127 lines
2.5 KiB
NASM
127 lines
2.5 KiB
NASM
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INCLUDE "globals.asm"
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INCLUDE "memcpy.asm"
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INCLUDE "hardwarectl.asm"
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INCLUDE "interrupts.asm"
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INCLUDE "res/tiles.inc"
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INCLUDE "res/gameplay_map.inc"
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SECTION "Code Entry Point", ROM0
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MainEntryPoint::
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; Turn off LCD during initialization.
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call DisableLCD
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call DisableAudio
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; We use a single set of tiles for the entire game, so we copy it at the start.
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ld de, Tiles
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ld hl, $9000
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ld bc, TilesEnd - Tiles
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call UnsafeMemCopy
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; The tilemap is just for testing for now.
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ld de, GameplayTilemap
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ld hl, $9800
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ld bc, GameplayTilemapEnd - GameplayTilemap
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call UnsafeMemCopy
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ld a, PALETTE_REGULAR
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call SetBGPalette
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call InitializeVariables
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call InitializeLCDCInterrupt
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; And turn it back on before we start.
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call EnableLCD
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; Make sure the first game loop starts just like all the future ones.
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wait_vblank
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wait_vblank_end
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GameLoop::
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call GetInput
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call HandleTimers
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ld bc, 20*10
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ld hl, wField
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: ld a, [wFill]
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ld [hl+], a
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dec bc
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ld a, b
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or a, c
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jp nz, :-
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ld a, [wFill]
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inc a
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ld [wFill], a
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; Handle gameplay here
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; TODO
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GameLoopEnd:
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wait_vblank
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call BlitField
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jp GameLoop
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; *****************************************************************************
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; * *
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; * Functions *
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; * *
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; *****************************************************************************
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SECTION "Functions", ROM0
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InitializeVariables:
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xor a, a
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ld [wLCDCCtr], a
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ret
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BlitField:
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; The first 16 rows can be blitted without checking for vram access.
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ld de, wField
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DEF row = 0
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REPT 16
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ld hl, FIELD_ROW_1+(32*row)
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REPT 10
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ld a, [de]
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ld [hl+], a
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inc de
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ENDR
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DEF row += 1
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ENDR
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; The last 4 rows need some care.
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REPT 4
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ld hl, FIELD_ROW_1+(32*row)
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REPT 2
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: ldh a, [rSTAT]
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and STATF_LCD
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cp STATF_HBL
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jr z, :-
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: ldh a, [rSTAT]
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and STATF_LCD
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cp STATF_HBL
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jr nz, :-
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REPT 5
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ld a, [de]
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ld [hl+], a
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inc de
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ENDR
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ENDR
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DEF row += 1
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ENDR
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ret
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GetInput:
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ret
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HandleTimers:
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ld a, [wEvenFrame]
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inc a
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and 1
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ld [wEvenFrame], a
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ret
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