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Assembly Source File | 1994-02-09 | 17.3 KB | 521 lines

page 55,132 title "PERUSEX = XMS interface for PERUSE" ; --------------------------------------------------------------------- ; ; PERUSEX - XMS interface for PERUSE ; First Published in PC Magazine April 12, 1994 ; ; --------------------------------------------------------------------- ; --------------------------------------------------------------------- ; $lgb$ ; 1.0 02/09/94 RVF Final beta complete. Can release if ; + no other errors found. ; $lge$ ; --------------------------------------------------------------------- ; $nokeywords$ ; ----------------------------------------------------------------------- ; ; Buffer Memory Interface Routines ; ; ----------------------------------------------------------------------- ; The folowing routines serve as the interface to the buffer memory. ; ; All (or in this case, both) modules have the same inteface that ; allows use of the buffer storage without the utilitie's specific ; knowledge of what memory is in use. ; ; Each module has a standard header that consists of the following: ; ; 2 byte length of module ; 1 byte module identifier (E = EMX, X = XMS) ; Note: Must be upper case ; JMP instrution to main entry point ; ; Nothing is guaranteed beyond the header. ; ; The module must be completely self contained, lying completely within ; it's own segment. Any references within the segment must be relative ; to that segment since PERUSE moves the module, in its entirety, to ; another segment aligned address where it is actually executed. ; ; ----------------------------------------------------------------------- ; ; Here are the specific calling sequences: ; ; ----------------------------------------------------------------------- ; General Return ; -------------- ; If any error occurs, the function sets the carry flag. ; ; carry flag = error ; Initialize Scroll Memory ; ------------------------ ; This call checks that the requested type of memory exists in ; sufficient quantity to complete the call. If so, it allocates the ; the memory and stores any information needed to access the memory. ; ; ax = 00h ; cx = number of 1k records needed ; Read scroll record ; ------------------ ; This function reads a record from the scroll buffer. If there are ; n used records in the scroll buffer, the application may request ; record numbers 0 to n-1. The contents of the record are placed in ; the buffer located at es:dx. ; ; The most recent record is considered record 0 and the oldest is n-1. ; ; ax = 01h ; bx = record number; where: 0=oldest record, n-1=most recent ; es:di -> buffer ; Write scroll record ; ------------------- ; This function writes a new record to the scroll buffer. If the ; scroll buffer has already filled, the oldest record is overwritten. ; ; ax = 02h ; ds:bx -> buffer to write ; Get number of used records ; -------------------------- ; This function returns the number of records used in the scroll buffer. ; ; ax = 03h ; ; returns: ; ax = number of records used ; Release scroll buffer ; --------------------- ; This function is called to release the scroll buffer before removing ; the TSR from memory. If this function is not called, the scroll ; buffer will not be released until the system is rebooted. ; ; ax = 04h ; Save record pointer ; ------------------- ; This function saves the current record information maintained by the ; interface routine. Any future records written to the buffer can then ; be "unsaved" by calling function 6. ; ; ah = 05h ; Restore pointers ; ---------------- ; This function restores the record pointers saved with function 5. ; Furthermore, it clears any records written after the save. ; ; ax = 06h ; ---------------------------------------------------------------------- IFNDEF Borland ; Assemble in MASM only MaxFunction equ 6 ; Maximum function number RecSize equ 1024 ; record size ENDIF ; ---------------------------------------------------------------------- ; ; Xms Interface Routine ; ; ---------------------------------------------------------------------- XmsInt segment para public 'code' ; Xms interface assume cs:XmsInt, ds:XmsInt ; called via far call XmsStart: XmsLen dw XmsEnd ; length of module db 'X' ; module identifier jmp short Xms ; jump to dispatcher XmsAdr dd 0 ; call address for XMS driver XmsDS dw 0 ; entry DS register ; ; XMS move structure ; XmsMvStr struc ; XMS move structure XmsMvLen dd 0 ; length to move XmsMvShnd dw 0 ; source handle XmsMvSoff dd 0 ; source offset XmsMvDhnd dw 0 ; destination handl XmsMvDoff dd 0 ; destination offset XmsMvStr ends ; ..end of structure XmsBlock XmsMvStr <> ; instance of XMS move structure ; ; Equates to access XMS move structure ; XmsBLen equ word ptr XmsBlock.XmsMvLen ; Length Field XmsBShnd equ XmsBlock.XmsMvShnd ; Source handle XmsBSoffL equ word ptr XmsBlock.XmsMvSoff ; Source offset low XmsBSoffH equ word ptr XmsBlock.XmsMvSoff+2; Source offset high XmsBDhnd equ XmsBlock.XmsMvDhnd ; Dest handle XmsBDoffL equ word ptr XmsBlock.XmsMvDoff ; Dest offset low XmsBDoffH equ word ptr XmsBlock.XmsMvDoff+2; Dest offset high XmsRecs dw 0 ; records allocated XmsUsed dw 0 ; records used XmsOld dw 0 ; Oldest Record XmsSUsed dw 0 ; saved records used XmsSOld dw 0 ; saved oldest record XmsWrites dw 0 ; writes since save XmsHndl dw 0 ; Xms handle XmsTbl label byte ; function dispatch table dw Xms0 ; Initialize dw Xms1 ; Read Record dw Xms2 ; Write Record dw Xms3 ; Get number of records dw Xms4 ; Free Xms memory dw Xms5 ; Save 4k dw Xms6 ; Restore 4k ; --------------------- ; Interface Entry Point ; --------------------- Xms proc Far ; dispatch the call push si ; save registers push ds push es mov cs:XmsDS, ds ; save entry DS register push cs ; save our segment pop ds ; ds -> this segment cmp ax, 07h ; q. out of range? jnb XmsRtnErr ; a. yes .. error shl ax, 1 ; ax = ax * 2 (table index) mov si, ax ; si = table index jmp word ptr XmsTbl[si] ; go to the routine ; -------------- ; Error return.. ; -------------- XmsRtnErr: stc ; set the carry bit pop es ; restore pop ds ; ..saved pop si ; .. ..registers ret ; return with error ; ----------- ; Return OK.. ; ----------- XmsRtnOk: clc ; reset carry bit pop es ; restore pop ds ; ..saved pop si ; .. ..registers ret ; return OK ; -------------------------------------------------- ; Initialization; cx = number of records to allocate ; -------------------------------------------------- Xms0 label byte push bx ; save registers push dx push di push si mov XmsRecs, cx ; save records requested mov ax, 4300h ; ax = XMS Installed request int 2fh ; ..ask if XMS installed cmp al, 80h ; q. XMS installed? jne Xms0Err ; a. no .. return with error ; ; Get the XMS call address ; mov ax, 4310h ; ax = get XMS call address int 2fh ; es:bx -> call address mov word ptr XmsAdr, bx ; save the offset mov word ptr XmsAdr+2, es ; ..and the segment ; ; XMS found .. Allocate the buffer (if possible) ; mov dx, XmsRecs ; dx = number of records req'd mov ah, 09h ; ah = allocate page call [XmsAdr] ; ..request memory cmp ax, 1 ; q. allocate ok? jne Xms0Err ; a. no .. return with error mov XmsHndl, dx ; save the handle ; ; Return with no error .. ; pop si ; restore registers pop di pop dx pop bx jmp XmsRtnOk ; ..return no error ; ; Return with an error .. ; Xms0Err: pop si ; restore registers pop di pop dx pop bx jmp XmsRtnErr ; ..return w/error ; ------------------------------------------------ ; Read record; bx = record number; es:di -> buffer ; ------------------------------------------------ Xms1 label byte cmp bx, XmsUsed ; q. valid record number? jae XmsRtnErr ; a. no .. exit now push cx ; save registers push dx push di add bx, XmsOld ; add in oldest record number cmp bx, XmsUsed ; q. beyond end of buffer? jb Xms1$10 ; a. no .. use this number sub bx, XmsUsed ; bx = record number Xms1$10: mov XmsBDhnd, 0 ; set the handle mov XmsBDoffL, di ; set the target address mov XmsBDoffH, es ; set the target segment mov di, XmsHndl ; di = our XMS handle mov XmsBShnd, di ; ..put in move structure mov ax, bx ; ax = record number mov cx, 1024 ; cx = multiplier (record length) mov XmsBLen, cx ; ..save as move length mul cx ; dx:ax = offset of record mov XmsBSoffL, ax ; save lsw of offset mov XmsBSoffH, dx ; save msw of offset mov ah, 0bh ; ah = move block mov si, offset XmsBlock ; ds:si -> XMS block call [XmsAdr] ; ask XMS to move the memory cmp ax, 1 ; q. move successful? jne Xms1Err ; a. no .. exit with error ; ; Return with no error .. ; pop di ; restore registers pop dx pop cx jmp XmsRtnOk ; return without error ; ; Return with an error .. ; Xms1Err: pop di ; restore registers pop dx pop cx jmp XmsRtnErr ; return with error ; ------------------------------------ ; Write record; ds:bx -> record buffer ; ------------------------------------ Xms2 label byte push bx ; save registers push dx mov XmsBShnd, 0 ; zero the source handle mov XmsBSoffL, bx ; ..save offset of record mov bx, XmsDS ; bs = record's segment mov XmsBSoffH, bx ; ..save record's segment mov bx, XmsUsed ; bx = records used cmp bx, XmsRecs ; q. all records used? jnb Xms2$10 ; a. yes .. use old to calc inc XmsUsed ; Add to used records jmp short Xms2$20 ; ..continue Xms2$10: mov bx, XmsOld ; bx = next record to write lea ax, 1[bx] ; ax = bx + 1 (next old record) cmp ax, XmsRecs ; q. hit the top of buffer? jb Xms2$15 ; a. no .. continue xor ax, ax ; else .. ax = first rec in Xms Xms2$15: mov XmsOld, ax ; XmsOld = oldest record number ; ; When we get here, bx contains the record number ; Xms2$20: mov ax, bx ; ax = record number mov bx, 1024 ; bx = multiplier (record length) mov XmsBLen, bx ; ..save as move length mul bx ; dx:ax = offset of record mov XmsBDoffL, ax ; save lsw of offset mov XmsBDoffH, dx ; save msw of offset mov ax, XmsHndl ; ax = memory handle mov XmsBDhnd, ax ; ..save the handle mov ah, 0bh ; ah = move block mov si, offset XmsBlock ; ds:si -> XMS block call [XmsAdr] ; ask XMS to move the memory inc cs:XmsWrites ; ..increment write count cmp ax, 1 ; q. move successful? jne Xms2Err ; a. no .. exit with error ; ; Return with no error .. ; pop dx pop bx jmp XmsRtnOk ; return without error ; ; Return with an error .. ; Xms2Err: pop dx ; restore registers pop bx jmp XmsRtnErr ; return with error ; -------------------------- ; Get number of used records ; -------------------------- Xms3 label byte mov ax, XmsUsed ; ax = records used jmp XmsRtnOk ; ..return ok ; --------------------- ; Release scroll buffer ; --------------------- Xms4 label byte push dx ; save registers mov ah, 0ah ; ah = deallocate Xms memory mov dx, XmsHndl ; dx = our Xms handle call [XmsAdr] ; ..Hey, Xms, deallocate it! pop dx jmp XmsRtnOk ; return no error ; -------------------- ; Save record pointers ; -------------------- Xms5 label byte push cs:XmsUsed ; save records used pop cs:XmsSUsed ; ..in save field push cs:XmsOld ; save oldest record pop cs:XmsSOld ; ..in save field mov cs:XmsWrites, 0 ; zero write counter jmp XmsRtnOk ; ..return without error ; ----------------------- ; Restore record pointers ; ----------------------- Xms6 label byte push cs:XmsSUsed ; reload used field pop cs:XmsUsed ; ..from save field push cs:XmsSOld ; reload oldest record pop cs:XmsOld ; ..from save field mov ax, cs:XmsWrites ; return number of writes jmp XmsRtnOk ; ..return without error align 16 ; boundary for next driver XmsEnd label byte Xms endp XmsInt ends IFNDEF Borland ; Assemble in MASM only ENDSTMT macro ; macro only needed with MASM end XmsStart ; end the assembly endm ENDIF ENDSTMT ; varies with Tasm and Asm