Apple-2gs-SW/iigs-game-engine
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Move dispatch table into K bank and save 9 cycles per tile in dispatch

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This commit is contained in:
Lucas Scharenbroich 2022-06-08 17:34:23 -05:00
parent 227643d7df
commit 3c41e97b0f
3 changed files with 14 additions and 15 deletions
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1
src/Core.s
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@ -46,7 +46,6 @@ ToolStartUp
rts
MasterId ds 2
;UserId ds 2
; Fatal error handler invoked by the _Err macro
PgmDeath tax

11
src/Tiles.s
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@ -111,7 +111,7 @@ InitTiles
bra :out
:fast
ldal FastTileProcs
sta TileStore+TS_BASE_TILE_DISP,x
stal K_TS_BASE_TILE_DISP,x
:out
; lda DirtyTileProcs ; Fill in with the first dispatch address
@ -213,7 +213,9 @@ _SetTile
:fast
ldal FastTileProcs,x
sta TileStore+TS_BASE_TILE_DISP,y
tyx
stal K_TS_BASE_TILE_DISP,x
:out
jmp _PushDirtyTileY ; on the next call to _ApplyTiles
@ -412,4 +414,7 @@ b_12_3 stpbit 12;3;]4
b_13_3 stpbit 13;3;]4
b_14_3 stpbit 14;3;]4
b_15_3 endbit 15;3;]4
<<<
<<<
; Store some tables in the K bank that will be used exclusively for jmp (abs,x) dispatch
K_TS_BASE_TILE_DISP ds TILE_STORE_SIZE

17
src/tiles/FastRenderer.s
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@ -13,25 +13,20 @@ NoSpriteFast
lda TileStore+TS_CODE_ADDR_HIGH,x ; load the bank of the target code field line
pha ; and put on the stack for later. Has TileStore bank in high byte.
ldy TileStore+TS_CODE_ADDR_LOW,x ; load the address of the code field
lda TileStore+TS_BASE_TILE_DISP,x ; go to the tile copy routine (just basics)
stal nsf_patch+1
; lda TileStore+TS_BASE_TILE_DISP,x ; go to the tile copy routine (just basics)
; stal nsf_patch+1
lda TileStore+TS_TILE_ADDR,x ; load the address of this tile's data (pre-calculated)
plb ; set the code field bank
nsf_patch jmp $0000
jmp (K_TS_BASE_TILE_DISP,x)
;nsf_patch jmp $0000
; The TS_BASE_TILE_DISP routines will come from this table when ENGINE_MODE_TWO_LAYER and
; ENGINE_MODE_DYN_TILES are both off.
FastTileProcs dw _TBCopyDataFast,_TBCopyDataFast,_TBCopyDataFast,_TBCopyDataFast
; dw _TBCopyDataFast,_TBCopyDataFast,_TBCopyDataVFast,_TBCopyDataVFast
; NOTE: Inlining the dispatch would eliminate a JSR,RTS,LDX, and JMP (abs,x) because the exit code
; could jump directly to the target address. Net savings of 20 cycles per tile. For a 16x16
; sprite with a 3x3 block coverage this is 180 cycles per frame per block... This would also
; preserve a register
;
; For comparison, a fast one sprite copy takes 22 cycles per word, so this would save
; about 1/2 block of render time per tile.
;
; Need to determine if the sprite or tile data is on top, as that will decide whether the
; sprite or tile data is copied into the temporary buffer first. Also, if TWO_LAYER is set
; then the mask information must be copied as well....This is the last decision point.