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[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.17.0/] [libgloss/] [mips/] [crt0_cygmon.S] - Blame information for rev 407

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1 148 jeremybenn
/*
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 * crt0_cygmon.S -- Minimal startup file for MIPS targets running Cygmon.
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 *
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 * Copyright (c) 1995, 1996, 1997, 2000 Red Hat, Inc.
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 *
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 * The authors hereby grant permission to use, copy, modify, distribute,
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 * and license this software and its documentation for any purpose, provided
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 * that existing copyright notices are retained in all copies and that this
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 * notice is included verbatim in any distributions. No written agreement,
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 * license, or royalty fee is required for any of the authorized uses.
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 * Modifications to this software may be copyrighted by their authors
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 * and need not follow the licensing terms described here, provided that
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 * the new terms are clearly indicated on the first page of each file where
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 * they apply.
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 */
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/*
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 * This file contains the minimal startup code necessary.
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 * This will not do any hardware initialization.  It is assumed that we are talking to Cygmon
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 * and therefore the hardware will be initialized properly.
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 */
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#ifdef __mips16
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/* This file contains 32 bit assembly code.  */
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        .set nomips16
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#endif
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#include "regs.S"
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/*
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 * Set up some room for a stack. We just grab a chunk of memory.
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 */
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#define STACK_SIZE  0x4000
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#define GLOBAL_SIZE 0x2000
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#define STARTUP_STACK_SIZE      0x0100
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        .comm   __memsize, 12
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        .comm   __lstack, STARTUP_STACK_SIZE
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        .comm   __stackbase,4
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        .text
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        .align  4
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    /*
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     * Without the following nop, GDB thinks _start is a data variable.
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     * This is probably a bug in GDB in handling a symbol that is at the
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     * start of the .text section.
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     */
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        nop
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        .globl  _start
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        .ent    _start
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_start:
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        .set    noreorder
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        la              gp, _gp                                 # set the global data pointer, defined in the linker script
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        .end    _start
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    /*
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     * zero out the bss section.
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     */
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        .globl  __memsize
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        .globl  get_mem_info .text
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        .globl  zerobss
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        .ent    zerobss
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zerobss:
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        la              v0, _fbss                               # These variables are defined in the linker script
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        la              v1, _end
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3:
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        sw              zero, 0(v0)
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        bltu    v0, v1, 3b
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        addiu   v0, v0, 4                               # executed in delay slot
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    /*
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     * Setup a small stack so we can run some C code,
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     * and get the usable memory size.
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     */
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        la              t0, __lstack
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        addiu   sp, t0, STARTUP_STACK_SIZE
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        la              a0, __memsize
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        jal             get_mem_info
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        nop
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        /*
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     * Setup the stack pointer --
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     *    get_mem_info returns the top of memory, so just use that In
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     *    addition, we must subtract 24 bytes for the 3 8 byte
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     *    arguments to main, in case main wants to write them back to
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     *    the stack.  The caller is supposed to allocate stack space
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     *    for parameters in registers in the old MIPS ABIs.  We must
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     *    do this even though we aren't passing arguments, because
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     *    main might be declared to have them.
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         *    Some ports need a larger alignment for the stack, so we
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         *    subtract 32, which satisifes the stack for the arguments and
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         *    keeps the stack pointer better aligned.
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     */
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        subu    v0, v0, 32
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        move    sp, v0
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        sw              sp, __stackbase                 # keep this for future ref
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        .end    zerobss
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    /*
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     * initialize target specific stuff. Only execute these
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     * functions it they exist.
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     */
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        .globl  hardware_init_hook .text
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        .globl  software_init_hook .text
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        .globl  __do_global_dtors .text
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        .globl  atexit .text
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        .globl  exit .text
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        .globl  init
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        .ent    init
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init:
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        la              t9, hardware_init_hook  # init the hardware if needed
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        beq             t9, zero, 6f
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        nop
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        jal             t9
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        nop
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6:
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        la              t9, software_init_hook  # init the software if needed
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        beq             t9, zero, 7f
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        nop
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        jal             t9
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        nop
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7:
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        la              a0, __do_global_dtors
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        jal             atexit
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        nop
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#ifdef GCRT0
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        .globl  _ftext
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        .globl  _extext
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        la              a0, _ftext
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        la              a1, _etext
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        jal             monstartup
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        nop
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#endif
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        move    a0,zero                                 # set argc to 0
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        jal             main                                    # call the program start function
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        nop
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        # fall through to the "exit" routine
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        jal             exit                                    # call libc exit to run the G++
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                                                                        # destructors
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        move    a0, v0                                  # pass through the exit code
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        .end    init
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/*
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 * _exit -- Exit from the application. Normally we cause a user trap
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 *          to return to the ROM monitor for another run. NOTE: This is
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 *          the only other routine we provide in the crt0.o object, since
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 *          it may be tied to the "_start" routine. It also allows
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 *          executables that contain a complete world to be linked with
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 *          just the crt0.o object.
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 */
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        .globl  _exit
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        .ent    _exit
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_exit:
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7:
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#ifdef GCRT0
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        jal             _mcleanup
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        nop
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#endif
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        # Cygmon expects a break 5
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        break   5
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        nop
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        b               7b                                              # loop back just in-case
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        nop
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        .end    _exit
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/* EOF crt0.S */

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