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EZ80.java
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9616 lines (7473 loc) · 235 KB
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/*
* @author André Luiz Veltroni Sanches - alvs
*
* Notes: undocumented opcodes are marked with a * character.
* DAA table borrowed from Chris White's JavaGear
* which is available at http://www.javagear.co.uk
*/
public final class EZ80 {
public int a, b, c, d, e, h, l; // General Purpose Registers.
public int a_, f_, b_, c_, d_, e_, h_, l_; // Shadow Registers.
public int ix, iy; // Index Registers.
public int flagreg, r, sp, pc; // Flags & Refresh register, Stack Pointer and Program Counter.
public boolean iff1, iff2; // Interrupt flip-flops and interrupt line register.
public boolean irq; // IRQ line
public int im; // Interrupt mode.
public int[] daa; // precalculated Decimal Adjust Accumulator table
public boolean[] parity; // precalculated parity table
public static final int FLAG_SIGN = 0x80;
public static final int FLAG_ZERO = 0x40;
public static final int FLAG_BIT5 = 0x20;
public static final int FLAG_HCARRY = 0x10;
public static final int FLAG_BIT3 = 0x08;
public static final int FLAG_PV = 0x04;
public static final int FLAG_NEG = 0x02;
public static final int FLAG_CARRY = 0x01;
public boolean EIDI_Last; // "True" if the last executed instruction was DI or EI.
public boolean halt; // for HALT instruction
public int counter; // Cycle Counter
private MemoryManager memory;
private VDP vdp;
private Ports ports;
private Debugger debugger;
private int opcode = 0;
private Mnemonic opcodes;
public Messages msg;
public EZ80(MemoryManager memory, Ports ports, VDP vdp, Debugger debugger) {
this.memory = memory;
this.debugger = debugger;
this.vdp = vdp;
this.ports = ports;
generateParityTable();
generateDAATable();
reset();
opcodes = new Mnemonic();
msg = new Messages();
}
public void reset() {
a = 0xFF; b = 0xFF; c = 0xFF; d = 0xFF; e = 0xFF; h = 0xFF; l = 0xFF;
a_ = 0xFF; f_ = 0xFF; b_ = 0xFF; c_ = 0xFF; d_ = 0xFF; e_ = 0xFF; h_ = 0xFF; l_ = 0xFF;
ix = 0xFFFF;
iy = 0xFFFF;
flagreg = 0xFF;
r = 0;
sp = 0xFF;
pc = 0;
counter = 0;
EIDI_Last = false;
halt = false;
iff1 = false;
iff2 = false;
}
public final void push(int value) {
sp--;
memory.writebyte(sp, value >> 8);
sp--;
memory.writebyte(sp, value);
}
public final int pop() {
int val;
val = memory.readbyte(sp);
sp++;
val |= (memory.readbyte(sp) << 8);
sp++;
return val;
}
public final void setIRQ() {
irq = true;
}
public final void interrupt() {
if((EIDI_Last == true) || (iff1 == false)) return;
if(halt) {
halt = false;
pc++;
}
int temp = r;
temp++;
r = (r & 0x80) | (temp & 0x7F); // increment refresh register preserving bit 7.
iff1 = false;
//iff2 = false;
irq = false;
switch(im) {
case 0:
case 1:
//System.out.println("INTERRUPT EXECUTED");
push(pc);
pc = 0x38;
counter -= 13;
break;
default: System.out.println("Interrupt mode 2 not yet implemented.");
}
}
public final void execute(int iperiod) {
counter += iperiod;
while(counter > 0) {
if(irq) interrupt(); // Execute interrupt
/* // ----------- THIS SECTION IS ONLY FOR DEBUGGING ----------
String op = null; // USED IN THE DEBUGGING SECTION BELOW
opcode = memory.readbyte(pc);
switch(opcode) {
case 0xCB:
op = opcodes.getCB(memory.readbyte(pc+1));
break;
case 0xED:
op = opcodes.getED(memory.readbyte(pc+1));
break;
case 0xDD:
if(memory.readbyte(pc+1) == 0xCB) {
op = Integer.toHexString(opcode).toUpperCase();
op += "CB";
op += " " + Integer.toHexString(memory.readbyte(pc+2)).toUpperCase();
op += " " + Integer.toHexString(memory.readbyte(pc+3)).toUpperCase();
}
else {
op = opcodes.getIndex(memory.readbyte(pc+1));
}
break;
case 0xFD:
if(memory.readbyte(pc+1) == 0xCB) {
op = Integer.toHexString(opcode).toUpperCase();
op += "CB";
op += " " + Integer.toHexString(memory.readbyte(pc+2)).toUpperCase();
op += " " + Integer.toHexString(memory.readbyte(pc+3)).toUpperCase();
}
else {
op = opcodes.getIndex(memory.readbyte(pc+1));
}
break;
default: op = opcodes.getOP(opcode);
}
//System.out.println("PC=$" + Integer.toHexString(pc) + " " + op);
System.out.println(op);
// --------------- END OF DEBUGGING PART --------------
*/
exec_opcode(memory.readbyte(pc));
}
//updateDebugger();
}
public final void exec_opcode(int opcode) {
int aux, addr, f;
f = flagreg;
int temp = r;
temp++;
r = (r & 0x80) | (temp & 0x7F); // increment refresh register preserving bit 7.
EIDI_Last = false;
switch(opcode) {
case 0x00: // NOP - 4 cycles.
counter -= 4;
pc++;
break;
case 0x01: // LD BC, nn - 10 cycles
b = memory.readbyte(pc+2);
c = memory.readbyte(pc+1);
counter -= 10;
pc += 3;
break;
case 0x02: // LD (BC), A - 7 cycles
memory.writebyte((b << 8) | c, a);
counter -= 7;
pc++;
break;
case 0x03: // INC BC - 6 cycles
c++;
if(c > 0xFF) {
c ^= c;
b = (b + 1) & 0xFF;
}
counter -= 6;
pc++;
break;
case 0x04: // INC B - 4 cycles
if((b & 0xF)+1 > 0xF) f |= FLAG_HCARRY;
else f &= ~FLAG_HCARRY;
b = ((b + 1) & 0xFF);
if(b == 0) { f |= FLAG_ZERO; f &= ~(FLAG_SIGN | FLAG_PV); }
else {
f &= ~FLAG_ZERO;
if(b == 0x80) f |= FLAG_PV | FLAG_SIGN;
else {
f &= ~FLAG_PV;
if((b & 0x80) != 0) f |= FLAG_SIGN;
else f &= ~FLAG_SIGN;
}
}
f &= ~FLAG_NEG;
counter -= 4;
pc++;
break;
case 0x05: // DEC B - 4 cycles
if(b == 0x80) f |= FLAG_PV;
else f &= ~FLAG_PV;
b = ((b - 1) & 0xFF);
if((b & 0xF) == 0xF) f |= FLAG_HCARRY;
else f &= ~FLAG_HCARRY;
if(b==0) f |= FLAG_ZERO;
else f &= ~FLAG_ZERO;
if((b & 0x80) != 0) f |= FLAG_SIGN;
else f &= ~FLAG_SIGN;
f |= FLAG_NEG;
counter -= 4;
pc++;
break;
case 0x06: // LD B, n - 7 cycles
b = memory.readbyte(pc+1);
counter -= 7;
pc += 2;
break;
case 0x07: // RLCA - 4 cycles
a = a << 1;
if((a & 0x100) != 0) {
a |= 0x01;
f |= FLAG_CARRY;
}
else {
a &= ~0x01;
f &= ~FLAG_CARRY;
}
a &= 0xFF;
f &= ~(FLAG_HCARRY | FLAG_NEG);
counter -= 4;
pc++;
break;
case 0x08: // EX AF, AF' - 4 cycles
aux = a;
a = a_;
a_ = aux;
aux = f;
f = f_;
f_ = aux;
pc++;
counter -= 4;
break;
case 0x09: // ADD HL, BC - 11 cycles
aux = ((h << 8) | l) & 0xFFF;
aux += ((b << 8) | c) & 0xFFF;
if(aux > 0xFFF) f |= FLAG_HCARRY;
else f &= ~FLAG_HCARRY;
aux = (h << 8) | l;
aux += ((b << 8) | c);
if(aux > 0xFFFF) f |= FLAG_CARRY;
else f &= ~FLAG_CARRY;
if((aux & 0x8000) != 0) f |= FLAG_SIGN;
else f &= ~FLAG_SIGN;
aux &= 0xFFFF;
if(aux == 0) f |= FLAG_ZERO;
else f &= ~FLAG_ZERO;
h = (aux >> 8) & 0xFF;
l = aux & 0xFF;
f &= ~FLAG_NEG;
counter -= 11;
pc++;
break;
case 0x0A: // LD A, (BC) - 7 cycles
a = memory.readbyte((b << 8) | c);
counter -= 7;
pc++;
break;
case 0x0B: // DEC BC - 6 cycles
c--;
if(c < 0) {
c = 0xFF;
b--;
if(b < 0) b = 0xFF;
}
counter -= 6;
pc++;
break;
case 0x0C: // INC C - 4 cycles
if((c & 0xF)+1 > 0xF) f |= FLAG_HCARRY;
else f &= ~FLAG_HCARRY;
c = ((c + 1) & 0xFF);
if(c == 0) { f |= FLAG_ZERO; f &= ~(FLAG_SIGN | FLAG_PV); }
else {
f &= ~FLAG_ZERO;
if(c == 0x80) f |= FLAG_PV | FLAG_SIGN;
else {
f &= ~FLAG_PV;
if((c & 0x80) != 0) f |= FLAG_SIGN;
else f &= ~FLAG_SIGN;
}
}
f &= ~FLAG_NEG;
counter -= 4;
pc++;
break;
case 0x0D: // DEC C - 4 cycles
if(c == 0x80) f |= FLAG_PV;
else f &= ~FLAG_PV;
c = ((c - 1) & 0xFF);
if((c & 0xF) == 0xF) f |= FLAG_HCARRY;
else f &= ~FLAG_HCARRY;
if(c==0) f |= FLAG_ZERO;
else f &= ~FLAG_ZERO;
if((c & 0x80) != 0) f |= FLAG_SIGN;
else f &= ~FLAG_SIGN;
f |= FLAG_NEG;
counter -= 4;
pc++;
break;
case 0x0E: // LD C, n - 7 cycles
c = memory.readbyte(pc+1);
counter -= 7;
pc += 2;
break;
case 0x0F: // RRCA - 4 cycles
if((a & 0x1) != 0) {
a |= 0x100;
f |= FLAG_CARRY;
}
else {
a &= 0xFF;
f &= ~FLAG_CARRY;
}
a = (a >> 1) & 0xFF;
f &= ~(FLAG_HCARRY | FLAG_NEG);
counter -= 4;
pc++;
break;
case 0x10: // DJNZ PC+d - 13/8 cycles
b = ((b - 1) & 0xFF);
if(b != 0) {
pc += memory.readsigned(pc+1);
pc &= 0xFFFF;
counter -= 13;
}
else counter -= 8;
pc += 2;
break;
case 0x11: // LD DE, nn - 10 cycles
d = memory.readbyte(pc+2);
e = memory.readbyte(pc+1);
counter -= 10;
pc += 3;
break;
case 0x12: // LD (DE), A - 7 cycles
memory.writebyte(((d << 8) | e), (a & 0xFF));
counter -= 7;
pc++;
break;
case 0x13: // INC DE - 6 cycles
e++;
if(e > 0xFF) {
e ^= e;
d = (d + 1) & 0xFF;
}
counter -= 6;
pc++;
break;
case 0x14: // INC D - 4 cycles
if((d & 0xF)+1 > 0xF) f |= FLAG_HCARRY;
else f &= ~FLAG_HCARRY;
d = ((d + 1) & 0xFF);
if(d == 0) { f |= FLAG_ZERO; f &= ~(FLAG_SIGN | FLAG_PV); }
else {
f &= ~FLAG_ZERO;
if(d == 0x80) f |= FLAG_PV | FLAG_SIGN;
else {
f &= ~FLAG_PV;
if((d & 0x80) != 0) f |= FLAG_SIGN;
else f &= ~FLAG_SIGN;
}
}
f &= ~FLAG_NEG;
counter -= 4;
pc++;
break;
case 0x15: // DEC D - 4 cycles
if(d == 0x80) f |= FLAG_PV;
else f &= ~FLAG_PV;
d = ((d - 1) & 0xFF);
if((d & 0xF) == 0xF) f |= FLAG_HCARRY;
else f &= ~FLAG_HCARRY;
if(d==0) f |= FLAG_ZERO;
else f &= ~FLAG_ZERO;
if((d & 0x80) != 0) f |= FLAG_SIGN;
else f &= ~FLAG_SIGN;
f |= FLAG_NEG;
counter -= 4;
pc++;
break;
case 0x16: // LD D, n - 7 cycles
d = memory.readbyte(pc+1);
counter -= 7;
pc += 2;
break;
case 0x17: // RLA - 4 cycles
a = a << 1;
if((f & FLAG_CARRY) != 0) a |= 0x1;
else a &= ~0x1;
if((a & 0x100) != 0) f |= FLAG_CARRY;
else f &= ~FLAG_CARRY;
a &= 0xFF;
f &= ~(FLAG_NEG | FLAG_HCARRY);
counter -= 4;
pc++;
break;
case 0x18: // JR PC+d - 12 cycles
pc += memory.readsigned(pc+1);
counter -= 12;
pc += 2;
pc &= 0xFFFF;
break;
case 0x19: // ADD HL, DE - 11 cycles
aux = ((h << 8) | l) & 0xFFF;
aux += ((d << 8) | e) & 0xFFF;
if(aux > 0xFFF) f |= FLAG_HCARRY;
else f &= ~FLAG_HCARRY;
aux = (h << 8) | l;
aux += ((d << 8) | e);
if(aux > 0xFFFF) f |= FLAG_CARRY;
else f &= ~FLAG_CARRY;
if((aux & 0x8000) != 0) f |= FLAG_SIGN;
else f &= ~FLAG_SIGN;
aux &= 0xFFFF;
if(aux == 0) f |= FLAG_ZERO;
else f &= ~FLAG_ZERO;
h = (aux >> 8) & 0xFF;
l = aux & 0xFF;
f &= ~FLAG_NEG;
counter -= 11;
pc++;
break;
case 0x1A: // LD A, (DE) - 7 cycles
a = memory.readbyte((d << 8) | e);
counter -= 7;
pc++;
break;
case 0x1B: // DEC DE - 6 cycles
e--;
if(e < 0) {
e = 0xFF;
d--;
if(d < 0) d = 0xFF;
}
counter -= 6;
pc++;
break;
case 0x1C: // INC E - 4 cycles
if((e & 0xF)+1 > 0xF) f |= FLAG_HCARRY;
else f &= ~FLAG_HCARRY;
e = (e + 1) & 0xFF;
if(e == 0) { f |= FLAG_ZERO; f &= ~(FLAG_SIGN | FLAG_PV); }
else {
f &= ~FLAG_ZERO;
if(e == 0x80) f |= FLAG_PV | FLAG_SIGN;
else {
f &= ~FLAG_PV;
if((e & 0x80) != 0) f |= FLAG_SIGN;
else f &= ~FLAG_SIGN;
}
}
f &= ~FLAG_NEG;
counter -= 4;
pc++;
break;
case 0x1D: // DEC E - 4 cycles
if(e == 0x80) f |= FLAG_PV;
else f &= ~FLAG_PV;
e = ((e - 1) & 0xFF);
if((e & 0xF) == 0xF) f |= FLAG_HCARRY;
else f &= ~FLAG_HCARRY;
if(e==0) f |= FLAG_ZERO;
else f &= ~FLAG_ZERO;
if((e & 0x80) != 0) f |= FLAG_SIGN;
else f &= ~FLAG_SIGN;
f |= FLAG_NEG;
counter -= 4;
pc++;
break;
case 0x1E: // LD E, n - 7 cycles
e = memory.readbyte(pc+1);
counter -= 7;
pc += 2;
break;
case 0x1F: // RRA - 4 cycles
if((f & FLAG_CARRY) != 0) a |= 0x100;
else a &= ~0x100;
if((a & 0x01) != 0) f |= FLAG_CARRY;
else f &= ~FLAG_CARRY;
a = (a >> 1) & 0xFF;
f &= ~(FLAG_NEG | FLAG_HCARRY);
counter -= 4;
pc++;
break;
case 0x20: // JR NZ, PC+d - 12/7 cycles
if((f & FLAG_ZERO) == 0) {
pc += memory.readsigned(pc+1);
counter -= 12;
}
else counter -= 7;
pc += 2;
break;
case 0x21: // LD HL, nn - 10 cycles
h = memory.readbyte(pc+2);
l = memory.readbyte(pc+1);
counter -= 10;
pc += 3;
break;
case 0x22: // LD (NN), HL - 20 cycles
aux = ((memory.readbyte(pc+2) << 8) | memory.readbyte(pc+1));
memory.writebyte(aux+1, h & 0xFF);
memory.writebyte(aux, l & 0xFF);
counter -= 20;
pc += 3;
break;
case 0x23: // INC HL - 6 cycles
l++;
if(l > 0xFF) {
l ^= l;
h = (h + 1) & 0xFF;
}
counter -= 6;
pc++;
break;
case 0x24: // INC H - 4 cycles
if((h & 0xF)+1 > 0xF) f |= FLAG_HCARRY;
else f &= ~FLAG_HCARRY;
h = ((h + 1) & 0xFF);
if(h == 0) { f |= FLAG_ZERO; f &= ~(FLAG_SIGN | FLAG_PV); }
else {
f &= ~FLAG_ZERO;
if(h == 0x80) f |= FLAG_PV | FLAG_SIGN;
else {
f &= ~FLAG_PV;
if((h & 0x80) != 0) f |= FLAG_SIGN;
else f &= ~FLAG_SIGN;
}
}
f &= ~FLAG_NEG;
counter -= 4;
pc++;
break;
case 0x25: // DEC H - 4 cycles
if(h == 0x80) f |= FLAG_PV;
else f &= ~FLAG_PV;
h = ((h - 1) & 0xFF);
if((h & 0xF) == 0xF) f |= FLAG_HCARRY;
else f &= ~FLAG_HCARRY;
if(h==0) f |= FLAG_ZERO;
else f &= ~FLAG_ZERO;
if((h & 0x80) != 0) f |= FLAG_SIGN;
else f &= ~FLAG_SIGN;
f |= FLAG_NEG;
counter -= 4;
pc++;
break;
case 0x26: // LD H, n - 7 cycles
h = memory.readbyte(pc+1);
counter -= 7;
pc += 2;
break;
case 0x27: // DAA - 4 cycles
if((f & FLAG_NEG) != 0) a |= 0x100;
if((f & FLAG_CARRY) != 0) a |= 0x200;
if((f & FLAG_HCARRY) != 0) a |= 0x400;
a = daa[a];
if(a > 0xFF) f |= FLAG_CARRY;
else f &= ~FLAG_CARRY;
a &= 0xFF;
if(parity[a]) f |= FLAG_PV;
else f &= ~FLAG_PV;
if(a == 0) f |= FLAG_ZERO;
else f &= ~FLAG_ZERO;
if((a & 0x80) != 0) f |= FLAG_SIGN;
else f &= ~FLAG_SIGN;
counter -= 4;
pc++;
break;
case 0x28: // JR Z, PC+d - 12/7 cycles
if((f & FLAG_ZERO) != 0) {
pc += memory.readsigned(pc+1);
counter -= 12;
}
else counter -= 7;
pc += 2;
pc &= 0xFFFF;
break;
case 0x29: // ADD HL, HL - 11 cycles
aux = ((h << 8) | l) & 0xFFF;
aux <<= 1;
if(aux > 0xFFF) f |= FLAG_HCARRY;
else f &= ~FLAG_HCARRY;
aux = (h << 8) | l;
aux <<= 1;
if(aux > 0xFFFF) f |= FLAG_CARRY;
else f &= ~FLAG_CARRY;
if((aux & 0x8000) != 0) f |= FLAG_SIGN;
else f &= ~FLAG_SIGN;
aux &= 0xFFFF;
if(aux == 0) f |= FLAG_ZERO;
else f &= ~FLAG_ZERO;
h = (aux >> 8) & 0xFF;
l = aux & 0xFF;
f &= ~FLAG_NEG;
counter -= 11;
pc++;
break;
case 0x2A: // LD HL, (NN) - 16 cycles
addr = ((memory.readbyte(pc+2) << 8) | memory.readbyte(pc+1));
h = memory.readbyte(addr + 1);
l = memory.readbyte(addr);
counter -= 16;
pc += 3;
break;
case 0x2B: // DEC HL - 6 cycles
l--;
if(l < 0) {
l = 0xFF;
h--;
if(h < 0) h = 0xFF;
}
counter -= 6;
pc++;
break;
case 0x2C: // INC L - 4 cycles
if((l & 0xF)+1 > 0xF) f |= FLAG_HCARRY;
else f &= ~FLAG_HCARRY;
l = ((l + 1) & 0xFF);
if(l == 0) { f |= FLAG_ZERO; f &= ~(FLAG_SIGN | FLAG_PV); }
else {
f &= ~FLAG_ZERO;
if(l == 0x80) f |= FLAG_PV | FLAG_SIGN;
else {
f &= ~FLAG_PV;
if((l & 0x80) != 0) f |= FLAG_SIGN;
else f &= ~FLAG_SIGN;
}
}
f &= ~FLAG_NEG;
counter -= 4;
pc++;
break;
case 0x2D: // DEC L - 4 cycles
if(l == 0x80) f |= FLAG_PV;
else f &= ~FLAG_PV;
l = ((l - 1) & 0xFF);
if((l & 0xF) == 0xF) f |= FLAG_HCARRY;
else f &= ~FLAG_HCARRY;
if(l==0) f |= FLAG_ZERO;
else f &= ~FLAG_ZERO;
if((l & 0x80) != 0) f |= FLAG_SIGN;
else f &= ~FLAG_SIGN;
f |= FLAG_NEG;
counter -= 4;
pc++;
break;
case 0x2E: // LD L, n - 7 cycles
l = memory.readbyte(pc+1);
counter -= 7;
pc += 2;
break;
case 0x2F: // CPL - 4 cycles
a = (~a) & 0xFF;
f |= (FLAG_NEG | FLAG_HCARRY);
counter -= 4;
pc++;
break;
case 0x30: // JR NC, PC+d - 12/7 cycles
if((f & FLAG_CARRY) == 0) {
pc += memory.readsigned(pc+1);
pc &= 0xFFFF;
counter -= 12;
}
else counter -= 7;
pc += 2;
break;
case 0x31: // LD SP, nn - 10 cycles
sp = (memory.readbyte(pc+2) << 8) | memory.readbyte(pc+1);
counter -= 10;
pc += 3;
break;
case 0x32: // LD (NN), A - 13 cycles
memory.writebyte((memory.readbyte(pc+2) << 8) | memory.readbyte(pc+1), a);
counter -= 13;
pc += 3;
break;
case 0x33: // INC SP - 6 cycles
sp = ((sp + 1) & 0xFFFF);
counter -= 6;
pc++;
break;
case 0x34: // INC (HL) - 11 cycles
addr = (h << 8) | l;
aux = memory.readbyte(addr);
if((aux & 0xF)+1 > 0xF) f |= FLAG_HCARRY;
else f &= ~FLAG_HCARRY;
aux = (aux + 1) & 0xFF;
memory.writebyte(addr, aux);
if(aux == 0) { f |= FLAG_ZERO; f &= ~(FLAG_SIGN | FLAG_PV); }
else {
f &= ~FLAG_ZERO;
if(aux == 0x80) f |= FLAG_PV | FLAG_SIGN;
else {
f &= ~FLAG_PV;
if((aux & 0x80) != 0) f |= FLAG_SIGN;
else f &= ~FLAG_SIGN;
}
}
f &= ~FLAG_NEG;
counter -= 11;
pc++;
break;
case 0x35: // DEC (HL) - 11 cycles
addr = (h << 8) | l;
aux = memory.readbyte(addr);
if(aux == 0x80) f |= FLAG_PV;
else f &= ~FLAG_PV;
aux = ((aux - 1) & 0xFF);
if((aux & 0xF) == 0xF) f |= FLAG_HCARRY;
else f &= ~FLAG_HCARRY;
if(aux == 0) f |= FLAG_ZERO;
else f &= ~FLAG_ZERO;
if((aux & 0x80) != 0) f |= FLAG_SIGN;
else f &= ~FLAG_SIGN;
memory.writebyte(addr, aux);
f |= FLAG_NEG;
counter -= 11;
pc++;
break;
case 0x36: // LD (HL), n - 10 cycles
memory.writebyte(((h << 8) | l), memory.readbyte(pc+1));
counter -= 10;
pc += 2;
break;
case 0x37: // SCF - 4 cycles
f |= FLAG_CARRY;
f &= ~(FLAG_HCARRY | FLAG_NEG);
counter -= 4;
pc++;
break;
case 0x38: // JR C, PC+d - 12/7 cycles
if((f & FLAG_CARRY) != 0) {
pc += memory.readsigned(pc+1);
counter -= 12;
}
else counter -= 7;
pc += 2;
break;
case 0x39: // ADD HL, SP - 11 cycles
aux = ((h << 8) | l) & 0xFFF;
aux += sp & 0xFFF;
if(aux > 0xFFF) f |= FLAG_HCARRY;
else f &= ~FLAG_HCARRY;
aux = (h << 8) | l;
aux += sp;
if(aux > 0xFFFF) f |= FLAG_CARRY;
else f &= ~FLAG_CARRY;
if((aux & 0x8000) != 0) f |= FLAG_SIGN;
else f &= ~FLAG_SIGN;
aux &= 0xFFFF;
if(aux == 0) f |= FLAG_ZERO;
else f &= ~FLAG_ZERO;
h = (aux >> 8) & 0xFF;
l = aux & 0xFF;
f &= ~FLAG_NEG;
counter -= 11;
pc++;
break;
case 0x3A: // LD A, (nn) - 13 cycles
a = memory.readbyte((memory.readbyte(pc+2) << 8) | memory.readbyte(pc+1));
counter -= 13;
pc += 3;
break;
case 0x3B: // DEC SP - 6 cycles
sp = (sp - 1) & 0xFFFF;
counter -= 6;
pc++;
break;
case 0x3C: // INC A - 4 cycles
if((a & 0xF)+1 > 0xF) f |= FLAG_HCARRY;
else f &= ~FLAG_HCARRY;
a = ((a + 1) & 0xFF);