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niconii/snes_main_loop.asm

Created September 10, 2018 00:19
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Example SNES main loop
Raw
snes_main_loop.asm
reset:
; initialize everything...
main:
; update game state...
; process sprites in a copy of OAM stored in WRAM...
; other stuff...
inc ReadyFlag ; signal that we're done processing for this frame
spin:
lda ReadyFlag ; wait until flag is cleared by NMI routine
bne spin
jmp main
nmi:
; save registers...
; set A to 8-bit and XY to 16-bit...
lda ReadyFlag ; if main loop not ready, skip to end
beq nmi_end
; turn on forced blank in case we take too long
; DMA to OAM...
; update graphics...
; poll controllers...
; other stuff...
; turn off forced blank
stz ReadyFlag ; since graphics were updated, clear flag
nmi_end:
; restore registers...
rti
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