| /* |
| * crt0.S -- startup file for PowerPC systems. |
| * |
| * Copyright (c) 1995 Cygnus Support |
| * |
| * The authors hereby grant permission to use, copy, modify, distribute, |
| * and license this software and its documentation for any purpose, provided |
| * that existing copyright notices are retained in all copies and that this |
| * notice is included verbatim in any distributions. No written agreement, |
| * license, or royalty fee is required for any of the authorized uses. |
| * Modifications to this software may be copyrighted by their authors |
| * and need not follow the licensing terms described here, provided that |
| * the new terms are clearly indicated on the first page of each file where |
| * they apply. |
| */ |
| |
| #include "ppc-asm.h" |
| |
| .file "crt0.S" |
| .section ".got2","aw" |
| .align 2 |
| |
| .LCTOC1 = .+32768 |
| |
| .extern FUNC_NAME(atexit) |
| .globl FUNC_NAME(__atexit) |
| .section ".sdata","aw" |
| .align 2 |
| FUNC_NAME(__atexit): /* tell C's eabi-ctor's we have an atexit function */ |
| .long FUNC_NAME(atexit)@fixup /* and that it is to register __do_global_dtors */ |
| |
| .section ".fixup","aw" |
| .align 2 |
| .long FUNC_NAME(__atexit) |
| |
| .section ".got2","aw" |
| .Ltable = .-.LCTOC1 |
| .long .LCTOC1 /* address we think .LCTOC1 is loaded at */ |
| |
| .Lsbss_start = .-.LCTOC1 |
| .long __sbss_start |
| |
| .Lsbss_end = .-.LCTOC1 |
| .long __sbss_end |
| |
| .Lbss_start = .-.LCTOC1 |
| .long __bss_start |
| |
| .Lend = .-.LCTOC1 |
| .long _end |
| |
| .Lstack = .-.LCTOC1 /* stack address if set by user */ |
| .long __stack |
| |
| .text |
| .Lptr: |
| .long .LCTOC1-.Laddr |
| |
| .globl _start |
| .type _start,@function |
| _start: |
| bl .Laddr /* get current address */ |
| .Laddr: |
| mflr r4 /* real address of .Laddr */ |
| lwz r5,(.Lptr-.Laddr)(r4) /* linker generated address of .LCTOC1 */ |
| add r5,r5,r4 /* correct to real pointer */ |
| lwz r4,.Ltable(r5) /* get linker's idea of where .Laddr is */ |
| subf r4,r4,r5 /* calculate difference between where linked and current */ |
| |
| /* clear bss and sbss */ |
| lwz r6,.Lbss_start(r5) /* calculate beginning of the BSS */ |
| lwz r7,.Lend(r5) /* calculate end of the BSS */ |
| add r6,r6,r4 /* adjust pointers */ |
| add r7,r7,r4 |
| |
| cmplw 1,r6,r7 |
| bc 4,4,.Ldone1 |
| |
| subf r8,r6,r7 /* number of bytes to zero */ |
| srwi r9,r8,2 /* number of words to zero */ |
| mtctr r9 |
| li r0,0 /* zero to clear memory */ |
| addi r6,r6,-4 /* adjust so we can use stwu */ |
| .Lloop: |
| stwu r0,4(r6) /* zero bss */ |
| bdnz .Lloop |
| |
| .Ldone1: |
| |
| lwz r6,.Lsbss_start(r5) /* calculate beginning of the SBSS */ |
| lwz r7,.Lsbss_end(r5) /* calculate end of the SBSS */ |
| add r6,r6,r4 /* adjust pointers */ |
| add r7,r7,r4 |
| |
| cmplw 1,r6,r7 |
| bc 4,4,.Ldone |
| |
| subf r8,r6,r7 /* number of bytes to zero */ |
| srwi r9,r8,2 /* number of words to zero */ |
| mtctr r9 |
| li r0,0 /* zero to clear memory */ |
| addi r6,r6,-4 /* adjust so we can use stwu */ |
| .Lloop2: |
| stwu r0,4(r6) /* zero bss */ |
| bdnz .Lloop2 |
| |
| .Ldone: |
| |
| lwz r0,.Lstack(r5) /* stack address or 0 */ |
| cmplwi 1,r0,0 /* equal to 0? */ |
| bc 12,6,.Lnostack /* use default stack if == 0 */ |
| mr sp,r0 /* use user defined stack */ |
| |
| .Lnostack: |
| /* set up initial stack frame */ |
| addi sp,sp,-4 /* make sure we don't overwrite debug mem */ |
| lis r0,0 |
| stw r0,0(sp) /* clear back chain */ |
| stwu sp,-64(sp) /* push another stack frame */ |
| |
| /* Let her rip */ |
| bl FUNC_NAME(main) |
| |
| /* return value from main is argument to exit */ |
| bl FUNC_NAME(exit) |
| trap |
| .Lstart: |
| .size _start,.Lstart-_start |
