; Collection of functions that deal with tiles. Primarily rendering tile data into ; the code fields. ; ; Tile data can be done faily often, so these routines are performance-sensitive. ; ; CopyTileConst -- the first 16 tile numbers are reserved and can be used ; to draw a solid tile block ; CopyTileLinear -- copies the tile data from the tile bank in linear order, e.g. ; 32 consecutive bytes are copied ; _RenderTile ; ; A high-level function that takes a 16-bit tile descriptor and dispatched to the ; appropriate tile copy routine based on the descriptor flags ; ; Bit 15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00 ; +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ ; |xx|xx|FF|MM|DD|VV|HH| | | | | | | | | | ; +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ ; \____/ | | | | | \________________________/ ; | | | | | | Tile ID (0 to 511) ; | | | | | | ; | | | | | +-- H : Flip tile horizontally ; | | | | +----- V : Flip tile vertically ; | | | +-------- D : Render as a Dynamic Tile (Tile ID < 32, V and H have no effect) ; | | +----------- M : Apply tile mask ; | +-------------- F : Overlay a fringe tile ; +------------------- Reserved (must be zero) ; ; Each logical tile (corresponding to each Tile ID) actually takes up 128 bytes of memory in the ; tile bank ; ; +0 : 32 bytes of tile data ; +32 : 32 bytes of tile mask ; +64 : 32 bytes of horizontally flipped tile data ; +96 : 32 bytes of horizontally flipped tile mask ; ; It is simply too slow to try to horizontally reverse the pixel data on the fly. This still allows ; for up to 512 tiles to be stored in a single bank, which should be sufficient. ; Use some temporary space for the spriteIdx array (maximum of 4 entries) stkSave equ tmp9 screenAddr equ tmp10 tileAddr equ tmp11 spriteIdx equ tmp12 ; Given an address to a Tile Store record, dispatch to the appropriate tile renderer. The Tile ; Store record contains all of the low-level information that's needed to call the renderer. ; ; There are two execution paths that are handled here. First, if there is no sprite, then ; the tile data is read directly and written into the code field in a single pass. If there ; are sprites that overlap the tile, then the sprite data is combined with the tile data ; and written to a temporary direct page buffer. If ; ; This routine sets the direct page register to the second page since we use that space to ; build and cache tile and sprite data, when necessary _RenderTile2 lda TileStore+TS_SPRITE_FLAG,x ; This is a bitfield of all the sprites that intersect this tile, only care if non-zero or not bne do_dirty_sprite ; Handle the non-sprite tile blit CopyNoSprites sep #$20 lda TileStore+TS_CODE_ADDR_HIGH,x ; load the bank of the target code field line pha ; and put on the stack for later lda TileStore+TS_BASE_ADDR+1,x ; load the base address of the code field ($0000 or $8000) sta _BASE_ADDR+1 ; so we can get by just copying the high byte rep #$20 lda TileStore+TS_BASE_TILE_DISP,x ; Get the address of the renderer for this tile stal :tiledisp+1 lda TileStore+TS_TILE_ID,x sta _TILE_ID ; Some tile blitters need to get the tile descriptor ldy TileStore+TS_CODE_ADDR_LOW,x ; load the address of the code field lda TileStore+TS_TILE_ADDR,x ; load the address of this tile's data (pre-calculated) pha lda TileStore+TS_WORD_OFFSET,x plx plb ; set the bank to the code field that will be updated ; B is set to the correct code field bank ; A is set to the tile word offset (0 through 80 in steps of 4) ; Y is set to the top-left address of the tile in the code field ; X is set to the address of the tile data :tiledisp jmp $0000 ; render the tile ; Let's make a macro helper for the bit test tree ; dobit src_offset,dest,next_target,end_target dobit MAC beq last_bit ldx: ]1,y stx ]2 jmp ]3 last_bit ldx: ]1,y stx ]2 jmp ]4 EOM ; The sprite code is just responsible for quickly copying all of the sprite data ; into the direct page temp area. do_dirty_sprite pei TileStoreBankAndTileDataBank ; Special value that has the TileStore bank in LSB and TileData bank in MSB plb ; Cache a couple of values into the direct page that are used across all copy routines lda TileStore+TS_TILE_ADDR,y ; load the address of this tile's data (pre-calculated) sta tileAddr ldx TileStore+TS_VBUFF_ADDR_COUNT,y jmp (dirty_sprite_dispatch,x) dirty_sprite_dispatch da CopyNoSprites da CopyOneSprite da CopyTwoSprites da CopyThreeSprites da CopyFourSprites ; MAX, don't bother with more than 4 sprites per tile ; This is very similar to the code in the dirty tile renderer, but we can't reuse ; because that code draws directly to the graphics screen, and this code draws ; to a temporary budder that has a different stride. ; ldy TileStore+TS_VBUFF_ARRAY_ADDR,x ; base address of the VBUFF sprite address array for this tile ; ; lsr ; bcc :loop_0_bit_1 ; dobit $0000;sprite_ptr0;:loop_1_bit_1;CopyOneSprite ;:loop_0_bit_1 lsr ; bcc :loop_0_bit_2 ; dobit $0002;sprite_ptr0;:loop_1_bit_2;CopyOneSprite ;:loop_0_bit_2 lsr ; bcc :loop_0_bit_3 ; dobit $0004;sprite_ptr0;:loop_1_bit_3;CopyOneSprite ;:loop_0_bit_3 lsr ; bcc :loop_0_bit_4 ; dobit $0006;sprite_ptr0;:loop_1_bit_4;CopyOneSprite ;:loop_0_bit_4 lsr ; bcc :loop_0_bit_5 ; dobit $0008;sprite_ptr0;:loop_1_bit_5;CopyOneSprite ;:loop_0_bit_5 lsr ; bcc :loop_0_bit_6 ; dobit $000A;sprite_ptr0;:loop_1_bit_6;CopyOneSprite ;:loop_0_bit_6 lsr ; bcc :loop_0_bit_7 ; dobit $000C;sprite_ptr0;:loop_1_bit_7;CopyOneSprite ;:loop_0_bit_7 lsr ; bcc :loop_0_bit_8 ; dobit $000E;sprite_ptr0;:loop_1_bit_8;CopyOneSprite ;:loop_0_bit_8 lsr ; bcc :loop_0_bit_9 ; dobit $0010;sprite_ptr0;:loop_1_bit_9;CopyOneSprite ;:loop_0_bit_9 lsr ; bcc :loop_0_bit_10 ; ldx: $0012,y ; stx spriteIdx ; cmp #0 ; jne :loop_1_bit_10 ; jmp CopyOneSprite ;:loop_0_bit_10 lsr ; bcc :loop_0_bit_11 ; dobit $0014;sprite_ptr0;:loop_1_bit_11;CopyOneSprite ;:loop_0_bit_11 lsr ; bcc :loop_0_bit_12 ; dobit $0016;sprite_ptr0;:loop_1_bit_12;CopyOneSprite ;:loop_0_bit_12 lsr ; bcc :loop_0_bit_13 ; dobit $0018;sprite_ptr0;:loop_1_bit_13;CopyOneSprite ;:loop_0_bit_13 lsr ; bcc :loop_0_bit_14 ; dobit $001A;sprite_ptr0;:loop_1_bit_14;CopyOneSprite ;:loop_0_bit_14 lsr ; bcc :loop_0_bit_15 ; dobit $001C;sprite_ptr0;:loop_1_bit_15;CopyOneSprite ;:loop_0_bit_15 ldx: $001E,y ; stx spriteIdx ; jmp CopyOneSprite ; We can optimize later, for now just copy the sprite data and mask into its own ; direct page buffer and combine with the tile data later ; We set up direct page pointers to the mask bank and use the bank register for the ; data. CopyFourSprites lda TileStore+TS_VBUFF_ADDR_0,y sta spriteIdx lda TileStore+TS_VBUFF_ADDR_1,y sta spriteIdx+4 lda TileStore+TS_VBUFF_ADDR_2,y sta spriteIdx+8 lda TileStore+TS_VBUFF_ADDR_3,y sta spriteIdx+12 ; Copy three sprites into a temporary direct page buffer LDA_IL equ $A7 ; lda [dp] LDA_ILY equ $B7 ; lda [dp],y AND_IL equ $27 ; and [dp] AND_ILY equ $37 ; and [dp],y CopyThreeSprites lda TileStore+TS_VBUFF_ADDR_0,y sta spriteIdx lda TileStore+TS_VBUFF_ADDR_1,y sta spriteIdx+4 lda TileStore+TS_VBUFF_ADDR_2,y sta spriteIdx+8 ]line equ 0 lup 8 ldy #]line*SPRITE_PLANE_SPAN lda (spriteIdx+8),y db AND_ILY,spriteIdx+4 ; Can't use long indirect inside LUP because of ']' ora (spriteIdx+4),y db AND_ILY,spriteIdx+0 ora (spriteIdx+0),y sta tmp_sprite_data+{]line*4} db LDA_ILY,spriteIdx+8 db AND_ILY,spriteIdx+4 db AND_ILY,spriteIdx+0 sta tmp_sprite_mask+{]line*4} ldy #]line*SPRITE_PLANE_SPAN+2 lda (spriteIdx+8),y db AND_ILY,spriteIdx+4 ora (spriteIdx+4),y db AND_ILY,spriteIdx+0 ora (spriteIdx+0),y sta tmp_sprite_data+{]line*4}+2 db LDA_ILY,spriteIdx+8 db AND_ILY,spriteIdx+4 db AND_ILY,spriteIdx+0 sta tmp_sprite_mask+{]line*4}+2 ]line equ ]line+1 --^ ; jmp FinishTile ; Copy two sprites into a temporary direct page buffer CopyTwoSprites lda TileStore+TS_VBUFF_ADDR_0,y sta spriteIdx lda TileStore+TS_VBUFF_ADDR_1,y sta spriteIdx+4 ]line equ 0 lup 8 ldy #]line*SPRITE_PLANE_SPAN lda (spriteIdx+4),y db AND_ILY,spriteIdx+0 ora (spriteIdx+0),y sta tmp_sprite_data+{]line*4} db LDA_ILY,spriteIdx+4 db AND_ILY,spriteIdx+0 sta tmp_sprite_mask+{]line*4} ldy #]line*SPRITE_PLANE_SPAN+2 lda (spriteIdx+4),y db AND_ILY,spriteIdx+0 ora (spriteIdx+0),y sta tmp_sprite_data+{]line*4}+2 db LDA_ILY,spriteIdx+4 db AND_ILY,spriteIdx+0 sta tmp_sprite_mask+{]line*4}+2 ]line equ ]line+1 --^ ; jmp FinishTile CopyOneSprite clc lda TileStore+TS_VBUFF_ADDR_0,y sta spriteIdx adc #2 sta spriteIdx+4 ]line equ 0 lup 8 ; ldal tiledata,x ; and [spriteIdx] ; ora (spriteIdx) ; sta tmp_sprite_data+{]line*4} ldal spritedata+{]line*SPRITE_PLANE_SPAN},x sta tmp_sprite_data+{]line*4} ldal spritedata+{]line*SPRITE_PLANE_SPAN}+2,x sta tmp_sprite_data+{]line*4}+2 ldal spritemask+{]line*SPRITE_PLANE_SPAN},x sta tmp_sprite_mask+{]line*4} ldal spritemask+{]line*SPRITE_PLANE_SPAN}+2,x sta tmp_sprite_mask+{]line*4}+2 ]line equ ]line+1 --^ ; jmp FinishTile ; Reference all of the tile rendering subroutines defined in the TileXXXXX files. Each file defines ; 8 entry points: ; ; One set for normal, horizontally flipped, vertically flipped and hors & vert flipped. ; A second set that are optimized for when EngineMode has BG1 disabled. TileProcs dw _TBSolidTile_00,_TBSolidTile_0H,_TBSolidTile_V0,_TBSolidTile_VH ; 00000 : normal tiles dw _TBDynamicTile_00,_TBDynamicTile_00,_TBDynamicTile_00,_TBDynamicTile_00 ; 00001 : dynamic tiles dw _TBMaskedTile_00,_TBMaskedTile_0H,_TBMaskedTile_V0,_TBMaskedTile_VH ; 00010 : masked normal tiles dw _TBDynamicMaskTile_00,_TBDynamicMaskTile_00 ; 00011 : masked dynamic tiles dw _TBDynamicMaskTile_00,_TBDynamicMaskTile_00 ; Fringe tiles not supported yet, so just repeat the block from above dw _TBSolidTile_00,_TBSolidTile_0H,_TBSolidTile_V0,_TBSolidTile_VH ; 00100 : fringed normal tiles dw _TBDynamicTile_00,_TBDynamicTile_00,_TBDynamicTile_00,_TBDynamicTile_00 ; 00101 : fringed dynamic tiles dw _TBMaskedTile_00,_TBMaskedTile_0H,_TBMaskedTile_V0,_TBMaskedTile_VH ; 00110 : fringed masked normal tiles dw _TBDynamicMaskTile_00,_TBDynamicMaskTile_00 ; 00111 : fringed masked dynamic tiles dw _TBDynamicMaskTile_00,_TBDynamicMaskTile_00 ; High-priority tiles without a sprite in front of them are just normal tiles. Repeat the top half dw _TBSolidTile_00,_TBSolidTile_0H,_TBSolidTile_V0,_TBSolidTile_VH ; 01000 : high-priority normal tiles dw _TBDynamicTile_00,_TBDynamicTile_00,_TBDynamicTile_00,_TBDynamicTile_00 ; 01001 : high-priority dynamic tiles dw _TBMaskedTile_00,_TBMaskedTile_0H,_TBMaskedTile_V0,_TBMaskedTile_VH ; 01010 : high-priority masked normal tiles dw _TBDynamicMaskTile_00,_TBDynamicMaskTile_00 ; 01011 : high-priority masked dynamic tiles dw _TBDynamicMaskTile_00,_TBDynamicMaskTile_00 dw _TBSolidTile_00,_TBSolidTile_0H,_TBSolidTile_V0,_TBSolidTile_VH ; 01100 : high-priority fringed normal tiles dw _TBDynamicTile_00,_TBDynamicTile_00,_TBDynamicTile_00,_TBDynamicTile_00 ; 01101 : high-priority fringed dynamic tiles dw _TBMaskedTile_00,_TBMaskedTile_0H,_TBMaskedTile_V0,_TBMaskedTile_VH ; 01110 : high-priority fringed masked normal tiles dw _TBDynamicMaskTile_00,_TBDynamicMaskTile_00 ; 01111 : high-priority fringed masked dynamic tiles dw _TBDynamicMaskTile_00,_TBDynamicMaskTile_00 ; Here are all the sprite variants of the tiles dw _TBSolidSpriteTile_00,_TBSolidSpriteTile_0H dw _TBSolidSpriteTile_V0,_TBSolidSpriteTile_VH ; 10000 : normal tiles w/sprite dw _TBDynamicSpriteTile_00,_TBDynamicSpriteTile_00 dw _TBDynamicSpriteTile_00,_TBDynamicSpriteTile_00 ; 10001 : dynamic tiles w/sprite dw _TBMaskedSpriteTile_00,_TBMaskedSpriteTile_0H dw _TBMaskedSpriteTile_V0,_TBMaskedSpriteTile_VH ; 10010 : masked normal tiles w/sprite dw _TBDynamicMaskedSpriteTile_00,_TBDynamicMaskedSpriteTile_00 dw _TBDynamicMaskedSpriteTile_00,_TBDynamicMaskedSpriteTile_00 ; 10011 : masked dynamic tiles w/sprite dw _TBSolidTile_00,_TBSolidTile_0H,_TBSolidTile_V0,_TBSolidTile_VH ; 10100 : fringed normal tiles w/sprite dw _TBSolidTile_00,_TBSolidTile_0H,_TBSolidTile_V0,_TBSolidTile_VH ; 10101 : fringed dynamic tiles w/sprite dw _TBSolidTile_00,_TBSolidTile_0H,_TBSolidTile_V0,_TBSolidTile_VH ; 10110 : fringed masked normal tiles w/sprite dw _TBSolidTile_00,_TBSolidTile_0H,_TBSolidTile_V0,_TBSolidTile_VH ; 10111 : fringed masked dynamic tiles w/sprite dw _TBSolidPrioritySpriteTile_00,_TBSolidPrioritySpriteTile_0H, dw _TBSolidPrioritySpriteTile_V0,_TBSolidPrioritySpriteTile_VH ; 11000 : high-priority normal tiles w/sprite dw _TBDynamicPrioritySpriteTile_00,_TBDynamicPrioritySpriteTile_00 dw _TBDynamicPrioritySpriteTile_00,_TBDynamicPrioritySpriteTile_00 ; 11001 : high-priority dynamic tiles w/sprite dw _TBMaskedPrioritySpriteTile_00,_TBMaskedPrioritySpriteTile_0H dw _TBMaskedPrioritySpriteTile_V0,_TBMaskedPrioritySpriteTile_VH ; 11010 : high-priority masked normal tiles w/sprite dw _TBDynamicMaskedPrioritySpriteTile_00,_TBDynamicMaskedPrioritySpriteTile_00 dw _TBDynamicMaskedPrioritySpriteTile_00,_TBDynamicMaskedPrioritySpriteTile_00 ; 11011 : high-priority masked dynamic tiles w/sprite dw _TBSolidTile_00,_TBSolidTile_0H,_TBSolidTile_V0,_TBSolidTile_VH ; 11100 : high-priority fringed normal tiles w/sprite dw _TBSolidTile_00,_TBSolidTile_0H,_TBSolidTile_V0,_TBSolidTile_VH ; 11101 : high-priority fringed dynamic tiles w/sprite dw _TBSolidTile_00,_TBSolidTile_0H,_TBSolidTile_V0,_TBSolidTile_VH ; 11110 : high-priority fringed masked normal tiles w/sprite dw _TBSolidTile_00,_TBSolidTile_0H,_TBSolidTile_V0,_TBSolidTile_VH ; 11111 : high-priority fringed masked dynamic tiles w/sprite ; _TBConstTile ; ; A specialized routine that fills in a tile with a single constant value. It's intended to be used to ; fill in solid colors, so there are no specialized horizontal or verical flipped variants _TBConstTile sta: $0001,y sta: $0004,y sta $1001,y sta $1004,y sta $2001,y sta $2004,y sta $3001,y sta $3004,y sta $4001,y sta $4004,y sta $5001,y sta $5004,y sta $6001,y sta $6004,y sta $7001,y sta $7004,y jmp _TBFillPEAOpcode ClearTile and #$00FF ora #$4800 sta: $0004,y sta $1004,y sta $2004,y sta $3004,y sta $4004,y sta $5004,y sta $6004,y sta $7004,y inc inc sta: $0001,y sta $1001,y sta $2001,y sta $3001,y sta $4001,y sta $5001,y sta $6001,y sta $7001,y sep #$20 lda #$B1 ; This is a special case where we can set all the words to LDA (DP),y sta: $0000,y sta: $0003,y sta $1000,y sta $1003,y sta $2000,y sta $2003,y sta $3000,y sta $3003,y sta $4000,y sta $4003,y sta $5000,y sta $5003,y sta $6000,y sta $6003,y sta $7000,y sta $7003,y rep #$20 rts ; Helper functions to copy tile data to the appropriate location in Bank 0 ; X = tile ID ; Y = dynamic tile ID CopyTileToDyn ENT txa jsr _GetTileAddr tax tya and #$001F ; Maximum of 32 dynamic tiles asl asl ; 4 bytes per page adc BlitterDP ; Add to the bank 00 base address adc #$0100 ; Go to the next page tay jsr CopyTileDToDyn ; Copy the tile data jsr CopyTileMToDyn ; Copy the tile mask rtl ; X = address of tile ; Y = tile address in bank 0 CopyTileDToDyn phb pea $0000 plb plb ldal tiledata+0,x sta: $0000,y ldal tiledata+2,x sta: $0002,y ldal tiledata+4,x sta $0100,y ldal tiledata+6,x sta $0102,y ldal tiledata+8,x sta $0200,y ldal tiledata+10,x sta $0202,y ldal tiledata+12,x sta $0300,y ldal tiledata+14,x sta $0302,y ldal tiledata+16,x sta $0400,y ldal tiledata+18,x sta $0402,y ldal tiledata+20,x sta $0500,y ldal tiledata+22,x sta $0502,y ldal tiledata+24,x sta $0600,y ldal tiledata+26,x sta $0602,y ldal tiledata+28,x sta $0700,y ldal tiledata+30,x sta $0702,y plb rts ; Helper function to copy tile mask to the appropriate location in Bank 0 ; ; X = address of tile ; Y = tile address in bank 0 ; ; Argument are the same as CopyTileDToDyn, the code takes care of adjust offsets. ; This make is possible to call the two functions back-to-back ; ; ldx tileAddr ; ldy dynTileAddr ; jsr CopyTileDToDyn ; jsr CopyTileMToDyn CopyTileMToDyn phb pea $0000 plb plb ldal tiledata+32+0,x sta: $0080,y ldal tiledata+32+2,x sta: $0082,y ldal tiledata+32+4,x sta $0180,y ldal tiledata+32+6,x sta $0182,y ldal tiledata+32+8,x sta $0280,y ldal tiledata+32+10,x sta $0282,y ldal tiledata+32+12,x sta $0380,y ldal tiledata+32+14,x sta $0382,y ldal tiledata+32+16,x sta $0480,y ldal tiledata+32+18,x sta $0482,y ldal tiledata+32+20,x sta $0580,y ldal tiledata+32+22,x sta $0582,y ldal tiledata+32+24,x sta $0680,y ldal tiledata+32+26,x sta $0682,y ldal tiledata+32+28,x sta $0780,y ldal tiledata+32+30,x sta $0782,y plb rts ; CopyBG0Tile ; ; A low-level function that copies 8x8 tiles directly into the code field space. ; ; A = Tile ID (0 - 511) ; X = Tile column (0 - 40) ; Y = Tile row (0 - 25) CopyBG0Tile ENT phb phk plb jsr _CopyBG0Tile plb rtl _CopyBG0Tile phb ; save the current bank phx ; save the original x-value pha ; save the tile ID tya ; lookup the address of the virtual line (y * 8) asl asl asl asl ; x2 because the table contains words, not tay sep #$20 ; set the bank register lda BTableHigh,y pha ; save for a few instruction rep #$20 txa asl ; there are two columns per tile, so multiple by 4 asl ; asl will clear the carry bit tax lda BTableLow,y sta _BASE_ADDR ; Used in masked tile renderer clc adc Col2CodeOffset+2,x ; Get the right edge (which is the lower physical address) tay plb ; set the bank pla ; pop the tile ID ; jsr _RenderTile :exit plx ; pop the x-register plb ; restore the data bank and return rts ; CopyBG1Tile ; ; A low-level function that copies 8x8 tiles directly into the BG1 data buffer. ; ; A = Tile ID (0 - 511) ; X = Tile column (0 - 40) ; Y = Tile row (0 - 25) CopyBG1Tile phb phk plb jsr _CopyBG1Tile plb rtl _CopyBG1Tile phb ; save the current bank phx ; save the original x-value pha ; save the tile ID tya ; lookup the address of the virtual line (y * 8) asl asl asl asl tay txa asl asl ; 4 bytes per tile column clc adc BG1YTable,y tay sep #$20 lda BG1DataBank pha plb ; set the bank rep #$20 pla ; pop the tile ID jsr _RenderTileBG1 plx ; pop the x-register plb ; restore the data bank and return rts ; Tile Store that holds tile records which contain all the essential information for rendering ; a tile. ; ; TileStore+TS_TILE_ID : Tile descriptor ; TileStore+TS_DIRTY : $0000 is clean, any other value indicated a dirty tile ; TileStore+TS_TILE_ADDR : Address of the tile in the tile data buffer ; TileStore+TS_CODE_ADDR_LOW : Low word of the address in the code field that receives the tile ; TileStore+TS_CODE_ADDR_HIGH : High word of the address in the code field that receives the tile ; TileStore+TS_WORD_OFFSET : Logical number of word for this location ; TileStore+TS_BASE_ADDR : Copy of BTableAddrLow ; TileStore+TS_SCREEN_ADDR : Address on the physical screen corresponding to this tile (for direct rendering) ; TileStore+TS_SPRITE_FLAG : A bit field of all sprites that intersect this tile ; TileStore+TS_SPRITE_ADDR_1 ; Address of the sprite data that aligns with this tile. These ; TileStore+TS_SPRITE_ADDR_2 ; values are 1:1 with the TS_SPRITE_FLAG bits and are not contiguous. ; TileStore+TS_SPRITE_ADDR_3 ; If the bit position in TS_SPRITE_FLAG is not set, then the value in ; TileStore+TS_SPRITE_ADDR_4 ; the TS_SPRITE_ADDR_* field is undefined. ; TileStore+TS_SPRITE_ADDR_5 ; TileStore+TS_SPRITE_ADDR_6 ; TileStore+TS_SPRITE_ADDR_7 ; TileStore+TS_SPRITE_ADDR_8 ; TileStore+TS_SPRITE_ADDR_9 ; TileStore+TS_SPRITE_ADDR_10 ; TileStore+TS_SPRITE_ADDR_11 ; TileStore+TS_SPRITE_ADDR_12 ; TileStore+TS_SPRITE_ADDR_13 ; TileStore+TS_SPRITE_ADDR_14 ; TileStore+TS_SPRITE_ADDR_15 ; TileStore+TS_SPRITE_ADDR_16 ; TileStore+ ;TileStore ENT ; ds TILE_STORE_SIZE*11 ; A list of dirty tiles that need to be updated in a given frame DirtyTileCount ds 2 DirtyTiles ds TILE_STORE_SIZE ; At most this many tiles can possibly be update at once _ClearDirtyTiles bra :hop :loop jsr _PopDirtyTile :hop lda DirtyTileCount bne :loop rts ; Append a new dirty tile record ; ; A = result of _GetTileStoreOffset for X, Y ; ; The main purpose of this function is to ; ; 1. Avoid marking the same tile dirty multiple times, and ; 2. Pre-calculating all of the information necessary to render the tile PushDirtyTile ENT phb phk plb jsr _PushDirtyTile plb rtl ; alternate version that is very slightly slower, but preserves the y-register _PushDirtyTile tax ; alternate entry point if the x-register is already set _PushDirtyTileX ldal TileStore+TS_DIRTY,x bne :occupied2 inc ; any non-zero value will work stal TileStore+TS_DIRTY,x ; and is 1 cycle faster than loading a constant value txa ldx DirtyTileCount ; 4 sta DirtyTiles,x ; 6 inx ; 2 inx ; 2 stx DirtyTileCount ; 4 = 18 rts :occupied2 txa ; Make sure TileStore offset is returned in the accumulator rts ; Remove a dirty tile from the list and return it in state ready to be rendered. It is important ; that the core rendering functions *only* use _PopDirtyTile to get a list of tiles to update, ; because this routine merges the tile IDs stored in the Tile Store with the Sprite ; information to set the TILE_SPRITE_BIT. This is the *only* place in the entire code base that ; applies this bit to a tile descriptor. PopDirtyTile ENT phb phk plb jsr _PopDirtyTile plb rtl _PopDirtyTile ldy DirtyTileCount bne _PopDirtyTile2 rts _PopDirtyTile2 ; alternate entry point dey dey sty DirtyTileCount ; remove last item from the list ldx DirtyTiles,y ; load the offset into the Tile Store lda #$FFFF stal TileStore+TS_DIRTY,x ; clear the occupied backlink rts ; Run through the dirty tile list and render them into the code field ApplyTiles ENT phb phk plb jsr _ApplyTiles plb rtl ; The _ApplyTiles function is responsible for rendering all of the dirty tiles into the code ; field. In this function we switch to the second direct page which holds the temporary ; working buffers for tile rendering. _ApplyTiles tdc clc adc #$100 ; move to the next page tcd bra :begin :loop ; Retrieve the offset of the next dirty Tile Store items in the X-register jsr _PopDirtyTile2 ; Call the generic dispatch with the Tile Store record pointer at by the X-register. phb jsr _RenderTile2 plb ; Loop again until the list of dirty tiles is empty :begin ldy DirtyTileCount bne :loop tdc ; Move back to the original direct page sec sbc #$100 tcd rts ; To make processing the tile faster, we do them in chunks of eight. This allows the loop to be ; unrolled, which means we don't have to keep track of the register value and makes it faster to ; clear the dirty tile flag after being processed. tdc ; Move to the dedicated direct page for tile rendering clc adc #$100 tcd phb ; Save the current bank tsc sta tmp0 ; Save it on the direct page bra at_loop ; The DirtyTiles array and the TileStore information is in the Tile Store bank. Because we ; process up to 8 tiles as a time and the tile code sets the bank register to the target ; code field bank, we need to restore the bank register each time. So, we pre-push ; 8 copies of the TileStore bank onto the stack. at_exit tdc ; Move back to the original direct page sec sbc #$100 tcd plb ; Restore the original data bank and return rts dt_base equ $FE ; top of second direct page space at_loop lda tmp0 tcs lda DirtyTileCount ; This is pre-multiplied by 2 beq at_exit ; If there are no items, exit ldx TileStoreBankDoubled phx phx phx cmp #16 ; If there are >= 8 elements, then bcs at_chunk ; do a full chunk stz DirtyTileCount ; Otherwise, this pass will handle them all tax jmp (at_table,x) at_table da at_exit,at_one,at_two,at_three da at_four,at_five,at_six,at_seven at_chunk sec sbc #16 sta DirtyTileCount ; Fall through ; Because all of the registers get used in the _RenderTile2 subroutine, we ; push the values from the DirtyTiles array onto the stack and then pop off ; the values as we go ldy dt_base ; Reload the base index ldx DirtyTiles+14,y ; Load the TileStore offset stz TileStore+TS_DIRTY,x ; Clear this tile's dirty flag jsr _RenderTile2 ; Draw the tile plb ; Reset the data bank to the TileStore bank at_seven ldy dt_base ldx DirtyTiles+12,y stz TileStore+TS_DIRTY,x jsr _RenderTile2 plb at_six ldy dt_base ldx DirtyTiles+10,y stz TileStore+TS_DIRTY,x jsr _RenderTile2 plb at_five ldy dt_base ldx DirtyTiles+8,y stz TileStore+TS_DIRTY,x jsr _RenderTile2 plb at_four ldy dt_base ldx DirtyTiles+6,y stz TileStore+TS_DIRTY,x jsr _RenderTile2 plb at_three ldy dt_base ldx DirtyTiles+4,y jsr _RenderTile2 plb at_two ldy dt_base ldx DirtyTiles+2,y stz TileStore+TS_DIRTY,x jsr _RenderTile2 plb at_one ldy dt_base ldx DirtyTiles+0,y stz TileStore+TS_DIRTY,x jsr _RenderTile2 plb jmp at_loop