don't over-stretch lowres lines during frameskip

fixes #92

Author: devinacker

bsnes/snes/alt/ppu-compatibility/ppu.hpp

@@ -66,6 +66,7 @@ class PPU : public Processor, public PPUcounter, public MMIO {
   void layer_enable(unsigned layer, unsigned priority, bool enable);
   unsigned frameskip;
   unsigned framecounter;
+  bool frame_skipped() const { return framecounter > 0; }
   unsigned get_frameskip() const { return frameskip; }
   void set_frameskip(unsigned frameskip);
 

bsnes/snes/alt/ppu-performance/ppu.hpp

@@ -19,6 +19,7 @@ class PPU : public Processor, public PPUcounter, public MMIO {
   void frame();
 
   void layer_enable(unsigned layer, unsigned priority, bool enable);
+  bool frame_skipped() const { return display.framecounter > 0; }
   unsigned get_frameskip() const { return display.frameskip; }
   void set_frameskip(unsigned frameskip);
 

bsnes/snes/ppu/ppu.hpp

@@ -17,6 +17,7 @@ class PPU : public Processor, public PPUcounter, public MMIO {
   void reset();
 
   void layer_enable(unsigned, unsigned, bool) {}
+  bool frame_skipped() const { return false; }
   unsigned get_frameskip() const { return 0; }
   void set_frameskip(unsigned) {}
 

bsnes/snes/video/video.cpp

@@ -60,12 +60,14 @@ void Video::update() {
 
   if(frame_hires) {
     width <<= 1;
-    //normalize line widths
-    for(unsigned y = 0; y < 240; y++) {
-      if(line_width[y] == 512) continue;
-      uint16_t *buffer = data + y * 1024;
-      for(signed x = 255; x >= 0; x--) {
-        buffer[(x * 2) + 0] = buffer[(x * 2) + 1] = buffer[x];
+    if(!ppu.frame_skipped()) {
+      //normalize line widths
+      for(unsigned y = 0; y < 240; y++) {
+        if(line_width[y] == 512) continue;
+        uint16_t *buffer = data + y * 1024;
+        for(signed x = 255; x >= 0; x--) {
+          buffer[(x * 2) + 0] = buffer[(x * 2) + 1] = buffer[x];
+        }
       }
     }
   }

bsnes/ui-qt/input/userinterface-emulationspeed.cpp

@@ -56,7 +56,7 @@ struct Speedup : HotkeyInput {
 
   void pressed() {
     if(SNES::PPU::SupportsFrameSkip) {
-	  frameskip = SNES::ppu.get_frameskip();
+      frameskip = SNES::ppu.get_frameskip();
       SNES::ppu.set_frameskip(9);
     }