cstrt386.asm

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;*****************************************************************************
;*
;*                            Open Watcom Project
;*
;*    Portions Copyright (c) 1983-2002 Sybase, Inc. All Rights Reserved.
;*
;*  ========================================================================
;*
;*    This file contains Original Code and/or Modifications of Original
;*    Code as defined in and that are subject to the Sybase Open Watcom
;*    Public License version 1.0 (the 'License'). You may not use this file
;*    except in compliance with the License. BY USING THIS FILE YOU AGREE TO
;*    ALL TERMS AND CONDITIONS OF THE LICENSE. A copy of the License is
;*    provided with the Original Code and Modifications, and is also
;*    available at www.sybase.com/developer/opensource.
;*
;*    The Original Code and all software distributed under the License are
;*    distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
;*    EXPRESS OR IMPLIED, AND SYBASE AND ALL CONTRIBUTORS HEREBY DISCLAIM
;*    ALL SUCH WARRANTIES, INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF
;*    MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR
;*    NON-INFRINGEMENT. Please see the License for the specific language
;*    governing rights and limitations under the License.
;*
;*  ========================================================================
;*
;* Description:  DOS 32-bit startup code.
;*
;*****************************************************************************


; Note: This module must contain the string 'WATCOM' (all caps) for DOS/4GW
;       to recognize a 'Watcom' executable.

;       This must be assembled using one of the following commands:
;               wasm cstrt386 -bt=DOS -ms -3r
;               wasm cstrt386 -bt=DOS -ms -3s
;
;   NOTE: All C library data should be defined in crwdata.asm -- That way
;         it's also available to ADS applications (who use adstart.asm).
;
        name    cstart

.387
.386p
        assume  nothing

        extrn   __CMain                 : near
        extrn   __InitRtns              : near
        extrn   __FiniRtns              : near
        extrn   __DOSseg__              : near

        extrn   _edata                  : byte  ; end of DATA (start of BSS)
        extrn   _end                    : byte  ; end of BSS (start of STACK)

        extrn   "C",_dynend             : dword
        extrn   "C",_curbrk             : dword
        extrn   "C",_psp                : word
        extrn   "C",_osmajor            : byte
        extrn   "C",_osminor            : byte
        extrn   "C",_STACKLOW           : dword
        extrn   "C",_STACKTOP           : dword
        extrn   "C",_child              : dword
        extrn   __no87                  : word
        extrn   "C",_Extender           : byte
        extrn   "C",_ExtenderSubtype    : byte
        extrn   "C",_Envptr             : dword
        extrn   "C",_Envseg             : word
        extrn   "C",__FPE_handler       : dword
        extrn   "C",_LpCmdLine          : dword
        extrn   "C",_LpPgmName          : dword

DGROUP group _NULL,_AFTERNULL,CONST,_DATA,DATA,TIB,TI,TIE,XIB,XI,XIE,YIB,YI,YIE,_BSS,STACK

; this guarantees that no function pointer will equal NULL
; (WLINK will keep segment 'BEGTEXT' in front)
; This segment must be at least 4 bytes in size to avoid confusing the
; signal function.

BEGTEXT  segment use32 para public 'CODE'
        assume  cs:BEGTEXT
forever label   near
        int     3h
        jmp     short forever
___begtext label byte
        nop     ;3
        nop     ;4
        nop     ;5
        nop     ;6
        nop     ;7
        nop     ;8
        nop     ;9
        nop     ;A
        nop     ;B
        nop     ;C
        nop     ;D
        nop     ;E
        nop     ;F
        public ___begtext
        assume  cs:nothing
BEGTEXT  ends

_TEXT   segment use32 dword public 'CODE'

        assume  ds:DGROUP

_NULL   segment para public 'BEGDATA'
__nullarea label word
        db      01h,01h,01h,00h
        public  __nullarea
_NULL   ends

_AFTERNULL segment word public 'BEGDATA'
_AFTERNULL ends

CONST   segment word public 'DATA'
CONST   ends

TIB     segment byte public 'DATA'
TIB     ends
TI      segment byte public 'DATA'
TI      ends
TIE     segment byte public 'DATA'
TIE     ends

XIB     segment word public 'DATA'
XIB     ends
XI      segment word public 'DATA'
XI      ends
XIE     segment word public 'DATA'
XIE     ends

YIB     segment word public 'DATA'
YIB     ends
YI      segment word public 'DATA'
YI      ends
YIE     segment word public 'DATA'
YIE     ends


_DATA    segment dword public 'DATA'
X_ERGO                  equ     0       ; Ergo OS/386 (unsupported)
X_RATIONAL              equ     1       ; DOS/4G(W) or compatible
X_PHARLAP_V2            equ     2       ; PharLap 386|DOS
X_PHARLAP_V3            equ     3
X_PHARLAP_V4            equ     4
X_PHARLAP_V5            equ     5
X_PHARLAP_V6            equ     6       ; PharLap TNT
X_INTEL                 equ     9       ; Intel CodeBuilder (unsupported)
X_WIN386                equ     10      ; Watcom Win386
XS_NONE                 equ     0
XS_RATIONAL_ZEROBASE    equ     0
XS_RATIONAL_NONZEROBASE equ     1
__D16Infoseg   dw       0020h   ; DOS/4G kernel segment
__x386_zero_base_selector dw 0  ; base 0 selector for X-32VM

        public  __D16Infoseg
        public  __x386_zero_base_selector
_DATA    ends


DATA    segment word public 'DATA'
DATA    ends

_BSS          segment word public 'BSS'
_BSS          ends

STACK_SIZE      equ     1000h

STACK   segment para stack 'STACK'
        db      (STACK_SIZE) dup(?)
STACK   ends


        assume  nothing
        public  _cstart_

        assume  cs:_TEXT

_cstart_ proc near
        jmp     short around

;
; copyright message (special - see comment at top)
;
        db      "Open WATCOM C/C++32 Run-Time system. "
include msgcpyrt.inc

        align   4
        dd      ___begtext      ; make sure dead code elimination
                                ; doesn't kill BEGTEXT
;
; miscellaneous code-segment messages
;
ConsoleName     db      "con",00h

around: sti                             ; enable interrupts

        assume  ds:DGROUP

PSP_SEG equ     24h
ENV_SEG equ     2ch

        and     esp,0fffffffch          ; make sure stack is on a 4 byte bdry
        mov     ebx,esp                 ; get sp
        mov     _STACKTOP,ebx           ; set stack top
        mov     _curbrk,ebx             ; set first available memory location
        mov     ax,PSP_SEG              ; get segment address of PSP
        mov     _psp,ax                 ; save segment address of PSP
;
;       get DOS & Extender version number
;
        ;mov    ebx,'PHAR'              ; set ebx to "PHAR"