ |
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| 93 | #if !defined(__mcoldfire__) |
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| 94 | dbra d0, 2b |
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| 95 | clrw d0 |
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| 96 | subql IMM(1), d0 |
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| 97 | jbcc 2b |
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| 98 | #else |
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| 99 | subql IMM(1), d0 |
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| 100 | jbpl 2b |
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| 101 | #endif |
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| 102 | |
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| 103 | 3: |
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| 104 | |
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| 105 | /* |
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| 106 | * initialize target specific stuff. Only execute these |
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| 107 | * functions it they exist. |
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| 108 | */ |
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| 109 | PICLEA SYM (hardware_init_hook), a0 |
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| 110 | cmpl IMM(0),a0 |
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| 111 | jbeq 4f |
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| 112 | jsr (a0) |
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| 113 | 4: |
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| 114 | |
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| 115 | PICLEA SYM (software_init_hook), a0 |
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| 116 | cmpl IMM(0),a0 |
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| 117 | jbeq 5f |
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| 118 | jsr (a0) |
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| 119 | 5: |
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| 120 | |
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| 121 | /* |
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| 122 | * call the main routine from the application to get it going. |
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| 123 | * main (argc, argv, environ) |
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| 124 | * we pass argv as a pointer to NULL. |
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| 125 | */ |
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| 126 | |
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| 127 | #ifdef ADD_DTORS |
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| 128 | /* put __do_global_dtors in the atexit list so the destructors get run */ |
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| 129 | movel IMM (SYM(__do_global_dtors)),(sp) |
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| 130 | PICCALL SYM (atexit) |
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| 131 | #endif |
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| 132 | movel IMM (__FINI_SECTION__),(sp) |
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| 133 | PICCALL SYM (atexit) |
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| 134 | |
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| 135 | PICCALL __INIT_SECTION__ |
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| 136 | |
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| 137 | pea 0 |
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| 138 | PICPEA SYM (environ),a0 |
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| 139 | pea sp@(4) |
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| 140 | pea 0 |
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| 141 | PICCALL SYM (main) |
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| 142 | movel d0, sp@- |
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| 143 | |
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| 144 | /* |
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| 145 | * drop down into exit incase the user doesn't. This should drop |
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| 146 | * control back to the ROM monitor, if there is one. This calls the |
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| 147 | * exit() from the C library so the C++ tables get cleaned up right. |
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| 148 | */ |
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| 149 | PICCALL SYM (exit) |
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