PAGE 81,132 ;INTRPT2.ASM ;-----------------------------------------------------------------------| ; -------- ---1991 Cornel H Huth ------------------- | ;-----------------------------------------------------------------------| ; date: 21 Jul 91 | ; function: 80xxx INTERRUPT dispatcher for QuickBASIC/BASIC PDS | ; caller: FAR call QuickBASIC convention, reference (INTERRUPT(X)) | ; call INTERRUPT(intnum%,ireg AS RegType,oreg AS RegType) | ; call INTERRUPTX(intnum%,ireg AS RegTypeX,oreg AS RegTypeX) | ; stack: +06 offset of return register pack | ; 08 offset of initial register pack | ; 10 interrupt number | ; return: interrupt return registers | ; NOTE: This routine is a direct replacement for QB's routine. | ; NOTE: INT24 handler is installed temporarily to handle fatal | ; DOS errors without the Abort, Retry, Fail or system crash. | ; NOTE: If intnum% is out of range intnum% is NOT returned as -1 | ; as the MS version does (no one is that stoopid, hey,hey). | ; NOTE: The interrupt is done without writing to the code segment. | ; NOTE: b$SaveBP is no longer needed with PDS version since fatal | ; errors are handled locally, not by the BASIC INT24 handler.| ; NOTE: For verbose source comments see INTRPT.ASM in QBNWS105. | ;-----------------------------------------------------------------------| ; This source file is based on: | ; INTERRUPT - BASCOM software interrupt calling routine | ; Copyright 1986, 1987 Microsoft Corporation | ;-----------------------------------------------------------------------| ;This source was assembled using MASM 5.1. Previous or other versions of| ;assemblers should handle this source without any difficulty except for | ;perhaps the retf and retn mnemonics. Easy enough to use a macro or db. | ;-----------------------------------------------------------------------| WPTR EQU BPTR EQU Aintnum EQU Aireg EQU Aoreg EQU OldSI EQU OldDI EQU OldDS EQU OldFLAGS EQU RegCnt EQU RegES EQU RegDS EQU RegFLAGS EQU RegDI EQU RegSI EQU RegBP EQU RegDX EQU RegCX EQU RegBX EQU RegAX EQU LocalSize = 30 PostBP EQU ;returned bp pushed here (after INT call return) _BSS SEGMENT WORD PUBLIC 'BSS' INT24error dw 1 dup(?) INT24seg dw 1 dup(?) INT24off dw 1 dup(?) _BSS ENDS _DATA SEGMENT WORD PUBLIC 'DATA' _DATA ENDS DGROUP GROUP _DATA,_BSS INTRPT2_TEXT SEGMENT WORD PUBLIC 'CODE' ASSUME cs:INTRPT2_TEXT,ds:DGROUP,es:DGROUP,ss:DGROUP PUBLIC INTERRUPT INTERRUPT PROC FAR push bp mov bp,sp sub sp,LocalSize mov RegCnt,8 ;8 registers passed for INTERRUPT jmp SHORT INTRPT1 PUBLIC INTERRUPTX INTERRUPTX LABEL FAR push bp mov bp,sp sub sp,LocalSize mov RegCnt,10 ;10 passed for INTERRUPTX ;set up for interrupt call INTRPT1: mov bx,Aintnum mov bx,[bx] ;bx=interrupt to execute or bh,bh ;>255? jz INTRPT2 ;no jmp INTRPTxit ;yes,just exit INTRPT2: push bx mov bl,1 ;trap fatal errors call INT24switch pop bx mov OldSI,si ;save what we need to mov OldDI,di mov OldDS,ds pushf ;in case RegFLAGS changes DF? pop OldFLAGS cld mov si,Aireg ;ds:si->ireg pack mov ax,ss mov es,ax lea di,RegAX ;es:di->local stack vars mov cx,RegCnt rep movsw push bp ;save original frame base cmp bl,25h ;INT25? je INTRPT3 ; or cmp bl,26h ;INT26? jne INTRPT4 ;no ;INT25/26 specific stack program INTRPT3: mov ax,10 push ax ;retf 10 mov ax,0CA90h ;nop push ax ;sti mov ax,0FB44h ;inc sp push ax ;inc sp mov ax,44FAh ;cli -ensure sp stays even push ax jmp SHORT INTRPT5 ;non-INT25/26 specific stack program INTRPT4: sub ax,ax push ax ;retf 6 mov ax,06CAh push ax ;for either, the actual INT?? instruction INTRPT5: mov ah,bl mov al,0CDh push ax ;INT?? ;set up the far return address for the stack program push cs mov ax,OFFSET INTRPT8 ;cs:ax->return to after INT?? push ax ;store the address of the stack program--on the stack push ss mov ax,sp add ax,6 ;ss:ax->start of stack program push ax ;set up the registers for the INT call mov ax,RegFLAGS and ax,0000111111010101b ;mask valid 8086 flags push ax ;save flags for a sec mov ax,RegAX mov bx,RegBX mov cx,RegCX mov dx,RegDX mov si,RegSI mov di,RegDI cmp RegCnt,8 ;call INTERRUPT? je INTRPT7 cmp RegDS,-1 ;no,INTERRUPTX,load ds segment? je INTRPT6 mov ds,RegDS ;ds<>ss! INTRPT6: cmp RegES,-1 ;how about es segment? je INTRPT7 mov es,RegES INTRPT7: mov bp,RegBP popf ;get the flags back retf ;execute the stack program ;come here after the stack program has executed the INT call INTRPT8: push bp ;save to PostBP mov bp,sp mov bp,[bp+2] ;get original frame base pushf ;get the return flags NOW pop RegFLAGS ;unhook temporary INT24 handler and process any error push bx ;we want sub bl,bl call INT24switch pop bx ;we need cmp ss:INT24error,0 ;fatal DOS error? je INTRPT9 ;no or RegFLAGS,1 ;set carry mov ah,30h ;clean up DOS int 21h mov ax,ss:INT24error ;return DOS error INTRPT9: push OldFlags popf ;save returned registers and send them back mov RegAX,ax mov RegBX,bx mov RegCX,cx mov RegDX,dx mov ax,PostBP ;get BP value returned from INT call mov RegBP,ax mov RegSI,si mov RegDI,di mov RegDS,ds mov RegES,es mov ds,OldDS ;ds=ss lea si,RegAX ;ds:si->stack vars (ds=ss) mov ax,ds mov es,ax mov di,Aoreg ;es:di->oreg pack mov cx,RegCnt rep movsw mov si,OldSI mov di,OldDI INTRPTxit: mov sp,bp ;deallocate locals pop bp retf 3*2 ;we're done ;temporary INT24 switch and handler INT24switch: push es push ds push dx push ax or bl,bl jz INT24s2 mov ss:INT24error,0 mov ax,3524h int 21h mov ss:INT24seg,es mov ss:INT24off,bx mov ax,2524h mov dx,OFFSET INT24handler push cs pop ds INT24s1: int 21h pop ax pop dx pop ds pop es retn INT24s2: mov ax,2524h mov dx,ss:INT24off mov ds,ss:INT24seg jmp INT24s1 ;store the error number and return INT24handler: sti add sp,6 add di,13h mov ss:INT24error,di pop ax pop bx pop cx pop dx pop si pop di pop bp pop ds pop es iret INTERRUPT ENDP INTRPT2_TEXT ENDS END