ASSEMBLY LANGUAGE
Move-It
by Jerry White
Move-It provides the ATARI programmer with the ability to move one byte of data into a range of memory locations. This assembly language routine is position independent. It is loaded into a string from data statements 250 and 260. The routine is useful for clearing sections of screen memory, Player/Missile memory, erasing a player, and clearing memory used in page flipping.
The parameters which control this routine are passed in a USR statement. The start location and the byte total to be moved are passed. There are no limitations on the total bytes which can be moved.
Interesting sounds are also generated by the BASIC routine. The soundless version moves bytes at the rate of almost a quarter of a million per second (256 x 960).
MACHINE LANGUAGE LISTING
10 ; This is a position independent subroutine 20 ; found in DATA statements line numbered 250 and 260 22 ; of BASIC listing 30 ; Calling Sequence from BASIC is: 40 ; A = USR(ADR($STR),Start Addr,Count) 50 ; 60 *= $600 ; can go anywhere 70 PLA ; ignore arguement count 80 PLA ; save lo-byte of dest addr 90 STA $CC 0100 PLA ; save hi-byte of dest addr 0110 STA $CB 0120 PLA ; save total to be moved 0130 STA $CE ; * 0140 PLA ; save total to be moved 0150 STA $CD ; * 0160 LDX $CE ; count of bytes to move 0170 LDY #0 ; init index 0180 LDA #0 ; init character to be moved 0190 MOV STA ($CB),Y ; move data 0200 DEY ; decrement index 0210 BNE MOV ; go move next character 0220 INC $CC ; incr dest addr lo-byte 0230 DEX ; decr lo-byte count to move 0240 BMI EXIT 0250 BNE MOV ; go move next character 0260 LDY $CD ; hi-byte of count to move 0270 BNE MOV ; go move next character 0280 EXIT DEC $CC ; decr lo-byte dest addr 0290 LDY #0 0300 STA ($CD),Y 0310 RTS ; return to BASIC 0320 .END
BASIC LISTING
5 GOTO 35 10 REM MOVIT UTILITY/DEMO BY JERRY WHITE 3/31/82 15 REM THATS INCREDIBLE SUBROUTINE 20 FOR M=0 TO 255 21 Z$(19,19)=CHR$(M) 22 Z=USR(ADR(Z$),SM,960) 23 NEXT M 24 RETURN 30 REM SM=SCREEN MEMORY C=SPEAKER 35 GRAPHICS 0 36 POKE 82,0 37 DIM Z$(42) 38 POKE 752,1 39 S=PEEK(560)+PEEK(561)*256+4 40 SM=PEEK(S)+PEEK(S+1)*256 41 C=53279 45 REM Z$=ASSEMBLER ROUTINE STRING (POSITION 19=CHARACTER TO MOVE) 50 REM Z=USR(ADR(Z$),START ADR,HOW MANY) 60 FOR X=1 TO 42 61 READ IT 62 Z$(X,X)=CHR$(IT) 63 NEXT X 64 POKE 82,0 65 ? "[backspace character]"; 66 POKE 83,39 67 SOUND 0,0,0,0 68 Z$(19,19)=CHR$(128) 69 Z=USR(ADR(Z$)SM,960) 70 POKE 710,113 71 POSITION 39,0 72 ? CHR$(160); 75 ? " This DEMO demonstrates an assembler " 76 ? " MOVE routine called from BASIC. " 80 ? " Possible uses would be to move " 81 ? " blanks or special characters to an " 85 ? " area of screen memory, or to clear " 86 ? " RAM used for player missiles or " 90 ? " page flipping etc. " 95 ? " SELECT OPTION NUMBER: " 96 ? " (1) FAST WITH SOUND ":GOSUB 230 100 ? " (2) VERY FAST WITH SOUND ":GOSUB 230 105 ? " (3) THAT'S INCREDIBLE (SILENT) ":GOSUB 230 110 POKE 764,255 111 CLOSE #1 112 OPEN #1,4,0,"K:" 113 GET #1,K 114 CLOSE #1 115 REM ACCEPT ONLY A 1 2 OR 3 120 IF K<49 OR K>51 THEN FOR ME=15 TO 0 STEP -0.5 121 SOUND 0,102,12,ME 122 NEXT ME 123 GOTO 110 130 REM I LOVE SOUND ROUTINES 135 FOR J=1 TO 7 136 POKE 710,J*16 137 FOR X=2 TO 0 STEP -1 138 FOR ME=14 TO 0 STEP -2 139 SOUND 0,X+J,2,ME 140 NEXT ME 141 NEXT X 142 NEXT J 145 REM EXECUTE SELECTED MOVIT ROUTINE 150 IF K=51 THEN GOSUB 20:GOTO 175 155 IF K=50 THEN GOSUB 190:GOTO 175 160 GOSUB 210:GOTO 175 170 REM DING...ALL DONE...START OVER 175 FOR ME=15 TO 0 STEP -0.2 176 SOUND 0,0,2,ME 177 NEXT ME 178 RUN 185 REM VERY FAST SUBROUTINE WITH SOUND 190 FOR M=0 TO 255 191 Z$(19,19)=CHR$(M) 192 POKE 53761,168 193 POKE 53763,168 194 POKE 53760,255-M 195 POKE 53768,13 196 POKE 712,M 197 POKE 53762,M 198 POKE 53762,M/8 199 POKE 53768,2 200 Z=USR(ADR(Z$),SM,960) 201 POKE 53761,0 202 POKE 53763,0 203 NEXT M 204 RETURN 205 REM FAST SUBROUTINE WITH SOUND 210 FOR M=255 TO 0 STEP -1 211 Z$(19,19)=CHR$(M) 212 POKE 53760,M 213 FOR V=175 TO 160 STEP -1 214 POKE 53761,V 215 POKE 53768,V-160 216 NEXT V 217 POKE 712,M 218 Z=USR(ADR(Z$),SM,960) 219 NEXT M 220 RETURN 225 REM BLINK & BUZZ SUBROUTINE 230 FOR JW=0 TO 8 231 POKE 755,1 232 POKE C,0 233 POKE C,8 234 NEXT JW 235 FOR JW=0 TO 8 236 POKE 755,2 237 NEXT JW 238 RETURN 240 REM DATA TO CREATE Z$ ASSEMBLER SUBROUTINE 250 DATA 104,104,133,204,104,133,203,104,133,206,104 255 DATA 133,205,166,206,160,0,169,0,145,203,136 260 DATA 208,251,230,204,202,48,6,208,244,164,205 265 DATA 208,240,198,204,160,0,145,203,96
Listing 1: MOVEIT.SRC Download / View
Listing 2: MOVEIT.BAS Download