Hi David,
> ; The hardware does this: next_bit5 = not(bit0 XOR bit1)
> ; lfsr cannot be initialized to 63
>
> lsr lfsr ; always shift lfsr and put bit0 into carry
> lda lfsr ; get bit1 (now in bit0 position)
> adc #$00 ; add bit0 (in carry) with bit one (effectively bit0 XOR
bit1)
> lsr ; (bit0 XOR bit1) now in carry
> bcs .skipOr ;
> lda lfsr ;
> ora #$20 ; set bit 5 if result was zero
> sta lfsr ;
> .skipOr
This looks similar to the PRNG Larry Kaplan uses...
NextRandom
lsr randomSeed
rol
eor randomSeed
lsr
lda randomSeed
bcs .leaveNextRandom
ora #$40
sta randomSeed
.leaveNextRandom
rts
Take care,
Dennis
