94 lines
3.1 KiB
ArmAsm
94 lines
3.1 KiB
ArmAsm
; A simple helper function that fills in all of the opcodes of a tile with the PEA opcode. This is
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; a separate functino because we can often just update the tile data if we know the opcodes are already
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; set. When we have to fill the opcodes, this function is used
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_TBFillPEAOpcode
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sep #$20
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lda #$F4
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sta: $0000,y
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sta: $0003,y
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sta $1000,y
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sta $1003,y
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sta $2000,y
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sta $2003,y
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sta $3000,y
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sta $3003,y
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sta $4000,y
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sta $4003,y
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sta $5000,y
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sta $5003,y
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sta $6000,y
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sta $6003,y
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sta $7000,y
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sta $7003,y
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rep #$20
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rts
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; Copy tile data into the direct page compositing buffer. The main reason to do this in full passes is
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; because we can avoid needing to use both the X and Y registers during the compositing process and
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; reserve Y to hold the code field address.
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;
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; Also, we can get away with not setting the bank register, this is a wash in terms of speed, but results
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; in simpler, more composable subroutines
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_TBCopyTileDataAndMaskToCBuff
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jsr _TBCopyTileDataToCBuff
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jmp _TBCopyTileMaskToCBuff
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_TBCopyTileDataAndMaskToCBuffV
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jsr _TBCopyTileDataToCBuffV
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jmp _TBCopyTileMaskToCBuffV
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_TBCopyTileDataToCBuff
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]line equ 0
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lup 8
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ldal tiledata+{]line*4},x
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sta blttmp+{]line*4}
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ldal tiledata+{]line*4}+2,x
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sta blttmp+{]line*4}+2
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]line equ ]line+1
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--^
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rts
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_TBCopyTileDataToCBuffV
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]src equ 7
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]dest equ 0
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lup 8
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ldal tiledata+{]src*4},x
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sta blttmp+{]dest*4}
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ldal tiledata+{]src*4}+2,x
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sta blttmp+{]dest*4}+2
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]src equ ]src-1
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]dest equ ]dest+1
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--^
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rts
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; Copy tile mask data into the direct page compositing buffer.
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_TBCopyTileMaskToCBuff
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]line equ 0
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lup 8
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ldal tiledata+{]line*4}+32,x
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sta blttmp+{]line*4}+32
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ldal tiledata+{]line*4}+32+2,x
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sta blttmp+{]line*4}+32+2
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]line equ ]line+1
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--^
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rts
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_TBCopyTileMaskToCBuffV
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]src equ 7
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]dest equ 0
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lup 8
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ldal tiledata+{]src*4}+32,x
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sta blttmp+{]dest*4}+32
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ldal tiledata+{]src*4}+32+2,x
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sta blttmp+{]dest*4}+32+2
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]src equ ]src-1
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]dest equ ]dest+1
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--^
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rts
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