?? c0.asm
字號:
;[]------------------------------------------------------------[]
;| C0.ASM -- Start Up Code for DOS |
;[]------------------------------------------------------------[]
;
; C/C++ Run Time Library - Version 5.0
;
; Copyright (c) 1987, 1992 by Borland International
; All Rights Reserved.
;
locals
__C0__ = 1
INCLUDE RULES.ASI
; Segment and Group declarations
_TEXT SEGMENT BYTE PUBLIC 'CODE'
ENDS
_FARDATA SEGMENT PARA PUBLIC 'FAR_DATA'
ENDS
_FARBSS SEGMENT PARA PUBLIC 'FAR_BSS'
ENDS
IFNDEF __TINY__
_OVERLAY_ SEGMENT PARA PUBLIC 'OVRINFO'
ENDS
_1STUB_ SEGMENT PARA PUBLIC 'STUBSEG'
ENDS
ENDIF
_DATA SEGMENT PARA PUBLIC 'DATA'
ENDS
_INIT_ SEGMENT WORD PUBLIC 'INITDATA'
InitStart label byte
ENDS
_INITEND_ SEGMENT BYTE PUBLIC 'INITDATA'
InitEnd label byte
ENDS
_EXIT_ SEGMENT WORD PUBLIC 'EXITDATA'
ExitStart label byte
ENDS
_EXITEND_ SEGMENT BYTE PUBLIC 'EXITDATA'
ExitEnd label byte
ENDS
_CVTSEG SEGMENT WORD PUBLIC 'DATA'
ENDS
_SCNSEG SEGMENT WORD PUBLIC 'DATA'
ENDS
IFNDEF __HUGE__
_BSS SEGMENT WORD PUBLIC 'BSS'
ENDS
_BSSEND SEGMENT BYTE PUBLIC 'BSSEND'
ENDS
ENDIF
IFNDEF __TINY__
_STACK SEGMENT STACK 'STACK'
ENDS
ENDIF
ASSUME CS:_TEXT, DS:DGROUP
; External References
extrn _main:DIST
extrn _exit:DIST
extrn __exit:DIST
extrn __nfile:word
extrn __setupio:near ;required!
extrn __stklen:word
IF LDATA EQ false
extrn __heaplen:word
ENDIF
SUBTTL Start Up Code
PAGE
;/* */
;/*-----------------------------------------------------*/
;/* */
;/* Start Up Code */
;/* ------------- */
;/* */
;/*-----------------------------------------------------*/
;/* */
PSPHigh equ 00002h
PSPEnv equ 0002ch
PSPCmd equ 00080h
public __AHINCR
public __AHSHIFT
__AHINCR equ 1000h
__AHSHIFT equ 12
IFDEF __NOFLOAT__
MINSTACK equ 128 ; minimal stack size in words
ELSE
MINSTACK equ 256 ; minimal stack size in words
ENDIF
;
; At the start, DS and ES both point to the segment prefix.
; SS points to the stack segment except in TINY model where
; SS is equal to CS
;
_TEXT SEGMENT
IFDEF __TINY__
ORG 100h
ENDIF
STARTX PROC NEAR
; Save general information, such as :
; DGROUP segment address
; DOS version number
; Program Segment Prefix address
; Environment address
; Top of far heap
IFDEF __TINY__
mov dx, cs ; DX = GROUP Segment address
ELSE
mov dx, DGROUP ; DX = GROUP Segment address
ENDIF
mov cs:DGROUP@@, dx ; __BOSS__
mov ah, 30h
int 21h ; get DOS version number
mov bp, ds:[PSPHigh]; BP = Highest Memory Segment Addr
mov bx, ds:[PSPEnv] ; BX = Environment Segment address
mov ds, dx
mov _version@, ax ; Keep major and minor version number
mov _psp@, es ; Keep Program Segment Prefix address
mov _envseg@, bx ; Keep Environment Segment address
mov word ptr _heaptop@ + 2, bp
;
; Save several vectors and install default divide by zero handler.
;
call SaveVectors
; Count the number of environment variables and compute the size.
; Each variable is ended by a 0 and a zero-length variable stops
; the environment. The environment can NOT be greater than 32k.
mov ax, _envseg@
mov es, ax
xor ax, ax
mov bx, ax
mov di, ax
mov cx, 07FFFh ; Environment cannot be > 32 Kbytes
cld
@@EnvLoop:
repnz scasb
jcxz InitFailed ; Bad environment !!!
inc bx ; BX = Nb environment variables
cmp es:[di], al
jne @@EnvLoop ; Next variable ...
or ch, 10000000b
neg cx
mov _envLng@, cx ; Save Environment size
mov cx, dPtrSize / 2
shl bx, cl
add bx, dPtrSize * 4
and bx, not ((dPtrSize * 4) - 1)
mov _envSize@, bx ; Save Environment Variables Nb.
; Determine the amount of memory that we need to keep
IFDEF _DSSTACK_
mov dx, ds
ELSE
mov dx, ss
ENDIF
sub bp, dx ; BP = remaining size in paragraphs
IF LDATA
mov di, seg __stklen
mov es, di
mov di, es:__stklen ; DI = Requested stack size
ELSE
mov di, __stklen ; DI = Requested stack size
ENDIF
;
; Make sure that the requested stack size is at least MINSTACK words.
;
cmp di, 2*MINSTACK ; requested stack big enough ?
jae AskedStackOK
mov di, 2*MINSTACK ; no --> use minimal value
IF LDATA
mov es:__stklen, di ; override requested stack size
ELSE
mov __stklen, di ; override requested stack size
ENDIF
AskedStackOK label near
IFDEF _DSSTACK_
add di, offset DGROUP: edata@
jb InitFailed ; DATA segment can NOT be > 64 Kbytes
ENDIF
IF LDATA EQ false
add di, __heaplen
jb InitFailed ; DATA segment can NOT be > 64 Kbytes
ENDIF
mov cl, 4
shr di, cl ; $$$ Do not destroy CL $$$
inc di ; DI = DS size in paragraphs
cmp bp, di
IF LDATA EQ false
jb InitFailed ; Not enough memory
cmp __stklen, 0
je ExpandDS ; Expand DS up to 64 Kb
cmp __heaplen, 0
jne ExcessOfMemory ; Much more available than needed
ExpandDS label near
mov di, 1000h
cmp bp, di
ja ExcessOfMemory ; Enough to run the program
mov di, bp
jmp short ExcessOfMemory ; Enough to run the program
ELSE
jnb ExcessOfMemory ; Much more available than needed
ENDIF
; All initialization errors arrive here
InitFailed label near
jmp near ptr _abort
; Return to DOS the amount of memory in excess
; Set far heap base and pointer
ExcessOfMemory label near
mov bx, di
add bx, dx
mov word ptr _heapbase@ + 2, bx
mov word ptr _brklvl@ + 2, bx
mov ax, _psp@
sub bx, ax ; BX = Number of paragraphs to keep
mov es, ax ; ES = Program Segment Prefix address
mov ah, 04Ah
push di ; preserve DI
int 021h ; this call clobbers SI,DI,BP !!!!!!
pop di ; restore DI
shl di, cl ; $$$ CX is still equal to 4 $$$
cli ; req'd for pre-1983 88/86s
mov ss, dx ; Set the program stack
mov sp, di
sti
IFNDEF _DSSTACK_
mov ax, seg __stklen
mov es, ax
mov es:__stklen, di ; If separate stack segment, save size
ENDIF
IFNDEF __HUGE__
; Reset uninitialized data area
xor ax, ax
mov es, cs:DGROUP@@
mov di, offset DGROUP: bdata@
mov cx, offset DGROUP: edata@
sub cx, di
cld
rep stosb
ENDIF
; If default number of file handles have changed then tell DOS
cmp __nfile, 20
jbe @@NoChange
cmp _osmajor@, 3 ; Check for >= DOS 3.3
jb @@NoChange
ja @@DoChange
cmp _osminor@, 1Eh
jb @@NoChange
@@DoChange:
mov ax, 5801h ; Set last fit allocation
mov bx, 2
int 21h
jc @@BadInit
mov ah, 67h ; Expand handle table
mov bx, __nfile
int 21h
jc @@BadInit
mov ah, 48h ; Allocate 16 bytes to find new
mov bx, 1 ; top of memory address
int 21h
jc @@BadInit
inc ax ; Adjust address to point after block
mov word ptr _heaptop@ + 2, ax
dec ax ; Change back and release block
mov es, ax
mov ah, 49h
int 21h
jc @@BadInit
mov ax, 5801h ; Set first fit allocation
mov bx, 0
int 21h
jnc @@NoChange
@@BadInit: jmp near ptr _abort
@@NoChange:
; Prepare main arguments
mov ah, 0
int 1ah ; get current BIOS time in ticks
mov word ptr _StartTime@,dx ; save it for clock() fn
mov word ptr _StartTime@+2,cx
or al,al ; was midnight flag set?
jz @@NotMidnight
mov ax,40h ; set BIOS midnight flag
mov es,ax ; at 40:70
mov bx,70h
mov byte ptr es:[bx],1
@@NotMidnight:
xor bp,bp ; set BP to 0 for overlay mgr
mov es, cs:DGROUP@@
mov si,offset DGROUP:InitStart ;si = start of table
mov di,offset DGROUP:InitEnd ;di = end of table
call Initialize
; ExitCode = main(argc,argv,envp);
IF LDATA
push word ptr __C0environ+2
push word ptr __C0environ
push word ptr __C0argv+2
push word ptr __C0argv
ELSE
push word ptr __C0environ
push word ptr __C0argv
ENDIF
push __C0argc
call _main
; Flush and close streams and files
push ax
call _exit
;---------------------------------------------------------------------------
; _cleanup() call all #pragma exit cleanup routines.
; _checknull() check for null pointer zapping copyright message
; _terminate(int) exit program with error code
;
; These functions are called by exit(), _exit(), _cexit(),
; and _c_exit().
;---------------------------------------------------------------------------
; Call cleanup routines
__cleanup PROC DIST
PUBLIC __cleanup
mov es, cs:DGROUP@@
push si
push di
mov si,offset DGROUP:ExitStart
mov di,offset DGROUP:ExitEnd
call Cleanup
pop di
pop si
ret
__cleanup ENDP
; Check for null pointers before exit
__checknull PROC DIST
PUBLIC __checknull
IF LDATA EQ false
IFNDEF __TINY__
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