Fixed many of the undocumented tests

Now it's up to 99% tests passing, 15362 are still failing, but many
of those are the unimplemented IN/OUT instructions, which the Genesis
doesn't seem to use

docs/discussion.txt

@@ -72,3 +72,37 @@ Signals, Etc.
     - what about interrupt controller?
 
 
+2023/05/22:
+
+Refactoring Execution of m68k
+-----------------------------
+
+* would it be possible to construct something that behaves more like the microcode executor using steps in chained form,
+  with side effects and quirks and flags (and exceptions) handled as such
+
+```
+// ADD
+executor.start()
+    .fetch_src(src)
+    .fetch_dest(dest)
+    .add()
+    .write_dest(dest)
+    .set_flags("XCNVS")
+    .finish()?;
+
+
+// BRA
+executor.start()
+    .branch_offset(offset)
+    .finish()?;
+
+// JMP
+executor.start()
+    .fetch_src(target)
+    .branch_absolute()
+    .finish()?;
+
+```
+
+
+

emulator/core/src/error.rs

@@ -73,5 +73,9 @@ impl Error {
             msg: msg.into(),
         }
     }
+
+    pub fn is_processor(&self, native: u32) -> bool {
+        self.err == ErrorType::Processor && self.native == native
+    }
 }
 

emulator/cpus/m68k/src/execute.rs

@@ -61,7 +61,6 @@ impl Transmutable for M68k {
 
 impl M68k {
     pub fn step_internal(&mut self, system: &System) -> Result<ClockCycles, Error> {
-        //self.current_clock = system.clock;
         self.init_cycle(system.clock);
         match self.state.status {
             Status::Init => self.reset_cpu(),
@@ -70,8 +69,6 @@ impl M68k {
                 match self.cycle_one(system) {
                     Ok(diff) => Ok(diff),
                     Err(Error { err: ErrorType::Processor, native, .. }) => {
-                    // TODO match arm conditional is temporary: illegal instructions generate a top level error in order to debug and fix issues with decode
-                    //Err(Error { err: ErrorType::Processor, native, .. }) if native != Exceptions::IllegalInstruction as u32 => {
                         self.exception(native as u8, false)?;
                         Ok(4)
                     },
@@ -86,6 +83,7 @@ impl M68k {
         self.decoder = M68kDecoder::new(self.cputype, self.is_supervisor(), self.state.pc);
         self.timing = M68kInstructionTiming::new(self.cputype, self.port.data_width());
         self.port.init_cycle(clock);
+        self.timing.reset();
     }
 
     pub fn reset_cpu(&mut self) -> Result<ClockCycles, Error> {
@@ -203,8 +201,6 @@ impl M68k {
     }
 
     pub fn decode_next(&mut self) -> Result<(), Error> {
-        self.timing.reset();
-
         let is_supervisor = self.is_supervisor();
         self.decoder.decode_at(&mut self.port, is_supervisor, self.state.pc)?;
 

emulator/cpus/z80/src/decode.rs

@@ -33,7 +33,10 @@ impl Z80Decoder {
 
     pub fn decode_one(&mut self, memory: &mut dyn Addressable) -> Result<Instruction, Error> {
         let ins = self.read_instruction_byte(memory)?;
+        self.decode_bare(memory, ins)
+    }
 
+    pub fn decode_bare(&mut self, memory: &mut dyn Addressable, ins: u8) -> Result<Instruction, Error> {
         match get_ins_x(ins) {
             0 => {
                 match get_ins_z(ins) {
@@ -380,19 +383,28 @@ impl Z80Decoder {
                                 let data = self.read_instruction_byte(memory)?;
                                 Ok(Instruction::LD(to_load_target(half_target), LoadTarget::ImmediateByte(data)))
                             },
-                            _ => Ok(Instruction::NOP),
+                            _ => self.decode_bare(memory, ins),
                         }
                     },
                     3 => {
-                        let offset = self.read_instruction_byte(memory)? as i8;
                         match ins {
-                            0x34 => Ok(Instruction::INC8(Target::IndirectOffset(index_reg, offset))),
-                            0x35 => Ok(Instruction::DEC8(Target::IndirectOffset(index_reg, offset))),
-                            0x36 => Ok(Instruction::LD(LoadTarget::IndirectOffsetByte(index_reg, offset), LoadTarget::ImmediateByte(self.read_instruction_byte(memory)?))),
-                            _ => Ok(Instruction::NOP),
+                            0x34 => {
+                                let offset = self.read_instruction_byte(memory)? as i8;
+                                Ok(Instruction::INC8(Target::IndirectOffset(index_reg, offset)))
+                            },
+                            0x35 => {
+                                let offset = self.read_instruction_byte(memory)? as i8;
+                                Ok(Instruction::DEC8(Target::IndirectOffset(index_reg, offset)))
+                            },
+                            0x36 => {
+                                let offset = self.read_instruction_byte(memory)? as i8;
+                                let immediate = self.read_instruction_byte(memory)?;
+                                Ok(Instruction::LD(LoadTarget::IndirectOffsetByte(index_reg, offset), LoadTarget::ImmediateByte(immediate)))
+                            },
+                            _ => self.decode_bare(memory, ins),
                         }
                     },
-                    _ => Ok(Instruction::NOP),
+                    _ => self.decode_bare(memory, ins),
                 }
             },
             1 => {
@@ -400,7 +412,7 @@ impl Z80Decoder {
                     0 | 1 => {
                         let target = match self.decode_index_target(memory, index_reg, get_ins_z(ins))? {
                             Some(target) => target,
-                            None => return Ok(Instruction::NOP),
+                            None => return self.decode_bare(memory, ins),
                         };
 
                         match (ins & 0x18) >> 3 {
@@ -438,7 +450,7 @@ impl Z80Decoder {
                     3 => {
                         if get_ins_q(ins) == 0 {
                             if get_ins_z(ins) == 6 {
-                                return Ok(Instruction::NOP);
+                                return self.decode_bare(memory, ins);
                             }
                             let src = get_register(get_ins_z(ins));
                             let offset = self.read_instruction_byte(memory)? as i8;
@@ -446,7 +458,7 @@ impl Z80Decoder {
                         } else {
                             let target = match self.decode_index_target(memory, index_reg, get_ins_z(ins))? {
                                 Some(target) => target,
-                                None => return Ok(Instruction::NOP),
+                                None => return self.decode_bare(memory, ins),
                             };
 
                             Ok(Instruction::LD(LoadTarget::DirectRegByte(Register::A), to_load_target(target)))
@@ -458,7 +470,7 @@ impl Z80Decoder {
             2 => {
                 let target = match self.decode_index_target(memory, index_reg, get_ins_z(ins))? {
                     Some(target) => target,
-                    None => return Ok(Instruction::NOP),
+                    None => return self.decode_bare(memory, ins),
                 };
 
 
@@ -481,7 +493,7 @@ impl Z80Decoder {
                     0xE5 => Ok(Instruction::PUSH(index_reg.into())),
                     0xE9 => Ok(Instruction::JPIndirect(index_reg.into())),
                     0xF9 => Ok(Instruction::LD(LoadTarget::DirectRegWord(RegisterPair::SP), LoadTarget::DirectRegWord(index_reg.into()))),
-                    _ => Ok(Instruction::NOP),
+                    _ => self.decode_bare(memory, ins),
                 }
             },
             _ => panic!("InternalError: impossible value"),

emulator/cpus/z80/src/execute.rs

@@ -479,7 +479,6 @@ impl Z80 {
 
     fn execute_inc8(&mut self, target: Target) -> Result<(), Error> {
         let value = self.get_target_value(target)?;
-
         let (result, _, overflow, half_carry) = add_bytes(value, 1);
         let carry = self.get_flag(Flags::Carry);        // Preserve the carry bit, according to Z80 reference
         self.set_arithmetic_op_flags(result as u16, Size::Byte, false, carry, overflow, half_carry);
@@ -717,7 +716,7 @@ impl Z80 {
         self.set_logic_op_flags(result, out_bit, false);
         self.set_target_value(target, result)?;
         if let Some(target) = opt_copy {
-            self.set_target_value(target, value)?;
+            self.set_target_value(target, result)?;
         }
         Ok(())
     }
@@ -738,7 +737,7 @@ impl Z80 {
         self.set_logic_op_flags(result, out_bit, false);
         self.set_target_value(target, result)?;
         if let Some(target) = opt_copy {
-            self.set_target_value(target, value)?;
+            self.set_target_value(target, result)?;
         }
         Ok(())
     }
@@ -777,7 +776,7 @@ impl Z80 {
         self.set_logic_op_flags(result, out_bit, false);
         self.set_target_value(target, result)?;
         if let Some(target) = opt_copy {
-            self.set_target_value(target, value)?;
+            self.set_target_value(target, result)?;
         }
         Ok(())
     }
@@ -798,7 +797,7 @@ impl Z80 {
         self.set_logic_op_flags(result, out_bit, false);
         self.set_target_value(target, result)?;
         if let Some(target) = opt_copy {
-            self.set_target_value(target, value)?;
+            self.set_target_value(target, result)?;
         }
         Ok(())
     }
@@ -885,7 +884,7 @@ impl Z80 {
         self.set_logic_op_flags(result, out_bit, false);
         self.set_target_value(target, result)?;
         if let Some(target) = opt_copy {
-            self.set_target_value(target, value)?;
+            self.set_target_value(target, result)?;
         }
         Ok(())
     }
@@ -897,7 +896,7 @@ impl Z80 {
         self.set_logic_op_flags(result, out_bit, false);
         self.set_target_value(target, result)?;
         if let Some(target) = opt_copy {
-            self.set_target_value(target, value)?;
+            self.set_target_value(target, result)?;
         }
         Ok(())
     }
@@ -910,7 +909,7 @@ impl Z80 {
         self.set_logic_op_flags(result, out_bit, false);
         self.set_target_value(target, result)?;
         if let Some(target) = opt_copy {
-            self.set_target_value(target, value)?;
+            self.set_target_value(target, result)?;
         }
         Ok(())
     }
@@ -922,7 +921,7 @@ impl Z80 {
         self.set_logic_op_flags(result, out_bit, false);
         self.set_target_value(target, result)?;
         if let Some(target) = opt_copy {
-            self.set_target_value(target, value)?;
+            self.set_target_value(target, result)?;
         }
         Ok(())
     }
@@ -1159,10 +1158,10 @@ impl Z80 {
 
     fn set_index_register_half_value(&mut self, reg: IndexRegisterHalf, value: u8) {
         match reg {
-            IndexRegisterHalf::IXH => { self.state.ix |= (value as u16) << 8; },
-            IndexRegisterHalf::IXL => { self.state.ix |= value as u16; },
-            IndexRegisterHalf::IYH => { self.state.iy |= (value as u16) << 8; },
-            IndexRegisterHalf::IYL => { self.state.iy |= value as u16; },
+            IndexRegisterHalf::IXH => { self.state.ix = (self.state.ix & 0x00FF) | (value as u16) << 8; },
+            IndexRegisterHalf::IXL => { self.state.ix = (self.state.ix & 0xFF00) | value as u16; },
+            IndexRegisterHalf::IYH => { self.state.iy = (self.state.iy & 0x00FF) | (value as u16) << 8; },
+            IndexRegisterHalf::IYL => { self.state.iy = (self.state.iy & 0xFF00) | value as u16; },
         }
     }
 

emulator/cpus/z80/src/timing.rs

@@ -38,11 +38,11 @@ impl Z80InstructionCycles {
             Instruction::XOR(target) => {
                 match target {
                     // TODO the undocumented DD version of this instruction is actually 8 cycles
-                    Target::DirectReg(_) => 4,
+                    Target::DirectReg(_) |
+                    Target::DirectRegHalf(_) => 4,
                     Target::IndirectReg(_) => 7,
                     Target::Immediate(_) => 7,
                     Target::IndirectOffset(_, _) => 19,
-                    _ => return Err(Error::new(format!("unexpected instruction: {:?}", instruction))),
                 }
             },
 
@@ -107,7 +107,8 @@ impl Z80InstructionCycles {
             Instruction::INC8(target) => {
                 // TODO the undocumented DD version of this instruction is actually 8 cycles
                 match target {
-                    Target::DirectReg(_) => 4,
+                    Target::DirectReg(_) |
+                    Target::DirectRegHalf(_) => 4,
                     Target::IndirectReg(_) => 11,
                     Target::IndirectOffset(_, _) => 23,
                     _ => return Err(Error::new(format!("unexpected instruction: {:?}", instruction))),
@@ -182,7 +183,11 @@ impl Z80InstructionCycles {
 
                     (LoadTarget::DirectRegByte(_), LoadTarget::DirectRegByte(_)) => 4,
 
-                    (LoadTarget::DirectRegByte(_), LoadTarget::ImmediateByte(_)) => 7,
+                    (LoadTarget::DirectRegHalfByte(_), LoadTarget::DirectRegByte(_)) |
+                    (LoadTarget::DirectRegByte(_), LoadTarget::DirectRegHalfByte(_)) |
+                    (LoadTarget::DirectRegHalfByte(_), LoadTarget::DirectRegHalfByte(_)) => 8,
+
+                    (LoadTarget::DirectRegByte(_) | LoadTarget::DirectRegHalfByte(_), LoadTarget::ImmediateByte(_)) => 7,
                     (LoadTarget::IndirectRegByte(_), LoadTarget::ImmediateByte(_)) => 10,
 
                     (LoadTarget::IndirectOffsetByte(_, _), _) |