6502.org

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lda a           ; Operation 7 (with carry clear).
asl
eor b
sta b
rol             ; Operation 9.
eor c
sta c
eor a           ; Operation 5.
sta a
lda b           ; Operation 15.
ror
eor c
sta c
eor b           ; Operation 6.
sta b

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         rep #%11111111        ;reset all SR bits
         sep #%00110000        ;8-bit registers
         lda #%00110000        ;operate timer B...
         sta $c104             ;as a counter
         rep #%00100000        ;16-bit .A
         stz $c106             ;preset timer to zero
         bra restart           ;start timer & halt
;
;
;	here we read the timer on the fly...
;
read     ldx $c10f             ;stop timer &...
         lda $c104             ;read it
         sta $c104             ;write it back as new preset
;
restart  ldx $c10e             ;restart timer
         sta $a0               ;save timer value
         brk
         nop
         bra read              ;play it again, Sam

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	.opt proc65816,caseinsensitive,swapbin
;===============================================================================
;
;PRNG SEED NOISE GENERATOR
;
;	—————————————————————————————————————————————————————————————————————
;	This bit of code sets up timer B as a free-running counter driven by
;	the X1 clock without scaling.  The timer will run down from $FFFF to
;	$0000, reload & repeat.  THe “noise” is gotten by briefly stopping
;	the timer, doing a 16-bit read of its registers & then restarting it.
;	The result will be a value somewhere in the 16-bit range.
;	—————————————————————————————————————————————————————————————————————
;
acrb     =$00c104              ;DUART ‘B’ aux control
ctb      =$00c106              ;DUART ‘B’ timer
ctstrtb  =$00c10e              ;DUART ‘B’ timer start
ctstopb  =$00c10f              ;DUART ‘B’ timer stop
;
setasctr =%00100000            ;counter mode using 1× X1 clock
;
noise    =$a0                  ;noise storage
;
         *=$000100
;
main     rep #%11111111        ;reset all SR bits
         lda !#0
         tax
         tay
         phk
         plb
         sep #%00010000        ;8-bit index
         ldx #setasctr         ;operate timer B...
         stx acrb              ;as a counter
         stz ctb               ;initial preset
         stz noise             ;reset...
         stz noise+2           ;noise
         bra restart           ;start timer & pause
;
read     ldx ctstopb           ;stop timer
         lda ctb               ;read timer
         sta ctb               ;write back as preset
         xba                   ;reverse endianess &...
         sta noise             ;save noise LSW
         eor !#-1              ;mix up things
         sta noise+2           ;save noise MSW
;
restart  ldx ctstrtb           ;start timer
         brk
         nop
         bra read              ;get some noise
;
	.end

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$ minisim -b couwenberg.xex  | ../../pr-095/RNG_test stdin8 -te 1 -tlmin 10 -tlmax 50 -tlmaxonly -multithreaded
RNG_test using PractRand version 0.95
RNG = RNG_stdin8, seed = unknown
test set = expanded, folding = standard (8 bit)

rng=RNG_stdin8, seed=unknown
length= 1 kilobyte (2^10 bytes), time= 0.1 seconds
  no anomalies in 16 test result(s)

rng=RNG_stdin8, seed=unknown
length= 2 kilobytes (2^11 bytes), time= 0.4 seconds
  no anomalies in 30 test result(s)

rng=RNG_stdin8, seed=unknown
length= 4 kilobytes (2^12 bytes), time= 1.0 seconds
  no anomalies in 38 test result(s)

rng=RNG_stdin8, seed=unknown
length= 8 kilobytes (2^13 bytes), time= 1.8 seconds
  Test Name                         Raw       Processed     Evaluation
  BRank(18):128(1)                  R= +2133  p~=  3.3e-643   FAIL !!!!!!!   
  ...and 60 test result(s) without anomalies

rng=RNG_stdin8, seed=unknown
length= 16 kilobytes (2^14 bytes), time= 2.8 seconds
  Test Name                         Raw       Processed     Evaluation
  BRank(18):128(2)                  R= +3017  p~=  3.3e-909   FAIL !!!!!!!   
  ...and 79 test result(s) without anomalies

rng=RNG_stdin8, seed=unknown
length= 32 kilobytes (2^15 bytes), time= 4.2 seconds
  Test Name                         Raw       Processed     Evaluation
  BRank(18):128(2)                  R= +3017  p~=  3.3e-909   FAIL !!!!!!!   
  ...and 95 test result(s) without anomalies

rng=RNG_stdin8, seed=unknown
length= 64 kilobytes (2^16 bytes), time= 5.8 seconds
  Test Name                         Raw       Processed     Evaluation
  BRank(18):128(2)                  R= +3017  p~=  3.3e-909   FAIL !!!!!!!   
  BRank(18):256(1)                  R= +4889  p~=  1e-1472    FAIL !!!!!!!!  
  [Low1/8]BRank(18):128(1)          R= +2133  p~=  3.3e-643   FAIL !!!!!!!   
  ...and 110 test result(s) without anomalies

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        lda seed
        beq doEor  ;if the input was $00, force EOR
         asl
         beq noEor ;if the input was $80, skip the EOR
         bcc noEor
doEor:    eor #$1d
noEor:  sta seed


; $00 : (shift and) perform EOR
; $80 : just shift
; %1xxxxxxx : shift and perform EOR
; %0xxxxxxx : just shift