Continued work on PPU fixes

6502.go

@@ -24,6 +24,7 @@ type Cpu struct {
 
 	InterruptRequested int
 	CyclesToWait       int
+    CycleTimestamp     int
 }
 
 func (cpu *Cpu) getCarry() bool {
@@ -917,21 +918,18 @@ func (cpu *Cpu) Bit(location int) {
 }
 
 func (cpu *Cpu) PerformNmi() {
-	// $2000.7 enables/disables NMIs
-	if ppu.NmiOnVblank != 0x0 {
-		high := ProgramCounter >> 8
-		low := ProgramCounter & 0xFF
+    high := ProgramCounter >> 8
+    low := ProgramCounter & 0xFF
 
-		cpu.pushToStack(Word(high))
-		cpu.pushToStack(Word(low))
+    cpu.pushToStack(Word(high))
+    cpu.pushToStack(Word(low))
 
-		cpu.pushToStack(cpu.P)
+    cpu.pushToStack(cpu.P)
 
-		h, _ := Ram.Read(0xFFFB)
-		l, _ := Ram.Read(0xFFFA)
+    h, _ := Ram.Read(0xFFFB)
+    l, _ := Ram.Read(0xFFFA)
 
-		ProgramCounter = int(h)<<8 + int(l)
-	}
+    ProgramCounter = int(h)<<8 + int(l)
 }
 
 func (cpu *Cpu) PerformReset() {
@@ -1480,5 +1478,7 @@ func (cpu *Cpu) Step() int {
 		panic("Invalid opcode")
 	}
 
+    cpu.CycleTimestamp = (cpu.CycleCount * 15)
+
 	return cpu.CycleCount
 }

6502_test.go

@@ -2,7 +2,9 @@ package main
 
 import (
 	"encoding/hex"
+	"fmt"
 	"io/ioutil"
+	"strconv"
 	"strings"
 	"testing"
 )
@@ -13,6 +15,7 @@ type CpuState struct {
 	Y  int
 	P  int
 	S  int
+    C  int
 	Op int
 }
 
@@ -21,6 +24,7 @@ func TestGoldLog(test *testing.T) {
 
 	Ram.Init()
 	cpu.Reset()
+	ppu.Init()
 
 	cpu.P = 0x24
 
@@ -43,7 +47,8 @@ func TestGoldLog(test *testing.T) {
 
 	log := strings.Split(string(logfile), "\n")
 
-	sentinel := 5003
+    sentinel := 100
+	//sentinel := 5003
 	for i := 0; i < sentinel; i++ {
 		op, _ := hex.DecodeString(log[i][:4])
 
@@ -59,18 +64,27 @@ func TestGoldLog(test *testing.T) {
 		y, _ := hex.DecodeString(strings.Split(registers[2], ":")[1])
 		p, _ := hex.DecodeString(strings.Split(registers[3], ":")[1])
 		sp, _ := hex.DecodeString(strings.Split(registers[4], ":")[1])
+        cyc, _ := strconv.Atoi(strings.TrimSpace(log[i][78:81]))
+
+        fmt.Printf("Cycle: %d\n", cyc)
 
 		expectedState := CpuState{
 			A:  int(a[0]),
 			X:  int(x[0]),
 			Y:  int(y[0]),
 			P:  int(p[0]),
 			S:  int(sp[0]),
+            C:  cyc,
 			Op: (int(high) << 8) + int(low),
 		}
 
 		verifyCpuState(ProgramCounter, &cpu, expectedState, test)
-		cpu.Step()
+		cycles := cpu.Step()
+
+		// 3 PPU cycles for each CPU cycle
+		for i := 0; i < 3*cycles; i++ {
+			ppu.Step()
+		}
 	}
 }
 
@@ -98,4 +112,8 @@ func verifyCpuState(pc int, c *Cpu, e CpuState, test *testing.T) {
 	if c.StackPointer != Word(e.S) {
 		test.Errorf("PC: 0x%X Stack pointer was 0x%X, was expecting 0x%X\n", pc, c.StackPointer, e.S)
 	}
+
+	if ppu.Cycle != e.C {
+		test.Errorf("PC: 0x%X PPU Cycle was %d, was expecting %d\n", pc, ppu.Cycle, e.C)
+	}
 }

controller.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"fmt"
 	"github.com/0xe2-0x9a-0x9b/Go-SDL/sdl"
 )
 
@@ -84,7 +85,15 @@ func JoypadListen() {
 					running = false
 				case sdl.K_r:
 					// Trigger reset interrupt
-					cpu.RequestInterrupt(InterruptReset)
+                    if e.Type == sdl.KEYDOWN {
+                        fmt.Printf("VRAM: 0x%X\n", ppu.VramAddress)
+                        cpu.RequestInterrupt(InterruptReset)
+                    }
+				case sdl.K_n:
+                    if e.Type == sdl.KEYDOWN {
+                        // Trigger reset interrupt
+                        ppu.DebugMode = !ppu.DebugMode
+                    }
 				}
 
 				switch e.Type {

machine.go

@@ -35,7 +35,7 @@ func main() {
 
 	Ram.Init()
 	cpu.Init()
-	v := ppu.Init()
+	v, d := ppu.Init()
 	controller.Init()
 
 	if contents, err := ioutil.ReadFile(os.Args[1]); err == nil {
@@ -51,7 +51,7 @@ func main() {
 		return
 	}
 
-	video.Init(v, os.Args[1])
+	video.Init(v, d, os.Args[1])
 	defer video.Close()
 
 	go JoypadListen()

memory.go

@@ -16,40 +16,6 @@ var (
 	Ram Memory
 )
 
-func PpuRegWrite(v Word, a int) {
-	switch a {
-	case 0x2000:
-		ppu.WriteControl(v)
-	case 0x2001:
-		ppu.WriteMask(v)
-	case 0x2003:
-		ppu.WriteOamAddress(v)
-	case 0x2004:
-		ppu.WriteOamData(v)
-	case 0x2005:
-		ppu.WriteScroll(v)
-	case 0x2006:
-		ppu.WriteAddress(v)
-	case 0x2007:
-		ppu.WriteData(v)
-	case 0x4014:
-		ppu.WriteDma(v)
-	}
-}
-
-func PpuRegRead(a int) (Word, error) {
-	switch a {
-	case 0x2002:
-		return ppu.ReadStatus()
-	case 0x2004:
-		return ppu.ReadOamData()
-	case 0x2007:
-		return ppu.ReadData()
-	}
-
-	return 0, nil
-}
-
 func fitAddressSize(addr interface{}) (v int, e error) {
 	switch a := addr.(type) {
 	case Word:
@@ -69,16 +35,30 @@ func (m *Memory) Init() {
 	}
 }
 
+func (m *Memory) WriteMirroredRam(v Word, a int) {
+	for i := 0; i < 0x2FFB; i += 8 {
+		m[0x2002+i] = v
+	}
+}
+
 func (m *Memory) Write(address interface{}, val Word) error {
 	if a, err := fitAddressSize(address); err == nil {
+		if a == 0x2002 {
+			return nil
+		}
+
 		m[a] = val
 
 		if a <= 0x2007 && a >= 0x2000 {
-			PpuRegWrite(val, a)
+			ppu.PpuRegWrite(val, a)
 		} else if a == 0x4014 {
-			PpuRegWrite(val, a)
+			ppu.PpuRegWrite(val, a)
 		} else if a == 0x4016 {
 			controller.Write(val)
+		} else if a >= 0x8000 && a <= 0xFFFF {
+			// MMC1
+			//rom.Write(val, a)
+			return nil
 		}
 
 		return nil
@@ -90,8 +70,12 @@ func (m *Memory) Write(address interface{}, val Word) error {
 func (m *Memory) Read(address interface{}) (Word, error) {
 	a, _ := fitAddressSize(address)
 
+    if a == 0x200A {
+        return m[0x2002], nil
+    }
+
 	if a <= 0x2007 && a >= 0x2000 {
-		return PpuRegRead(a)
+		return ppu.PpuRegRead(a)
 	} else if a == 0x4016 {
 		return controller.Read(), nil
 	}