uxn/projects/examples/demos/prng.tal

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Tal
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2021-08-25 16:04:25 -04:00
( pseudo-random number generator )
( 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 ]
|b0 @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) )
.DateTime/month DEI .DateTime/day DEI
#00 .DateTime/second #a0 SFT2 EOR2
#00 .DateTime/minute #40 SFT2 EOR2
.DateTime/hour EOR
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
,prng JSR
#00 SWP .Screen/x DEO2
#00 SWP .Screen/y DEO2
#01 .Screen/pixel DEO
JMP2r
@prng ( -- number* )
( returns the next number in the 65,535-long sequence,
which is never zero but every other 16-bit number
appears once before the sequence repeats )
,&seed LDR2
DUP2 #70 SFT2 EOR2
DUP2 #09 SFT2 EOR2
DUP2 #80 SFT2 EOR2
,&seed STR2k POP
JMP2r
&seed $2