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Assembly Source File | 1986-03-01 | 13.0 KB | 372 lines

; This program is described in BYTE, November 1983, Pages 99 - 116. ; Article is entitled "ENHANCING SCREEN DISPLAYS FOR THE IBM PC", ; author is Tim Field. ; Define interrupt vectors for both keyboard interrupt 16H and screen ; interrupt 10H. Both are in segment 0: KEYVECT SEGMENT AT 0 ;Define KEYBOARD int. vector ORG 16H*4 KEYINT LABEL DWORD KEYVECT ENDS SCRVECT SEGMENT AT 0 ;Define SCREEN int. vector ORG 10H*4 SCRINT LABEL DWORD SCRVECT ENDS ; Define constants: BW_VAL EQU 07H ;Standard B&W attribute EQUIP_FLAG EQU 410H ;RAM address of equipment stat CHK_MODE EQU 15 ;INT fn: Check screen mode MONO_MODE EQU 7 ;Mode 7 = monochrome monitor COLOR_ADPT EQU 3 ;Modes 0-3: non-graphics color ; Start code area: CODE SEGMENT PARA ;Start code at offset 100H ASSUME CS:CODE ;from starting segment; leaves ORG 100H ;room for PSP KEY PROC FAR ; Initialization code - used only once during startup: START: JMP INIT_CODE ;Call initialization routine ; Define storage areas and data structures: ; Define keystroke scan codes for the five SCREEN functions: FORE_INC DW 5E00H ;Foreground increment BACK_INC DW 6000H ;Background increment C80_40 DW 6200H ;80x25 to 40x25 flip-flop key COL_MON DW 6400H ;COLOR/MONO flip-flop key REPAINT DW 6600H ;Repaint scrn using curr. mode CUR_MODE DW COL80_AREA ;Initialize starting mode MONO_SET DW MONO_AREA ;Pointer to monochrome area COLOR_SET DW COL80_AREA ;Pointer to active color area SCRN_ATTR DB 70H ;Current screen attribute SCRN_MODE DB 255 ;Save current screen mode ; Define structure used to contain information about 40 and 80 column color ; modes as well as monochrome mode: S STRUC CORNER DW 0 ;Defines COL/ROW count of ;characters for the monitor BF DW 0 ;Colors of FORE and BACK EQUIP DW 0 ;Equipment setting MODE DW 0 ;AX value for setting the mode S ENDS ;of the monitor ; Now set up three screen structures with default condition: COL80_AREA S <5019H,0107H,20H,3> ;80x25 white FORE, blue BACK COL40_AREA S <2819H,0107H,10H,1> ;40x25 brown FORE, black BACK MONO_AREA S <5019H,0007H,30H,7> ;Monochrome, reverse video KEY_CALL: DB 0EAH ;Far JMP address to KEYBOARD DD 0 ;interrupt. See article ; Procedure KEY_RTNE intercepts keyboard interrupt and determines if the ; keystroke is one of the five SCREEN ones: KEY_RTNE: STI ;Turn on interrupts CMP AH,0 JNE KEY_CALL PUSH DS ;Save registers PUSH BX PUSH CX PUSH DX PUSH ES PUSH DI PUSH CS ;Point DS to CS segment by POP DS ;PUSH / POP operation ASSUME DS:CODE INT_LOOP: ;IBM keyboard procedure PUSHF ;expects an interrupt call MOV BX,OFFSET KEY_CALL+1 ;Address to ROM keyboard code CALL DWORD PTR [BX] ;Call keyboard routine MOV BX,CUR_MODE ;Get current mode address CMP AX,COL_MON ;See if COLOR/MON flip flop JNE TEST_FORE ;key. Exit if not. Otherwise: CMP BX,MONO_SET ;Flip flop screen mode JE SET_COLOR ;If monochrome, swap to color CMP MONO_SET,0 ;See if monochrome installed JE NEXT_KEY ;Ignore command if not MOV BX,MONO_SET ;Otherwise set up monochrome JMP SHORT DO_CHG SET_COLOR: CMP COLOR_SET,0 ;See if COLOR monitor enabled JE NEXT_KEY ;Skip if not MOV BX,COLOR_SET ;Set up for color DO_CHG: CALL SCREEN_CHG ;Implement screen change NEXT_KEY: MOV AH,0 ;Set up to fetch keystroke JMP INT_LOOP ;Fetch next key input TEST_FORE: PUSH AX ;Save registers PUSH BX ;See if in GRAPHICS mode MOV AH,CHK_MODE INT 10H POP BX ;Restore BX register CMP AL,COLOR_ADPT ;If between 0-3, not graphics JLE NOT_GRAPH CMP AL,MONO_MODE ;Monochrome mode JGE NOT_GRAPH POP AX ;Restore stack JMP DONE ;If color-graphics mode, do NOT_GRAPH: ;not change modes POP AX ;Restore AX CMP AX,FORE_INC ;Increment FOREGROUND color? JNE TEST_BACK ;Skip if not CMP BX,COLOR_SET ;See if currently using color JNE BW_FLOP ;If not, go deal with B&W MOV AX,[BX].BF ;Gets BACK in AL, FORE in AH EQ_FORE: INC AL ;Increment FOREGROUND color AND AL,7 ;Keep it within bounds CMP AL,AH ;See if same as BACKGROUND JE EQ_FORE ;Increment again if yes MOV [BX].BF,AX ;Save back to structure JMP DO_CHG ;Redraw the screen TEST_BACK: CMP AX,BACK_INC ;Increment BACKGROUND color? JNE TEST_REPAINT ;Skip if not CMP BX,COLOR_SET ;See if currently using color JNE BW_FLOP ;If not, go deal with B&W MOV AX,[BX].BF ;Gets BACK in AL, FORE in AH EQ_BACK: INC AH ;Increment BACKGROUND color AND AH,7 ;Keep it within bounds CMP AH,AL ;See if same as FOREGROUND JE EQ_BACK ;Increment again if yes MOV [BX].BF,AX ;Save back to structure JMP DO_CHG ;Redraw the screen BW_FLOP: ;Flip flop B&W monitor MOV AX,[BX].BF ;BACK in AH, FORE in Al XCHG AH,AL ;Swap FOREGROUND, BACKGROUND MOV [BX].BF,AX ;Save back to structure JMP DO_CHG ;Redraw the screen TEST_REPAINT: CMP AX,REPAINT ;Repaint the screen? JE DO_CHG ;If yes, then repaint screen TEST_80_40: CMP AX,C80_40 ;80-40 flip flop key? JNE DONE ;Exit if not CMP BX,OFFSET COL40_AREA ;Is curr. pointer area 40x25? JNE TST80 ;Skip if not MOV BX,OFFSET COL80_AREA ;Otherwise, flip to 80x25 JMP SHORT SAVE_COL ;Save to COLOR_SET TST80: CMP BX,OFFSET COL80_AREA ;Is current 80x25 color? JNE NEXT_KEY ;Ignore key if not MOV BX,OFFSET COL40_AREA SAVE_COL: MOV COLOR_SET,BX ;Save to COLOR_SET JMP SET_COLOR ;Implement DONE: POP DI ;Restore registers POP ES POP DX POP CX POP BX POP DS IRET ;Return from interrupt KEY ENDP ;End of main routine ; This routine changes current monitor screen mode. On input, BX points to ; the current monitor structure: SCREEN_CHG PROC NEAR MOV AX,0 ;Get segment address for RAM MOV ES,AX ;EQUIP_FLAG MOV AX,ES:EQUIP_FLAG ;Get set of EQUIP flags AND AL,0CFH ;Scrap current monitor flag OR AX,[BX].EQUIP ;Set up new monitor flag MOV ES:EQUIP_FLAG,AX ;Save back in RAM MOV CUR_MODE,BX ;Indicate new mode ; Now set up attribute for FOREGROUND and BACKGROUND: MOV DX,[BX].BF ;Get both FORE and BACK in DX MOV CL,4 ;Shift count SHL DH,CL ;Shift BACK into upper nibble OR DH,DL ;Move FORE into lower nibble MOV SCRN_ATTR,DH ;Save results ; See if we need to reset monitor (switching to new monitor?): MOV AX,[BX].MODE ;Get screen mode CMP AL,SCRN_MODE ;Compare with current mode JE SET_ATTR ;Skip if the same MOV SCRN_MODE,AL ;Otherwise, save current mode INT 10H ;And reset to new monitor SET_ATTR: CALL CH_ATTR ;Change attributes of current RET ;screen SCREEN_CHG ENDP ; This routine repaints the active screen so that every character on the ; current screen is displayed with the new attributes. On input, BX points ; to the current monitor structure: CH_ATTR PROC NEAR ; See if we need to redraw border for color mode CMP BX,OFFSET MONO_SET ;In color? JE NO_BORDER ;Skip border code if not PUSH AX ;Save registers PUSH BX MOV BX,[BX].BF ;Get BACKGROUND color in BL MOV BL,BH MOV BH,0 ;Select border coloring MOV AH,11 ;Fn. call: set color palette INT 10H ;Execute VIDEO I/O interrupt POP BX ;Restore registers POP AX NO_BORDER: MOV AX,[BX].CORNER ;Get COL and ROW for current MOV CORNR,AX ;Save in temporary data area MOV AH,CHK_MODE ;Get page number INT 10H ; BX contains the active page: MOV AH,3 ;Get current cursor position INT 10H PUSH DX ;Save position on stack XOR DX,DX ;Zero-out DX MOV CX,1 ;Set up counter MOV BL,SCRN_ATTR ;Get current attribute REP_ATTR: MOV AH,2 ;Set cursor position INT 10H MOV AH,8 ;Read next character INT 10H ; AH contains the current character attribute: AND AH,88H ;Get intensity bit AND BL,77H ;Ensure attr. intensity is off OR BL,AH ;Create current attribute MOV AH,9 ;Display char. with new attr. INT 10H INC DL CMP DL,TCOL ;Are we done with this column? JLE REP_ATTR ;If so, jump XOR DL,DL ;Otherwise, zero-out DL INC DH ;Move to next row CMP DH,TROW ;Are we done with this screen? JLE REP_ATTR ;Loop until done POP DX ;Restore orig. cursor position MOV AH,2 INT 10H RET CORNR LABEL WORD TROW DB 0 ;Temp. store for ROW TCOL DB 0 ;Temp. store for COL CH_ATTR ENDP ; This routine replaces the SCREEN interrupt so that it can intercept B&W ; character writes and change the display attributes: SCR_RTNE PROC NEAR STI PUSH DS ;Save DS PUSH CS ;Point DS to CS segment by POP DS ;PUSH / POP operation ASSUME DS:CODE CMP AH,6 ;Spot SCROLLUP and SCROLLDOWN JL NORMAL_SCR ;calls CMP AH,7 JG NOT_SCROLL SCROLL: CALL GET_CH ;Update attribute for scroll JMP NORMAL_SCR ;Now execute scroll NOT_SCROLL: CMP AH,9 ;Check for "WRITE ATTR / CHAR" JNE NORMAL_SCR ;command. Send out any other XCHG BH,BL ;commands as normal. Get attr. CALL GET_CH ;in BL and update attribute XCHG BH,BL ;Move attribute back to BH for NORMAL_SCR: ;command POP DS ;Restore DS segment register JMP_SCR: DB 0EAH ;See article DD 0 SCR_RTNE ENDP ; This routine replaces the B&W character with the current replacement ; attributes and allows for the INTENSITY bit setting. On input, BH ; contains the attribute to be modified: GET_CH PROC NEAR MOV SAVECH,BH ;Save character AND BH,77H ;Remove intensity / blink bits CMP BH,BW_VAL ;See if cur. defined B&W value MOV BH,SAVECH ;Otherwise, modify to current JNE OUT ;attribute. Exit if not AND BH,88H ;Get rid of B&W part OR BH,SCRN_ATTR ;Move in current attr. part OUT: RET ;Done SAVECH DB 0 ;Temporary character store GET_CH ENDP ; All code after this label is freed to DOS use after this program has been ; initialized: LASTONE: ; This routine loads and initializes the SCREEN program. It sets up DOS to ; keep all code before the label LASTONE safe from overlay during normal ; system operation: INIT_CODE PROC NEAR ; Initialize KEYBOARD intercept code: MOV AX,KEYVECT ;Point ES to interrupt vectors MOV ES,AX ;(segment at 0H) ASSUME ES:KEYVECT MOV AX,ES:KEYINT ;Get address of interrupt MOV BX,OFFSET KEY_CALL+1 ;vector and save both the MOV [BX],AX ;segment and offset values of MOV AX,ES:KEYINT[2] ;this routine in our data area MOV [BX+2],AX ;Now, replace the original MOV ES:KEYINT,OFFSET KEY_RTNE ;interrupt vector with the MOV AX,CS ;address of our own routine MOV ES:KEYINT[2],AX ; Initialize SCREEN intercept code: MOV AX,SCRVECT ;Point ES to interrupt vectors MOV ES,AX ;(segment at 0H) ASSUME ES:SCRVECT MOV AX,ES:SCRINT ;Get address of interrupt MOV BX,OFFSET JMP_SCR+1 ;vector and save both the MOV [BX],AX ;segment and offset values of MOV AX,ES:SCRINT[2] ;this routine in our data area MOV [BX+2],AX ;Now, replace the original MOV ES:SCRINT,OFFSET SCR_RTNE ;interrupt vector with the MOV AX,CS ;address of our own routine MOV ES:SCRINT[2],AX ; Initialize screen: MOV BX,CUR_MODE ;Set up initial screen mode CALL SCREEN_CHG ;Initialize screen mode ; Now, terminate and stay resident: MOV DX,OFFSET LASTONE ;Save all code up to LASTONE INT 27H ;Terminate and stay resident INIT_CODE ENDP CODE ENDS END START