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Diffstat (limited to 'c/src/lib/libbsp/powerpc/helas403/dlentry/dlentry.S')
| -rw-r--r-- | c/src/lib/libbsp/powerpc/helas403/dlentry/dlentry.S | 144 |
1 files changed, 144 insertions, 0 deletions
diff --git a/c/src/lib/libbsp/powerpc/helas403/dlentry/dlentry.S b/c/src/lib/libbsp/powerpc/helas403/dlentry/dlentry.S new file mode 100644 index 0000000000..3944d2bc47 --- /dev/null +++ b/c/src/lib/libbsp/powerpc/helas403/dlentry/dlentry.S @@ -0,0 +1,144 @@ +/* dlentry.s + * + * This file contains the entry code for RTEMS programs starting + * after download to RAM + * + * Author: Thomas Doerfler <td@imd.m.isar.de> + * IMD Ingenieurbuero fuer Microcomputertechnik + * + * COPYRIGHT (c) 1998 by IMD + * + * Changes from IMD are covered by the original distributions terms. + * This file has been derived from the papyrus BSP: + * + * This file contains the entry veneer for RTEMS programs + * downloaded to Papyrus. + * + * Author: Andrew Bray <andy@i-cubed.co.uk> + * + * COPYRIGHT (c) 1995 by i-cubed ltd. + * + * To anyone who acknowledges that this file is provided "AS IS" + * without any express or implied warranty: + * permission to use, copy, modify, and distribute this file + * for any purpose is hereby granted without fee, provided that + * the above copyright notice and this notice appears in all + * copies, and that the name of i-cubed limited not be used in + * advertising or publicity pertaining to distribution of the + * software without specific, written prior permission. + * i-cubed limited makes no representations about the suitability + * of this software for any purpose. + * + * $Id$ + */ + +#include "asm.h" + +/* + * The helas403 ELF link scripts support three special sections: + * .entry The actual entry point + * .vectors The section containing the interrupt entry veneers. + */ + +/* + * Downloaded code loads the vectors separately to 0x00000100, + * so .entry can be over 256 bytes. + * + * The other sections are linked in the following order: + * .entry + * .text + * .data + * .bss + * see linker command file for section placement + * + * The initial stack is set to stack.end + * + * All the entry veneer has to do is to clear the BSS. + */ + +/* + * GDB likes to have debugging information for the entry veneer. + * Here was some DWARF information. IMD removed it, because we + * could not check, whether it was still correct. Sorry. + + */ + +#if PPC_ASM == PPC_ASM_ELF + .section .entry +#else + .csect .text[PR] +#endif + + PUBLIC_VAR (download_entry) +SYM(download_entry): + bl .startup +base_addr: + +/*--------------------------------------------------------------------------- + * Parameters from linker + *--------------------------------------------------------------------------*/ +toc_pointer: +#if PPC_ASM == PPC_ASM_ELF + .long s.got +#else + .long TOC[tc0] +#endif +bss_length: + .long bss.size +bss_addr: + .long bss.start +stack_top: + .long stack.end +/*--------------------------------------------------------------------------- + * Reset_entry. + *--------------------------------------------------------------------------*/ +.startup: + /* Get start address, stack grows down from here... */ + mflr r1 + + /* Assume Bank regs set up..., cache etc. */ + bl bssclr + + .extern SYM(__vectors) + + lis r2,__vectors@h /* set EVPR exc. vector prefix */ + mtspr evpr,r2 + + /*------------------------------------------------------------------- + * C_setup. + *------------------------------------------------------------------*/ + lwz r2,toc_pointer-base_addr(r1) /* set r2 to toc */ + lwz r1,stack_top-base_addr(r1) /* set r1 to stack_top */ + + addi r1,r1,-56-4 /* start stack at text_addr - 56 */ + addi r3,r0,0x0 /* clear r3 */ + stw r3, 0(r1) /* Clear stack chain */ + stw r3, 4(r1) + stw r3, 8(r1) + stw r3, 12(r1) + .extern SYM (boot_card) + b SYM (boot_card) /* call the first C routine */ + +/*--------------------------------------------------------------------------- + * bssclr. + *--------------------------------------------------------------------------*/ +bssclr: + /*------------------------------------------------------------------- + * Data move finished, zero out bss. + *------------------------------------------------------------------*/ + lwz r2,bss_addr-base_addr(r1) /* start of bss set by loader */ + lwz r3,bss_length-base_addr(r1) /* bss length */ + rlwinm. r3,r3,30,0x3FFFFFFF /* form length/4 */ + beqlr /* no bss */ + mtctr r3 /* set ctr reg */ + xor r6,r6,r6 /* r6 = 0 */ +clear_bss: + stswi r6,r2,0x4 /* store r6 */ + addi r2,r2,0x4 /* update r2 */ + bdnz clear_bss /* decrement counter and loop */ + blr /* return */ +.L_text_e: + +#if PPC_ABI == PPC_ABI_POWEROPEN + DESCRIPTOR (startup) +#endif |