Subversion Repositories NedoOS

;--------------------------------------------------------------------------
;  crt0.s - Generic crt0.s for a Z80
;
;  Copyright (C) 2000, Michael Hope
;
;  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
        ei
        reti
        ei
        .org    0x10
        ei
        reti
        .org    0x18
        ei
        reti
        .org    0x20
        ei
        reti
        .org    0x28
        ei
        reti
        .org    0x30
        ei
        reti
        .org    0x38
        ei
        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     0x08
        ret

_exit::
        ;; Exit - special code to the emulator
        ld      a,#0
        rst     0x08
1$:
        halt
        jr      1$

        .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