Added the 8 conditional branch instructions

execute.go

@@ -157,6 +157,16 @@ func buildOpUpdateFlag(flag uint8, value bool) opFunc {
 	}
 }
 
+func buildOpBranch(flag uint8, value bool) opFunc {
+	return func(s *state, line []uint8, opcode opcode) {
+		if s.registers.getFlag(flag) == value {
+			pc := s.registers.getPC()
+			pc += uint16(int8(line[1]))
+			s.registers.setPC(pc)
+		}
+	}
+}
+
 /*
 TODO:
 
@@ -177,14 +187,6 @@ CPY
 
 BRK
 
-BCC
-BCS
-BEQ
-BMI
-BPL
-BVC
-BVS
-
 JMP
 JSR
 RTI
@@ -266,6 +268,15 @@ var opcodes = [256]opcode{
 	0xAC: opcode{"LDY", 3, 4, buildOpLoad(modeAbsolute, regY)},
 	0xBC: opcode{"LDY", 3, 4, buildOpLoad(modeAbsoluteX, regY)}, // Extra cycles
 
+	0x90: opcode{"BCC", 2, 2, buildOpBranch(flagC, false)}, // Extra cycles
+	0xB0: opcode{"BCS", 2, 2, buildOpBranch(flagC, true)},  // Extra cycles
+	0xD0: opcode{"BNE", 2, 2, buildOpBranch(flagZ, false)}, // Extra cycles
+	0xF0: opcode{"BEQ", 2, 2, buildOpBranch(flagZ, true)},  // Extra cycles
+	0x10: opcode{"BPL", 2, 2, buildOpBranch(flagN, false)}, // Extra cycles
+	0x30: opcode{"BMI", 2, 2, buildOpBranch(flagN, true)},  // Extra cycles
+	0x50: opcode{"BVC", 2, 2, buildOpBranch(flagV, false)}, // Extra cycles
+	0x70: opcode{"BVS", 2, 2, buildOpBranch(flagV, true)},  // Extra cycles
+
 	0xEA: opcode{"NOP", 1, 2, opNOP},
 }
 

execute_test.go

@@ -185,3 +185,25 @@ func TestClearSetFlag(t *testing.T) {
 	}
 
 }
+
+func TestBranch(t *testing.T) {
+	var s state
+	s.registers.setPC(0xC600)
+	s.registers.setFlag(flagV)
+	executeLine(&s, []uint8{0x50, 0x20})
+	if s.registers.getPC() != 0xC600 {
+		t.Errorf("Error in BVC, %v", s.registers)
+	}
+
+	executeLine(&s, []uint8{0x70, 0x20})
+	if s.registers.getPC() != 0xC620 {
+		t.Errorf("Error in BVS, %v", s.registers)
+	}
+
+	s.registers.setPC(0xD600)
+	s.registers.clearFlag(flagC)
+	executeLine(&s, []uint8{0x90, 0xA0})
+	if s.registers.getPC() != 0xD5A0 {
+		t.Errorf("Error in BCC, %v", s.registers)
+	}
+}