Petit Computer Journal #31

Digital Koto

A while back, I wrote a little piano program. It includes song player. It's just a little simple music player, so I used BEEP instead of MML command. However, I'm rather curious since most of the code is created for the interface. In other words, drawing the piano keys. So, I'm wondering whether or not it's simpler to just draw the keys straight. Well, what kind of musical instrument is like that? The answer is simple: Japanese Koto. In truth, different cultures have different ideas and names for what basically amounts to a bunch of strings mounted on a board.

Still, the idea of it is interesting, and it's simple enough for me to do. So, let' do it! There are several different parts, but generally speaking, once you touch the screen, you come up with a string number and beep the appropriate sound. That's just look up table. Touch screen is easy. About the only thing that's difficult is drawing the strings proportionately. A little mathematic should do it.

1. INIT
2. Build BEEP table
3. Build Note table
4. Build String table
5. LOOP
6. Draw Strings
7. If Touch screen
8. Highlight nearest string
9. Play BEEP sound
10. GOTO LOOP

So, do you think this will take you one hour to do? Time for another "Hour of Code" challenge!

1. ACLS:CLEAR
2. DIM BP[49]:'BEEP TABLE
3. DIM NT$[49]:'NOTE TABLE
4. DIM ST[16]:'STRING TABLE
5. BREPEAT 0,60,12
6. BREPEAT 1,60,12
7. BREPEAT 2,60,12
8. BREPEAT 3,60,12
9. 
   
10. @INIT
11. NSI=0
12. P=4096/12:T$="CcDdEFfGgAaB"
13. FOR I=-24 TO 24:J=I+24
14. BP[J]=P*I
15. NT$[J]=MID$(T$,(J%12),1)
16. NEXT
17. ST[0]=14:ST[1]=19
18. ST[2]=21:ST[3]=22
19. ST[4]=26:ST[5]=27
20. ST[6]=31:ST[7]=33
21. ST[8]=34:ST[9]=38
22. ST[10]=39:ST[11]=43
23. ST[12]=45:ST[13]=0
24. ST[14]=0:ST[15]=0
25. 
    
26. ACLS

That's about it for the Initialization table. I want to fiddle with the string, so I'll put in button interface so I can change the string values on the fly.

1. @LOOP
2. NS=13:A=256/NS:B=A/2
3. VSYNC 1:BT=BTRIG():TX=FLOOR(TCHX*NS/256)
4. IF NS<1 THEN NS=1
5. FOR I=0 TO NS-1
6. GLINE B+I*A,16,B+I*A,192,15
7. LOCATE (B+I*A)/8,0:?FLOOR(ST[I]/12)
8. LOCATE (B+I*A)/8,0:?NT$[ST[I]]
9. NEXT
10. GLINE B+TX*A,16,B+TX*A,192,8
11. IF TCHTIME>0 THEN BEEP 20,BP[ST[TX]]
12. GOTO @LOOP

And that's about it. 35 minutes so far, and that's because I was having trouble with the math. The truth is, had I did the math correctly beforehand, I wouldn't have had so much trouble and I wouldn't have spend the time debugging.

Oh, yeah, about the tuning on the fly. I think that it is nice to be able to change the notes. So, what I'll do is add some button interface. That's what the BREPEAT command is for. Also, I may as well throw the instrument along with it. Instead of the locked in BEEP 20, I substitute it with a variable that will allow you to choose your own instrument.

Finally, we're going to move the whole thing down to the lower screen for ease of play. What should we put on the top of the screen? I don't know. Title screen, maybe? Or some internal variables?

1. REM DIGITAL KOTO
2. REM BY HARRY HARDJONO
3. REM DEC 2013
4. 
   
5. ACLS:CLEAR
6. DIM BP[49]:'BEEP TABLE
7. DIM NT$[49]:'NOTE TABLE
8. DIM ST[16]:'STRING TABLE
9. BREPEAT 0,60,12
10. BREPEAT 1,60,12
11. BREPEAT 2,60,12
12. BREPEAT 3,60,12
13. PNLTYPE "OFF"
14. 
    
15. @INIT
16. NSI=0
17. CI=16:'CURRENT INSTRUMENT
18. P=4096/12:T$="CcDdEFfGgAaB"
19. FOR I=-24 TO 24:J=I+24
20. BP[J]=P*I
21. NT$[J]=MID$(T$,(J%12),1)
22. NEXT
23. ST[0]=14:ST[1]=19
24. ST[2]=21:ST[3]=22
25. ST[4]=26:ST[5]=27
26. ST[6]=31:ST[7]=33
27. ST[8]=34:ST[9]=38
28. ST[10]=39:ST[11]=43
29. ST[12]=45:ST[13]=0
30. ST[14]=0:ST[15]=0
31. 
    
32. GPAGE 1:ACLS
33. 
    
34. @LOOP
35. NS=13:A=256/NS:B=A/2
36. VSYNC 1:BT=BTRIG():TX=FLOOR(TCHX*NS/256)
37. IF NS<1 THEN NS=1
38. GPAGE 1,1,1
39. FOR I=0 TO NS-1
40. GLINE B+I*A,16,B+I*A,192,15
41. LOCATE (B+I*A)/8,0:?FLOOR(ST[I]/12)
42. LOCATE (B+I*A)/8,0:?NT$[ST[I]]
43. NEXT
44. GLINE B+TX*A,16,B+TX*A,192,8
45. IF TCHTIME>0 THEN BEEP CI,BP[ST[TX]]
46. 
    
47. IF BT AND 1 THEN ST[NSI]=ST[NSI]+1
48. IF BT AND 2 THEN ST[NSI]=ST[NSI]-1
49. IF BT AND 4 THEN NSI=NSI-1
50. IF BT AND 8 THEN NSI=NSI+1
51. IF BT AND 16 THEN CI=CI+1:GOSUB @DISP
52. IF BT AND 32 THEN CI=CI-1:GOSUB @DISP
53. NSI=(NSI+NS)%NS
54. ST[NSI]=(ST[NSI]+49)%49
55. CI=(CI+70)%70
56. GOTO @LOOP
57. 
    
58. @DISP
59. ACLS
60. ?"INST: ";CI
61. FOR I=0 TO 15
62. ?I,ST[I]
63. NEXT
64. RETURN

Oh, by the way. The actual problem is so simple, that you can actually fit the minimalistic version of the program into one screen. That's right. It's another single screen challenge program!

1. REM DIGITAL KOTO
2. REM BY HARRY HARDJONO
3. ACLS:CLEAR:DIM BP[49]
4. DIM NT$[49]:DIM ST[16]
5. P=4096/12:T$="CcDdEFfGgAaB"
6. FOR I=-24 TO 24:J=I+24
7. BP[J]=P*I
8. NT$[J]=MID$(T$,(J%12),1):NEXT
9. ST[0]=14:ST[1]=19:ST[2]=21
10. ST[3]=22:ST[4]=26:ST[5]=27
11. ST[6]=31:ST[7]=33:ST[8]=34
12. ST[9]=38:ST[10]=39:ST[11]=43
13. ST[12]=45:ST[13]=0:ST[14]=0
14. @LOOP
15. NS=13:A=256/NS:B=A/2
16. VSYNC 1:TX=FLOOR(TCHX*NS/256)
17. GPAGE 1,1,1:FOR I=0 TO NS-1
18. GLINE B+I*A,0,B+I*A,192,15
19. NEXT
20. GLINE B+TX*A,16,B+TX*A,192,8
21. SD=BP[ST[TX]]
22. IF TCHTIME>0 THEN BEEP 16,SD
23. GOTO @LOOP