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/* dlentry.s
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*
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* This file contains the entry code for RTEMS programs starting
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* after download to RAM
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*
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* Author: Thomas Doerfler
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* IMD Ingenieurbuero fuer Microcomputertechnik
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*
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* COPYRIGHT (c) 1998 by IMD
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*
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* Changes from IMD are covered by the original distributions terms.
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* This file has been derived from the papyrus BSP:
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*
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* This file contains the entry veneer for RTEMS programs
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* downloaded to Papyrus.
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*
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* Author: Andrew Bray
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*
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* COPYRIGHT (c) 1995 by i-cubed ltd.
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*
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* To anyone who acknowledges that this file is provided "AS IS"
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* without any express or implied warranty:
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* permission to use, copy, modify, and distribute this file
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* for any purpose is hereby granted without fee, provided that
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* the above copyright notice and this notice appears in all
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* copies, and that the name of i-cubed limited not be used in
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* advertising or publicity pertaining to distribution of the
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* software without specific, written prior permission.
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* i-cubed limited makes no representations about the suitability
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* of this software for any purpose.
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*
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* $Id: dlentry.S,v 1.2 2001-09-27 12:00:36 chris Exp $
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*/
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#include "asm.h"
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/*
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* The helas403 ELF link scripts support three special sections:
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* .entry The actual entry point
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* .vectors The section containing the interrupt entry veneers.
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*/
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/*
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* Downloaded code loads the vectors separately to 0x00000100,
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* so .entry can be over 256 bytes.
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*
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* The other sections are linked in the following order:
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* .entry
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* .text
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* .data
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* .bss
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* see linker command file for section placement
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*
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* The initial stack is set to stack.end
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*
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* All the entry veneer has to do is to clear the BSS.
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*/
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/*
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* GDB likes to have debugging information for the entry veneer.
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* Here was some DWARF information. IMD removed it, because we
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* could not check, whether it was still correct. Sorry.
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*/
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#if PPC_ASM == PPC_ASM_ELF
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.section .entry
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#else
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.csect .text[PR]
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#endif
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PUBLIC_VAR (download_entry)
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SYM(download_entry):
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bl .startup
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base_addr:
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/*---------------------------------------------------------------------------
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* Parameters from linker
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*--------------------------------------------------------------------------*/
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toc_pointer:
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#if PPC_ASM == PPC_ASM_ELF
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.long s.got
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#else
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.long TOC[tc0]
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#endif
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bss_length:
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.long bss.size
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bss_addr:
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.long bss.start
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stack_top:
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.long stack.end
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/*---------------------------------------------------------------------------
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* Reset_entry.
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*--------------------------------------------------------------------------*/
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.startup:
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/* Get start address, stack grows down from here... */
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mflr r1
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/* Assume Bank regs set up..., cache etc. */
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bl bssclr
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.extern SYM(__vectors)
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lis r2,__vectors@h /* set EVPR exc. vector prefix */
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mtspr evpr,r2
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/*-------------------------------------------------------------------
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* C_setup.
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*------------------------------------------------------------------*/
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lwz r2,toc_pointer-base_addr(r1) /* set r2 to toc */
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lwz r1,stack_top-base_addr(r1) /* set r1 to stack_top */
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addi r1,r1,-56-4 /* start stack at text_addr - 56 */
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addi r3,r0,0x0 /* clear r3 */
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stw r3, 0(r1) /* Clear stack chain */
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stw r3, 4(r1)
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stw r3, 8(r1)
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stw r3, 12(r1)
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.extern SYM (boot_card)
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b SYM (boot_card) /* call the first C routine */
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/*---------------------------------------------------------------------------
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* bssclr.
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*--------------------------------------------------------------------------*/
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bssclr:
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/*-------------------------------------------------------------------
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* Data move finished, zero out bss.
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*------------------------------------------------------------------*/
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lwz r2,bss_addr-base_addr(r1) /* start of bss set by loader */
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lwz r3,bss_length-base_addr(r1) /* bss length */
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rlwinm. r3,r3,30,0x3FFFFFFF /* form length/4 */
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beqlr /* no bss */
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mtctr r3 /* set ctr reg */
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xor r6,r6,r6 /* r6 = 0 */
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clear_bss:
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stswi r6,r2,0x4 /* store r6 */
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addi r2,r2,0x4 /* update r2 */
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bdnz clear_bss /* decrement counter and loop */
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blr /* return */
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.L_text_e:
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#if PPC_ABI == PPC_ABI_POWEROPEN
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DESCRIPTOR (startup)
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#endif
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