Atari ST series - Page 217

Random
Get Pseudo-Random Number
Random() Opcode = 17
T his fu n ction re tu rn s th e n ex t 24 -b it p se u d o-ran d om n u m b er in th e series
g en era te d b y th e alg orith m :
SEED = (SEED * 3141592621) + 1
T h e va lu e retu rn ed is th e n ew se ed valu e, sh ifte d eig h t bits to th e righ t.
Since th e initial se ed v alu e is tak en from th e s cr ee n 's ve rtical blank fra m e
co u n te r, th e seq u en ce sh ou ld b e d iffere n t ea ch tim e th e m ach in e is tu rn ed
on .
C macro format
lon g m d n u m ;
m d n u m = R a n d o m ()
Machine language format
m o v e .w # 1 7 , - ( s p )
trap # 1 4
ad d q .l # 2 ,s p
Inputs
N o ne
Results
DO rn d n u m lon g A 24 -b it p se u d o -ran d om n u m b er (bits 2 4 -3 1 a re 0)
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