1 files changed, 10 insertions, 11 deletions
diff --git a/src/ppu.rs b/src/ppu.rs
index 62a8261..9938373 100644
--- a/src/ppu.rs
+++ b/src/ppu.rs
@@ -447,7 +447,7 @@ impl<'a> PPU<'a> {
 let ppustatus = 0xa0;
 let oamaddr = 0x00;
 let buffered_read = 0x00;
- let cycle = 370;
+ let cycle = 340;
 let scanline = 240;
 PPU {
 scanline,
@@ -478,7 +478,7 @@ impl<'a> PPU<'a> {
 self.ppustatus = self.ppustatus & 0x80;
 self.w = false;
 self.buffered_read = 0x00;
- self.cycle = 370;
+ self.cycle = 340;
 self.scanline = 240;
 }
 
@@ -528,18 +528,11 @@ impl<'a> PPU<'a> {
 self.reset_cx();
 self.fetch_sprite();
 }
- if pre_line {
- if cycle == 1 {
- /* clear vblank, sprite zero hit & overflow */
- self.ppustatus &= !(PPU::FLAG_VBLANK |
- PPU::FLAG_SPRITE_ZERO | PPU::FLAG_OVERFLOW);
- self.bg_pixel = 0
- } else if cycle == 339 && self.f {
+ if pre_line && cycle == 339 && self.f {
 self.scanline = 0;
 self.cycle = 0;
 self.f = !self.f;
 return false;
- }
 }
 }
 } else {
@@ -549,11 +542,17 @@ impl<'a> PPU<'a> {
 self.ppustatus |= PPU::FLAG_VBLANK;
 }
 self.scr.render();
- self.cycle += 1;
+ self.cycle = 2;
 self.early_read = false;
 return !self.early_read && self.get_flag_nmi(); /* trigger cpu's NMI */
 }
 }
+ if pre_line && cycle == 1 {
+ /* clear vblank, sprite zero hit & overflow */
+ self.ppustatus &= !(PPU::FLAG_VBLANK |
+ PPU::FLAG_SPRITE_ZERO | PPU::FLAG_OVERFLOW);
+ self.bg_pixel = 0;
+ }
 self.cycle += 1;
 if self.cycle > 340 {
 self.cycle = 0;