Subversion Repositories NedoOS

;--------------------------------------------------------------------------
;  crt0.s - Generic crt0.s for a rabbit 2000
;       derived from "Generic crt0.s for a Z80"
;
;  Copyright (C) 2000, Michael Hope
;  Modified for rabbit by Leland Morrison 2011
;
;  This library is free software; you can redistribute it and/or modify it
;  under the terms of the GNU General Public License as published by the
;  Free Software Foundation; either version 2, or (at your option) any
;  later version.
;
;  This library is distributed in the hope that it will be useful,
;  but WITHOUT ANY WARRANTY; without even the implied warranty of
;  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;  GNU General Public License for more details.
;
;  You should have received a copy of the GNU General Public License 
;  along with this library; see the file COPYING. If not, write to the
;  Free Software Foundation, 51 Franklin Street, Fifth Floor, Boston,
;   MA 02110-1301, USA.
;
;  As a special exception, if you link this library with other files,
;  some of which are compiled with SDCC, to produce an executable,
;  this library does not by itself cause the resulting executable to
;  be covered by the GNU General Public License. This exception does
;  not however invalidate any other reasons why the executable file
;   might be covered by the GNU General Public License.
;--------------------------------------------------------------------------

        .module crt0
        .globl  _main

        .area   _HEADER (ABS)
        ;; Reset vector
        .org    0
        jp      init

        .org    0x08
        reti
        .org    0x10
        reti
        .org    0x18
        reti
        .org    0x20
        reti
        .org    0x28
        reti
        .org    0x30
        reti
        .org    0x38
        reti

        .org    0x100
init:
        ;; Set stack pointer directly above top of memory.
        ld      sp,#0x0000

        ;; Initialise global variables
        call    gsinit
        call    _main
        jp      _exit

        ;; Ordering of segments for the linker.
        .area   _HOME
        .area   _CODE
        .area   _INITIALIZER
        .area   _GSINIT
        .area   _GSFINAL

        .area   _DATA
        .area   _INITIALIZED
        .area   _BSEG
        .area   _BSS
        .area   _HEAP

        .area   _CODE
__clock::
        ld      a,#2
        rst     #0x28
        ret

_exit::
        ;; Exit - special code to the emulator
        ld      a,#0
        rst     #0x28
1$:
        ;halt           ; opcode for halt used for 'altd' on rabbit processors
        jr      1$

        .area   _GSINIT
gsinit::
        ld      bc, #l__INITIALIZER
        ld      a, b
        or      a, c
        jr      Z, gsinit_next
        ld      de, #s__INITIALIZED
        ld      hl, #s__INITIALIZER
        ldir
gsinit_next:

        .area   _GSFINAL
        ret