Merge branch 'master' of https://github.com/andrew-hoffman/halfnes

src/com/grapeshot/halfnes/APU.java

@@ -472,7 +472,7 @@ private void setvolumes() {
     private final static int[] dmcperiods = {428, 380, 340, 320, 286, 254,
         226, 214, 190, 160, 142, 128, 106, 84, 72, 54};
     private int dmcrate = 0x36, dmcpos = 0, dmcshiftregister = 0, dmcbuffer = 0,
-            dmcvalue = 0, dmcsamplelength = 0, dmcsamplesleft = 0,
+            dmcvalue = 0, dmcsamplelength = 1, dmcsamplesleft = 0,
             dmcstartaddr = 0xc000, dmcaddr = 0xc000, dmcbitsleft = 8;
     private boolean dmcsilence = true, dmcirq = false, dmcloop = false, dmcBufferEmpty = true;
 
@@ -512,7 +512,7 @@ private void dmcfillbuffer() {
         if (dmcsamplesleft > 0) {
             dmcbuffer = cpuram.read(dmcaddr++);
             dmcBufferEmpty = false;
-            cpu.stealcycles(2);
+            cpu.stealcycles(4);
             //DPCM Does steal cpu cycles - this should actually vary between 1-4
             //can't do this properly without a cycle accurate cpu/ppu
             if (dmcaddr > 0xffff) {

src/com/grapeshot/halfnes/CPU.java

@@ -15,9 +15,10 @@ public final class CPU {
     private boolean carryFlag = false, zeroFlag = false,
             interruptsDisabled = true, decimalModeFlag = false;
     private boolean overflowFlag = false, negativeFlag = false,
-            previntflag = false, nmi = false, prevnmi = false, nmiNext = false;
+            previntflag = false, nmi = false, prevnmi = false;
     private int pb = 0;// set to 1 if access crosses page boundary
     public int interrupt = 0;
+    public boolean nmiNext = false;
     private final static int ntscframe = 29780;
     private final static boolean logging = false, decimalModeEnable = false;
     //NES 6502 is missing decimal mode, but most other 6502s have it
@@ -61,7 +62,7 @@ public void init() {// different than reset
         ram.write(0x4015, 0x00);
         ram.write(0x4017, 0x00);
 
-        clocks = 27394; //correct for position we start vblank in
+        //clocks = 27393; //correct for position we start vblank in
         A = 0;
         X = 0;
         Y = 0;
@@ -95,7 +96,7 @@ public final void runcycle(final int scanline, final int pixel) {
         if (ram.apu.sprdma_count > 0) {
             ram.apu.sprdma_count--;
             if (ram.apu.sprdma_count == 0) {
-                cycles += 514;
+                cycles += 513;
             }
         }
 

src/com/grapeshot/halfnes/NES.java

@@ -26,7 +26,7 @@ public class NES {
     private boolean frameLimiterOn = true;
     private String curRomPath, curRomName;
     private final GUIInterface gui = new GUIImpl(this);
-    private FrameLimiterInterface limiter = new FrameLimiterImpl(this);
+    private final FrameLimiterInterface limiter = new FrameLimiterImpl(this);
     // Pro Action Replay device
     private ActionReplay actionReplay;
 
@@ -79,6 +79,9 @@ public void run() {
     private synchronized void runframe() {
         //the main method sequencing everything that has to happen in the nes each frame
         //loops unrolled a bit to avoid some conditionals every cycle
+        for (int scanline = 0; scanline <= 240; ++scanline) {
+            runLine(scanline);
+        }
 
         //run for scanlines of vblank
         for (int scanline = 241; scanline < 262; ++scanline) {
@@ -95,9 +98,6 @@ private synchronized void runframe() {
         cpu.modcycles();
 
         //run cpu, ppu for active drawing time
-        for (int scanline = 0; scanline <= 240; ++scanline) {
-            runLine(scanline);
-        }
 
         //render the frame
         ppu.renderFrame(gui);

src/com/grapeshot/halfnes/PPU.java

@@ -15,7 +15,7 @@ public class PPU {
     private int loopyV = 0x0;//ppu memory pointer
     private int loopyT = 0x0;//temp pointer
     private int loopyX = 0;//fine x scroll
-    private int scanline = 241;
+    private int scanline = 0;
     private int cycles = 0;
     private int framecount = 0;
     private int div = 2;
@@ -59,11 +59,21 @@ public final int read(final int regnum) {
         switch (regnum) {
             case 2:
                 even = true;
-                if (scanline == 241 && cycles == 1) {
-                    //suppress NMI flag if it was just turned on this same cycle
-                    setvblankflag(false);
+                if (scanline == 241) {
+                    if (cycles == 1) {//suppress NMI flag if it was just turned on this same cycle
+                        setvblankflag(false);
+                    }
+                    //OK, uncommenting this makes blargg's NMI suppression test
+                    //work but breaks Antarctic Adventure.
+                    //I'm going to need a cycle accurate CPU to fix that...
+//                    if (cycles < 4) {
+//                        //show vblank flag but cancel pending NMI before the CPU
+//                        //can actually do anything with it
+//                        //TODO: use proper interface for this
+//                        mapper.cpu.nmiNext = false;
+//                    }
                 }
-                final int tmp = ppuregs[2];
+                final int tmp = (ppuregs[2] & ~0x1f) + (openbus & 0x1f);
                 setvblankflag(false);
                 openbus = tmp;
                 break;
@@ -184,17 +194,19 @@ public final void write(final int regnum, final int data) {
 
     /**
      * PPU is on if either background or sprites are enabled
-     * @return true 
+     *
+     * @return true
      */
     private boolean ppuIsOn() {
         return getbit(ppuregs[1], 3) || getbit(ppuregs[1], 4);
     }
-    
+
     /**
      * MMC3 scan line counter isn't clocked if background and sprites are using
      * the same half of the pattern table
-     * @return true if PPU is rendering and BG and sprites are 
-     * using different pattern tables
+     *
+     * @return true if PPU is rendering and BG and sprites are using different
+     * pattern tables
      */
     public final boolean mmc3CounterClocking() {
         return (bgpattern != sprpattern) && ppuIsOn();
@@ -228,31 +240,32 @@ public final void clock() {
             sprite0hit = false;
             ppuregs[2] |= 0x40;
         }
-        //handle nmi
-        if (vblankflag && getbit(ppuregs[0], 7)) {
-            //pull NMI line on when conditions are right
-            mapper.cpu.setNMI(true);
-        } else {
-            mapper.cpu.setNMI(false);
-        }
         //handle vblank on / off
         if (scanline < 240 || scanline == 261) {
             //on all rendering lines
             if (cycles >= 257 && cycles <= 341) {
                 //clear the oam address from pxls 257-341 continuously
                 ppuregs[3] = 0;
             }
-            if (scanline == 261 && cycles == 1) {
+            if (scanline == 261 && cycles == 0) {
                 // turn off vblank, sprite 0, sprite overflow flags
                 setvblankflag(false);
                 ppuregs[2] &= 0x9F;
             }
         } else if (scanline == 241 && cycles == 1) {
             setvblankflag(true);
         }
+        //handle nmi
+        if (vblankflag && getbit(ppuregs[0], 7)) {
+            //pull NMI line on when conditions are right
+            mapper.cpu.setNMI(true);
+        } else {
+            mapper.cpu.setNMI(false);
+        }
 
         //clock CPU, once every 3 ppu cycles
-        if ((++div % 3) == 0) {
+        div = (div + 1) % 3;
+        if (div == 0) {
             mapper.cpu.runcycle(scanline, cycles);
         }
         if (cycles == 257) {