mirror of https://git.sr.ht/~rabbits/uxn
83 lines
1.9 KiB
Tal
83 lines
1.9 KiB
Tal
( pseudo-random number generator,
|
|
based on two 16-bit xorshift algorithms by George Marsaglia
|
|
http://www.jstatsoft.org/v08/i14/paper )
|
|
|
|
( devices )
|
|
|
|
|00 @System [ &vector $2 &wst $1 &rst $1 &pad $4 &r $2 &g $2 &b $2 &debug $1 &halt $1 ]
|
|
|20 @Screen [ &vector $2 &width $2 &height $2 &pad $2 &x $2 &y $2 &addr $2 &pixel $1 &sprite $1 ]
|
|
|c0 @DateTime [ &year $2 &month $1 &day $1 &hour $1 &minute $1 &second $1 &dotw $1 &doty $2 &isdst $1 ]
|
|
|
|
( variables )
|
|
|
|
|0000
|
|
|
|
( program )
|
|
|
|
|0100 ( -> )
|
|
( init )
|
|
;on-frame .Screen/vector DEO2
|
|
|
|
( seed prng (must be nonzero) )
|
|
#00 .DateTime/second DEI
|
|
#00 .DateTime/minute DEI #60 SFT2 EOR2
|
|
#00 .DateTime/hour DEI #c0 SFT2 EOR2 ;prng2/x STA2
|
|
#00 .DateTime/hour DEI #04 SFT2
|
|
#00 .DateTime/day DEI #10 SFT2 EOR2
|
|
#00 .DateTime/month DEI #60 SFT2 EOR2
|
|
.DateTime/year DEI2 #a0 SFT2 EOR2 ;prng2/y STA2
|
|
;prng2/x LDA2 ;prng2/y LDA2 EOR2
|
|
ORAk ,&non-zero JCN INC2 &non-zero
|
|
;prng/seed STA2
|
|
|
|
( theme )
|
|
#0fe5 .System/r DEO2
|
|
#0fc5 .System/g DEO2
|
|
#0f25 .System/b DEO2
|
|
BRK
|
|
|
|
@on-frame ( -> )
|
|
#c0
|
|
&loop
|
|
,draw-pixel JSR
|
|
INC
|
|
DUP ,&loop JCN
|
|
POP
|
|
BRK
|
|
|
|
@draw-pixel
|
|
,prng2 JSR
|
|
#00 SWP .Screen/x DEO2
|
|
#00 SWP .Screen/y DEO2
|
|
#01 .Screen/pixel DEO
|
|
JMP2r
|
|
|
|
@prng ( -- number* )
|
|
( returns the next number in a 65,535-long sequence,
|
|
which is never zero but every other 16-bit number
|
|
appears once before the sequence repeats )
|
|
( http://www.retroprogramming.com/2017/07/xorshift-pseudorandom-numbers-in-z80.html )
|
|
,&seed LDR2
|
|
DUP2 #70 SFT2 EOR2
|
|
DUP2 #09 SFT2 EOR2
|
|
DUP2 #80 SFT2 EOR2
|
|
,&seed STR2k POP
|
|
JMP2r
|
|
|
|
&seed $2
|
|
|
|
@prng2 ( -- number* )
|
|
( returns the next number in a (2^32-1)-long sequence )
|
|
( http://b2d-f9r.blogspot.com/2010/08/16-bit-xorshift-rng-now-with-more.html )
|
|
,&x LDR2
|
|
DUP2 #50 SFT2 EOR2
|
|
DUP2 #03 SFT2 EOR2
|
|
,&y LDR2 DUP2 ,&x STR2
|
|
DUP2 #01 SFT2 EOR2 EOR2
|
|
,&y STR2k POP
|
|
JMP2r
|
|
|
|
&x $2
|
|
&y $2
|
|
|