Changed ADD to clear and populate carry.

Run/Step only when not halted.
Reversed speed control.

arduino/Interface.cpp

@@ -55,17 +55,19 @@ void Interface::loop() {
     uint8_t addrInputL = ~reverse8(input->getInput(1));
     uint8_t swInput = input->getInput(2);
     uint16_t addrInput = (addrInputH << 8) + addrInputL;
+
     //Check for buttons on rising edge
     if ((swLast & SW_RUN) == 0 && (swInput & SW_RUN) == SW_RUN) {
       if (vm->run) {
         vm->run = false;
       } else {
-        vm->run = true;
-        vm->halted = false;
+        if (vm->halted == false) {
+          vm->run = true;
+        }
       }
     }
     else if ((swLast & SW_STEP) == 0 && (swInput & SW_STEP) == SW_STEP) {
-      if (vm->run == false) {
+      if (vm->run == false && vm->halted == false) {
         vm->halted = false;
         vm_step(vm);
       }
@@ -148,10 +150,6 @@ void Interface::loop() {
   //Program counter and Instruction
   uint16_t pc = vm->PC;
   uint16_t instr = (mem->read(pc) << 8) + mem->read(pc + 1);
-//  disp->output((uint8_t)0xF);
-//  disp->output((uint8_t)0xF);
-//  disp->output((uint8_t)0xF);
-//  disp->output((uint8_t)0xF);
   disp->output16(instr);
   disp->output16(pc);
 

arduino/ShiftInput.cpp

@@ -20,10 +20,12 @@ limitations under the License.
 ShiftInput::ShiftInput(uint8_t chipCount, uint8_t loadPin, uint8_t clockPin, uint8_t clockInhPin, uint8_t dataPin) {
   this->input = (uint8_t*)calloc(chipCount, sizeof(uint8_t));
   this->chipCount = chipCount;
+  
   this->loadPin = loadPin;
   this->clockPin = clockPin;
   this->clockInhPin = clockInhPin;
   this->dataPin = dataPin;
+  
   pinMode(loadPin, OUTPUT);
   digitalWrite(loadPin, HIGH);
   pinMode(clockPin, OUTPUT);
@@ -47,23 +49,39 @@ uint8_t ShiftInput::getChipCount() {
 }
 
 bool ShiftInput::updateInput() {
+  uint8_t dataBit = digitalPinToBitMask(this->dataPin);
+  volatile uint8_t *dataPort = portInputRegister(digitalPinToPort(this->dataPin));
+  uint8_t loadBit = digitalPinToBitMask(this->loadPin);
+  volatile uint8_t *loadPort = portOutputRegister(digitalPinToPort(this->loadPin));
+  uint8_t clkBit = digitalPinToBitMask(this->clockPin);
+  volatile uint8_t *clkPort = portOutputRegister(digitalPinToPort(this->clockPin));
+  uint8_t clkInhBit = 0;
+  volatile uint8_t *clkInhPort = NULL;
+  if (this->clockInhPin > 0){
+    clkInhBit = digitalPinToBitMask(this->clockInhPin);
+    clkInhPort = portOutputRegister(digitalPinToPort(this->clockInhPin));
+  }
+  uint8_t oldSREG = SREG;
+  cli();
+  
   //Load values
-  digitalWrite(this->loadPin, LOW);
-  digitalWrite(this->clockPin, HIGH);
-  digitalWrite(this->loadPin, HIGH);
-  digitalWrite(this->clockPin, LOW);
+  *loadPort &= ~loadBit; //Load Low
+  *clkPort |= clkBit; //Clock High
+  *loadPort |= loadBit; //Load High
+  *clkPort &= ~clkBit; //Clock Low
   
   bool change = false;
   uint8_t input = 0;
   if (this->clockInhPin > 0){
-    digitalWrite(this->clockInhPin, LOW);
+    *clkInhPort &= ~clkInhBit;//Clock Inh Low
   }
+  
   for(uint8_t chip = 0; chip < this->chipCount; chip++) {
     input = 0;
     for(uint8_t inputBit = 0; inputBit < 8; inputBit++) {
-      input |= (digitalRead(this->dataPin) == HIGH ? 1 : 0) << inputBit;
-      digitalWrite(clockPin, HIGH);
-      digitalWrite(clockPin, LOW);
+      *clkPort &= ~clkBit; //Clock Low
+      input |= ((*dataPort & dataBit) ? 1 : 0) << inputBit;
+      *clkPort |= clkBit; //Clock High
     }
     if (this->input[chip] != input) {
       this->input[chip] = input;
@@ -71,8 +89,9 @@ bool ShiftInput::updateInput() {
     }
   }
   if (this->clockInhPin > 0){
-    digitalWrite(this->clockInhPin, HIGH);
+    *clkInhPort |= clkInhBit; //Clock Inh High
   }
   
+  SREG = oldSREG;
   return change;
 }

arduino/VM.c

@@ -71,6 +71,9 @@ inline uint16_t vm_get_rx(VM *vm, uint8_t r) {
 }
 
 inline void vm_put_r(VM *vm, uint8_t r, uint8_t v) {
+    if (r == 0) {
+      return;
+    }
     if (r < VM_REG_SIZE) {
         vm->R[r] = v;
     }
@@ -164,12 +167,7 @@ void vm_step(VM *vm) {
             rd = inst.imm;
             break;
         case OP_ADD:
-            vm_decode_S(&inst, raw);
             vm->carry = 0;
-            rx = vm_get_r(vm, inst.rx);
-            ry = vm_get_r(vm, inst.ry);
-            rd = rx + ry;
-            break;
         case OP_ADC:
             vm_decode_S(&inst, raw);
             rx = vm_get_r(vm, inst.rx);

arduino/VM.h

@@ -42,7 +42,7 @@ limitations under the License.
 
 #define VM_ERR_MISALIGN 0x1
 #define VM_ERR_UNKNOWN_OP 0x2
-#define VM_ERR_OUT_OF_BOUNDS 0x3
+#define VM_ERR_OUT_OF_BOUNDS 0x4
 
 #ifdef __cplusplus
 extern "C" {

arduino/arduino.ino

@@ -16,7 +16,8 @@ limitations under the License.
 
 /**
  * Example Programs
- * Hello World: 311833021210c0323401411412103416e4203406d400000048656c6c6f20576f726c640a
+ * Hello World: 3118 3302 1210 c032 3401 4114 1210 3416 e420 3406 d400 0000 48656c6c6f20576f726c640a
+ * 32-bit Counter: 3601 3704 4556 5440 5330 5220 5110 D700
  */
 
 //Options
@@ -111,12 +112,13 @@ void setup() {
 }
 
 unsigned long int nextRun = 0;
+uint8_t err = 0;
 
 void loop() {
   if (vm.run) {
     if (nextRun == 0 || nextRun < millis()) {
       vm_step(&vm);
-      int delayTime = analogRead(PIN_SPEED);
+      int delayTime = 1024 - analogRead(PIN_SPEED);
       if (delayTime < 10) {
         nextRun = 0;
       } else {
@@ -132,10 +134,12 @@ void loop() {
 }
 
 void vm_print_error(uint8_t err) {
-  Serial.print("\n");
+  vm.R[0] = err;
+  Serial.print("\nPC 0x");
+  Serial.print(vm.PC, HEX);
   switch(err) {
     case VM_ERR_MISALIGN:
-      Serial.println("Halted. PC misaligned.");
+      Serial.println("\nHalted. PC misaligned.");
       break;
     case VM_ERR_UNKNOWN_OP:
       //Will only happen if an instruction is not handled in the vm