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deckarep/rand.6502.asm

Created January 23, 2021 06:49
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6502 assembly - simple RAND subroutine
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rand.6502.asm
rand equ $04
;uint8_t next_rnd(void)
;{
; static uint8_t rnd;
; rnd = rnd * 5 + 17;
; return rnd;
;}
; returns a pseudo rand store at memory location: rand
next_rand:
lda rand
asl ; A = RND * 2
asl ; A = RND * 4
clc
adc rand ; A = RND * 5
clc
adc #17 ; A = RND * 5 + 17
sta rand
rts
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http://www.dabeaz.com/superboard/asm6502.py

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