Files
GB-GameOfLife/Code/main.asm

763 lines
14 KiB
NASM

INCLUDE "hardware.inc"
_VRAM_BG_TILES EQU $9000
SECTION "Memory Copy", ROM0
; hl = destination
; de = source
; bc = count
MemoryCopy:
ld a, [de]
ld [hl+], a
inc de
dec bc
ld a, b
or c
jr nz, MemoryCopy
ret
SECTION "Memory Set", ROM0
; hl = destination
; d = data
; bc = count
MemorySet:
ld a, d
ld [hl+], a
dec bc
ld a, b
or c
jr nz, MemorySet
ret
SECTION "Timer Interrupt Handler", ROM0[$50]
TimerInterruptHandler:
reti
SECTION "Serial Interrupt Handler", ROM0[$58]
SerialInterruptHandler:
reti
SECTION "Joypad Interrupt Handler", ROM0[$60]
JoypadInterruptHandler:
reti
SECTION "Header", ROM0[$100]
EntryPoint:
di
jp Start
REPT $150 - $104
db 0
ENDR
SECTION "Main", ROM0[$150]
Start:
; shut sound off
ld [rNR52], a
; set old and rendered pointers to buffer0
ld a, HIGH(Buffer0)
ldh [Old + 1], a
ldh [Rendered + 1], a
; set new pointer to buffer1
ld a, HIGH(Buffer1)
ldh [New + 1], a
; set video pointer to first tilemap
ld a, HIGH(_SCRN0)
ldh [Video + 1], a
; reset low bytes of pointers (all buffers are aligned)
xor a
ldh [New], a
ldh [Old], a
ldh [Rendered], a
ldh [Video], a
; set lines and tiles left to 0 to avoid rendering in interrupts
ldh [LinesLeft], a
ldh [TilesLeft], a
; enable v-blank interrupt
ld a, IEF_VBLANK
ld [rIE], a
; enable interrupts while clearing interrupt flags
xor a
ei
ldh [rIF], a
; wait for v-blank
halt
; disable screen
xor a
ld [rLCDC], a
; load bg palette [0=black, 1=dark gray, 2=light gray, 3=white]
ld a, %11100100
ld [rBGP], a
; load 18 tiles
; 0..15: 2x2 cell combinations
; 16: sprite selection tile
; 17: empty tile
ld hl, _VRAM_BG_TILES
ld de, Tiles
ld bc, TilesEnd - Tiles
call MemoryCopy
; set scrolling to (0, 0)
xor a
ld [rSCX], a
ld [rSCY], a
; clear screen (both buffers)
ld hl, _SCRN0
ld d, 17 ; empty tile
ld bc, 32 * 32 * 2
call MemorySet
; clear screen (both buffers)
ld hl, _SCRN1
ld d, 0 ; empty tile
ld bc, 32 * 32
call MemorySet
; init buffer 0
ld hl, Buffer0
ld de, DefaultMap
ld bc, 20 * 18
call MemoryCopy
; set total to render to start rendering
ld a, 18
ldh [LinesLeft], a
ld a, 20
ldh [TilesLeft], a
; enable h-blank interrupt in lcd stat
ld a, STATF_MODE00
ld [rSTAT], a
; enable screen but don't display anything yet
ld a, LCDCF_ON
ld [rLCDC], a
.mainloop
; enable v-blank and lcd stat interrupt for h-blank
di
ld a, IEF_VBLANK | IEF_LCDC
ld [rIE], a
xor a
ei
ldh [rIF], a
.topleft
; handle top left corner
ld hl, TopLeftCorner
call ConwayGroup
; advance to next cell in top row
ld hl, New
inc [hl]
ld hl, Old
inc [hl]
; handle all cells in top row except corners
ld a, 18
.top
ld [XLoop], a
; handle top row cell
ld hl, TopRow
call ConwayGroup
; advance to next cell in top row
ld hl, New
inc [hl]
ld hl, Old
inc [hl]
; loop horizontally
ld a, [XLoop]
dec a
jr nz, .top
; handle top right corner
.topright
ld hl, TopRightCorner
call ConwayGroup
; advance pointers to next row
ld hl, New
inc [hl]
ld hl, Old
inc [hl]
ld a, 16
.leftcolumn
ld [YLoop], a
; handle first element in row
ld hl, LeftColumn
call ConwayGroup
; advance to next cell
ld hl, New
inc [hl]
ld hl, Old
inc [hl]
ld a, 18
.inner
ld [XLoop], a
; handle element inside row
ld hl, Inner
call ConwayGroup
; advance to next cell
ld hl, New
inc [hl]
ld hl, Old
inc [hl]
jr nz, .noCarry
inc hl ; old+1
inc [hl]
ld hl, New + 1
inc [hl]
.noCarry
; loop horizontally
ld a, [XLoop]
dec a
jr nz, .inner
; handle last element in row
.rightcolumn
ld hl, RightColumn
call ConwayGroup
; advance to next row
ld hl, New
inc [hl]
ld hl, Old
inc [hl]
; loop vertically
ld a, [YLoop]
dec a
jr nz, .leftcolumn
; handle bottom left element
.bottomleft
ld hl, BottomLeftCorner
call ConwayGroup
; advance to next cell in bottom row
ld hl, New
inc [hl]
ld hl, Old
inc [hl]
; handle all cells in bottom row except corners
ld a, 18
.bottom
ld [XLoop], a
; handle top row cell
ld hl, BottomRow
call ConwayGroup
; advance to next cell in top row
ld hl, New
inc [hl]
ld hl, Old
inc [hl]
; loop horizontally
ld a, [XLoop]
dec a
jr nz, .bottom
; handle last element
.bottomright
ld hl, BottomRightCorner
call ConwayGroup
; increment old pointer to first byte after buffer
ld hl, Old
inc [hl]
; wait end of rendering
.waitLines
; check high byte of TotalToRender
ldh a, [LinesLeft]
or a
jr z, .waitTiles
halt
jr .waitLines
.waitTiles
; check low byte of TotalToRender
ldh a, [TilesLeft]
or a
jr z, .swap
halt
jr .waitTiles
.swap
; enable only v-blank interrupt
di
ld a, IEF_VBLANK
ld [rIE], a
xor a
ei
ldh [rIF], a
; wait v-blank
halt
; check which buffer has just been rendered
ldh a, [Old + 1]
cp a, HIGH(Buffer1)
jr nc, .newToBuffer1
.newToBuffer0
; set old and rendered pointers to buffer1
ld a, HIGH(Buffer1)
ldh [Old + 1], a
ldh [Rendered + 1], a
; set new pointer to buffer0
ld a, HIGH(Buffer0)
ldh [New + 1], a
; set video pointer to first tilemap
ld a, HIGH(_SCRN1)
ldh [Video + 1], a
; display bg 9800 that has just been filled
ld a, LCDCF_ON | LCDCF_BGON | LCDCF_BG9800
ld [rLCDC], a
jr .resetLowBytes
.newToBuffer1
; set old and rendered pointers to buffer0
ld a, HIGH(Buffer0)
ldh [Old + 1], a
ldh [Rendered + 1], a
; set new pointer to buffer1
ld a, HIGH(Buffer1)
ldh [New + 1], a
; set video pointer to second tilemap
ld a, HIGH(_SCRN0)
ldh [Video + 1], a
; display bg 9C00 that has just been filled
ld a, LCDCF_ON | LCDCF_BGON | LCDCF_BG9C00
ld [rLCDC], a
.resetLowBytes
; reset low bytes of pointers
xor a
ldh [New], a
ldh [Old], a
ldh [Rendered], a
ldh [Video], a
; set total to render to restart rendering
ld a, 20
ldh [TilesLeft], a
ld a, 18
ldh [LinesLeft], a
jp .mainloop
SECTION "Load cell group and 8 neighbors to HRAM, then compute", ROM0
; hl = pointer to neighbor offsets
; destroys all registers
ConwayGroup:
; save pointer to neighbors
push hl
; pointer to HRAM
ld c, LOW(Cells)
; load old pointer into hl
ld hl, Old
ld a, [hl+]
ld h, [hl]
ld l, a
; load cell group
ld a, [hl]
; write cell group into hram
ld [$FF00+c], a
; increment hram pointer
inc c
; counter to 8
ld b, 8
.loop
; restore pointer to neighbors
pop hl
; load offset into de
ld a, [hl+]
ld e, a
ld a, [hl+]
ld d, a
; save incremented pointer to neighbors
push hl
; load old pointer into hl
ld hl, Old
ld a, [hl+]
ld h, [hl]
ld l, a
; add offset
add hl, de
; load neighbor
ld a, [hl]
; store neighbor into hram
ld [$FF00+c], a
; increment pointer into hram
inc c
; decrement counter
dec b
; continue to next neighbor if any
jr nz, .loop
.compute
; remove pointer to offsets from stack
pop hl
; reset result
xor a
ldh [Result], a
; compute all 4 cells
ld hl, TopLeftMask
call Conway
ld hl, TopRightMask
call Conway
ld hl, BottomLeftMask
call Conway
ld hl, BottomRightMask
call Conway
; load new pointer
ld hl, New
ld a, [hl+]
ld h, [hl]
ld l, a
; load result
ldh a, [Result]
; save result to new buffer
ld [hl], a
ret
SECTION "Conway cell compute", ROM0
; hl = pointer to cell group masks
Conway:
; reset alive counter
xor a
ldh [Alive], a
; load cells pointer
ld c, LOW(Cells)
.loop
; load next mask
ld a, [hl+]
; move mask to d
ld d, a
; load data
ld a, [$FF00+c]
; mask data
and a, d
; count bits set
ld de, BitsSet
add a, e
ld e, a
ld a, [de]
ld b, a
; add to alive
ldh a, [Alive]
add a, b
ldh [Alive], a
; increment cells pointer
inc c
; loop over all neighbors
ld a, c
cp a, LOW(Cells + 9)
jr nz, .loop
.decide
; load current group mask
ld b, [hl]
; load current cell group
ldh a, [Cells]
; mask data
and a, b
; load alive count
ldh a, [Alive]
jr z, .dead
.alive
; check if there is two or three neighbors
cp a, 2
ret c
cp a, 4
ret nc
.writealive
; add mask to result
ldh a, [Result]
or a, b
ldh [Result], a
ret
.dead
; check if there is three neighbors
cp a, 3
jr z, .writealive
.writedead
ret
SECTION "V-Blank Interrupt Handler", ROM0[$40]
VBlankInterruptHandler:
; save registers
push af
push de
push bc
push hl
; render
jp Render
SECTION "LCD Stat Interrupt Handler", ROM0[$48]
LCDStatInterruptHandler:
; save registers
push af
push de
push bc
push hl
; render
jp Render
SECTION "Render", ROM0
Render:
; check there are lines to render
ldh a, [LinesLeft]
and a
jr z, .exit
; check there are tiles to render
ldh a, [TilesLeft]
and a
jr z, .exit
.render
; load buffer pointer into DE
ld hl, Rendered
ld a, [hl+]
ld d, [hl]
ld e, a
; load video pointer into HL
ld hl, Video
ld a, [hl+]
ld h, [hl]
ld l, a
; set c to point to tiles left to render
.nextline
ld c, LOW(TilesLeft)
.loop
; check we can still render
ldh a, [rSTAT]
and a, STATF_BUSY
jr nz, .finish
; copy one byte
ld a, [de]
ld [hl+], a
inc de
; loop while there are tiles to render
ld a, [$FF00+c]
dec a
ld [$FF00+c], a
jr nz, .loop
; go to next line
push de
ld de, 32 - 20
add hl, de
pop de
ld c, 20
; loop while there are lines to render
ld c, LOW(LinesLeft)
ld a, [$FF00+c]
dec a
ld [$FF00+c], a
jr z, .finish
ld a, 20
ldh [TilesLeft], a
jr .nextline
; save incremented video and buffer pointers
.finish
ld a, l
ldh [Video], a
ld a, h
ldh [Video + 1], a
ld a, e
ldh [Rendered], a
ld a, d
ldh [Rendered + 1], a
.exit
; restore registers saved in interrupt handler
pop hl
pop bc
pop de
pop af
; return from v-blank or lcd interrupt
reti
; automata buffers with 4 cells per byte
; 2x2 bytes per cell, bit ordering:
; ___ ___
; |0 1| |0 1|
; |2 3| eg. |1 0| is %0110 = 6
; ‾‾‾ ‾‾‾
; bits 4, 5, 6 and 7 are not used
SECTION "Automata buffer 0", WRAM0, ALIGN[9]
Buffer0: ds 20 * 18
SECTION "Automata buffer 1", WRAM0, ALIGN[9]
Buffer1: ds 20 * 18
SECTION "Compute Memory", HRAM
Old: ds 2 ; pointer to bufferX
New: ds 2 ; pointer to bufferX
Alive: ds 1
XLoop: ds 1
YLoop: ds 1
Cells: ds 9
Result: ds 1
SECTION "Render Memory", HRAM
LinesLeft: ds 1 ; number of lines left to render
TilesLeft: ds 1 ; number of tiles left to render in current line
Video: ds 2 ; pointer to tilemap
Rendered: ds 2 ; pointer to bufferX
SECTION "Game of Life neighboring cells offset tables", ROM0
; for a looping grid of 20x18 cells
; order matters R, BR, B, BL, L, TL, T, TR
TopLeftCorner: dw 1, 21, 20, 39, 19, 359, 340, 341
TopRightCorner: dw -19, 1, 20, 19, -1, 339, 340, 321
BottomLeftCorner: dw 1, -339, -340, -321, 19, -1, -20, -19
BottomRightCorner: dw -19, -359, -340, -341, -1, -21, -20, -39
TopRow: dw 1, 21, 20, 19, -1, 339, 340, 341
BottomRow: dw 1, -339, -340, -341, -1, -21, -20, -19
LeftColumn: dw 1, 21, 20, 39, 19, -1, -20, -19
RightColumn: dw -19, 1, 20, 19, -1, -21, -20, -39
Inner: dw 1, 21, 20, 19, -1, -21, -20, -19
SECTION "Game of Life neighboring masks", ROM0
; order matters I, R, BR, B, BL, L, TL, T, TR, SELF
TopLeftMask: db 14, 0, 0, 0, 0, 10, 8, 12, 0, 1
TopRightMask: db 13, 5, 0, 0, 0, 0, 0, 12, 4, 2
BottomLeftMask: db 11, 0, 0, 3, 2, 10, 0, 0, 0, 4
BottomRightMask: db 7, 5, 1, 3, 0, 0, 0, 0, 0, 8
SECTION "Bits Set", ROM0, ALIGN[4]
BitsSet:
db 0; 0 = 0000
db 1; 1 = 0001
db 1; 2 = 0010
db 2; 3 = 0011
db 1; 4 = 0100
db 2; 5 = 0101
db 2; 6 = 0110
db 3; 7 = 0111
db 1; 8 = 1000
db 2; 9 = 1001
db 2; 10 = 1010
db 3; 11 = 1011
db 2; 12 = 1100
db 3; 13 = 1101
db 3; 14 = 1110
db 4; 15 = 1111
SECTION "Default Map", ROM0
DefaultMap:
; 20x18 map with a glider on the top left corner
db 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
db 0, 1, 2, 4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
db 0, 9,12, 5, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
db 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
db 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
db 0, 3, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
db 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
db 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
db 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
db 0, 0, 3, 1, 0, 3, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
db 0, 5, 0,10,10, 0, 0, 5, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
db 0, 1,12, 6, 2,12, 4, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
db 0, 0,12, 4, 0,12, 4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
db 0, 5, 0,10,10, 0, 0, 5, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
db 0, 1, 0, 2, 2, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
db 0, 0, 3, 1, 0, 3, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
db 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
db 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
SECTION "Graphics", ROM0
Tiles:
INCBIN "Tiles.bin"
TilesEnd: ds 0