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Assembly Source File | 1992-06-10 | 26.3 KB | 764 lines

;[]------------------------------------------------------------[] ;| 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__ push si push di mov es, cs:DGROUP@@ xor ax, ax mov si, ax mov cx, lgth_CopyRight ComputeChecksum label near add al, es:[si] adc ah, 0 inc si loop ComputeChecksum sub ax, CheckSum jz @@SumOK mov cx, lgth_NullCheck mov dx, offset DGROUP: NullCheck call ErrorDisplay @@SumOK: pop di pop si ENDIF ENDIF ret __checknull ENDP ; Exit to DOS __terminate PROC DIST PUBLIC __terminate mov bp,sp mov ah,4Ch mov al,[bp+cPtrSize] int 21h ; Exit to DOS __terminate ENDP STARTX ENDP SUBTTL Vector save/restore & default Zero divide routines PAGE ;[]------------------------------------------------------------[] ;| | ;| Interrupt Save/Restore routines and default divide by zero | ;| handler. | ;| | ;[]------------------------------------------------------------[] ZeroDivision PROC FAR mov cx, lgth_ZeroDivMSG mov dx, offset DGROUP: ZeroDivMSG jmp MsgExit3 ZeroDivision ENDP ;-------------------------------------------------------------------------- ; savevectors() ; ; Save vectors for 0, 4, 5 & 6 interrupts. This is for extended ; signal()/raise() support as the signal functions can steal these ; vectors during runtime. ;-------------------------------------------------------------------------- SaveVectors PROC NEAR push ds ; Save INT 0 mov ax, 3500h int 021h mov word ptr _Int0Vector@, bx mov word ptr _Int0Vector@+2, es ; Save INT 4 mov ax, 3504h int 021h mov word ptr _Int4Vector@, bx mov word ptr _Int4Vector@+2, es ; Save INT 5 mov ax, 3505h int 021h mov word ptr _Int5Vector@, bx mov word ptr _Int5Vector@+2, es ; Save INT 6 mov ax, 3506h int 021h mov word ptr _Int6Vector@, bx mov word ptr _Int6Vector@+2, es ; ; Install default divide by zero handler. ; mov ax, 2500h mov dx, cs mov ds, dx mov dx, offset ZeroDivision int 21h pop ds ret SaveVectors ENDP ;-------------------------------------------------------------------------- ; _restorezero() puts back all the vectors that SaveVectors took. ; ;NOTE : TSRs must BE AWARE that signal() functions which take these ; vectors will be deactivated if the keep() function is executed. ; If a TSR wants to use the signal functions when it is active it ; will have to save/restore these vectors itself when activated and ; deactivated. ;-------------------------------------------------------------------------- __restorezero PROC DIST PUBLIC __restorezero IFDEF __HUGE__ push ds mov ds, cs: DGROUP@@ ENDIF push ds mov ax, 2500h lds dx, _Int0Vector@ int 21h pop ds push ds mov ax, 2504h lds dx, _Int4Vector@ int 21h pop ds push ds mov ax, 2505h lds dx, _Int5Vector@ int 21h pop ds IFNDEF __HUGE__ push ds ENDIF mov ax, 2506h lds dx, _Int6Vector@ int 21h pop ds ret ENDP ;------------------------------------------------------------------ ; Loop through a startup/exit (SE) table, ; calling functions in order of priority. ; ES:SI is assumed to point to the beginning of the SE table ; ES:DI is assumed to point to the end of the SE table ; First 64 priorities are reserved by Borland ;------------------------------------------------------------------ PNEAR EQU 0 PFAR EQU 1 NOTUSED EQU 0ffh SE STRUC calltype db ? ; 0=near,1=far,ff=not used priority db ? ; 0=highest,ff=lowest addrlow dw ? addrhigh dw ? SE ENDS Initialize proc near @@Start: mov ax,100h ;start with lowest priority mov dx,di ;set sentinel to end of table mov bx,si ;bx = start of table @@TopOfTable: cmp bx,di ;and the end of the table? je @@EndOfTable ;yes, exit the loop cmp es:[bx.calltype],NOTUSED;check the call type je @@Next mov cl, es:[bx.priority] ;move priority to CX xor ch, ch cmp cx,ax ;check the priority jae @@Next ;too high? skip mov ax,cx ;keep priority mov dx,bx ;keep index in dx @@Next: add bx,SIZE SE ;bx = next item in table jmp @@TopOfTable @@EndOfTable: cmp dx,di ;did we exhaust the table? je @@Done ;yes, quit mov bx,dx ;bx = highest priority item cmp es:[bx.calltype],PNEAR ;is it near or far? mov es:[bx.calltype],NOTUSED;wipe the call type push es ;save es je @@NearCall @@FarCall: call DWORD PTR es:[bx.addrlow] pop es ;restore es jmp short @@Start @@NearCall: call WORD PTR es:[bx.addrlow] pop es ;restore es jmp short @@Start @@Done: ret endp Cleanup proc near @@Start: mov ah,0 ;start with highest priority mov dx,di ;set sentinel to end of table mov bx,si ;bx = start of table @@TopOfTable: cmp bx,di ;and the end of the table? je @@EndOfTable ;yes, exit the loop cmp es:[bx.calltype],NOTUSED;check the call type je @@Next cmp es:[bx.priority],ah ;check the priority jb @@Next ;too low? skip mov ah,es:[bx.priority] ;keep priority mov dx,bx ;keep index in dx @@Next: add bx,SIZE SE ;bx = next item in table jmp @@TopOfTable @@EndOfTable: cmp dx,di ;did we exhaust the table? je @@Done ;yes, quit mov bx,dx ;bx = highest priority item cmp es:[bx.calltype],PNEAR ;is it near or far? mov es:[bx.calltype],NOTUSED;wipe the call type push es ;save es je @@NearCall @@FarCall: call DWORD PTR es:[bx.addrlow] pop es ;restore es jmp short @@Start @@NearCall: call WORD PTR es:[bx.addrlow] pop es ;restore es jmp short @@Start @@Done: ret endp ;------------------------------------------------------------------ ErrorDisplay PROC NEAR mov ah, 040h mov bx, 2 int 021h ret ErrorDisplay ENDP _abort PROC DIST PUBLIC _abort mov cx, lgth_abortMSG mov dx, offset DGROUP: abortMSG MsgExit3 label near mov ds, cs: DGROUP@@ call ErrorDisplay CallExit3 label near mov ax, 3 push ax call __exit ; _exit(3); ENDP ; The DGROUP@ variable is used to reload DS with DGROUP PubSym@ DGROUP@, <dw ?>, __PASCAL__ ; __MMODEL is used to determine the memory model or the default ; pointer types at run time. public __MMODEL __MMODEL dw MMODEL _TEXT ENDS SUBTTL Start Up Data Area PAGE ;[]------------------------------------------------------------[] ;| Start Up Data Area | ;| | ;| WARNING Do not move any variables in the data | ;| segment unless you're absolutely sure | ;| that it does not matter. | ;[]------------------------------------------------------------[] _DATA SEGMENT ; Magic symbol used by the debug info to locate the data segment public DATASEG@ DATASEG@ label byte ; The CopyRight string must NOT be moved or changed without ; changing the null pointer check logic CopyRight db 4 dup(0) db 'Borland C++ - Copyright 1991 Borland Intl.',0 lgth_CopyRight equ $ - CopyRight IF LDATA EQ false IFNDEF __TINY__ CheckSum equ 00D5Ch NullCheck db 'Null pointer assignment', 13, 10 lgth_NullCheck equ $ - NullCheck ENDIF ENDIF ZeroDivMSG db 'Divide error', 13, 10 lgth_ZeroDivMSG equ $ - ZeroDivMSG abortMSG db 'Abnormal program termination', 13, 10 lgth_abortMSG equ $ - abortMSG ; ; Interrupt vector save areas ; ; Interrupt vectors 0,4,5 & 6 are saved at startup and then restored ; when the program terminates. The signal/raise functions might ; steal these vectors during execution. ; ; Note: These vectors save area must not be altered ; without changing the save/restore logic. ; PubSym@ _Int0Vector <dd 0>, __CDECL__ PubSym@ _Int4Vector <dd 0>, __CDECL__ PubSym@ _Int5Vector <dd 0>, __CDECL__ PubSym@ _Int6Vector <dd 0>, __CDECL__ ; ; Miscellaneous variables ; PubSym@ _C0argc, <dw 0>, __CDECL__ dPtrPub@ _C0argv, 0, __CDECL__ dPtrPub@ _C0environ, 0, __CDECL__ PubSym@ _envLng, <dw 0>, __CDECL__ PubSym@ _envseg, <dw 0>, __CDECL__ PubSym@ _envSize, <dw 0>, __CDECL__ PubSym@ _psp, <dw 0>, __CDECL__ PubSym@ _version, <label word>, __CDECL__ PubSym@ _osversion, <label word>, __CDECL__ PubSym@ _osmajor, <db 0>, __CDECL__ PubSym@ _osminor, <db 0>, __CDECL__ PubSym@ errno, <dw 0>, __CDECL__ PubSym@ _StartTime, <dw 0,0>, __CDECL__ ; Memory management variables IF LDATA EQ false PubSym@ __heapbase, <dw DGROUP:edata@>, __CDECL__ ENDIF IFNDEF __HUGE__ PubSym@ __brklvl, <dw DGROUP:edata@>, __CDECL__ ENDIF PubSym@ _heapbase, <dd 0>, __CDECL__ PubSym@ _brklvl, <dd 0>, __CDECL__ PubSym@ _heaptop, <dd 0>, __CDECL__ ; If stack in DS and Large data model then override location of __emu IFDEF _DSSTACK_ IF LDATA public __emu __emu db 044h DUP (0) db 0CCh DUP (?) ENDIF ENDIF _DATA ENDS _CVTSEG SEGMENT PubSym@ _RealCvtVector, <label word>, __CDECL__ ENDS _SCNSEG SEGMENT PubSym@ _ScanTodVector, <label word>, __CDECL__ ENDS IFNDEF __HUGE__ _BSS SEGMENT bdata@ label byte ENDS _BSSEND SEGMENT edata@ label byte ENDS ENDIF IFNDEF __TINY__ _STACK SEGMENT db 128 dup(?) ;minimum stack size ENDS ENDIF ; __TINY__ END STARTX