Subversion Repositories openrisc_2011-10-31

/*

 * crt0_cfe.S -- Runtime startup for MIPS targets running CFE.

 *

 * Copyright 2003

 * Broadcom Corporation. All rights reserved.

 *

 * This software is furnished under license and may be used and copied only

 * in accordance with the following terms and conditions.  Subject to these

 * conditions, you may download, copy, install, use, modify and distribute

 * modified or unmodified copies of this software in source and/or binary

 * form. No title or ownership is transferred hereby.

 *

 * 1) Any source code used, modified or distributed must reproduce and

 *    retain this copyright notice and list of conditions as they appear in

 *    the source file.

 *

 * 2) No right is granted to use any trade name, trademark, or logo of

 *    Broadcom Corporation.  The "Broadcom Corporation" name may not be

 *    used to endorse or promote products derived from this software

 *    without the prior written permission of Broadcom Corporation.

 *

 * 3) THIS SOFTWARE IS PROVIDED "AS-IS" AND ANY EXPRESS OR IMPLIED

 *    WARRANTIES, INCLUDING BUT NOT LIMITED TO, ANY IMPLIED WARRANTIES OF

 *    MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR

 *    NON-INFRINGEMENT ARE DISCLAIMED. IN NO EVENT SHALL BROADCOM BE LIABLE

 *    FOR ANY DAMAGES WHATSOEVER, AND IN PARTICULAR, BROADCOM SHALL NOT BE

 *    LIABLE FOR 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), EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

/*

 * Derived from crt0_cygmon.S:

 *

 * Copyright (c) 1995, 1996, 1997, 2000 Red Hat, Inc.

 *

 * 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.

 */

/*

 * This file does minimal runtime startup for code running under

 * CFE firmware.

 *

 * It does minimal hardware initialization.  In particular

 * it sets Status:FR to match the requested floating point

 * mode.

 *

 * It is meant to be linked with the other files provided by libcfe.a,

 * and calls routines in those files.

 */

#ifdef __mips16

/* This file contains 32 bit assembly code.  */

        .set nomips16

#endif

#ifdef __mips_embedded_pic

# error -membedded-pic is not supported.

#endif

#include "regs.S"

/*

 * Set up some room for a stack. We just grab a chunk of memory.

 */

#define STARTUP_STACK_SIZE      (1 * 1024)

        .comm   _lstack, STARTUP_STACK_SIZE

        .text

        .align  4

    /*

     * Without the following nop, GDB thinks _start is a data variable.

     * This is probably a bug in GDB in handling a symbol that is at the

     * start of the .text section.

     */

        nop

    /*

     * On entry, the following values have been passed in registers

     * by the firmware:

     *

     * a0: firmware handle

     * a1: zero (unused)

     * a2: firmware callback entrypoint

     * a3: CFE entrypoint seal (unused)

     *

     * They must be preserved until the CFE entrypoint and handle

     * are passed to __libcfe_init().

     */

        .globl  _start

        .ent    _start

_start:

        .set    noreorder

    /* Set the global data pointer, defined in the linker script.  */

        la              gp, _gp

#ifndef __mips_soft_float

    /* If compiled for hard float, set the FPU mode based on the

       compilation flags.  Note that this assumes that enough code

       will run after the mtc0 to clear any hazards.  */

        mfc0    t0, C0_SR

        or      t0, t0, (SR_CU1 | SR_FR)

#if (__mips_fpr == 32)

        xor     t0, t0, SR_FR           /* If 32-bit FP mode, clear FR.  */

#endif

        mtc0    t0, C0_SR

#endif

        .end    _start

    /*

     * zero out the bss section.

     */

        .globl  _zerobss

        .ent    _zerobss

_zerobss:

    /* These variables are defined in the linker script.  */

        la              v0, _fbss

        la              v1, _end

3:

        sw              zero, 0(v0)

        bltu    v0, v1, 3b

        addiu   v0, v0, 4               /* Delay slot.  */

        .end    _zerobss

    /*

     * Setup a small stack so we can run some C code, and do

     * the library initialization.  (32 bytes are saved for

     * the argument registers' stack slots.)

     */

        .globl  _stackinit

        .ent    _stackinit

_stackinit:

        la      t0, _lstack

        addiu   sp, t0, (STARTUP_STACK_SIZE - 32)

        jal     __libcfe_init

        nop

    /*

     * Setup the stack pointer --

     *    __libcfe_init() returns the value to be used as the top of

     *    the program's stack.

     *

     *    We subtract 32 bytes for the 4 argument registers, in case

     *    main() wants to write them back to the stack.  The caller

     *    allocates stack space for parameters in the old MIPS ABIs.

     *    We must do this even though we aren't passing arguments,

     *    because main might be declared to have them.)

     *

     *    We subtract 32 more bytes for the argv/envp setup for the

     *    call to main().

     */

        subu    v0, v0, 64

        move    sp, v0

        .end    _stackinit

    /*

     * initialize target specific stuff. Only execute these

     * functions it they exist.

     */

        .globl  hardware_init_hook .text

        .globl  software_init_hook .text

        .type   _fini,@function

        .type   _init,@function

        .globl  atexit .text

        .globl  exit .text

        .globl  _crt0init

        .ent    _crt0init

_crt0init:

        la              t9, hardware_init_hook  # init the hardware if needed

        beq             t9, zero, 6f

        nop

        jal             t9

        nop

6:

        la              t9, software_init_hook  # init the software if needed

        beq             t9, zero, 7f

        nop

        jal             t9

        nop

7:

        la              a0, _fini

        jal             atexit

        nop

#ifdef GCRT0

        .globl  _ftext

        .globl  _extext

        la              a0, _ftext

        la              a1, _etext

        jal             monstartup

        nop

#endif

        jal     _init                   # run global constructors

        nop

        addiu   a1,sp,32                        # argv = sp + 32

        addiu   a2,sp,40                        # envp = sp + 40

#if __mips64

        sd      zero,(a1)                       # argv[argc] = 0

        sd      zero,(a2)                       # envp[0] = 0

#else

        sw      zero,(a1)

        sw      zero,(a2)

#endif

        jal     main                    # call the program start function

        move    a0,zero                 # set argc to 0; delay slot.

        # fall through to the "exit" routine

        jal     exit                    # call libc exit to run the G++

                                        # destructors

        move    a0, v0                  # pass through the exit code

        .end    _crt0init

/*

 * _exit -- Exit from the application.  This is provided in this file because

 *          program exit should shut down profiling (if GCRT0 is defined),

 *          and only this file is compiled with GCRT0 defined.

 */

        .globl  _exit

        .ent    _exit

_exit:

7:

        move    s0, a0                  /* Save in case we loop.  */

#ifdef GCRT0

        jal     _mcleanup

        nop

#endif

        la      t0, hardware_exit_hook

        beq     t0,zero,1f

        nop

        jal     t0

        nop

1:

        /* Call into the library to do the heavy lifting.  */

        jal     __libcfe_exit

        move    a0, s0                  /* Delay slot.  */

        b       7b                      /* Loop back just in case.  */

        nop

        .end    _exit

/* EOF crt0_cfe.S */