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https://github.com/lscharen/iigs-game-engine.git
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Stub in more tile rendering functions; does not crash but renders incorrectly
This commit is contained in:
Lucas Scharenbroich
parent
90124b04bc
commit
652729081e
@ -15,6 +15,22 @@ _Deref MAC
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plb ; restore the caller's data bank register
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<<<
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_Mul128 mac
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asl
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asl
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asl
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asl
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asl
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asl
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asl
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<<<
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; xba ; Naive is 7 ASL instructions = 14 cycles
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; lsr ; By using XBA, we can save a couple cycles
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; bcc *+5
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; ora #$8000
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; and #$007F
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_Mul4096 mac
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xba
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asl
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@ -184,6 +200,8 @@ next
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@ -314,7 +314,7 @@ _UpdateBG0TileMap
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ldx :BlkX
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ldy :BlkY
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jsr RenderTile
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jsr CopyTile
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lda :BlkX
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inc
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@ -470,5 +470,6 @@ _UpdateBG0TileMap
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@ -22,7 +22,7 @@ Col2CodeOffset lup 82
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--^
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dw CODE_TOP
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; A parallel table to Col2CodeOffset that hold the offset to the exception handler address for each column
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; A parallel table to Col2CodeOffset that holds the offset to the exception handler address for each column
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SNIPPET_SIZE equ 32
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]step equ 0
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JTableOffset lup 82
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@ -250,3 +250,4 @@ BG1YOffsetTable lup 26
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@ -595,14 +595,29 @@ epilogue_1 tsc
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; start lda (00),y ; 6
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; and #MASK ; 3
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; ora #DATA ; 3 = 12 cycles to load the data
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; pha ; 4
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; bcs alt_exit ; 2/3
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; out jmp next ; 3 Fast-path completes in 5 additional cycles
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; pha ; 4
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; out brl next ; 4 Fast-path completes in 5 additional cycles
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;
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; alt_exit bvs r_edge ; 2/3
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; clc ; 2
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; brl l_jmp_rtn ; 3
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; r_edge rep #$41
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; brl r_jmp_rtn ; 3
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;
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;
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; For dynamic masked tiles, we re-write bytes 2 - 8 as this, which mostly
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; avoids an execution speed pentaly for having to fill in the two extra bytes
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; with an instruction
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;
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; start lda (00),y ; 6
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; and $80,x ; 5
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; ora $00,x ; 5 = 16 cycles to load the data
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; bcc *+4 ;
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; bcs alt_exit ; 2/3
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; pha
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; ...
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; alt_exit clc ; 2
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; bvs r_edge ; 2/3 Need to switch if doing the left edge
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; jmp exit_rtn ; 3
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; r_edge jmp entry_rtn ; 3
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ds \,$00 ; pad to the next page boundary
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]index equ 0
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@ -626,3 +641,10 @@ top
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@ -26,6 +26,16 @@
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; | +----------- M : Apply tile mask
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; +----------------- Reserved
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;
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; Each logical tile (corresponding to each Tile ID) actually takes up 128 bytes of memory in the
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; tile bank
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;
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; +0 : 32 bytes of tile data
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; +32 : 32 bytes of tile mask
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; +64 : 32 bytes of horizontally flipped tile data
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; +96 : 32 bytes of horizontally flipped tile mask
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;
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; It is simply too slow to try to horizontally reverse the pixel data on the fly. This still allows
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; for up to 512 tiles to be stored in a single bank, which should be sufficient.
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TILE_ID_MASK equ $01FF
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TILE_MASK_BIT equ $1000
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@ -52,7 +62,8 @@ RenderTile
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phx ; Save the tile offset
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tax
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and #TILE_ID_MASK ; Mask out the ID and save just tha
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and #TILE_ID_MASK ; Mask out the ID and save just that
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_Mul128 ; multiplied by 128
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pha
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txa
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@ -120,12 +131,6 @@ FillPEAOpcode
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CopyTileMem
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CopyTileMem0
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asl ; Each tile takes up 64 bytes, 32 bytes for the
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asl ; 8x8 data and 32 bytes for the 8x8 mask.
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asl
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asl
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asl
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asl
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tax
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ldal tiledata+0,x ; The low word goes in the *next* instruction
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@ -179,24 +184,16 @@ CopyTileMem0
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; ]1 = address of tile data
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; ]2 = address of tile mask
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; ]3 = address of target in code field
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;
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; This is a relatively efficient way to handle the three different modes. Focus on this and
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; then we will adjust the setup code...
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CopyTileMemM
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_X_REG equ tiletmp
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_Y_REG equ tiletmp+2
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_T_PTR equ tiletmp+4 ; Copy of the tile address pointer
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_BASE_ADDR equ tiletmp+6 ; Copy of BTableLow for this tile
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CopyTileMemM
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stx _X_REG ; Save these values as we will need to reload them
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sty _Y_REG ; at certain points
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asl ; Each tile takes up 64 bytes, 32 bytes for the
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asl ; 8x8 data and 32 bytes for the 8x8 mask.
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asl
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asl
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asl
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asl
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sta _T_PTR
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tax
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@ -219,6 +216,32 @@ _BASE_ADDR equ tiletmp+6 ; Copy of BTab
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rts
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CopyTileMemMV
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stx _X_REG ; Save these values as we will need to reload them
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sty _Y_REG ; at certain points
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sta _T_PTR
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tax
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CopyMaskedWord tiledata+0;tiledata+32+0;$7003
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CopyMaskedWord tiledata+2;tiledata+32+2;$7000
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CopyMaskedWord tiledata+4;tiledata+32+4;$6003
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CopyMaskedWord tiledata+6;tiledata+32+6;$6000
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CopyMaskedWord tiledata+8;tiledata+32+8;$5003
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CopyMaskedWord tiledata+10;tiledata+32+10;$5000
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CopyMaskedWord tiledata+12;tiledata+32+12;$4003
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CopyMaskedWord tiledata+14;tiledata+32+14;$4000
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CopyMaskedWord tiledata+16;tiledata+32+16;$3003
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CopyMaskedWord tiledata+18;tiledata+32+18;$3000
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CopyMaskedWord tiledata+20;tiledata+32+20;$2003
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CopyMaskedWord tiledata+22;tiledata+32+22;$2000
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CopyMaskedWord tiledata+24;tiledata+32+24;$1003
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CopyMaskedWord tiledata+28;tiledata+32+26;$1000
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CopyMaskedWord tiledata+30;tiledata+32+28;$0003
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CopyMaskedWord tiledata+32;tiledata+32+30;$0000
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rts
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TilePatterns dw $0000,$1111,$2222,$3333
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dw $4444,$5555,$6666,$7777
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dw $8888,$9999,$AAAA,$BBBB
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@ -269,12 +292,6 @@ ClearTile sep #$20
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; Copy a tile, but vertically flip the data
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CopyTileMemV
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asl ; Each tile takes up 64 bytes, 32 bytes for the
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asl ; 8x8 data and 32 bytes for the 8x8 mask.
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asl
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asl
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asl
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asl
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tax
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ldal tiledata+0,x ; The low word goes in the *next* instruction
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@ -368,10 +385,11 @@ solid
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pla
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rts
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; Not implemented yet, fallback to regular tile rendering
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solid_hflip
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plx
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pla
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clc
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adc #64 ; Advance to the flipped version
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brl CopyTileMem
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solid_vflip
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@ -379,10 +397,11 @@ solid_vflip
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pla
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brl CopyTileMemV
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; Not implemented, fallback to just vertical flips
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solid_hvflip
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plx
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pla
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clc
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adc #64 ; Advance to the flipped version
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brl CopyTileMemV
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masked
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@ -391,16 +410,34 @@ masked
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brl CopyTileMemM
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masked_hflip
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plx
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pla
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clc
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adc #64 ; Advance to the flipped version
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brl CopyTileMemM
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masked_vflip
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plx
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pla
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brl CopyTileMemMV
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masked_hvflip
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plx
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pla
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clc
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adc #64 ; Advance to the flipped version
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brl CopyTileMemMV
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dynamic
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dyn_masked
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plx
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pla
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rts
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; CopyTile
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;
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; A low-level function that copies 8x8 tiles directly into the code field space.
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;
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; A = Tile ID (0 - 1023)
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; A = Tile ID (0 - 511)
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; X = Tile column (0 - 40)
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; Y = Tile row (0 - 25)
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CopyTile
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@ -429,14 +466,27 @@ CopyTile
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asl ; there are two columns per tile, so multiple by 4
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asl ; asl will clear the carry bit
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tax
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lda Col2CodeOffset,x
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lda BTableLow,y
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sta _BASE_ADDR ; Used in masked tile renderer
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clc
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adc BTableLow,y
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adc Col2CodeOffset,x
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tay
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; Optimization note: We could make a Tile2CodeOffset table that is pre-reversed, which should simplify
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; the code starting after the 'rep #$20' to just be this. Saves around 16 cycles / tile...
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;
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; There would need to be a similar modification made to the JTable as well.
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;
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; txa
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; asl
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; tax
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; lda BTableLow,y
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; sta _BASE_ADDR ; Used in masked tile renderer
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; adc Col2CodeOffset,x
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plb ; set the bank
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pla ; pop the tile ID
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jsr CopyTileMem0
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jsr RenderTile
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plx ; pop the x-register
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plb ; restore the data bank and return
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@ -449,3 +499,23 @@ CopyTile
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