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Assembly Source File | 1990-10-09 | 25KB | 1,452 lines

; modify on ss:sp ; .386 %NOINCL page 85,132 include xmhd.inc include xmmsg.def include xmmac.mac _DATA segment para public USE16 'DATA' extrn DosCallP: word public debugflag public Param ; ends _TEXT segment para public USE16 'CODE' public ToProtection,Gate public orig_code, orig_size extrn PrintTrace:near extrn retos:near extrn DosExit:near extrn putpointer:near extrn Ty_Debugger:near extrn puttracereg:near extrn copy_original:near extrn a20_off:near, a20_on:near extrn OSExit:near _TEXT ends _STACK segment para STACK USE16 'STACK' StackSize equ 512 db StackSize dup (?) _STACK ends COMMUNICATION segment para public USE16 'DATA' public ToDosDS, ToDosES, FromDosDS, FromDosES ToDosDS dw ? ToDosES dw ? FromDosDS dw ? FromDosES dw ? CommLimit equ 7 COMMUNICATION ends _DATA segment para public USE16 'DATA' extrn Handle: word ; ; ; debug information ; ; DebugFlag dflag <TraceReg, TrapDOS, TraceDOS, MsgToCom> db 0,0 public traceCount TraceCount dw 0 even orig_code label dword dw 1800h dw -1 orig_size dw 256 ; ; Control387 dw ? public exessesp, exeesp, exess ExeSSESP label fword ExeESP dd 60 * 1024 ;STACK_HI ExeSS dw ExeDataSel,0 public savedcseip, savedeip, savedcs SavedCSEIP label fword SavedEIP dd 0 SavedCS dw 0,0 public savedssesp, savedesp, savedss SavedSSESP label fword SavedESP dd 0 SavedSS dw 0,0 public stack_log align dword stack_log dd 60h dup (3a3a3ah) public gateeax GateEAX dd ? public gatessesp, gateesp, gatess GateSSESP label fword GateESP dd ? GateSS dw 0,0 public gateCarry GateCarry label byte dw 0,0 SavedIntN dw 0 align dword public savedflags SavedFlags label dword SavedFlag_lo dw ? dw ? public savedeax, savedax SavedEAX label dword SavedAX dw ? dw ? SavedEBX dd ? SavedECX dd ? SavedESI dd ? SavedEBP dd ? TempEBX dd ? TempDS dw ? TempES dw ? DosFuncNo dw ? DosCallNo dw ? public exeeax, exeax ExeEAX label dword ExeAX dw ? dw ? public execseip, exeeip, execs align dword ExeCSEIP label fword ExeEIP dd ? ExeCS dw ? public thisssesp, thissp, thisss align dword ThisSSESP label fword ThisSP dw ? dw 0 ThisSS dw ? align 8 ; ;type of AccessRights = p,dpl,1,typ,a or p,dpl,0,type ar_data equ 10010010b ar_code equ 10011010b ar_stk equ 10010110b ; DPL0 equ 00000000b DPL1 equ 00100000b DPL2 equ 01000000b DPL3 equ 01100000b ; ;type of Granularity = g,x,0,avl,limit19-16 ; gr_16 equ 10000000b ; G=1, default 16 bit (286 compatible) gr_16s equ 00000000b ; G=0, default 16 bit (286 compatible) gr_32 equ 11000000b ; G=1, default 32 bit gr_32s equ 01000000b ; G=0, default 32 bit ; ; <lim0-15,bs0-15,bs16-23,ar,gr,bs24-31> ; ; grobal segment ; align dword GDT label byte ;global descriptor table starts here NULL Desc <> ;Null descriptor ProgCode Desc <0ffffh,,,ar_code,gr_32,0> ;code descriptor ProgData Desc <0ffffh,,,ar_data,gr_32,0> ;data descriptor ThisCode Desc <0ffffh,,,ar_code,gr_16+15,> ;.code ThisData Desc <0ffffh,,,ar_data,gr_16+15,> ;.data CommData Desc <0ffffh,,,ar_data,00000000b,> ;communication LDTDesc Desc <LDTLimit,,,82h,,> ;selector to LDT GDTDesc Desc <GDTLimit,,,82h,,> ;selector to GDT FlatData Desc <0ffffh,0,0,ar_data,gr_32,0> ;flat 256MB data GDT_END label byte GDTLimit equ GDT_END - GDT -1 NULLSelector equ 0 ;0 ProgCSel equ ProgCode - GDT ;+ 7 ProgDsel equ ProgData - GDT ;+ 7 ThisCodeSel equ ThisCode - GDT ;18h ThisDataSel equ ThisData - GDT ;20h CommDataSel equ CommData - GDT ;28h LDTSel equ LDTDesc - GDT ;30h GDTSel equ GDTDesc - GDT ;38h FlatDataSel equ FlatData - GDT ;40h ; ; local segment ; for the compatibility to Phar Lap's ; ; <lim0-15,bs0-15,bs16-23,ar,gr,bs24-31> ; align dword LDT label byte ;local descriptor table starts here CallGate Desc <Gate,ThisCodeSel,0,0ech,0,0> ;gate to proc Gate ExeCode Desc <0ffffh,,,ar_code,gr_32,> ;code descriptor ExeData Desc <0ffffh,,,ar_data,gr_32,> ;data descriptor LSEG_VRAM Desc <256/4,0,0ah,ar_data,gr_32,0> ; Video RAM LSEG_PSP2 Desc < 512,,,ar_data,gr_32s,0> ; PSP for user program LSEG_ENV Desc <4096,,,ar_data,gr_32s,0> ; Environment LSEG_LOWMEM Desc <1024/4,0,0,ar_data,gr_32,0> ; LowMemory (limit=1MB) LDT_END label byte ; LDTLimit equ LDT_END -LDT -1 GateSel equ CallGate - LDT + 4 ;first entry in LDT, RPL 3 ExeCodeSel equ ExeCode - LDT + 4 ;c ExeDataSel equ ExeData - LDT + 4 ;14 VramSel equ LSEG_VRAM - LDT + 4 ;1c PSP2Sel equ LSEG_PSP2 - LDT + 4 ;24 ENVSel equ LSEG_ENV - LDT + 4 ;2c LowMemSel equ LSEG_LowMem-LDT + 4 ;34 %NOMACS align 8 IDT label byte IntDesc macro n dw Intr&n ;;offset 0 15 dw ThisCodeSel ;;selector db 0 ;;word count db 10001110b ;;gate type dw 0 ;;offset 16 31 endm x = 0 rept 256 IntDesc %x x = x+1 endm align dword ;FlushPtr label dword ; dw Flush ; dw _TEXT ProtectedPtr label dword dw Protected dw ThisCodeSel public gdtlimitbase, idtlimitbase GDTLimitBase label fword dw GDTLimit GDTBase dd ? IDTLimitBase label fword dw 256*8-1 IDTBase dd ? public rmidtlimitbase RMIDTLimitBase label fword dw 256*4-1 dd 0 LDTBase dd ? public EData, EBSS public ECode ; public Parm EData sect <,,> ;1 EBSS sect <,,> ;0 ECode sect <,,> ;1 ProgENV sect <,,> ;0 ProgPSP sect <,,> ;0 public thiscodebase, thisdatabase, commdatabase ThisCodeBase dd ? ThisDataBase dd ? CommDataBase dd ? BrkVal dd ? NextTime dd ? Param dd 8 dup (?) ; max 8 params ArgP dd ? PSP dw ? ; My PSP segment EnvSeg dw ? ; My ENV segment ArgLen db ? public SavedOpCode SavedOpCode db 90h ; nop instruction for default public ErrorOffset ErrorOffset db ? ; input: lower nibble, output: upper nibble ; register only = 0, ; 1 = ds:dx, 2 = es:bx, 3 = es:di, 4 = ds:di ; ; end of dos functions ; include termio.inc include stat.inc ;cons_tio termio <1805h,01bdh,003bh,00000h,00h,7fh,1ch,08h,40h,04h,0,0,0> ;file_tio termio <0000h,0000h,0000h,0ffffh,00h,00h,00h,00h,00h,00h,0,0,0> include exp.inc extrn fhdr:filehdr extrn pspwork:byte, DosBuffer:byte extrn DosworkI:byte, Dosworko:byte extrn Mywork:byte, comp_buffer:byte _DATA ends _TEXT segment para public USE16 'CODE' assume cs: _TEXT, ds: _DATA EntryPointer label fword EntryEIP dd ? EntrySel dw ExeCodeSel ; stack frame: 0 gs ; 2 fs ; 4 es ; 8 ds ; 10 ret-offset ; 14 ret-segment ; 16 ret-offset to caller of system library ; 20 parameters... .386P Gate proc far iret cli endp extrn ReadFOHdr:near, ReadSHdr:near extrn OpenExe:near ; ; ; Silly design on BIOS, used INTEL reserved interrupt. ; ; .386 IF PCAT %out " This is PC/AT version " IRC1 = 020h IRC2 = 0a0h public P8259 P8259 proc near pushf cli outb IRC1, 11h outbd IRC1+1, ah outbd IRC1+1, 4 outbd IRC1+1, 1 outbd IRC1+1, 00h outbd IRC1, 20h comment % ; IRC 2 outb IRC2 + 0, 11h outbd IRC2 + 1, ah outbd IRC2 + 1, 4 outbd IRC2 + 1, 1 outbd IRC2 + 1, 00h outbd IRC2 + 0, 20h ; % ; popf ret P8259 endp ENDIF .386 extrn CopyVectors:near SetDescriptor proc near ; bx descriptor ; eax base ; ecx limit mov [bx].Base_0_15, ax shr eax, 16 mov [bx].Base_16_23, al mov [bx].Base_24_31, ah cmp ecx, 0fffffh ;greater than 1 MB? jbe LimOK shr ecx, PAGESHIFT ;size in pages or ecx, 800000h ;set Granularity bit to 1 LimOK: mov [bx].Limit_0_15, cx shr ecx, 16 mov al, [bx].Granularity and al, NOT 8fh or al, cl mov [bx].Granularity, al ret SetDescriptor endp SetDesc macro b, a, c mov bx, offset b mov eax, a mov ecx, c call SetDescriptor endm extrn setenvp:near public PushToExeStack PushToExeStack proc near IF FMR70 call a20_on ENDIF mov edi, ExeESP sub edi, 4 mov ExeESP, edi add edi, EData.Base sub edi, ThisDataBase mov [edi], eax ret PushToExeStack endp SetArgP proc near movzx ecx, ArgLen mov edi, ArgP mov ebx, EData.Base sub ebx, ThisDataBase sub esi, esi ;argc sub eax, eax ;separator & NULL dec edi MoreArgs: jcxz PushToExeStack ;eax==0 to stack SkipZeros: inc edi prefix32 cmp byte ptr [edi][ebx], 0 loope SkipZeros ;eax==0 to stack jcxz PushToExeStack push edi ;remember the vaddr beginning inc esi ;++argc SkipArg: inc edi prefix32 cmp byte ptr [edi][ebx], 0 loopne SkipArg call MoreArgs pop eax ;restore the argument pointer jmp PushToExeStack ;push it endp ; ; cpu_setup32 proc near mov ax, _DATA mov ds, ax mov es, ax mov fs, ax mov gs, ax cwde shl eax, 4 SetDesc ThisData, eax, 0ffffffffh jmp cpu_setup endp cpu_setup16 proc near mov ax, _DATA mov ds, ax mov es, ax mov ThisData.Granularity, 0 ; G=0, default = 16bit mov ThisData.Limit_0_15, 0ffffh jmp cpu_setup endp .386P cpu_setup proc near mov ax, _DATA cwde shl eax, 4 add eax, offset GDT mov GDTBase, eax cli lgdt GDTLimitBase ;global descriptor table mov eax, CR0 or al, 11h ; keep ET bit as it is and al, NOT 0eh mov CR0, eax ;protection on jmp $+2 nop nop mov ax, ThisDataSel ;select ThisData mov ds, ax mov es, ax mov fs, ax mov gs, ax mov eax, CR0 and al, NOT 1 mov CR0, eax ;enter REAL mode db 0eah ;far jump to Flush dw __Flush dw _TEXT __Flush: mov ax, _DATA ;all segments to .data mov ds, ax mov es, ax mov fs, ax mov gs, ax xor eax,eax mov edx, eax mov ebx, eax mov ecx, eax ret endp .386 extrn memoryconfig:near extrn memscan:near, memmax:near .HimemInvalid label near push ds mov ax, _DATA mov ds, ax mov dx, offset MemValidQ call Msg call getchar and al, 1101111B cmp al, 'Y' pop ds je .HimemValid IF FMR70 call a20_off ENDIF mov ax, 4c02h int 21h ; IF FMR70 .386P SetCPU proc near mov ax, _DATA mov ds, ax mov es, ax or ThisCode.Granularity, 8fh or ThisData.Granularity, 8fh cwde ;base for GDT shl eax, 4 add eax, offset GDT mov GDTBase, eax mov ax, cs ;.code shl ax, 4 mov ThisCode.Base_0_15, ax mov ax, cs shr ax, 12 mov ThisCode.Base_16_23, al mov ax, ds ;.data shl ax, 4 mov ThisData.Base_0_15, ax mov ax, ds shr ax, 12 mov ThisData.Base_16_23, al cli lgdt GDTLimitBase ;global descriptor table mov eax, CR0 or al, 11h and al, NOT 0eh mov CR0, eax ;protection on fjmp ThisCodeSel, set_prot set_prot: mov ax, ThisDataSel ;select ThisData mov ds, ax mov es, ax mov fs, ax mov gs, ax mov eax, CR0 and al, NOT 1 mov CR0, eax ;enter REAL mode fjmp _TEXT, set_flush .386 set_Flush: mov ax, _DATA ;all segments to .data mov ds, ax mov es, ax mov fs, ax mov gs, ax ret endp ENDIF .Nomemory proc near mov ax, 4c09h int 21h endp ; ; Main entry ; Start proc near push ds IF FMR70 call setCPU ENDIF call a20_on IF PCAT call cpu_setup32 ENDIF call MemoryConfig IF FMR70 call a20_off ENDIF pop ds mov ax, ds mov es, ax jc .HimemInvalid .initCOM: IF PCAT mov ah, 0 mov dx, CommPort ; use com0: mov al, 11100011b ; 9600bps,nop,1stop,8bit int 14h ENDIF IF FMR70 ENDIF .HimemValid: mov bx, 80h mov byte ptr [bx][7fh], ' ' movzx cx, byte ptr[bx] inc cx push cx cmp cx, 1 ja SpaceThem mov ax, _DATA mov ds, ax jmp .no_parm SpaceThem: inc bx ;81h cmp byte ptr [bx], ' ' ja IsChar mov byte ptr [bx], ' ' IsChar: loop SpaceThem pop ax push ax mov cx, 07fh sub cx, ax ZeroThem: mov byte ptr[bx], ' ' inc bx loop ZeroThem pop cx push cx cmp cx, MAXFILENAME jbe NameLenOK mov cx, MAXFILENAME NameLenOK: mov di, 81h mov al, ' ' repe scasb mov ax, _DATA mov es, ax mov es: PSP, ds pop ax mov es: ArgLen, al lea si, [di-1] mov di, offset FileName ; .copyPname: movsb cmp byte ptr[si], ' ' loopne .copyPname mov al, 0 stosb ; ; copy param into psp-work. 7-17 ; push di push si lea di, PSPwork[129] mov cx, 128 rep movsb lea di, PSPwork mov cx, 129 mov si, 0 rep movsb pop si pop di ; mov ax, es mov ds, ax IF Testing mov dx, offset HelloS call Msg ENDIF ; ; Store my (=this program) own environment. ; mov ThisSS, ss mov ThisSP, sp mov ax, cs ;.code cwde shl eax, 4 mov ThisCodeBase, eax mov ax, ds ;.data cwde shl eax, 4 mov ThisDataBase, eax ; ; Store/setup program's environment ; ; mov eax, MEM_LO mov ECode.Base, eax mov EData.Base, eax mov EBSS.Base, eax mov ECode.Lo, 0 mov EData.Lo, 0 mov EBSS.Lo, 0 mov esi, eax call MemMax IF FMR70 call a20_off ENDIF push esi sub esi, ECode.Base mov ECode.Hi, esi pop esi sub esi, EData.Base mov EData.Hi, esi mov EBSS.Hi, esi ; sub esi, PageSize - 3 and esi, not 3 mov ExeESP, esi ;90-7-8 mov ax, ds movzx eax, ax shl eax, 4 add eax, (offset PSPwork) mov ProgPSP.Base, eax ; ; setup EnvSeg and contents of psp ; push ds mov ax, _DATA mov es, ax lea di, PSPwork mov ds, es: PSP ; my PSP segment mov si, psp_envseg ; my ENV segment mov si, [si] mov es:EnvSeg, si pop ds ; ; setup param field ; mov si, offset PSPwork + 128 lodsb movzx cx, al ; ; Store/setup PSP ; movzx eax, EnvSeg shl eax, 4 mov ProgEnv.Base, eax mov ProgEnv.Hi, 2048 ; Temporal patch ; call CopyArg ; ; Set up parameter to program ; or esi, esi ;argc jnz SaveArgc .no_parm: mov dx, offset UsageS call Msg ; jmp OSExit ; <-- We need OsExit function SaveArgc: xchg eax, esi IF FMR70 call a20_on ENDIF call PushToExeStack ;push argc call OpenExe call ReadFOHdr call ReadSHdr IF FMR70 call a20_off ENDIF public TP_load TP_load label near mov ax, _DATA mov ds, ax ; ; clear BSS ; mov edi, EBSS.Lo add edi, EBSS.Base sub edi, ThisDataBase ; mov ecx, ahdr.bsize movzx ecx, fhdr.f_minalloc shl ecx, 12 IF FMR70 call a20_on ENDIF mov al, 0 prefix32 ;32-bit addrs rep stosb ;zero bss IF FMR70 call a20_off ENDIF mov ax, ds ;base for GDT cwde shl eax, 4 add eax, offset GDT mov GDTBase, eax mov ax, ds ;base for IDT cwde shl eax, 4 add eax, offset IDT mov IDTBase, eax mov ax, ds ;base for LDT cwde shl eax, 4 add eax, offset LDT mov LDTBase, eax mov eax, COMMUNICATION ;base for communication shl eax, 4 mov CommDataBase, eax SetDesc LDTDesc, LDTBase, LDTLimit SetDesc GDTDesc, GDTBase, GDTLimit SetDesc ExeCode, ECode.Base, ECode.Hi SetDesc ExeData, EData.Base, EData.Hi SetDesc ThisCode, ThisCodeBase, 0fffffh ; ; we use ThisData to access both thisdata and ExeData, ; so, it's limit must be enogh (very large) value. ; SetDesc ThisData, ThisDataBase, 0ffffffffh SetDesc CommData, CommDataBase, CommLimit SetDesc LSEG_PSP2,ProgPSP.Base, 512 SetDesc LSEG_ENV, ProgENV.Base, ProgENV.Hi mov eax, fhdr.f_eip mov [EntryEIP], eax IF FMR70 call a20_off ENDIF ; ; show memory allocation ; IF Testing mov dx, offset GDTBaseS call Msg mov eax, GDTBase call Hex32 mov dx, offset LDTBaseS call Msg mov eax, LDTBase call Hex32 mov dx, offset IDTBaseS call Msg mov eax, IDTBase call Hex32 mov dx, offset ExeCodeS call Msg mov eax, ECode.Base call Hex32 mov dx, offset ExeDataS call Msg mov eax, EData.Base call Hex32 mov dx, offset ExeEntry call Msg mov eax, EntryEIP call Hex32 mov dx, offset ExeLimits call Msg mov eax, ECode.Hi call Hex32 mov eax, EData.Hi call Hex32s mov eax, EBss.Hi call Hex32s mov dx, offset ThisCodeS call Msg mov eax, ThisCodeBase call Hex32 mov dx, offset ThisDataS call Msg mov eax, ThisDataBase call Hex32 mov dx, offset ProtectedS call Msg pop es call getchar IF FMR70 call a20_on ENDIF cmp al, 'c' jnz .st_mode1 or DebugFlag, MASK Sys_Out_COM .st_mode1: cmp al, 'r' jnz .st_mode2 or DebugFlag, MASK Deb_Trace_Reg .st_mode2: cmp al, ' ' jnz .st_mode3 mov DebugFlag, 0 mov TraceCount, 0 jmp .st_modex .st_mode3: and al, 1fh mov ah, 0 mov TraceCount, ax .st_modex: ENDIF IF 0 IF Trace OR I7 push ds sub bx, bx mov ds, bx IF Trace mov word ptr [bx][1*4+0], offset Int1 mov word ptr [bx][1*4+2], cs mov word ptr [bx][3*4+0], offset Int3 mov word ptr [bx][3*4+2], cs ENDIF IF I7 mov word ptr [bx][7*4+0], offset Int7 mov word ptr [bx][7*4+2], cs ENDIF IF I2 mov word ptr [bx][2*4+0], offset Int2 mov word ptr [bx][2*4+2], cs ENDIF pop ds ENDIF ENDIF ; test DebugFlag, MASK Deb_Trap_DOS ; jz .notrap call Copy_original IF PCAT call CopyVectors mov ah, 50h call P8259 ENDIF public TP_Vect TP_Vect label near IF FMR70 call a20_on ENDIF .386P ;;IF WithFPU ; with or without FPU fninit fstcw Control387 fwait or Control387, 3fh fldcw Control387 fclex fsetpm ;;ENDIF cli lidt IDTLimitBase ;interrupt descriptor table lgdt GDTLimitBase ;global descriptor table mov eax, CR0 or al, ONCR0 and al, OFFCR0 mov CR0, eax ;protection on fjmp ThisCodeSel, ToProtection endp ToProtection proc far mov ax, LDTSel lldt ax ;local descriptor table mov ax, ThisDataSel mov ds, ax mov [TraceCount],0 lss esp, ExeSSESP mov ax, ExeDataSel mov ds, ax mov es, ax mov gs, ax mov fs, ax sti IF Trace pushf or word ptr [esp], 100h popf ENDIF jmp cs:[EntryPointer] ;do image endp ; ; fault trap ; IRout macro n Int&n proc near pushad mov dx, offset Int&n&S jmp CommonTrap Int&n endp endm CommonTrap proc near mov ax, _DATA mov ds, ax call Msg mov dx, offset RegS call Msg mov bp, sp add bp, 7*4 mov cx, 8 PrintRegs: mov eax, [bp] call Hex32S sub bp, 4 loop PrintRegs mov ErrorOffset, 4 call PrintTrace call PrintStack mov eax, CR0 jmp OSExit CommonTrap endp ; PrintStack proc near push esi push ecx push eax mov esi, SavedESP call CRLF mov ax, SavedSS test al, 04 jz .prints1 push ax ; mov al,'L' ; call putchar pop ax add esi, EData.base sub esi, ThisDataBase .prints1: ; les eax, SavedSSESP ; call printPointer ; mov dx, offset msg_stack call Msg cld prefix32 lodsw call Hex mov cx, 5 .prints2: prefix32 lodsw call Hexs loop .prints2 mov cx, 5 .prints3: prefix32 lodsd call Hex32s loop .prints3 pop eax pop ecx pop esi ret PrintStack endp IRout 0 IRout 2 IRout 4 IRout 5 IRout 6 IRout 7 IRout 8 IRout 9 IRout 10 IRout 11 IRout 12 IRout 13 IRout 14 IRout 15 IRout 16 IRout 117 ; 75h = NDP trap PutReg proc near mov ebp,esp mov ecx,16 putreg1: mov eax, [ebp] call Hex32S add ebp, 4 loop putreg1 call CRLF ret PutReg endp extrn Int1:near, Int3:near ;Come here thru Interrupt gate N .386P IntrN macro n Intr&n: push ds ;B-bit set, use ESP push es push fs push gs ; push eax mov ax,ThisDataSel ;select ThisData mov ds, ax pop eax mov SavedIntN, n ;remeber interrupt # jmp near ptr IntServer endm TrapN macro n Intr&n: push ds ;B-bit set, use ESP push es push fs push gs ; test 12:00 push eax mov ax, ThisDataSel ;select ThisData mov ds, ax pop eax mov SavedIntN, offset Int&n ;remeber interrupt # jmp near ptr TrapServer endm x = 0 rept 10h-0h+1 TrapN %x x = x+1 endm rept 20h-11h+1 ;11h..20h IntrN %x x = x+1 endm ; IntrN 33 x = 22h ;x becomes 22h rept 3fh-22h+1 ;22h..74h IntrN %x x = x+1 endm x = 40h ;x becomes 22h rept 4fh-40h+1 IntrN %x x = x+1 endm x = 50h ;x becomes 22h rept 74h-50h+1 ;22h..74h IntrN %x x = x+1 endm TrapN 117 x = 76h rept 0ffh-76h+1 IntrN %x x = x+1 endm .386P IntServer proc far mov SavedSS, ss ;remember Image's stack mov SavedESP, esp mov SavedEAX, eax ;store mov ax, ds mov es, ax ;all segments to ThisData mov ss, ax mov fs, ax mov gs, ax mov eax, CR0 and al, NOT 1 mov CR0, eax ;enter REAL mode fjmp _TEXT, Flush Flush label far mov ax, _DATA ;all segments to .data mov ds, ax mov gs, ax mov ax, COMMUNICATION mov es, ax assume es: COMMUNICATION mov ax, 0 ;except fs to 0 mov fs, ax lidt RMIDTLimitBase ;real mode interrupts lss esp, ThisSSESP mov ax, SavedIntN ;get intr index cwde mov ds, ToDosDS mov es, ToDosES pushf ;emulate int push cs push offset RetI push dword ptr fs: [4*eax] ;push address of int. routine mov eax, gs: SavedEAX ;restore EAX ret ;goto int routine IntServer endp ; ;come here from int routine n ; RetI proc far cli push COMMUNICATION pop fs mov fs: FromDosDS, ds mov fs: FromDosES, es push _DATA pop ds mov SavedEAX, eax lidt IDTLimitBase ;protected mode ints lgdt GDTLimitBase mov eax, CR0 ;enter protected mode or al, ONCR0 and al, OFFCR0 mov CR0, eax fjmp ThisCodeSel, Protected .386P Protected: mov ax, LDTSel lldt ax ;local descriptors mov ax, ThisDataSel ;ThisData mov ds, ax mov eax, SavedEAX lss esp, SavedSSESP ;restore image's stack ; B-bit now set, use ESP pop gs ;restore segment registers pop fs pop es pop ds iretd ;return to image RetI endp .386P TrapServer proc far mov SavedSS, ss ;remember Image's stack mov SavedESP, esp mov SavedEAX, eax ;store mov ax, ds mov es, ax ;all segments to ThisData mov fs, ax mov gs, ax comment % IF TransPort push edi push esi push ebp push ebx mov edi, offset stack_log mov ebx, 0 cld mov eax, ebp stosd .trap_ss1: mov eax, ss:[ebp + ebx*4] stosd inc bx cmp bx, 1fh jb .trap_ss1 pop ebx pop ebp pop esi pop edi ENDIF % mov ss, ax mov eax, CR0 and al, NOT 1 mov CR0, eax ;enter REAL mode fjmp _TEXT, TrapFlush TrapFlush label far mov ax, _DATA ;all segments to .data mov ds, ax mov es, ax mov fs, ax mov gs, ax lss esp, ThisSSESP lidt RMIDTLimitBase ;real mode interrupts sti mov eax, SavedEAX call SavedIntN ;call the routine cli lidt IDTLimitBase ;protected mode ints lgdt GDTLimitBase mov eax, CR0 ;enter protected mode or al, ONCR0 and al, OFFCR0 mov CR0, eax fjmp ThisCodeSel, TrapProtected .386P TrapProtected: mov ax, LDTSel lldt ax ;local descriptors mov ax, ThisDataSel ;ThisData mov ds, ax mov eax, SavedEAX lss esp, SavedSSESP ;restore image's stack ; ; B-bit now set, use ESP ; pop gs ;restore segment registers pop fs pop es pop ds iretd ;return to image TrapServer endp ; ; ; int 21 from protected mode ; Hardware interrupt may occure while CPU executing this routine. ; So, we must not share save area with other interrupt handlers. ; .386P DosServer proc far Intr33 label far push ds push es push fs push gs push eax ; setup accessability cli ; mov ax, ThisDataSel mov ds, ax mov es, ax ; ; save registers ; pop eax mov ExeEAX, eax mov eax, [esp].sp_eip mov ExeEIP, eax mov ax, [esp].sp_cs mov ExeCS, ax mov eax, [esp].sp_flag mov SavedFlags, eax mov ExeESP, esp mov ExeSS, ss ; mov ax, ds mov ds, ax mov es, ax mov fs, ax mov gs, ax mov ss, ax ; mov eax, CR0 and al, NOT 1 mov CR0, eax ; extrn DosFlush:far fjmp _TEXT, DosFlush endp public dosprotected DosProtected proc far mov ax, LDTsel lldt ax mov ax, ThisDataSel mov ds, ax mov es, ax ; ; labeled just for temporaly ; lss esp, ExeSSESP mov eax, SavedFlags mov ss:[esp].sp_flag,eax mov eax, ExeEAX pop gs pop fs pop es pop ds sti iretd endp _TEXT ends end Start