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