Computer Select (Limited Edition)

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Assembly Source File | 1991-05-28 | 19.0 KB | 561 lines

NAME c0 PAGE 60,132 LOCALS ;[]-------------------------------------------------------------------[] ;| C0.ASM -- Start Up Code for MIO | ;| | ;| Turbo C++ Run Time Library | ;| | ;| Portions Copyright (c) 1991, Stuart G. Phillips. | ;| All rights reserved. | ;| | ;| Copyright (c) 1987, 1991 by Borland International Inc. | ;| All rights reserved. | ;| | ;| This software is subject to the terms and conditions of the | ;| license agreement distributed with Borland C++. | ;[]-------------------------------------------------------------------[] __C0__ = 1 INCLUDE RULES.ASI ; Segment and Group declarations _BOOT SEGMENT BYTE PUBLIC 'CODE' AT 0FFFFh ORG 0 boot_vector LABEL BYTE ENDS _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 __stklen:word IF LDATA EQ false extrn __heaplen:word ENDIF SUBTTL Start Up Code PAGE ;/* */ ;/*-----------------------------------------------------*/ ;/* */ ;/* Start Up Code */ ;/* ------------- */ ;/* */ ;/*-----------------------------------------------------*/ ;/* */ ; public __AHINCR ; __AHINCR equ 1000h ; public __AHSHIFT ; __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__ ENDIF STARTX PROC NEAR jmp START ORG 2000h START: ; Save general information, such as : ; DGROUP segment 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 mov ds,dx ; Set DGROUP as data segment mov bp,0c000h ; BP = segment at top of memory ; Calculate the first free segment value by finding the top of data ; in the DGROUP data group - add in the offset of the end and convert ; to paragraphs. mov ax,dx mov dx,offset DGROUP:edata@ add dx,15 mov cl,4 shr dx,cl add ax,dx mov word ptr _heaptop@ + 2, ax ; Set temporary stack at top of used memory - it gets changed later cli mov ss,ax mov sp,100h sti push ax ; ; Save several vectors and install default divide by zero handler. ; call SaveVectors ; Determine the amount of memory that we need to keep pop ax IFDEF _DSSTACK_ mov dx, ds ELSE mov dx, ax 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 ; 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 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 mov word ptr _first_stack@, di mov word ptr _first_stack@ + 2, dx IFNDEF _DSSTACK_ ; Set the stack to a known pattern mov bx,di mov es,dx ; ES is stack segment mov cx,di shr cx,1 ; Convert to words mov di,0 mov ax,'ST' cld rep stosw mov di,bx ENDIF 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 ; Prepare main arguments xor bp,bp ; set BP to 0 for overlay mgr IFNDEF __TINY__ mov ax,DGROUP mov ds,ax mov si,offset DGROUP:InitStart ;si = start of table mov di,offset DGROUP:InitEnd ;di = end of table ELSE mov si,offset DGROUP:InitStart ;si = start of table mov di,offset DGROUP:InitEnd ;di = end of table ENDIF call StartExit mov ds, cs:DGROUP@@ ; OK, to save space we use self-modifying code. ; Replace the JA instruction in the startup/exit logic with ; a JB instruction. This allows us to scan the table on exit ; executing functions in reverse priority. Also change the ; immediate which is stored in ah at the first instruction to a 0. mov byte ptr cs:JA_JB,72h mov byte ptr cs:StartExit+1,0 ; MIO main program is called with no parameters - set argc to ; a zero count and argv to a null pointer ; ExitCode = main(argc,argv); xor ax,ax IF LDATA push ax push ax ; Null argv pointer ELSE push ax ; Null argv pointer ENDIF push ax ; arc = 0 call _main ; Clean up - MIO has no files or streams but clean up the ; interrupt vectors and then jump back to the EPROM boot code ; ready for the next download push ax jmp far ptr boot_vector ;--------------------------------------------------------------------------- ; _exit() ; ; Restore interrupt vectors taken during startup. ; ; Jump back to EPROM boot code ; ;--------------------------------------------------------------------------- __exitclean PROC NEAR PUBLIC __exitclean IFNDEF __TINY__ mov ax,DGROUP mov ds,ax mov si,offset DGROUP:ExitStart mov di,offset DGROUP:ExitEnd ELSE mov si,offset DGROUP:ExitStart mov di,offset DGROUP:ExitEnd ENDIF call StartExit mov ds, cs:DGROUP@@ ENDP __exit PROC DIST PUBLIC __exit mov ds, cs:DGROUP@@ call DIST ptr __restorezero ; restore captured INT vectors jmp far ptr boot_vector 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 ret ZeroDivision ENDP ; ; Install default divide by zero handler. ; SaveVectors PROC FAR mov ax, 0 push es ; Save current es push di ; ... and di mov es,ax mov di,0 mov es:[di], cs mov dx, offset ZeroDivision mov es:[di+2],dx pop di pop es ret SaveVectors ENDP ;-------------------------------------------------------------------------- ; restorezero() resets the divide by zero interrupt to point to the ; boot prom entry point ; ;-------------------------------------------------------------------------- __restorezero PROC DIST PUBLIC __restorezero push es ; Save es push di ; ...and di xor ax,ax mov es,ax mov di,0 mov word ptr es:[si],0 mov word ptr es:[si+2],0ffffh pop di pop es ret ENDP ;------------------------------------------------------------------ ; Loop through a startup/exit (SE) table, ; calling functions in order of priority. ; DS:SI is assumed to point to the beginning of the SE table ; DS: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 StartExit PROC NEAR @@Start: mov ah,0ffh ; 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 [bx.calltype],NOTUSED ; check the call type je @@Next cmp [bx.priority],ah ; check the priority JA_JB: ja @@Next ; too high? skip mov ah,[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 push ds ; save ds pop es push es ; es = ds cmp [bx.calltype],PNEAR ; is it near or far? mov [bx.calltype],NOTUSED ; wipe the call type mov ds, cs:DGROUP@@ je @@NearCall @@FarCall: call DWORD PTR es:[bx.addrlow] pop ds ; restore ds jmp @@Start @@NearCall: call WORD PTR es:[bx.addrlow] pop ds ; restore ds jmp @@Start @@Done: ret StartExit ENDP _abort PROC DIST PUBLIC _abort 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 CopyRight db 4 dup(0) db 'Borland C++ - Copyright 1991 Borland Intl.',0 ; ; 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@ _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__ PubSym@ __brklvl, <dw DGROUP:edata@>, __CDECL__ ENDIF PubSym@ _heapbase, <dd 0>, __CDECL__ PubSym@ _brklvl, <dd 0>, __CDECL__ PubSym@ _heaptop, <dd 0>, __CDECL__ PubSym@ _first_stack <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 END STARTX