Subversion Repositories openrisc_2011-10-31

/*

 * C startup code for the Fujitsu SPARClite demo board

 *

 * Copyright (c) 1995, 1996 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.

 */

#include "asm.h"

.data

        .align  8

        .ascii  "DaTa"          ! this is the first address in the data section

        .long   SYM(sdata)

SYM(environ):

        .long   0

        .text

        .align 8

        .globl SYM(_start)

SYM(_start):

        .globl SYM(start)

SYM(start):

        /* see if the stack is already setup. if not, then default

         *  to using the value of %sp as set by the ROM monitor

         */

        sethi   %hi(__stack), %g1

        or      %g1,%lo(__stack),%g1

        cmp     %g0,%g1

        be      1f

        mov     %g1, %sp                                ! set the stack pointer

        mov     %sp, %fp

1:

        /* zero the bss section */

        sethi %hi(__bss_start),%g2

        or    %g2,%lo(__bss_start),%g2          ! start of bss

        sethi %hi(_end),%g3

        or    %g3,%lo(_end),%g3                 ! end of bss

        mov   %g0,%g1                           ! so std has two zeros

zerobss:

        std    %g0,[%g2]

        add    %g2,8,%g2

        cmp    %g2,%g3

        bleu,a zerobss

        nop

/*

 * copy prom & trap vectors to sram.

 */

        set 0x30000000, %l0

        set 0xfff8, %l1

        tst %l1                                 ! Set condition codes

copyloop:

        ldd [%l1], %l2

        std %l2, [%l0 + %l1]

        bg copyloop

        deccc 8, %l1

        set 0x30000000, %l0                     ! Base of new trap vector

        mov %l0, %tbr                           ! Install the new tbr

        set SYM(win_ovf_trap), %l1              ! Setup window overflow trap

        ldd [%l1], %l2

        std %l2, [%l0 + 5 * 16]

        ldd [%l1 + 8], %l2

        std %l2, [%l0 + 5 * 16 + 8]

        set SYM(win_unf_trap), %l1              ! Setup window underflow trap

        ldd [%l1], %l2

        std %l2, [%l0 + 6 * 16]

        ldd [%l1 + 8], %l2

        std %l2, [%l0 + 6 * 16 + 8]

/*

 * Try enabling the FPU by setting EF.  If that causes a trap, then we probably

 * don't have an FPU.

 */

        ldd [%l0 + 2 * 16], %l4                 ! Save original trap routine

        set SYM(no_fpu_trap), %l1               ! Install new one

        ldd [%l1], %l2

        std %l2, [%l0 + 2 * 16]

        mov %psr, %l0

        sethi %hi(0x1000), %l1

        bset %l1, %l0

!       mov %l0, %psr

        std %l4, [2 * 16]                       ! Restore original trap routine

/*

 * Move the data segment from it's ROM address to RAM where it

 * belongs.

 */

relocd:

#if 0   /* This code is broken.  FIXME */

        set (_sdata),%g2                        ! %g2 = start of data in aout file

        set SYM(environ),%g4                    ! %g4 = actual data base address

        set (_edata),%g3                        ! %g3 = end of where data should go

        subcc   %g3, %g4, %g5                   ! %g5 = length of data

        subcc   %g4, %g2, %g0                   ! need to relocate data ?

        ble     init

        ld      [%g4], %g6

        subcc   %g6, 1, %g0

        be      init

mvdata:

        subcc   %g5, 8, %g5

        ldd     [%g2 + %g5], %g6

        bg      mvdata

#endif

/*

 * initialize target specific stuff. Only execute these

 * functions it they exist.

 */

init:

        sethi   %hi(SYM(hardware_init_hook)), %g1

        or      %g1,%lo(SYM(hardware_init_hook)),%g1

        cmp     %g0,%g1

        be      1f

        nop

        call    SYM(hardware_init_hook)

        nop

1:

        sethi   %hi(SYM(software_init_hook)), %g1

        or      %g1,%lo(SYM(software_init_hook)),%g1

        cmp     %g0,%g1

        be      2f

        nop

        call    SYM(software_init_hook)

        nop

2:

        call SYM(main)

        nop

        /* call exit from the C library so atexit gets called, and the

         * C++ destructors get run. This calls our exit routine below

         * when it's done.

         */

        call    SYM(exit)

        nop

/*

 * This should drop control back to the ROM monitor, if there is

 * one.

 */

        .globl  SYM(_exit)

SYM(_exit):

        call    0

        nop

/*

 * Trap handlers.

 */

        .align 8

SYM(win_ovf_trap):

        sethi %hi(SYM(win_ovf)), %l3

        jmpl %lo(SYM(win_ovf))+%l3, %g0

        mov %wim, %l0

        nop

SYM(win_unf_trap):

        sethi %hi(SYM(win_unf)), %l3

        jmpl %lo(SYM(win_unf))+%l3, %g0

        mov %wim, %l0

        nop

SYM(no_fpu_trap):                       ! Come here when no fpu exists.

        jmpl %l2, %g0                   ! This just skips the

        rett %l2+4                      ! offending instruction.