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;**************************************************************************;* TASK2.ASM;*;* Assembly support for the task enumeration routines.;*;**************************************************************************
INCLUDE TOOLPRIV.INC
PMODE32 = 0PMODE = 0SWAPPRO = 0 INCLUDE TDB.INCifdef WOW INCLUDE WOW.INCendif
;** Data
sBegin DATA
lpfnRetAddr DD 0 ;Return address after stack switch
sEnd
;** External functionsexternNP HelperHandleToSelexternNP HelperVerifySegexternFP GetCurrentTaskexternFP DirectedYieldifdef WOWexternFP PostAppMessageendif
;** Functions
.286p
sBegin CODE assumes CS,CODE assumes DS,DATA
; TaskSetCSIP; Allows the user to set the CS:IP of a sleeping task so that it will; begin execution at this address when the task is yielded to.; Returns the old address.
cProc TaskSetCSIP, <PUBLIC,FAR>, <si> parmW hTask parmW wCS parmW wIPcBegin assumes DS,nothing assumes ES,nothing
;** If this is the current task, do nothing: we only work on ;** sleeping tasks cCall GetCurrentTask ;Gets current task in AX mov bx,hTask ;Get desired task cmp ax,bx ;Same? jne @F ;No, it's OK xor ax,ax ;Return a DWORD zero cwd jmp SHORT TC_End@@:
;** Get the TDB SS:SP mov es,bx ;Point to TDB with ES les si,DWORD PTR es:[TDB_TaskSP] ;Get a pointer to the task stackifdef WOW ; ; ES:SI now points to the place where we had the TDB's SS:SP pointing ; This spot in wow is actually the SS:BP frame of the WOW16CALL ; function. The definitions for this frame come from WOW.INC (WOW.H). ; The addition of this strange value adjusts the SS:SP pointer back ; onto the stack, undoing a previous adjustment in TASKING.ASM add si,(vf_vpCSIP-vf_wThunkCSIP)endif ;** Change the CS:IP mov ax,wIP ;Get the new IP value xchg ax,es:[si].Task_IP ;Swap with the old one mov dx,wCS ;Get the new CS value xchg dx,es:[si].Task_CS ;Swap with the old one
TC_End:cEnd
; TaskGetCSIP; Gets the next CS:IP that this task will run at.
cProc TaskGetCSIP, <PUBLIC,FAR>, <si> parmW hTaskcBegin assumes DS,nothing assumes ES,nothing
;** If this is the current task, do nothing: we only work on ;** sleeping tasks cCall GetCurrentTask ;Gets current task in AX mov bx,hTask ;Get desired task cmp ax,bx ;Same? jne @F ;No, it's OK xor ax,ax ;Return a DWORD zero cwd jmp SHORT TG_End@@:
;** Get the TDB SS:SP mov es,bx ;Point to TDB with ES les si,DWORD PTR es:[TDB_TaskSP] ;Get a pointer to the task stack
ifdef WOW ; ; ES:SI now points to the place where we had the TDB's SS:SP pointing ; This spot in wow is actually the SS:BP frame of the WOW16CALL ; function. The definitions for this frame come from WOW.INC (WOW.H). ; The addition of this strange value adjusts the SS:SP pointer back ; onto the stack, undoing a previous adjustment in TASKING.ASM add si,(vf_vpCSIP-vf_wThunkCSIP)endif ;** Change the CS:IP mov ax,es:[si].Task_IP ;Get the CS:IP to return mov dx,es:[si].Task_CS
TG_End:cEnd
; TaskSwitch; Switches to the indicated task from the current one.; Returns FALSE if it couldn't task switch.; Jumps to the address given by lpJmpAddr
cProc TaskSwitch, <PUBLIC,FAR>, <si,di> parmW hTask parmD lpJmpAddrcBegin push ds mov ax, _DATA ;Make sure to set DS mov ds, ax assumes ds,DATA
;** Check to make sure TOOLHELP is installed cmp wLibInstalled,0 ;Library installed? pop ds assumes ds,nothing jnz @F ;Yes xor ax,ax ;Return FALSE jmp TS_End ;No. Fail the API@@:
;** Get the task handle cCall GetCurrentTask ;Get the current task cmp ax,hTask ;Switch to current task? jne @F ;No, it's OK xor ax,ax ;Yes, we can't do that so return FALSE
ifdef WOW jmp TS_Endelse jmp SHORT TS_Endendif
@@: cCall HelperVerifySeg, <hTask,TDB_sig+1> ;Verify the segment or ax,ax ;Segment OK? jz TS_End ;Nope. Get out mov es,hTask ;Get the TDB xor ax,ax ;Get a zero just in case cmp es:[TDB_sig], TDB_SIGNATURE ;Signature match? jne TS_End ;Return FALSE
;** Poke in the address to jump to mov si,es ;Save the hTask lea ax,TS_FromYield ;Point to new task address cCall TaskSetCSIP, <si,cs,ax> ;Set the new address mov es,si ;Get hTask back
;** Save the jump address from the stack so we can jump to it later push ds mov ax,_DATA ;Point to our data segment mov ds,ax assumes ds,DATA mov ax,WORD PTR lpJmpAddr[0];Get the low word of the ret address mov WORD PTR lpfnRetAddr[0],ax mov ax,WORD PTR lpJmpAddr[2];Get the selector value mov WORD PTR lpfnRetAddr[2],ax pop ds
ifdef WOW ;** Force a task switch by posting a message. This is because the ;** event count is not used under WOW. cCall PostAppMessage,<es, 0, 0, 0, 0>else ;** Force a task switch by tampering with the event count inc es:[TDB_nEvents] ;Force at least one event so we ; will switch to this task nextendif ;WOW
;** Switch to the new task. DirectedYield() returns only when this ;** task is next scheduled cCall DirectedYield, <si> ;Switch to the new task mov ax,1 ;Return TRUE jmp SHORT TS_End ;Get out
;** Restore from the directed yieldTS_FromYield:
;** Make a stack frame to work on. We can't trash any regs PUBLIC TS_FromYield sub sp,4 ;Save room for a far ret frame push bp ;Make a stack frame mov bp,sp pusha ;Save everything push ds push es
;** Get our jump address from our DS and put in far ret frame mov ax,_DATA ;Get the TOOLHELP DS mov ds,ax mov ax,WORD PTR lpfnRetAddr[0] ;Get the offset mov [bp + 2],ax ;Put it on the stack mov ax,WORD PTR lpfnRetAddr[2] ;Get the selector mov [bp + 4],ax ;Put on the stack
;** Restore the event count mov es,segKernel ;Get the KERNEL segment mov bx,npwTDBCur ;Get the current task pointer mov es,es:[bx] ;Get the TDB pointer in ESifndef WOW dec es:[TDB_nEvents] ;Clear the dummy event we put inendif
;** Clear the stack and 'return' to the new address pop es pop ds popa pop bp retf
TS_End:cEnd
; TaskInfo;; Returns information about the task with the given block handle
cProc TaskInfo, <PUBLIC,NEAR>, <si,di,ds> parmD lpTask parmW wTaskcBegin ;** Start by verifying the selector mov ax,wTask ;Get the selector cCall HelperHandleToSel, <ax> ;Convert it to a selector push ax ;Save it mov bx,TDBSize cCall HelperVerifySeg, <ax,bx> pop bx ;Get selector back or ax,ax ;FALSE return? jnz TI_SelOk ;Selector's OK xor ax,ax ;Return FALSE jmp TI_EndTI_SelOk:
;** Verify that the TDB signature matches mov ds,bx ;Point with DS cmp ds:[TDB_sig],TDB_SIGNATURE ;Is this really a TDB? jz TI_SigOk ;Must be xor ax,ax ;Return FALSE jmp SHORT TI_EndTI_SigOk:
;** Now, get information from the TDB les di,lpTask ;Point to destination buffer mov ax,ds:[TDB_next] ;Get the next TDB handle mov es:[di].te_hNext,ax ;Save in public structure mov ax,wTask ;Get this task's handle mov es:[di].te_hTask,ax ;Save in buffer mov ax,ds:[TDB_Parent] ;Get this task's parent mov es:[di].te_hTaskParent,ax ;Save mov ax,ds:[TDB_taskSS] ;Get the SS mov es:[di].te_wSS,ax mov ax,ds:[TDB_taskSP] ;Get the SP mov es:[di].te_wSP,ax mov ax,ds:[TDB_nEvents] ;Event counter mov es:[di].te_wcEvents,ax mov ax,ds:[TDB_Queue] ;Queue pointer mov es:[di].te_hQueue,ax mov ax,ds:[TDB_PDB] ;Offset of DOS PSP mov es:[di].te_wPSPOffset,ax mov ax,ds:[TDB_Module] ;Instance handle (DS) of task mov es:[di].te_hInst,ax mov ax,ds:[TDB_pModule] ;Module database handle mov es:[di].te_hModule,ax mov cx,8 ;Copy module name push di ;Save structure pointer mov si,TDB_ModName ;Point to the string add di,te_szModule ; and to the string dest cld repnz movsb ;Copy the string mov BYTE PTR es:[di],0 ;Zero terminate it pop di ;Get structure pointer back
;** Get information from the stack segment. Vars from KDATA.ASM mov ax,es:[di].te_wSS ;Get the SS value verr ax ;OK to read here? jnz TI_SkipThis ;No, so don't do it mov ds,ax ;Point with DS mov ax,ds:[0ah] ;Lowest value of SP allowed mov es:[di].te_wStackTop,ax ;Save in structure mov ax,ds:[0ch] ;Get stack minimum value so far mov es:[di].te_wStackMinimum,ax ;Save in structure mov ax,ds:[0eh] ;Largest value of SP allowed mov es:[di].te_wStackBottom,ax ;Save in structure
;** Return TRUE on successTI_SkipThis: mov ax,1 ;Return TRUE codeTI_End:cEnd
sEnd
END
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