mirror of
https://github.com/lscharen/iigs-game-engine.git
synced 2024-06-20 18:29:31 +00:00
Resolve horizontal scrolling issue with PEA code
This commit is contained in:
Lucas Scharenbroich
parent
26e39e3bfd
commit
63bfe5e8e7
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@ -51,7 +51,7 @@ Demo
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stz frameCount
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:loop
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lda #1
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jsr MoveDown
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jsr MoveLeft
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inc frameCount
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ldal KBD_STROBE_REG
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@ -82,3 +82,5 @@ Demo
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bra :loop
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FPSStr str 'FPS'
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101
src/App.Main.s
101
src/App.Main.s
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@ -289,7 +289,7 @@ DoTiles
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:rowloop
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lda #0
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sta :column,s
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lda #$0010
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lda #$0015
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sta :tile,s
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:colloop
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@ -301,7 +301,7 @@ DoTiles
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jsr CopyTile
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lda :tile,s
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inc
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eor #$0003
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sta :tile,s
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lda :column,s
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@ -667,100 +667,3 @@ qtRec adrl $0000
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put blitter/Template.s
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put blitter/Tiles.s
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put blitter/Vert.s
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@ -47,13 +47,22 @@ tiledata ENT
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hex 00FFF000
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hex 00000000
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hex 01234567
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hex 01234567
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hex 01234567
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hex 01234567
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hex 01234567
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hex 01234567
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hex 01234567
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hex 01234567
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hex 89ABCDEF
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hex 89ABCDEF
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hex 89ABCDEF
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hex 89ABCDEF
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hex 89ABCDEF
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hex 89ABCDEF
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hex 89ABCDEF
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hex 89ABCDEF
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tileend
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@ -84,6 +84,3 @@ stk_save lda #0000 ; load the stack
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plb ; restore the bank
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rts
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@ -13,7 +13,6 @@ StartY equ 18 ; Which code buffer line is the top of the s
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EngineMode equ 20 ; Defined the mode/capabilities that are enabled
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; bit 0: 0 = Single Background, 1 = Parallax
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DirtyBits equ 22 ; Identify values that have changed between frames
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LastPatchOffset equ 24 ; Offset into code field that was patched with BRA instructions
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BG1DataBank equ 24 ; Data bank that holds BG1 layer data
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BlitterDP equ 25 ; Direct page address the holder blitter data
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@ -21,6 +20,8 @@ BlitterDP equ 25 ; Direct page address the holder blitter dat
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OldStartX equ 26
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OldStartY equ 28
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LastPatchOffset equ 30 ; Offset into code field that was patched with BRA instructions
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bstk equ 208 ; 16-byte stack to push bank addresses
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tmp8 equ 224
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@ -54,3 +55,4 @@ DIRTY_BIT_BG1_Y equ $0008
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@ -352,6 +352,7 @@ _ApplyBG0XPos
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; 8-bit operation and, since the PEA code is bank aligned, we use the entry_offset value directly
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sep #$20
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ldx :draw_count_x2
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lda :entry_offset
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ldy :base_address
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@ -364,7 +365,7 @@ _ApplyBG0XPos
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ldy :base_address
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jsr SetCodeEntryOpcode
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; If this is an odd entry, also set the odd_entry low byte
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; If this is an odd entry, also set the odd_entry low byte and save the operand high byte
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lda :odd_entry_offset
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beq :not_odd
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@ -373,6 +374,12 @@ _ApplyBG0XPos
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ldy :base_address
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jsr SetOddCodeEntry
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ldx :draw_count_x2
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ldy :base_address
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pei :exit_address
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jmp :SaveHighOperand ; Only used once, so "inline" it
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:save_high_op_rtn
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:not_odd
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rep #$20
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@ -395,6 +402,88 @@ _ApplyBG0XPos
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plb
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rts
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; SaveHighOperand
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;
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; Save the high byte of the 3-byte code field instruction into the odd handler at the end
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; of each line. This is only needed
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;
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; X = number of lines * 2, 0 to 32
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; Y = starting line * $1000
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; A = code field location * $1000
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:SaveHighOperand
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jmp (:tbl,x)
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:tbl da :bottom
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da :do01,:do02,:do03,:do04
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da :do05,:do06,:do07,:do08
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da :do09,:do10,:do11,:do12
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da :do13,:do14,:do15,:do16
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:do15 plx
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bra :x15
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:do14 plx
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bra :x14
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:do13 plx
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bra :x13
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:do12 plx
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bra :x12
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:do11 plx
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bra :x11
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:do10 plx
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bra :x10
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:do09 plx
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bra :x09
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:do08 plx
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bra :x08
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:do07 plx
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bra :x07
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:do06 plx
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bra :x06
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:do05 plx
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bra :x05
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:do04 plx
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bra :x04
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:do03 plx
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bra :x03
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:do02 plx
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bra :x02
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:do01 plx
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bra :x01
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:do16 plx
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:x16 lda $F002,x
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sta OPCODE_HIGH_SAVE+$F000,y
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:x15 lda $E002,x
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sta OPCODE_HIGH_SAVE+$E000,y
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:x14 lda $D002,x
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sta OPCODE_HIGH_SAVE+$D000,y
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:x13 lda $C002,x
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sta OPCODE_HIGH_SAVE+$C000,y
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:x12 lda $B002,x
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sta OPCODE_HIGH_SAVE+$B000,y
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:x11 lda $A002,x
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sta OPCODE_HIGH_SAVE+$A000,y
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:x10 lda $9002,x
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sta OPCODE_HIGH_SAVE+$9000,y
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:x09 lda $8002,x
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sta OPCODE_HIGH_SAVE+$8000,y
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:x08 lda $7002,x
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sta OPCODE_HIGH_SAVE+$7000,y
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:x07 lda $6002,x
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sta OPCODE_HIGH_SAVE+$6000,y
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:x06 lda $5002,x
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sta OPCODE_HIGH_SAVE+$5000,y
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:x05 lda $4002,x
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sta OPCODE_HIGH_SAVE+$4000,y
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:x04 lda $3002,x
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sta OPCODE_HIGH_SAVE+$3000,y
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:x03 lda $2002,x
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sta OPCODE_HIGH_SAVE+$2000,y
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:x02 lda $1002,x
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sta OPCODE_HIGH_SAVE+$1000,y
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:x01 lda: $0002,x
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sta: OPCODE_HIGH_SAVE+$0000,y
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:bottom jmp :save_high_op_rtn
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; SaveOpcode
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;
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; Save the values to the restore location. This should only be used to patch the
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@ -477,7 +566,6 @@ SaveOpcode
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sta: OPCODE_SAVE+$0000,y
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:bottom rts
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; RestoreOpcode
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;
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; Restore the values back to the code field.
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@ -654,120 +742,3 @@ SetCodeEntryOpcode
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sta CODE_ENTRY_OPCODE+$1000,y
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sta: CODE_ENTRY_OPCODE+$0000,y
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:bottom rts
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@ -215,11 +215,3 @@ BlitBuff ds 4*13
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; that everything can use the same indexing offsets
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BTableHigh ds 208*2*2
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BTableLow ds 208*2*2
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@ -17,6 +17,7 @@ CODE_TOP equ loop-base
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CODE_LEN equ top-base
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CODE_EXIT equ even_exit-base
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OPCODE_SAVE equ odd_exit-base+1 ; spot to save the code field opcode when patching exit BRA
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OPCODE_HIGH_SAVE equ odd_high_byte-base+1 ; save the third byte
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FULL_RETURN equ full_return-base ; offset that returns from the blitter
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ENABLE_INT equ enable_int-base ; offset that re-enable interrupts and continues
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LINES_PER_BANK equ 16
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@ -856,28 +857,36 @@ odd_exit lda #0000 ; This operand field is
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; left edge is odd-aligned, we are able to immediately load the value and perform
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; similar logic to the right_odd code path above
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left_odd bit #$000B
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beq l_is_pea
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bit #$000B
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bne :chk_jmp
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bit #$0040
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bne l_is_jmp
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sep #$20
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odd_high_byte lda #00 ; patch with high byte code operand
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long_4 stal *+4-base
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dfb $00,$00
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l_is_pea xba
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sep #$30
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; Fall-through when we have to push a byte on the left edge. Must be 8-bit on entry. Optimize
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; for the PEA $0000 case -- only 19 cycles to handle the edge, so pretty good
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:left_byte
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pha
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rep #$30
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bra even_exit
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l_is_jmp sep #$01 ; Set the C flag (V is always cleared at this point) which tells a snippet to push only the high byte
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long_5 ldal entry_jmp+1-base
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long_6 stal *+5-base
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dfb $4C,$00,$00 ; Jump back to address in entry_jmp (this takes 13 cycles, is there a better way?)
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rep #$20
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; JMP opcode = $4C, JML opcode = $5C
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even_exit jmp $1000 ; Jump to the next line.
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ds 1 ; space so that the last line in a bank can be patched into a JML
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:chk_jmp
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bit #$0040
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bne :l_is_jmp
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long_4 stal *+4-base
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dfb $00,$00
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sep #$20
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bra :left_byte
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:l_is_jmp sec ; Set the C flag (V is always cleared at this point) which tells a snippet to push only the high byte
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long_5 ldal entry_jmp+1-base
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long_6 stal *+5-base
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dfb $4C,$00,$00 ; Jump back to address in entry_jmp (this takes 13 cycles, is there a better way?)
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; Special epilogue: skip a number of bytes and jump back into the code field. This is useful for
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; large, floating panels in the attract mode of a game, or to overlay solid
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; dialog while still animating the play field
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@ -899,7 +908,7 @@ epilogue_1 tsc
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; are:
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;
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; 1. Carry Clear -> 16-bit write and return to the next code field operand
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; 2. Carry Set
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; 2. Carry Set
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; a. Overflow set -> Low 8-bit write and return to the next code field operand
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; b. Overflow clear -> High 8-bit write and exit the line
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; c. Always clear the Carry flags. It's actually OK to leave the overflow bit in
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@ -908,77 +917,24 @@ epilogue_1 tsc
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;
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; Snippet Samples:
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;
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; Standard Two-level Mix (27 bytes)
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; Standard Two-level Mix (23 bytes)
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;
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; Optimal = 18 cycles (LDA/AND/ORA/PHA)
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; 16-bit write = 23 cycles
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; 8-bit low = 35 cycles
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; 8-bit high = 36 cycles
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; Optimal = 18 cycles (LDA/AND/ORA/PHA/JMP)
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; 16-bit write = 21 cycles
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; 8-bit low = 30 cycles
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; 8-bit high = 29 cycles
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;
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; start lda (00),y
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; and #MASK
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; ora #DATA ; 14 cycles to load the data
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; bcs 8_bit
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; pha
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; out jmp next ; Fast-path completes in 9 additional cycles
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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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; 8_bit sep #$30 ; Switch to 8 bit mode
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; bvs r_edge ; Need to switch if doing the left edge
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; xba
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; r_edge pha ; push the value
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; rep #$31 ; put back into 16-bit mode and clear the carry bit, as required
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; bvs out ; jmp out and continue if this is the right edge
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; jmp even_exit ; exit the line otherwise
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; ;
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; ; The slow paths have 21 and 22 cycles for the right and left
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; ; odd-aligned cases respectively.
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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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; snippets ds 32*82
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top
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