devices working

src/emu.c

@@ -1,9 +1,7 @@
 #include "emu.h"
 
 static inline Instruction fetchInst(Emulator* emu) {
-    Instruction inst = decodeInstruction(emu->mem, &emu->pc);
-    printf("%s\n", instructionToCStr(inst));
-    return inst;
+    return decodeInstruction(emu->mem, &emu->pc);
 }
 
 static inline void updateFlagsRegister(Emulator* emu, int32_t value) {
@@ -16,6 +14,17 @@ static inline void updateFlagsRegister(Emulator* emu, int32_t value) {
     }
 }
 
+static inline void updateDevices(Emulator* emu) {
+    for (size_t i = 0; i < MAX_DEVICES; i++) {
+        Device* device = emu->devices[i];
+        if (!device) continue;
+
+        if (device->update) {
+            device->update(device);
+        }
+    }
+}
+
 void startEmulator(Emulator* emu) {
     static void* dispatchTable[] = {
         &&MOV,
@@ -32,15 +41,16 @@ void startEmulator(Emulator* emu) {
         &&JIZ,
         &&CALL,
         &&RET,
-        &&SYS,
+        &&PORT,
         &&HLT
     };
 
     emu->halted = false;
     Instruction inst;
 
-    #define DISPATCH() inst = fetchInst(emu); \
-                       goto *dispatchTable[inst.opcode];
+    #define DISPATCH() updateDevices(emu); \
+                       inst = fetchInst(emu); \
+                       goto *dispatchTable[inst.opcode]
 
     DISPATCH();
 
@@ -133,8 +143,39 @@ void startEmulator(Emulator* emu) {
         emu->pc = ((uint32_t*)emu->mem->data)[++emu->sp];
         DISPATCH();
     }
-    SYS: {
-        // TODO
+    PORT: {
+        uint16_t port = emu->regs[inst.operands[0]];
+        if (port >= MAX_DEVICES) {
+            DISPATCH();
+        }
+
+        uint8_t direction = inst.operands[2];
+
+        Device* device = emu->devices[port];
+        if (!device) {
+            DISPATCH();
+        }
+
+        if (direction == 0) {
+            uint16_t value = emu->regs[inst.operands[1]];
+
+            if (device->inPos == DEVICE_BUFFER_LENGTH) {
+                DISPATCH();
+            }
+
+            device->in[device->inPos] = value;
+            device->inPos++;
+        } else {
+            if (device->outPos == 0) {
+                emu->regs[inst.operands[1]] = 0;
+                DISPATCH();
+            }
+
+            emu->regs[inst.operands[1]] = device->out[device->outPos-1];
+            if (device->outPos > 0)
+                device->outPos--;
+        }
+
         DISPATCH();
     }
     HLT: {
@@ -170,3 +211,8 @@ void freeEmulator(Emulator* emu) {
     freeMemory(emu->mem);
     free(emu);
 }
+
+void installDevice(Emulator* emu, Device* device, uint8_t deviceNumber) {
+    assert(deviceNumber < MAX_DEVICES);
+    emu->devices[deviceNumber] = device;
+}