mirror of https://github.com/deater/tb1.git
131 lines
2.6 KiB
ArmAsm
131 lines
2.6 KiB
ArmAsm
;
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; title_screen.s
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; by Vince Weaver <vince _at_ deater.net>
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;
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; Draws the title screen in Mode 3
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;
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display_title:
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rep #$10 ; X/Y = 16 bit
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.i16
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sep #$20 ; mem/A = 8 bit
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.a8
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;===============================================
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;===============================================
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; Display to the screen
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;===============================================
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;===============================================
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;==========================
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; Setup Background
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;==========================
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; we want the BG1 Tilemap to start at VRAM $F000 (60k)
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; Format is
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; aaaa aass a is shifted by 10 for address
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; ss = size of screen in tiles 00 = 32x32
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;
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; 0111 0000
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lda #$70 ; BG1 Tilemap starts at VRAM $e000/2
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sta $2107 ; bg1 src
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; aaaa bbbb a= BG2 tiles, b= BG1 tiles
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; bbbb<<13
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; 0000 0000
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; our BG1 tiles are stored starting in VRAM $0000
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lda #$00
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sta $210b ; bg1 tile data starts at VRAM 0000
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;==========================
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; Load Title Screen Palette
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;==========================
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stz $2121 ; start with color 0
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ldy #(256*2) ; we have 256 colors
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lda #^title_screen_palette
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ldx #.LOWORD(title_screen_palette)
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jsr svmw_load_palette
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;=====================
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; Load Title Tile Data
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;=====================
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ldx #$0000 ;
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stx $2116 ; set adddress for VRAM read/write
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; multiply by 2, so 0x0000
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lda #^title_screen_tile_data
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ldx #.LOWORD(title_screen_tile_data)
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ldy #$7780 ; Copy 478 tiles, which are 64 bytes each
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; 8x8 tile with 8bpp
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; (478*64) = 30592 = 0x7780
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jsr svmw_load_vram
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;===================================
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; Load Title Tile Map
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;===================================
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ldx #$7000 ;
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stx $2116 ; set adddress for VRAM read/write
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; multiply by 2, so 0xe000
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lda #^title_screen_tilemap
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ldx #.LOWORD(title_screen_tilemap)
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ldy #$0700 ; 32x28 = 896 * 2 = 0x700
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jsr svmw_load_vram
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;===================================
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; Setup Video
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;===================================
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title_setup_video:
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; abcd efff
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; abcd = 8 (0) or 16 width for BG1234
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; e = priority for BG3
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; fff = background mode
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lda #$03
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sta $2105 ; set Mode 3
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; 000abcde
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; a = object, b=BG4 c=BG3 d=BG2 e=BG1
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lda #$01 ; Enable BG1
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sta $212c
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; disable subscreen
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stz $212d
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; a000 bbbb
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; a = screen on/off (0=on), ffff = brightness
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lda #$0f
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sta $2100 ; Turn on screen, full Brightness
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lda #$81 ; Enable NMI (VBlank Interrupt) and joypads
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sta $4200 ;
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jsr svmw_fade_in
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jsr svmw_repeat_until_keypressed
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jsr svmw_fade_out
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rts
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;============================================================================
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.segment "HIGHROM"
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.include "tb1_title.tiles"
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