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TITLE GLRU - Primitives for LRU management
.xlistinclude kernel.incinclude newexe.incinclude tdb.incinclude protect.inc.list
.386p
DataBegin
externB Kernel_InDOSexternB Kernel_flags;externW curTDBexternW loadTDBexternW pGlobalHeap;externW hExeSweep;externW WinFlags
if ROMexternW gdtdscendif DataEnd
sBegin CODEassumes CS,CODE
externNP DPMIProc
ife ROMexternW gdtdscendif
;-----------------------------------------------------------------------;; lrusweep ;; ;; Searches all of the exe headers in the system for segments that have ;; been accessed since the last time through. For each segment found ;; its referenced byte is reset and that segment is moved to the top ;; of the lru chain. This routine is called (default) every 4 timer ;; ticks from the int 8 handler. ;; ;; Arguments: ;; none ;; ;; Returns: ;; nothing ;; ;; Error Returns: ;; ;; Registers Preserved: ;; DX,DI,SI,DS ;; ;; Registers Destroyed: ;; AX,BX,CX,ES ;; ;; Calls: ;; glrutop ;; ;; History: ;; ;; Tue Apr 21, 1987 06:22:41p -by- David N. Weise [davidw] ;; Added the check for discarded segments. ;; ;; Wed Apr 08, 1987 11:00:59a -by- David N. Weise [davidw] ;; Made it clear only the curTask's private handle table. ;; ;; Wed Feb 18, 1987 08:13:35p -by- David N. Weise [davidw] ;; Added the sweeping of the private handle tables. ;; ;; Tue Feb 10, 1987 02:11:40a -by- David N. Weise [davidw] ;; Added this nifty comment block. ;;-----------------------------------------------------------------------;
cProc lrusweep,<PUBLIC,FAR>cBegin nogen
push edx push edi push esi push ds push es push fs xor edx,edx xor edi,edi SetKernelDS fs
; [notes from code review 4/91, added by donc 4/16/91; 1) should check WinFlags1 for WF_PAGING,; 2) insist on direct LDT access; 3) try assembling without DPMI; 4) have LRUSweepFreq= setting in .ini file to control update rate; ] ; Excuses not to do the sweep: cmp kernel_InDOS,0 ; SMARTDrive and EMS may be present jnz short dont_do_it ; => disk buffers over the code segs cmp di,loadTDB ; Ignore interrupt if loading task jnz short dont_do_it mov ds,pGlobalHeap cmp di,ds:[di].gi_lrulock ; Ignore interrupt if inside memory jz short do_it ; manager
dont_do_it: jmp sweepdone
do_it: mov cx, ds:[di].gi_lrucount jcxz dont_do_it mov esi, ds:[di].gi_lruchain
mov bx, gdtdsc or bx, bx ; See if we can poke at the LDT jz short sweep_loop_dpmi ; no, must use DPMI calls mov es, bx ; yes, ES points to the LDT
; Direct LDT access loopsweep_loop: mov esi, [esi].pga_lrunext mov bx, [esi].pga_handle
sel_check bx
if KDEBUG test es:[bx].dsc_hlimit, DSC_DISCARDABLE ; Ensure it really is discardable jnz short sweep_ok Debug_Out "lrusweep: Bad lru entry"sweep_ok:endif
btr word ptr es:[bx].dsc_access, 0 ; Test and reset accessed bit.errnz DSC_ACCESSED-1 jnc short sweep_next call glrutop ; Accessed objects are most recently used
sweep_next: loop sweep_loop jmps sweepdone
; DPMI loopsweep_loop_dpmi: mov esi, [esi].pga_lrunext mov bx, [esi].pga_handle lar edx, ebx shr edx, 8 ; Access bits in DX if KDEBUG test dh, DSC_DISCARDABLE ; Ensure it really is discardable jnz short sweep_ok_dpmi Debug_Out "lrusweep: Bad lru entry"sweep_ok_dpmi:endif
btr dx, 0 ; Segment accessed?.errnz DSC_ACCESSED-1 jnc short sweep_next_dpmi ; no, leave it where it is on LRU list push cx mov cx, dx DPMICALL 0009h ; Set access word pop cx
call glrutop ; Accessed objects are most recently used
sweep_next_dpmi: loop sweep_loop_dpmi
sweepdone: pop fs pop es pop ds pop esi pop edi pop edx ret UnSetKernelDS fscEnd nogen
;; Entry:; DI == 0; DS:SI.gi_lruchain -> head of list; ES:0 -> arena header of object to insert; DX = 0 => insert at head of list; !=0 => insert at tail of list;; Exit:; BX,DX destroyed;cProc LRUInsert,<PUBLIC,NEAR>cBegin nogen inc ds:[di].gi_lrucount ; Increment count of LRU entries mov ebx,ds:[di].gi_lruchain ; BX = head of list or dx,dx ; Inserting at head of chain? jnz short lruins0 ; No, tail so dont update head mov ds:[di].gi_lruchain,esi ; Yes, make new one the new headlruins0: or ebx,ebx ; List empty? jnz short lruins1 mov ds:[esi].pga_lruprev,esi; Yes, make circular mov ds:[esi].pga_lrunext,esi mov ds:[di].gi_lruchain,esi retlruins1: mov edx,esi ; DX = new xchg ds:[ebx].pga_lruprev,edx mov ds:[edx].pga_lrunext,esi
mov ds:[esi].pga_lruprev,edx mov ds:[esi].pga_lrunext,ebx
retcEnd nogen
;; Entry:; DI == 0; DS:DI.gi_lruchain -> head of list; DS_ESI -> arena header of object to delete;; Exit:; EBX,EDX destroyed;;cProc LRUDelete,<PUBLIC,NEAR>cBegin nogen
;; This is basically a consistency check, in case we don't fix; GlobalRealloc() for 3.1.; push eax mov eax,ds:[esi].pga_lrunext or eax,ds:[esi].pga_lruprev pop eax jz lrudel_ret
dec ds:[di].gi_lrucount ; Decrement count of LRU entries jnz short lrudel0 mov ds:[di].gi_lruchain,edi ; List empty, zero LRU chain. mov ds:[esi].pga_lruprev,edi; Zero pointers in deleted object mov ds:[esi].pga_lrunext,edi retlrudel0: mov edx,esi cmp ds:[di].gi_lruchain,edx ; Are we deleting the head? jne short lrudel1 mov edx,ds:[esi].pga_lrunext mov ds:[di].gi_lruchain,edx ; Yes, make it point to the next onelrudel1: xor ebx,ebx ; Zero pointers in deleted object xchg ds:[esi].pga_lrunext,ebx
xor edx,edx xchg ds:[esi].pga_lruprev,edx mov ds:[edx].pga_lrunext,ebx mov ds:[ebx].pga_lruprev,edxlrudel_ret: retcEnd nogen
cProc glruSetup,<PUBLIC,NEAR>cBegin nogen mov bx,ds:[esi].pga_handle test bl, GA_FIXED jz short gsmoveable xor bx, bx ; Set ZF jmps gsdonegsmoveable: push ebx lar ebx, ebx test ebx, DSC_DISCARDABLE SHL 16 pop ebx jz short gsdone or sp,spgsdone: retcEnd nogen
;-----------------------------------------------------------------------;; glrutop ;; ;; Moves a discardable object to the head of the LRU chain. ;; ;; Arguments: ;; DS:DI = address of global heap info ;; ES:DI = global arena of moveable object ;; ;; Returns: ;; Updated LRU chain ;; ;; Error Returns: ;; ;; Registers Preserved: ;; CX,DX,SI,DS,ES ;; ;; Registers Destroyed: ;; ;; Calls: ;; ;; History: ;; ;; Wed Feb 18, 1987 08:30:45p -by- David N. Weise [davidw] ;; Added support for EMS. ;; ;; Mon Oct 27, 1986 04:20:10p -by- David N. Weise [davidw] ;; Rewrote it to eliminate the handle table as intermediary. ;;-----------------------------------------------------------------------;
cProc glrutop,<PUBLIC,NEAR>cBegin nogen push ebx push edx push esi call glruSetup jz short glrutop1
call LRUDelete xor dx,dx ; DX == 0 means insert at head call LRUInsertglrutop1: pop esi pop edx pop ebxif KDEBUG call check_lru_listendif retcEnd nogen
;-----------------------------------------------------------------------;; glrubot ;; ;; Moves a discardable object to the tail of the LRU chain. ;; ;; Arguments: ;; DS:DI = address of global heap info ;; ES:DI = global arena of moveable object ;; ;; Returns: ;; Updated LRU chain ;; ;; Error Returns: ;; ;; Registers Preserved: ;; CX,DX,SI,DS,ES ;; ;; Registers Destroyed: ;; ;; Calls: ;; ;; History: ;; ;; Wed Feb 18, 1987 08:30:45p -by- David N. Weise [davidw] ;; Added support for EMS. ;; ;; Mon Oct 27, 1986 04:20:10p -by- David N. Weise [davidw] ;; Rewrote it to eliminate the handle table as intermediary. ;;-----------------------------------------------------------------------;
cProc glrubot,<PUBLIC,NEAR>cBegin nogen push bx push dx push si call glruSetup jz short glrubot1
call LRUDelete mov dx,sp ; DX != 0 means insert at tail call LRUInsertglrubot1: pop si pop dx pop bxif KDEBUG call check_lru_listendif retcEnd nogen
;-----------------------------------------------------------------------;; glruadd ;; ;; Adds a discardable object to the head of the LRU chain. ;; ;; Arguments: ;; DS:DI = address of global heap info ;; ES:DI = arena header of object ;; ;; Returns: ;; Updated LRU chain ;; ;; Error Returns: ;; ;; Registers Preserved: ;; AX,BX,CX,DX,DI,SI,DS ;; ;; Registers Destroyed: ;; none ;; ;; Calls: ;; nothing ;; ;; History: ;; ;; Wed Feb 18, 1987 08:30:45p -by- David N. Weise [davidw] ;; Added support for EMS. ;; ;; Mon Oct 27, 1986 04:23:35p -by- David N. Weise [davidw] ;; Rewrote it to eliminate the handle table as intermediary. ;;-----------------------------------------------------------------------;
cProc glruadd,<PUBLIC,NEAR>cBegin nogen push bx push dx push si
call glruSetup jz short glruadd1
xor dx,dx ; DX == 0 means insert at head call LRUInsertglruadd1: pop si pop dx pop bxif KDEBUG call check_lru_listendif retcEnd nogen
;-----------------------------------------------------------------------;; glrudel ;; ;; Removes a discardable object from the LRU chain. ;; ;; Arguments: ;; ES:DI = arena header of object ;; DS:DI = address of global heap info ;; ;; Returns: ;; Nothing. ;; ;; Error Returns: ;; ;; Registers Preserved: ;; All ;; ;; Registers Destroyed: ;; ;; Calls: ;; ;; History: ;; ;; Wed Feb 18, 1987 08:30:45p -by- David N. Weise [davidw] ;; Added support for EMS. ;; ;; Mon Oct 27, 1986 04:36:49p -by- David N. Weise [davidw] ;; Rewrote it to eliminate the handle table as intermediary. ;;-----------------------------------------------------------------------;
cProc glrudel,<PUBLIC,NEAR>cBegin nogen push bx push dx push si
call glruSetup jz short glrudel1
call LRUDeleteglrudel1: pop si pop dx pop bxif KDEBUG call check_lru_listendif retcEnd nogen
if KDEBUG
;-----------------------------------------------------------------------;; check_lru_list ;; ;; Checks the glru list for consistency. ;; ;; Arguments: ;; EDI 0 ;; ;; Returns: ;; ;; Error Returns: ;; ;; Registers Preserved: ;; All ;; ;; Registers Destroyed: ;; ;; Calls: ;; nothing ;; ;; History: ;; ;; Wed Feb 18, 1987 08:30:45p -by- David N. Weise [davidw] ;; Added support for EMS. ;; ;; Wed Oct 29, 1986 10:13:42a -by- David N. Weise [davidw] ;; Wrote it. ;;-----------------------------------------------------------------------;
cProc check_lru_list,<PUBLIC,NEAR>cBegin nogen push ds SetKernelDS test Kernel_flags,kf_check_free jz cll_ret
push ax push ebx push cx push edx push esi mov ds,pGlobalHeap UnSetKernelDSdo_it_again: mov ebx,[di].gi_lruchain mov cx,[di].gi_lrucount ; without ems gi_alt_count is 0 or cx,cx jz all_done
mov esi,ebxcheck_chain_loop: mov edx,ds:[esi].pga_lruprev mov esi,ds:[esi].pga_lrunext cmp ds:[edx].pga_lrunext,ebx jz short prev_okay kerror 0FFh,<lru: prev bad>,dx,bxprev_okay: cmp ds:[esi].pga_lruprev,ebx jz short next_okay kerror 0FFh,<lru: next bad>,bx,sinext_okay: mov ebx,esi loop check_chain_loop cmp [di].gi_lruchain,ebx jz short all_done kerror 0FFh,<lru: count bad>,bx,[di].gi_lrucountall_done: pop esi pop edx pop cx pop ebx pop axcll_ret: pop ds retcEnd nogen
endif
sEnd CODE
end
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