Microsoft Programmer's Library 1.3

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Assembly Source File | 1989-06-13 | 6.5 KB | 272 lines

;============================================================================= ; Sample program for EMS Toolbox Routines ; written by Douglas Boling ; (c) 1989 Microsoft Corporation ;============================================================================= DOSSEG .MODEL small .STACK 512 .DATA EMShandle dw 0 ;EMS handle pageframe_seg dw 0 active db 0 ;Flag to indicate int9 active key_code db 0 ;Code of key pressed cursor_pos dw 0 ;Saved position of cursor save_index dw 0 save_area db 100 dup (0) save_area_end = $ .CODE EXTRN GetEMSMem:PROC EXTRN SaveEMSMem:PROC EXTRN RestoreEMSMem:PROC int09h dd 0 ;Saved interrupt 9 vector ;---------------------------------------------------------------------------- ;Keyboard Interrupt. This routine checks for the hotkey then saves or ; restores the video page as necessary. ;---------------------------------------------------------------------------- kbdint proc far assume cs:_text,ds:nothing,es:nothing push ax mov ah,2 ;Get keyboard shift state int 16h cmp al,08h ;See if ALT key pressed jne goto_kbdbios in al,60h ;Read keyboard port cmp al,13h ;See if 'R' key pressed je kbd0 cmp al,2Eh ;See if 'C' key pressed jne goto_kbdbios kbd0: push ds push ax mov ax,@data ;Point DS to data segment. mov ds,ax pop ax assume ds:_data mov key_code,al ;Save key value (C or R) cmp active,0 je kbd1 pop ds goto_kbdbios: pop ax jmp cs:int09h kbd1: inc active sti push bx ;Save registers push cx push dx push di push si push es mov di,@data mov es,di ;Point to save area mov di,offset save_area mov cx,offset save_area_end - offset save_area call SaveEMSMem ;Save state of EMS driver or ah,ah ;Check for error, if error, jne kbd_exit ; exit. mov save_index,dx mov ax,4400h ;EMS Map page 0 xor bx,bx ;Logical page 0 mov dx,EMShandle int 67h or ah,ah ;Check for error, if error, jne kbd_restore ; exit. mov ah,0fh ;Get display mode int 10h ;Check for valid modes 2,3,7 cmp al,7 je kbd2 cmp al,2 jb kbd_restore cmp al,3 ja kbd_restore kbd2: push ax mov ah,3 ;Save cursor position int 10h mov cursor_pos,dx pop ax mov es,pageframe_seg xor di,di ;Saved scr at offset 0 cmp key_code,2eh ;See if capture function je kbd3 mov di,1000h ;Save current scr at 1000h kbd3: call save_scr ;Save current screen call kb_reset ;Reset keyboard controller cmp key_code,2eh ;See if capture function je kbd_restore ;If so, were done. push ds mov ds,pageframe_seg xor si,si call restore_scr ;Display saved screen pop ds kb4: xor ah,ah ;Get key int 16h cmp al,27 ;Check for ESC key. If found jne kb4 ; exit. Else get another key. push ds ;Restore original screen mov ds,pageframe_seg mov si,1000h call restore_scr pop ds kbd_restore: mov si,offset save_area ;Restore EMS mapping context mov dx,save_index call RestoreEMSMem mov ah,2 ;Set cursor position mov dx,cursor_pos int 10h kbd_exit: mov active,0 ;Clear active flag pop es pop si pop di pop dx pop cx pop bx kbd_exit1: pop ds pop ax iret kbdint endp ;---------------------------------------------------------------------------- ;Save screen. ;---------------------------------------------------------------------------- save_scr proc near stosw ;Save video mode mov ax,1234h ;Buffer initialized flag stosw mov cx,25 ;25 rows xor dx,dx saves1: push cx mov cx,80 ;80 columns xor dl,dl saves2: mov ah,2 ;Set cursor position int 10h mov ah,8 ;Read char and attribute int 10h stosw ;Store in EMS buffer inc dl ;Point to next column loop saves2 pop cx inc dh ;Point to next row loop saves1 ret save_scr endp ;---------------------------------------------------------------------------- ;Restore screen. ;---------------------------------------------------------------------------- restore_scr proc near lodsw ;Get video mode xor ah,ah ;Set mode cmp word ptr [si],1234h ;See if initialized jne restore_exit int 10h inc si inc si mov cx,25 ;25 rows xor dx,dx ;Start at row 0 restores1: push cx mov cx,80 ;80 columns xor dl,dl ;Start at column 0 restores2: push cx mov ah,2 ;Set cursor position int 10h lodsw ;Get char and attr from buffer mov bl,ah ;Copy attribute mov cx,1 ;Write 1 character mov ah,9 ;Write char and attribute int 10h inc dl ;Point to next column pop cx loop restores2 pop cx inc dh ;Point to next row loop restores1 restore_exit: ret restore_scr endp ;----------------------------------------------------------------------------- ;KB_RESET resets the keyboard and signals end-of-interrupt to the 8259 ;----------------------------------------------------------------------------- kb_reset proc near assume cs:_text in al,61h ;get control port value mov ah,al ;save it in AH or al,80h ;set bit 7 out 61h,al ;send reset value mov al,ah ;get original value out 61h,al ;send to enable keyboard cli ;suspend interrupts mov al,20h ;get EOI value out 20h,al ;send EOI to 8259 sti ;enable interrupts ret kb_reset endp ;---------------------------------------------------------------------------- ;Initialization. Reserve EMS memory and hook into keyboard interrupt. ;---------------------------------------------------------------------------- main: mov ax,@data ;Set DS to data segment mov ds,ax mov bx,1 ;Get 1 page mov si,-1 call GetEMSMem ;Allocate EMS memory or ah,ah jne ems_error mov EMShandle,dx ;Save EMS handle mov pageframe_seg,bx ;Save EMS page frame push es mov ax,3509h ;Get and Set int 9 vector int 21h mov word ptr int09h,bx mov word ptr int09h[2],es mov ax,2509h push ds push cs pop ds mov dx,offset kbdint int 21h pop ds pop es mov dx,ds add dx,10h mov bx,es sub dx,bx mov ax,3100h ;TSR int 21h ems_error: mov al,ah ;Copy EMS return code mov ah,4ch ;terminate with return code int 21h END main