20000317 sourceware import
This commit is contained in:
128
libgloss/rs6000/crt0.S
Normal file
128
libgloss/rs6000/crt0.S
Normal file
@ -0,0 +1,128 @@
|
||||
/*
|
||||
* 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
|
Reference in New Issue
Block a user