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[/] [openrisc/] [trunk/] [gnu-old/] [newlib-1.17.0/] [libgloss/] [sparc/] [crt0.S] - Blame information for rev 148

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1 148 jeremybenn
/*
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 * C startup code for the Fujitsu SPARClite demo board
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 *
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 * Copyright (c) 1995, 1996 Cygnus Support
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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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#include "asm.h"
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.data
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        .align  8
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        .ascii  "DaTa"          ! this is the first address in the data section
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        .long   SYM(sdata)
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SYM(environ):
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        .long   0
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        .text
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        .align 8
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        .globl SYM(_start)
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SYM(_start):
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        .globl SYM(start)
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SYM(start):
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        /* see if the stack is already setup. if not, then default
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         *  to using the value of %sp as set by the ROM monitor
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         */
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        sethi   %hi(__stack), %g1
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        or      %g1,%lo(__stack),%g1
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        cmp     %g0,%g1
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        be      1f
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        mov     %g1, %sp                                ! set the stack pointer
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        mov     %sp, %fp
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1:
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        /* zero the bss section */
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        sethi %hi(__bss_start),%g2
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        or    %g2,%lo(__bss_start),%g2          ! start of bss
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        sethi %hi(_end),%g3
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        or    %g3,%lo(_end),%g3                 ! end of bss
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        mov   %g0,%g1                           ! so std has two zeros
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zerobss:
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        std    %g0,[%g2]
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        add    %g2,8,%g2
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        cmp    %g2,%g3
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        bleu,a zerobss
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        nop
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/*
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 * copy prom & trap vectors to sram.
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 */
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        set 0x30000000, %l0
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        set 0xfff8, %l1
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        tst %l1                                 ! Set condition codes
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copyloop:
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        ldd [%l1], %l2
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        std %l2, [%l0 + %l1]
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        bg copyloop
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        deccc 8, %l1
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        set 0x30000000, %l0                     ! Base of new trap vector
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        mov %l0, %tbr                           ! Install the new tbr
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        set SYM(win_ovf_trap), %l1              ! Setup window overflow trap
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        ldd [%l1], %l2
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        std %l2, [%l0 + 5 * 16]
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        ldd [%l1 + 8], %l2
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        std %l2, [%l0 + 5 * 16 + 8]
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        set SYM(win_unf_trap), %l1              ! Setup window underflow trap
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        ldd [%l1], %l2
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        std %l2, [%l0 + 6 * 16]
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        ldd [%l1 + 8], %l2
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        std %l2, [%l0 + 6 * 16 + 8]
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/*
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 * Try enabling the FPU by setting EF.  If that causes a trap, then we probably
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 * don't have an FPU.
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 */
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        ldd [%l0 + 2 * 16], %l4                 ! Save original trap routine
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        set SYM(no_fpu_trap), %l1               ! Install new one
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        ldd [%l1], %l2
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        std %l2, [%l0 + 2 * 16]
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        mov %psr, %l0
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        sethi %hi(0x1000), %l1
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        bset %l1, %l0
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!       mov %l0, %psr
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        std %l4, [2 * 16]                       ! Restore original trap routine
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/*
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 * Move the data segment from it's ROM address to RAM where it
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 * belongs.
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 */
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relocd:
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#if 0   /* This code is broken.  FIXME */
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        set (_sdata),%g2                        ! %g2 = start of data in aout file
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        set SYM(environ),%g4                    ! %g4 = actual data base address
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        set (_edata),%g3                        ! %g3 = end of where data should go
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        subcc   %g3, %g4, %g5                   ! %g5 = length of data
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        subcc   %g4, %g2, %g0                   ! need to relocate data ?
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        ble     init
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        ld      [%g4], %g6
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        subcc   %g6, 1, %g0
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        be      init
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mvdata:
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        subcc   %g5, 8, %g5
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        ldd     [%g2 + %g5], %g6
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        bg      mvdata
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#endif
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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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init:
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        sethi   %hi(SYM(hardware_init_hook)), %g1
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        or      %g1,%lo(SYM(hardware_init_hook)),%g1
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        cmp     %g0,%g1
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        be      1f
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        nop
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        call    SYM(hardware_init_hook)
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        nop
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1:
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        sethi   %hi(SYM(software_init_hook)), %g1
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        or      %g1,%lo(SYM(software_init_hook)),%g1
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        cmp     %g0,%g1
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        be      2f
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        nop
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        call    SYM(software_init_hook)
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        nop
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2:
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        call SYM(main)
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        nop
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        /* call exit from the C library so atexit gets called, and the
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         * C++ destructors get run. This calls our exit routine below
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         * when it's done.
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         */
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        call    SYM(exit)
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        nop
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/*
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 * This should drop control back to the ROM monitor, if there is
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 * one.
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 */
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        .globl  SYM(_exit)
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SYM(_exit):
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        call    0
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        nop
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/*
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 * Trap handlers.
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 */
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        .align 8
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SYM(win_ovf_trap):
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        sethi %hi(SYM(win_ovf)), %l3
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        jmpl %lo(SYM(win_ovf))+%l3, %g0
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        mov %wim, %l0
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        nop
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SYM(win_unf_trap):
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        sethi %hi(SYM(win_unf)), %l3
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        jmpl %lo(SYM(win_unf))+%l3, %g0
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        mov %wim, %l0
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        nop
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SYM(no_fpu_trap):                       ! Come here when no fpu exists.
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        jmpl %l2, %g0                   ! This just skips the
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        rett %l2+4                      ! offending instruction.

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