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random16: update the cycle counts

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This commit is contained in:
Vince Weaver 2018-09-06 01:09:23 -04:00
parent 803591a93c
commit 816d1a81f7
2 changed files with 72 additions and 42 deletions
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57
asm_routines/random16.s
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@ -11,35 +11,50 @@ SEEDH = $4F
XOR_MAGIC = $7657 ; "vW" XOR_MAGIC = $7657 ; "vW"
;=============================
; random16
;=============================
; takes:
; not 0, cc = 5+ = 27
; not 0, cs = 5+12+19 = 36
; $0000 = 5+7+19 = 31
; $8000 = 5+6+14 = 25
; $XX00 = 5+6+7+19 = 37
random16: random16:
lda SEEDL lda SEEDL ; 3
beq lowZero ; $0000 and $8000 are special values // ; Do a normal shift beq lowZero ; $0000 and $8000 are special values ; 2
asl SEEDL
lda SEEDH asl SEEDL ; Do a normal shift ; 5
rol lda SEEDH ; 3
bcc noEor rol ; 2
bcc noEor ; 2
doEor: doEor:
; high byte is in .A ; high byte is in A
eor #>XOR_MAGIC
sta SEEDH
lda SEEDL eor #>XOR_MAGIC ; 2
eor #<XOR_MAGIC sta SEEDH ; 3
sta SEEDL lda SEEDL ; 3
rts eor #<XOR_MAGIC ; 2
sta SEEDL ; 3
rts ; 6
lowZero: lowZero:
lda SEEDH ; 1
beq doEor ; High byte is also zero, so apply the EOR lda SEEDH ; 3
beq doEor ; High byte is also zero ; 3
; so apply the EOR
; -1
; wasn't zero, check for $8000 ; wasn't zero, check for $8000
asl asl ; 2
beq noEor ; if $00 is left after the shift beq noEor ; if $00 is left after the shift ; 2
; then it was $80 ; then it was $80
bcs doEor ; else, do the EOR based on the carry bit bcs doEor ; else, do the EOR based on the carry ; 3
noEor: noEor:
sta SEEDH ; 1
sta SEEDH ; 3
rts rts ; 6

57
fireworks/random16.s
View File

@ -11,35 +11,50 @@ SEEDH = $4F
XOR_MAGIC = $7657 ; "vW" XOR_MAGIC = $7657 ; "vW"
;=============================
; random16
;=============================
; takes:
; not 0, cc = 5+ = 27
; not 0, cs = 5+12+19 = 36
; $0000 = 5+7+19 = 31
; $8000 = 5+6+14 = 25
; $XX00 = 5+6+7+19 = 37
random16: random16:
lda SEEDL lda SEEDL ; 3
beq lowZero ; $0000 and $8000 are special values // ; Do a normal shift beq lowZero ; $0000 and $8000 are special values ; 2
asl SEEDL
lda SEEDH asl SEEDL ; Do a normal shift ; 5
rol lda SEEDH ; 3
bcc noEor rol ; 2
bcc noEor ; 2
doEor: doEor:
; high byte is in .A ; high byte is in A
eor #>XOR_MAGIC
sta SEEDH
lda SEEDL eor #>XOR_MAGIC ; 2
eor #<XOR_MAGIC sta SEEDH ; 3
sta SEEDL lda SEEDL ; 3
rts eor #<XOR_MAGIC ; 2
sta SEEDL ; 3
rts ; 6
lowZero: lowZero:
lda SEEDH ; 1
beq doEor ; High byte is also zero, so apply the EOR lda SEEDH ; 3
beq doEor ; High byte is also zero ; 3
; so apply the EOR
; -1
; wasn't zero, check for $8000 ; wasn't zero, check for $8000
asl asl ; 2
beq noEor ; if $00 is left after the shift beq noEor ; if $00 is left after the shift ; 2
; then it was $80 ; then it was $80
bcs doEor ; else, do the EOR based on the carry bit bcs doEor ; else, do the EOR based on the carry ; 3
noEor: noEor:
sta SEEDH ; 1
sta SEEDH ; 3
rts rts ; 6