Source Code 1992 March

home *** CD-ROM | disk | FTP | other *** search

/ Source Code 1992 March / Source_Code_CD-ROM_Walnut_Creek_March_1992.iso / msdos / pcmag / asm4.arc / SNAPSHOT.ASM < prev next >

Wrap

Assembly Source File | 1986-06-05 | 14.4 KB | 284 lines

INTERRUPTS SEGMENT AT 0H ;This is where the keyboard interrupt ORG 9H*4 ;holds the address of its service routine KEYBOARD_INT LABEL DWORD INTERRUPTS ENDS SCREEN SEGMENT AT 0B000H ;A dummy segment to use as the SCREEN ENDS ;Extra Segment ROM_BIOS_DATA SEGMENT AT 40H ;BIOS statuses held here, also keyboard buffer ORG 1AH HEAD DW ? ;Unread chars go from Head to Tail TAIL DW ? BUFFER DW 16 DUP (?) ;The buffer itself BUFFER_END LABEL WORD ROM_BIOS_DATA ENDS CODE_SEG SEGMENT ASSUME CS:CODE_SEG ORG 100H ;ORG = 100H to make this into a .COM file FIRST: JMP LOAD_SNAPSHOT ;First time through jump to initialize routine COPY_RIGHT DB '(C) S. HOLZNER 1985' ;An Ascii signature ; KEYS DW 310EH,2106H,1E01H,3002H,2E03H ;A Sample: ^N,^F,^A,^B,^C KEYS DW 5 DUP(0) FLASHED DB 0 ;Have we flashed a screenful? 1=yes SNAPSHOT_OFFSET DW 0 ;Chooses 1st 250 bytes or 2nd SCREEN_SEG_OFFSET DW 0 ;0 for mono, 8000H for graphics IO_CHAR DW ? ;Holds addr of Put or Get_Char FILE_SIZE DW 0 ;Read in this many bytes OLD_KEYBOARD_INT DD ? ;Location of old kbd interrupt FILE DB 'A.DAT',0 ;Asciiz. Changed to B.Dat, etc. WS_FLAG DB 0 ;<-- Set to 1 to strip WordStar SNAPSHOT DB 10000 DUP (32) ;Storage for screens SNAP PROC NEAR ;The keyboard interrupt will now come here. ASSUME CS:CODE_SEG PUSH AX ;Save the used registers for good form PUSH BX PUSH CX PUSH DX PUSH DI PUSH SI PUSH DS PUSH ES PUSHF ;First, call old keyboard interrupt CALL OLD_KEYBOARD_INT ASSUME DS:ROM_BIOS_DATA ;Examine the char just put in MOV BX,ROM_BIOS_DATA MOV DS,BX MOV BX,TAIL ;Point to current tail CMP BX,HEAD ;If at head, kbd int has deleted char JE IN ;So leave SUB BX,2 ;Point to just read in character CMP BX,OFFSET BUFFER ;Did we undershoot buffer? JAE NO_WRAP ;Nope MOV BX,OFFSET BUFFER_END ;Yes -- move to buffer top SUB BX,2 ;Point to just read in character NO_WRAP:MOV DX,[BX] ;** Typed character in DX now ** LEA SI,KEYS ;Point to Keys for search CMP FLASHED,1 ;Should we restore screen? JE RESTORE ;Yes, jump there CMP DX,CS:[SI] ;Compare to first key (Store screen) JE STORE ;So Store ADD SI,2 ;Point to next key CMP DX,CS:[SI] ;Second key -- should we flash screen? JE FLASH ;Yes MOV CX,3 ;No -- check for .Dat keys (A.Dat,etc) MOV SNAPSHOT_OFFSET,4000 ;Point to beginning of .Dats in memory TEST: ADD SI,2 ;Increment to next key CMP DX,CS:[SI] ;Is it right? JE DATS ;Yes, flash a .Dat file on screen ADD SNAPSHOT_OFFSET,2000 ;Point to next .Dat LOOP TEST ;And go back until all three are done JMP OUT ;No keys matched. Jump Out. STORE: MOV TAIL,BX ;Delete character from buffer MOV FLASHED,0 ;Switch Modes on Flashed MOV SNAPSHOT_OFFSET,0 ;Point to screen storage part of pad LEA AX,GET_CHAR ;Make IO use Get_char so current screen MOV IO_CHAR,AX ;is stored CALL IO ;Store Screen IN: JMP OUT ;Done here, let's go. FLASH: MOV TAIL,BX MOV FLASHED,1 ;Switch Modes, next key will restore screen MOV SNAPSHOT_OFFSET,2000 ;Point to screen storage part LEA AX,GET_CHAR ;Make IO use Get_char so current screen MOV IO_CHAR,AX ;is stored CALL IO ;Store Screen MOV SNAPSHOT_OFFSET,0 ;Use 1st 250 bytes of Snapshot memory LEA AX,PUT_CHAR ;Make IO use Put-Char so it does MOV IO_CHAR,AX CALL IO ;Put result on screen JMP OUT ;Done here. RESTORE: MOV FLASHED,0 ;Restore screen from memory MOV TAIL,BX ;Delete character from buffer MOV SNAPSHOT_OFFSET,2000 ;Point to storage part of memory LEA AX,PUT_CHAR ;Make IO call Put_Char as it scans MOV IO_CHAR,AX ;over all locations in screen CALL IO ;Restore screen JMP OUT ;And leave DATS: MOV TAIL,BX MOV FLASHED,1 ;Switch Modes, next key will restore screen PUSH SNAPSHOT_OFFSET ;Save this while Offset set for storing MOV SNAPSHOT_OFFSET,2000 ;Point to screen storage part LEA AX,GET_CHAR ;Make IO use Get_char so current screen MOV IO_CHAR,AX ;is stored CALL IO ;Store Screen POP SNAPSHOT_OFFSET ;Restore pointer to stored .Dat LEA AX,PUT_CHAR ;Make IO use Put-Char so it does MOV IO_CHAR,AX CALL IO ;Put result on screen OUT: POP ES ;Do the Pops of all registers. POP DS POP SI POP DI POP DX POP CX POP BX POP AX IRET ;An interrupt needs an IRET SNAP ENDP GET_CHAR PROC NEAR ;Gets a char from screen and advances position PUSH DX MOV SI,2 ;Loop twice, once for char, once for attribute G_WAIT_LOW: MOV AH,ES:[DI] ;Do the move from the screen, one byte at a time INC DI ;Move to next screen location DEC SI ;Decrement loop counter CMP SI,0 ;Are we done? JE LEAVE ;Yes MOV SNAPSHOT[BX],AH ;No -- put char we got into snapshot JMP G_WAIT_LOW ;Do it again LEAVE: INC BX ;Update location POP DX RET GET_CHAR ENDP PUT_CHAR PROC NEAR ;Puts one char on screen and advances position PUSH DX MOV AH,SNAPSHOT[BX] ;Get the char to be put onto the screen MOV SI,2 ;Loop twice, once for char, once for attribute MOV ES:[DI],AH ;Move to screen, one byte at a time ADD DI,2 SUB SI,2 INC BX ;Point to next char POP DX RET ;Exeunt PUT_CHAR ENDP IO PROC NEAR ;This scans over all screen positions ASSUME ES:SCREEN ;Use screen as extra segment MOV BX,SCREEN MOV ES,BX MOV DI,SCREEN_SEG_OFFSET ;DI will be pointer to screen postion MOV BX,SNAPSHOT_OFFSET ;BX will be location pointer MOV CX,25 ;There will be 10 lines LINE_LOOP: MOV DX,80 ;And 25 spaces across CHAR_LOOP: CALL IO_CHAR ;Call Put-Char or Get-Char DEC DX ;Decrement character loop counter JNZ CHAR_LOOP ;If not zero, scan over next character LOOP LINE_LOOP ;And now go back to do next line RET ;Finished IO ENDP READ_FILE PROC NEAR ;Reads .Dats and formats in memory. PUSH CX ;Save used registers PUSH DX PUSH DI ASSUME DS:CODE_SEG,ES:CODE_SEG MOV BX,AX ;Put passed file handle in BX MOV CX,2000 ;Ask for 2000 bytes (Tops) LEA DX,DATA ;Point DS:DX at Data area at end MOV AH,3FH ;Ask for reading service INT 21H ;And go get 'em MOV CX,AX ;Store number of bytes read MOV AH,3EH ;Now close file INT 21H CALL WS ;Strip high bit if necessary LEA SI,DATA ;Transfer from CS:[SI] to DS:[BX] now CMP CX,2000 ;Make sure on number of bytes read in. JBE THE_LOOP MOV CX,2000 ;Format file into Snapshot area now THE_LOOP: ;Loop over character by character CMP BYTE PTR [SI],9 ;Is it a tab? JNE NOTAB ;Add 8 spaces for tabs ADD DI,8 INC SI ;And point to next character JMP CONT NOTAB: CMP BYTE PTR [SI],13 ;Is it a carriage return? JNE OK ;No, store the character FILL: INC SI ;Found a <CR>. Fill to end of line DEC CX ;Get rid of line feeds CMP BYTE PTR [SI],13 ;Treat additional <CR>s as new lines JE CR CMP BYTE PTR [SI],' ' ;Bona Fide character? JB FILL ;No, keep going past all linefeeds CR: CMP CX,0 ;Yes, start to fill to end of line here JLE FIN ;Check on loop index INC CX ;And readjust it from skipping lf.s MOV AX,DI ;AH will check if we're at end of line SUB AX,OFFSET SNAPSHOT+4000 ;Get distance into screen MOV DL,80 ;Divide by 80 to find columns DIV DL CHECK: CMP AH,79 ;Remainder of 79? JA CONT ;If more, have begun a new line. ADD: INC DI ;Add a space by incrementing DI INC AH ;And keep track by incrementing AH too. JMP CHECK ;At edge of screen? OK: CMP DI,OFFSET SNAP ;Past end of storage area? (Many tabs and CRs) JAE FIN ;Yes, don't move byte into it MOVSB ;No, safe to move byte from [SI] to [DI] CONT: LOOP THE_LOOP ;And keep going for all bytes in file FIN: POP DI POP DX POP CX RET ;Exit here. READ_FILE ENDP WS PROC NEAR ;This will strip high bits from the CMP WS_FLAG,1 ; read-in file if WS_Flag = 1 JNE RETWS ;IF WS_Flag is not 1, exit PUSH SI ;Store used registers PUSH CX LEA SI,DATA ;Point to read-in file MOV CX,2000 ;Do 2000 bytes ALOOP: AND BYTE PTR CS:[SI],127 ;Strip top bit INC SI ;Point to next one. LOOP ALOOP ;And keep going POP CX ;Pops POP SI RETWS: RET ;And Exit. WS ENDP LOAD_SNAPSHOT PROC NEAR ;This procedure intializes everything ASSUME DS:INTERRUPTS ;The data segment will be the Interrupt area MOV AX,INTERRUPTS MOV DS,AX MOV AX,word ptr KEYBOARD_INT ;Get the old interrupt service routine MOV word ptr OLD_KEYBOARD_INT,AX ;address, put it into our location MOV AX,word ptr KEYBOARD_INT[2] ;OLD_KEYBOARD_INT so we can call it. MOV word ptr OLD_KEYBOARD_INT[2],AX MOV word ptr KEYBOARD_INT,OFFSET SNAP ;Load address of our program MOV word ptr KEYBOARD_INT[2],CS ;routine into the keyboard interrupt MOV AH,15 ;Ask for service 15 of INT 10H INT 10H ;This tells us how display is set up TEST AL,4 ;Is it? JNZ READ ;Yes - jump out MOV SCREEN_SEG_OFFSET,8000H ;No - set up for graphics display READ: PUSH CS ;Now read in A.Dat, B.Dat etc. POP DS ;Set DS correctly MOV CX,3 ;Loop over three files LEA DI,SNAPSHOT+4000 ;Store starting in this area LOOP: ASSUME DS:CODE_SEG ;Loop over files LEA DX,FILE ;Point to file name MOV AX,3D00H ;Service 3DH, attribute 0 for file INT 21H ;Open file JC EXIT ;If not found, exit ; PUSH DI ;Store CALL READ_FILE ;Pass file handle in AX to Read_File ; POP DI ADD DI,2000 ;Point to next storage area MOV BX,DX ;Change A.Dat into B.Dat etc. INC BYTE PTR CS:[BX] ;A.DAT-->B.DAT etc. LOOP LOOP ;Keep going over all files. EXIT: MOV DX,OFFSET LOAD_SNAPSHOT ;Set up everything but LOAD_SNAPSHOT to INT 27H ;stay and attach itself to DOS LOAD_SNAPSHOT ENDP DATA: CODE_SEG ENDS END FIRST ;END "FIRST" so 8088 will go to FIRST first.