Apple-2gs-SW/iigs-game-engine
1
0
Fork 0
mirror of https://github.com/lscharen/iigs-game-engine.git synced 2024-11-30 17:51:24 +00:00
Code Issues Projects Releases Wiki Activity

Copy OAM source on-demand instead of on DMA REG access

Browse Source
This commit is contained in:
Lucas Scharenbroich 2023-06-30 15:53:43 -05:00
parent 576c402d0b
commit 63d2f0ea46
1 changed files with 11 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
demos/smb/ppu.s
View File

@ -571,6 +571,7 @@ no_pal
; Trigger a copy from a page of memory to OAM. Since this is a DMA operation, we can cheat and do a 16-bit copy
PPUDMA_WRITE ENT
rtl
php
pha
@ -613,24 +614,29 @@ scanOAMSprites
ldy #0
:loop
lda PPU_OAM,x ; Y-coordinate
; lda PPU_OAM,x ; Y-coordinate
ldal ROMBase+$200,x
cmp #max_nes_y+1 ; Skip anything that is beyond this line
bcs :skip
cmp #y_offset
bcc :skip
lda PPU_OAM+1,x ; $FC is an empty tile, don't draw it
; lda PPU_OAM+1,x ; $FC is an empty tile, don't draw it
ldal ROMBase+$201,x
cmp #$FC
beq :skip
lda PPU_OAM+3,x ; If X-coordinate is off the edge skip it, too.
; lda PPU_OAM+3,x ; If X-coordinate is off the edge skip it, too.
ldal ROMBase+$203,x
cmp #255-8
bcs :skip
rep #$20
lda PPU_OAM,x
; lda PPU_OAM,x
ldal ROMBase+$200,x
sta OAM_COPY,y
lda PPU_OAM+2,x
; lda PPU_OAM+2,x
ldal ROMBase+$202,x
sta OAM_COPY+2,y
sep #$20