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base:16bit_xorshift_random_generator

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base:16bit_xorshift_random_generator [2019-05-10 02:09] – vsariolabase:16bit_xorshift_random_generator [2019-05-10 02:37] – vsariola
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 </code> </code>
  
-Here is an implementation for the C64. 25 cycles without the RTS.+Here is an implementation for the C64. 30 cycles without the RTS.
  
 <code asm> <code asm>
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         ...         ...
         ; the RNG, you can get 8-bit random numbers in A, leaves X/Y unchanged         ; the RNG, you can get 8-bit random numbers in A, leaves X/Y unchanged
-random  LDA rng_zp_low+random  LDA rng_zp_high
         LSR         LSR
 +        LDA rng_zp_low
 +        ROR
         EOR rng_zp_high         EOR rng_zp_high
         STA rng_zp_high ; high part of x ^= x << 7 done         STA rng_zp_high ; high part of x ^= x << 7 done
-        ROR             ; A has now x >> 9 and the high bit of the low byte +        ROR             ; A has now x >> 9 and high bit comes from low byte 
-        EOR rng_zp_low +        EOR rng_zp_low
         STA rng_zp_low  ; x ^= x >> 9 done         STA rng_zp_low  ; x ^= x >> 9 done
         EOR rng_zp_high          EOR rng_zp_high 
base/16bit_xorshift_random_generator.txt · Last modified: 2019-08-12 15:41 by ftc