git.y1.nz

commit 8df4497c47820261e93c3bd57296b63178791c5f
parent 33030947181f59382fdbd2c234dd8281b25897a7
Author: Michel Iwaniec <46843052+michel-iwaniec@users.noreply.github.com>
Date:   Wed, 26 Mar 2025 15:10:21 +0000

NES: Re-introduce optimization to exit NMI handler early if LCD ISR is disabled (#754)

- Add check to terminate buffer if LCD-ISR disabled (.jmp_to_LCD_isr starts with RTS opcode) in vsync
Diffstat:
M
gbdk-lib/libc/targets/mos6502/nes/crt0.s
8
++++++++

1 file changed, 8 insertions(+), 0 deletions(-)
diff --git a/gbdk-lib/libc/targets/mos6502/nes/crt0.s b/gbdk-lib/libc/targets/mos6502/nes/crt0.s
@@ -491,6 +491,14 @@ _vsync::
     iny
     sty *.lcd_buf_index
 
+    ; Ensure second entry (actual LCD) starts off with zero (end-of-list)
+    lda #0
+    sta __lcd_isr_delay_num_scanlines,y
+    ; Skip to end if LCD isr functionality is disabled (0x60 = RTS means LCD isr disabled)
+    lda .jmp_to_LCD_isr
+    cmp #0x60
+    beq _wait_vbl_done_waitForNextFrame
+
     lda *.lcd_scanline_previous
 
     jmp 2$

This webpage is intended to be an accessible preview of this repository. To get a fuller picture, clone it and use the git CLI.