lda #0
sta $0
lda #2
sta $1

;====================================================
loopOne:
lda $FE
and #1
sta ($0),y

clc
lda $0
adc #1
sta $0
lda $1
adc #0
sta $1
cmp #6
beq memoryFilled
jmp loopOne


;====================================================
memoryFilled:
jsr resetEverything
notDoneYet:
jsr countLife ;count life around cell
lda ($0),y
cmp #1
beq cellWasAlive
;otherwise, the cell is NOT living
jsr currentCellDead
jmp cellChecked

cellWasAlive:
jsr currentCellAlive
jmp cellChecked


cellChecked:
sta ($4),y ;Store final cell checked value in the buffer

jsr incrementPointers
lda $1
cmp #6
beq doneNow
;it was not equal, jump back
jmp notDoneYet

doneNow: ;here lies the rub, done now is not jumping here properly
jsr resetEverything
jsr copyNewBuffer
jmp memoryFilled


;reset stuff, including $10

;====================================================
resetEverything:
lda #0 ;screen pointer
sta $0
lda #2
sta $1

lda #0 ;screen reading pointer
sta $2
lda #2
sta $3

lda #0 ;buffer pointer
sta $4
lda #7
sta $5


lda #0  ;life count
sta $10
rts



;====================================================
countLife:
;center screen reading pointer
lda $0
sta $2
lda $1
sta $3

;TODO!!
;since the data is all in one stream, we need to account for the fact that
;the map is 2d, and wraps around every 32 pixels.
;if cell is far left, don't calculate up left, left, or down left
;if cell is far right, don't calculate up right, right, or down right
ldx #0

;x--
;---
;---
sec
lda $2
sbc #33 ;move up one row, left a column
sta $2
lda $3
sbc #0  ;carry subtract
sta $3
jsr addLife

;-x-
;---
;---
clc
lda $2
adc #1 ;move right one
sta $2
lda $3
adc #0
sta $3
jsr addLife

;--x
;---
;---
clc
lda $2
adc #1 ;move right one
sta $2
lda $3
adc #0
sta $3
jsr addLife

;center screen reading pointer
lda $0
sta $2
lda $1
sta $2

;---
;x--
;---
sec
lda $2
sbc #1 ;move left one
sta $2
lda $3
sbc #0  ;carry subtract
sta $3
jsr addLife

;---
;--x
;---
clc
lda $2
adc #2 ;move right two
sta $2
lda $3
adc #0
sta $3
jsr addLife


;center screen reading pointer
lda $0
sta $2
lda $1
sta $2

;---
;---
;x--
clc
lda $2
adc #31 ;move down one, left one
sta $2
lda $3
adc #0
sta $3
jsr addLife

;---
;---
;-x-
clc
lda $2
adc #1 ;move right one
sta $2
lda $3
adc #0
sta $3
jsr addLife

;---
;---
;--x
clc
lda $2
adc #1 ;move right one
sta $2
lda $3
adc #0
sta $3
jsr addLife

rts



;====================================================
addLife:
lda ($2),y
cmp #1
bne noLife
inc $10
noLife:
rts



;====================================================
currentCellDead:
;  If there are 3 neighboring cells, it is alive
;  Any other case, it is dead.
lda $10
cmp #3
beq deadCellAlive
;no? then it's dead.
lda #0
jmp currentCellDeadEnd

deadCellAlive:
lda #1
jmp currentCellDeadEnd

currentCellDeadEnd:
rts



;====================================================
currentCellAlive:
lda $10
;useless notes - cmp actually compares and sets flags as if
;subtract had taken place... so if it's equal, carry flag will
;be set, and the equal flag will be set. If it's more than,
;just the carry flag will be set. If it's less than, none
;of the flags will be set.

;  Any live cell with fewer than two live neighbours dies,
;  Any live cell with two or three live neighbours lives
;  Any live cell with more than three live neighbours dies

cmp #2
bcs cellEQGT2
;less than 2, cell dies
lda #0
jmp currentCellAliveEnd

cellEQGT2:
BNE cellGT2
;equal to 2, cell lives
lda #1
jmp currentCellAliveEnd

cellGT2:
cmp #3
bne cellGT3
;equal to 3, cell lives
lda #1
jmp currentCellAliveEnd

cellGT3:
;greater than 3, cell dies
lda #0
jmp currentCellAliveEnd

currentCellAliveEnd:
rts



;====================================================
incrementPointers:
clc
lda $0 ;increment screen pointer
adc #1
sta $0
lda $1
adc #0
sta $1

clc
lda $4 ;increment buffer pointer
adc #1
sta $4
lda $5
adc #0
sta $5
rts


;====================================================
copyNewBuffer:
lda ($4),y
sta ($0),y
jsr incrementPointers
lda $1
cmp #6
bne copyNewBuffer
rts