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/*

 * crt0.S -- startup file for MIPS.

 *

 * Copyright (c) 1995, 1996, 1997, 2001 Cygnus Support

 *

 * 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.

 */

#ifdef __mips16

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

        .set nomips16

#endif

#include "regs.S"

/*

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

 */

#define STACK_SIZE  0x4000

#define GLOBAL_SIZE 0x2000

#define STARTUP_STACK_SIZE      0x0100

/* This is for referencing addresses that are not in the .sdata or

   .sbss section under embedded-pic, or before we've set up gp.  */

#ifdef __mips_embedded_pic

# ifdef __mips64

#  define LA(t,x) la t,x-PICBASE ; daddu t,s0,t

# else

#  define LA(t,x) la t,x-PICBASE ; addu t,s0,t

# endif

#else /* __mips_embedded_pic */

# define LA(t,x) la t,x

#endif /* __mips_embedded_pic */

        .comm   __memsize, 12

        .comm   __lstack, STARTUP_STACK_SIZE

        .comm   __stackbase,4

        .text

        .align  2

/* 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

        .globl  _start

        .ent    _start

_start:

        .set    noreorder

#ifdef __mips_embedded_pic

        PICBASE = .+8

        bal     PICBASE

        nop

        move    s0,$31

#endif

#if (__mips < 3) || (__mips_fpr==32)

#define STATUS_MASK (SR_CU1|SR_PE)

#else

# For mips3 or mips4, turn on 64-bit addressing and additional float regs

#define STATUS_MASK (SR_CU1|SR_PE|SR_FR|SR_KX|SR_SX|SR_UX)

#endif

        li      v0, STATUS_MASK

        mtc0    v0, C0_SR

        mtc0    zero, C0_CAUSE

        nop

/* Check for FPU presence.  Don't check if we know that soft_float is

   being used.  (This also avoids illegal instruction exceptions.)  */

#ifndef __mips_soft_float

        li      t2,0xAAAA5555

        mtc1    t2,fp0          /* write to FPR 0 */

        mtc1    zero,fp1        /* write to FPR 1 */

        mfc1    t0,fp0

        mfc1    t1,fp1

        nop

        bne     t0,t2,1f        /* check for match */

        nop

        bne     t1,zero,1f      /* double check */

        nop

        j       2f              /* FPU is present. */

        nop

#endif

1:

        /* FPU is not present.  Set status register to say that. */

        li      v0, (STATUS_MASK-(STATUS_MASK & SR_CU1))

        mtc0    v0, C0_SR

        nop

2:

/* Fix high bits, if any, of the PC so that exception handling

   doesn't get confused.  */

        LA (v0, 3f)

        jr      v0

        nop

3:

        LA (gp, _gp)                            # set the global data pointer

        .end _start

/*

 * zero out the bss section.

 */

        .globl  __memsize

        .globl  get_mem_info .text

        .globl  __stack

        .globl  __global

        .ent    zerobss

zerobss:

        LA (v0, _fbss)

        LA (v1, _end)

3:

        sw      zero,0(v0)

        bltu    v0,v1,3b

        addiu   v0,v0,4                         # executed in delay slot

        la      t0, __lstack                    # make a small stack so we

        addiu   sp, t0, STARTUP_STACK_SIZE      # can run some C code

        la      a0, __memsize                   # get the usable memory size

        jal     get_mem_info

        nop

        /* setup the stack pointer */

        LA (t0, __stack)                        # is __stack set ?

        bne     t0,zero,4f

        nop

        /* NOTE: a0[0] contains the amount of memory available, and

                 not the last memory address. */

        lw      t0,0(a0)                        # last address of memory available

        la      t1,K0BASE                       # cached kernel memory

        addu    t0,t0,t1                        # get the end of memory address

        /* We must subtract 24 bytes for the 3 8 byte arguments to main, in

           case main wants to write them back to the stack.  The caller is

           supposed to allocate stack space for parameters in registers in

           the old MIPS ABIs.  We must do this even though we aren't passing

           arguments, because main might be declared to have them.

           Some ports need a larger alignment for the stack, so we subtract

           32, which satisifes the stack for the arguments and keeps the

           stack pointer better aligned.  */

        subu    t0,t0,32                        # and generate a starting stack-pointer

4:

        move    sp,t0                           # set stack pointer

        sw      sp,__stackbase                  # keep this for future ref

        .end    zerobss

/*

 * 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

        .ent    init

init:

        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 hardware 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

        move    a0,zero                         # set argc to 0

        jal     main                            # call the program start function

        nop

        # 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    init

/*

 * _exit -- Exit from the application. Normally we cause a user trap

 *          to return to the ROM monitor for another run. NOTE: This is

 *          the only other routine we provide in the crt0.o object, since

 *          it may be tied to the "_start" routine. It also allows

 *          executables that contain a complete world to be linked with

 *          just the crt0.o object.

 */

        .globl  _exit

        .ent _exit

_exit:

7:

#ifdef GCRT0

        jal     _mcleanup

        nop

#endif

        # break instruction can cope with 0xfffff, but GAS limits the range:

        break   1023

        nop

        b       7b                              # but loop back just in-case

        nop

        .end _exit

/* EOF crt0.S */