/*      $NetBSD: srtbegin.S,v 1.7 2005/12/11 12:17:10 christos Exp $    */

/*
 * Copyright (c) 2002 Wasabi Systems, Inc.
 * All rights reserved.
 *
 * Written by Jason R. Thorpe for Wasabi Systems, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed for the NetBSD Project by
 *      Wasabi Systems, Inc.
 * 4. The name of Wasabi Systems, Inc. may not be used to endorse
 *    or promote products derived from this software without specific prior
 *    written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY WASABI SYSTEMS, INC. ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL WASABI SYSTEMS, INC
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <machine/asm.h>
#include <arm/armreg.h>

#define STACKSIZE       1024

ENTRY(start)
        /*
         * We assume we've been loaded VA==PA, or that the MMU
         * is disabled.  Make sure the MMU is disabled so that
         * we don't have to care about the caches.
         */
        mrc     p15, 0, r2, c1, c0, 0
        bic     r2, r2, #CPU_CONTROL_MMU_ENABLE
        mcr     p15, 0, r2, c1, c0, 0

        nop
        nop
        nop

        /*
         * Check to see if __text_store == &start.  If not, we're most
         * likely running from flash.  Flash is slow, and we'd
         * really like to run the code from RAM.  Copy it out.
         */
        adr     r1, Ltext
        ldmia   r1, {r1-r3}
        cmp     r1, r2                  /* __text_store == &start? */
        beq     relocated               /* yes, in RAM */

        /* Copy text segment from ROM to RAM */
1:      ldrb    r0, [r1], #0x01
        strb    r0, [r2], #0x01
        cmp     r2, r3                  /* copy done? */
        bne     1b

        /*
         * Okay, we are finished relocating the text segment.  Now
         * we need to leap to the next instruction.
         */
        adr     r1, Lrelocated
        ldr     pc, [r1]

relocated:
        /*
         * Check to see if __data_store == __data_start.  If not,
         * we're most likely built for running from flash,
         * and must copy the data segment out to RAM.
         */
        adr     r1, Ldata
        ldmia   r1, {r1-r3}
        cmp     r1, r2                  /* __data_store == __data_start? */
        beq     2f                      /* yes, in RAM */

        cmp     r2, r3                  /* __data_store == _edata? */
        beq     2f                      /* yes, skip copy */

        /* Copy data segment from ROM to RAM */
1:      ldrb    r0, [r1], #0x01
        strb    r0, [r2], #0x01
        cmp     r2, r3                  /* copy done? */
        bne     1b

2:
        /* Clear the BSS. */
        adr     r1, Lbss
        ldmia   r1, {r1, r2}
        sub     r2, r2, r1
        mov     r3, #0

1:      strb    r3, [r1], #0x01
        subs    r2, r2, #0x01
        bgt     1b

        /* Set the stack pointer */
        adr     r1, Lstack
        ldr     r1, [r1]
        add     sp, r1, #STACKSIZE

        b       _C_LABEL(main)

Lrelocated:
        .word   relocated

Ltext:
        .word   _C_LABEL(__text_store)
        .word   _C_LABEL(start)
        .word   _C_LABEL(_etext)

Ldata:
        .word   _C_LABEL(__data_store)
        .word   _C_LABEL(__data_start)

Lbss:
        .word   _C_LABEL(_edata)
        .word   _C_LABEL(_end)

Lstack:
        .word   Lstackspace

        .comm   Lstackspace, STACKSIZE