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/*  dlentry.s

 *

 *  $Id: start.S,v 1.2 2001-09-27 12:00:36 chris Exp $

 *

 *  This file contains the entry veneer for RTEMS programs

 *  downloaded to the eth-comm board.

 *

 * This file was written by Jay Monkman (jmonkman@fracsa.com)

 * It was based on the dlentry.s file for the Papyrus BSP,

 * written by:

 *

 *  Author:     Andrew Bray 

 *

 *  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.

 *

 */

#include "asm.h"

/*

 *  The initial stack is set to run BELOW the code base address.

 *  (between the vectors and text sections)

 *

 *  All the entry veneer has to do is to clear the BSS.

 */

/*

 *  GDB likes to have debugging information for the entry veneer.

 *  Here is some DWARF information.

 */

/*

 * There was some debugging info here, but I removed it because I

 * couldn't get it to work. It isn't really necessary as far as I

 * can tell. It should still be in the papyrus BSP. -Jay

 */

/*

 * On entry to download_entry, R3 will hold a pointer to a Board Info

 *  Block (boardinfo_t). This should be copied as soon as possible

 *  to the global M860_binfo. (The block should be copied, _NOT_

 *  the pointer)

 */

        .section ".entry"  /* This might have to be the first thing in the

                            * text section. At one time, it had to be

                            * first, but I don't believe it is true

                            * andy more. */

        PUBLIC_VAR (start)

SYM(start):

        bl      .startup

base_addr:

/*

 * Parameters from linker

 */

toc_pointer:

        .long   s.got

bss_length:

        .long   bss.size

bss_addr:

        .long   bss.start

PUBLIC_VAR (text_addr)

text_addr:

        .long   text.start

PUBLIC_VAR (text_length)

text_length:

        .long   text.size

/*

 * Initialization code

 */

.startup:

        /* Get start address */

        mflr    r1

        /* clear the bss section */

        bl      bssclr

/*

 * Copy the Board Info Block

 */

        .extern SYM(M860_binfo)

        lis     r6, SYM(M860_binfo)@ha

        addi    r6, r6, SYM(M860_binfo)@l

        lhz     r4, 0(r3)                /* Load the size of the block */

        rlwinm. r4, r4, 30, 0x3fffffff   /* get number of words */

        mtctr   r4

cpy_b:  lwz     r5, 0(r3)                /* In with the old ...  */

        stw     r5, 0(r6)                /* ... Out with the new */

        addi    r6, r6, 0x4              /* Go to the next word */

        addi    r3, r3, 0x4

        bdnz    cpy_b                    /* decrement counter and loop */

/*

 * C_setup.

 */

        /* set toc */

        lwz r2, toc_pointer-base_addr(r1)

        /* Set up stack pointer = beginning of text section - 56 */

        addi    r1, r1, -56-4

        lis     r9, 0xff00

        addi    r10, 0, -16384

        sth     r10, 0x950(r9)

        lis     r9, 0x0000

        addi    r9, r9, 0x0007

        mtspr   0x9e, r9

        /* clear argc and argv */

        xor     r3, r3, r3

        xor     r4, r4, r4

        .extern SYM (boot_card)

        bl      SYM (boot_card)                  /* call the first C routine */

loopstop:

        b       loopstop

/*

 * bssclr - zero out bss

 */

bssclr:

        lwz     r4, bss_addr-base_addr(r1)      /* Start of bss */

        lwz     r5, bss_length-base_addr(r1)    /* Length of bss */

        rlwinm. r5,r5,30,0x3FFFFFFF             /* form length/4 */

        beqlr                                   /* no bss */

        mtctr   r5                              /* set ctr reg */

        xor     r6,r6,r6                        /* r6 = 0 */

clear_bss:

        stswi   r6,r4,0x4                       /* store r6 */

        addi    r4,r4,0x4                       /* update r2 */

        bdnz    clear_bss                       /* dec counter and loop */

        blr                                     /* return */