main:
INPUT x
PRINT bitreverse(x, 16)
GOTO main

FUNCTION bitreverse(num, k)
' reverse bit order
' num = integer to reverse
' k = number of bits (8 or 16)
LOCAL n
FOR n = 1 TO k
IF (num AND 2^(n-1)) > 0 THEN
bitreverse =bitreverse+ 2^(k-n)
ENDIF
NEXT n
END FUNCTION

clk=83886 ' pwm to clk in on synth
inp=11000 ' SPI to control on synth
SetPin 5,2 ' rx for SPI (not used)
For p=1 To 3: SetPin p,8: Next p
Pin(1)=1 ' data latch

playnote:
If KeyDown=0 Then GoTo playnote
If KeyDown=128 Then clk=clk*1.001
If KeyDown=129 Then clk=clk/1.001
If KeyDown=130 Then inp=inp/1.001
If KeyDown=131 Then inp=inp*1.001

PWM clk,50,50
Pin(1)=0
A= SPI( 5,3,2,bitrev(inp),L,3,16 )
Pin(1)=1
Cls
Print " clk =";clk
Print " inp =";inp
Print " bitrev =";bitrev(inp)
Print " freq =";(inp*clk)/(2^23)
GoTo playnote
End

Function bitrev(inp)
For n=1 To 16
If (inp And 2^(n-1)) > 0 Then
bitrev = bitrev + 2^(16-n)
EndIf
Next n
End Function