MOS6502 CPU buildout.

src/chip/MOS6502/cpu.js

@@ -1,23 +1,196 @@
 /*
  * Emulate a basic 6502 (MOS) chip.
  */
-
+const BIT = require('../../utils/bitman.js');
 var Memory = require('../../common/memory.js');
 
+
+function ADC(cpu){
+
+}
+
+function AND(cpu){
+
+}
+
+function ASL(cpu){
+
+}
+
+function BIT(cpu){
+
+}
+
+function BRANCH(cpu){
+
+}
+
+function BRK(cpu){
+
+}
+
+function CMP(cpu){
+
+}
+
+function CPX(cpu){
+
+}
+
+function CPY(cpu){
+
+}
+
+function DEC(cpu){
+
+}
+
+function EOR(cpu){
+
+}
+
+function FLAG(cpu){
+
+}
+
+function INC(cpu){
+
+}
+
+function JMP(cpu){
+
+}
+
+function JRS(cpu){
+
+}
+
+function LDA(cpu){
+
+}
+
+function LDX(cpu){
+
+}
+
+function LDY(cpu){
+
+}
+
+function LSR(cpu){
+
+}
+
+function ORA(cpu){
+
+}
+
+function REGISTER(cpu){
+
+}
+
+function ROL(cpu){
+
+}
+
+function ROR(cpu){
+
+}
+
+function RTI(cpu){
+
+}
+
+function RTS(cpu){
+
+}
+
+function SBC(cpu){
+
+}
+
+function STA(cpu){
+
+}
+
+function STACK(cpu){
+
+}
+
+function STX(cpu){
+
+}
+
+function STY(cpu){
+
+}
+
+
+// --------------------------------------------------------------------------------------------
+
+// Test to see if both a and b's high byte is the same... same page.
+function SamePage(a, b){
+  return ((a >> 8) == (b >> 8));
+}
+
+function PCHI(cpu, b){
+  cpu.__PC = (cpu.__PC & 0x00FF) | (b << 8);
+}
+
+function PCLOW(cpu, b){
+  cpu.__PC = (cpu.__PC & 0xFF00) | b;
+}
+
+function PCUp(cpu, amount){
+  if (cpu.__pcc === 1){
+    PCHI(cpu, ((cpu.__PC & 0xFF00) >> 8) + 1);
+    cpu.__pcc = 0;
+  } else if ((cpu.__PC & 0x00FF) + amount > 255){
+    cpu.__pcc = 1;
+    PCLOW(cpu, ((cpu.__PC & 0x00FF) + amount) - 256);
+  } else {
+    PCLOW(cpu, (cpu.__PC & 0x00FF) + amount);
+  }
+}
+
+function PCDown(cpu, amount){
+  if (cpu.__pcc === -1){
+    PCHI(cpu, ((cpu.__PC & 0xFF00) >> 8) - 1);
+    cpu.__pcc = 0;
+  } else if ((cpu.__PC & 0x00FF) - amount < 0){
+    cpu.__pcc = -1;
+    PCLOW(cpu, ((cpu.__PC & 0x00FF) - amount) + 256);
+  } else {
+    PCLOW(cpu, (cpu.__PC & 0x00FF) - amount);
+  }
+}
+
+// --------------------------------------------------------------------------------------------
+// --------------------------------------------------------------------------------------------
+// --------------------------------------------------------------------------------------------
+
+
 class CPU{
   constructor(){
     // Registers
     this.__PC = 0;   // Program Counter (16 bit)
     this.__IRQ = 0;  // IRQ interrupt address code (16 bit)
-    this.__SR = 0;   // Status Register (8 bit)
+    this.__PR = 0;   // Status Register (8 bit)
     this.__XR = 0;   // X Register (8 bit)
     this.__YR = 0;   // Y Register (8 bit)
     this.__AR = 0;   // Accumulator Register (8 bit)
 
-    // Variables to watch for Interrupts.
+    // Variables to watch for Hardware Interrupts.
     this.__nmi = false;
     this.__irq = false;
 
+    // Variable for tracking tick operations.
+    this.__op = -1;
+    this.__opmem = 0;
+    this.__opv = 0;
+    this.__step = 0;
+    this.__pcc = 0; // Program Counter Carry.
+
     // Memory module or controller.
     this.__mem = null; // Must be explicitly attached.
 
@@ -25,6 +198,16 @@ class CPU{
     this.__clkfn = null;
   }
 
+  // ----------------------------------------
+  // CPU Registers. Here for debug purposes.
+  get PC(){return this.__PC;}
+  get P(){return this.__SR;}
+  get X(){return this.__XR;}
+  get Y(){return this.__YR;}
+  get A(){return this.__AR;}
+
+  // ----------------------------------------
+  // Hardware interrupt triggers. Settable only.
   set NMI(n){
     this.__nmi = (n === true);
   }
@@ -40,20 +223,114 @@ class CPU{
     // TODO: Reset status registers that get changed on a reset.
   }
 
+  // -----------------------------------------
+  // Set and Get Memory property.
+  get memory(){return this.__mem;}
+  set memory(m){
+    if (!(mem instanceof Memory))
+      throw new ValueError("Expected Memory instance object.");
+    this.__mem = m;
+  }
+
+
+  // -----------------------------------------
+
   clk(){
     if (this.__clkfn === null){
       this.__clkfn = (function(){
-        // TODO: All the work!!
+        if (this.__pcc !== 0){
+          if (this.__pcc > 0) {
+            PCUp(this, 1);
+          } else {
+            PCDown(this, 1);
+          }
+        } else if (this.__op < 0){
+          if (this.__nmi) {
+            // TODO: Handle NMI Interrupt.
+          } else if (this.__irq) {
+            this.__irq = false;
+            if (!BIT.isOn(this.__PR, 5)){
+              // TODO: Handle IRQ Interrupt.
+            }
+          } else {
+            this.__step = 0;
+            this.__op = this.__mem.byte;
+            PCUp(this, 1);
+          }
+        } else {
+          switch(this.__op){
+            case 0x69: case 0x65: case 0x75: case 0x6D: case 0x7D: case 0x79: case 0x61: case 0x71:
+              ADC(this); break;
+            case 0x29: case 0x25: case 0x35: case 0x2D: case 0x3D: case 0x39: case 0x21: case 0x31:
+              AND(this); break;
+            case 0x0A: case 0x06: case 0x16: case 0x0E: case 0x1E:
+              ASL(this); break;
+            case 0x24: case 0x2C:
+              BIT(this); break;
+            case 0x10: case 0x30: case 0x50: case 0x70: case 0x90: case 0xB0: case 0xD0: case 0xF0:
+              BRANCH(this); break;
+            case 0x00:
+              BRK(this); break;
+            case 0xC9: case 0xC5: case 0xD5: case 0xCD: case 0xDD: case 0xD9: case 0xC1: case 0xD1:
+              CMP(this); break;
+            case 0xE0: case 0xE4: case 0xEC:
+              CPX(this); break;
+            case 0xC0: case 0xC4: case 0xCC:
+              CPY(this); break;
+            case 0xC6: case 0xD6: case 0xCE: case 0xDE:
+              DEC(this); break;
+            case 0x49: case 0x45: case 0x55: case 0x4D: case 0x5D: case 0x59: case 0x41: case 0x51:
+              EOR(this); break;
+            case 0x18: case 0x38: case 0x58: case 0x78: case 0xB8: case 0xD8: case 0xF8:
+              FLAG(this); break;
+            case 0xE6: case 0xF6: case 0xEE: case 0xFE:
+              INC(this); break;
+            case 0x4C: case 0x6C:
+              JMP(this); break;
+            case 0x20:
+              JSR(this); break;
+            case 0xA9: case 0xA5: case 0xB5: case 0xAD: case 0xBD: case 0xB9: case 0xA1: case 0xB1:
+              LDA(this); break;
+            case 0xA2: case 0xA6: case 0xB6: case 0xAE: case 0xBE:
+              LDX(this); break;
+            case 0xA0: case 0xA4: case 0xB4: case 0xAC: case 0xBC:
+              LDY(this); break;
+            case 0x4A: case 0x46: case 0x56: case 0x4E: case 0x5E:
+              LSR(this); break;
+            case 0xEA:
+              // NOP
+              if (this.__step == 1){
+                this.__op = -1;
+              } else {this.__step += 1;}
+              break;
+            case 0x09: case 0x05: case 0x15: case 0x0D: case 0x1D: case 0x19: case 0x01: case 0x11:
+              ORA(this); break;
+            case 0xAA: case 0x8A: case 0xCA: case 0xE8: case 0xA8: case 0x98: case 0x88: case 0xC8:
+              REGISTER(this); break;
+            case 0x2A: case 0x26: case 0x36: case 0x2E: case 0x3E:
+              ROL(this); break;
+            case 0x6A: case 0x66: case 0x76: case 0x6E: case 0x7E:
+              ROR(this); break;
+            case 0x40:
+              RTI(this); break;
+            case 0x60:
+              RTS(this); break;
+            case 0xE9: case 0xE5: case 0xF5: case 0xED: case 0xFD: case 0xF9: case 0xE1: case 0xF1:
+              SBC(this); break;
+            case 0x85: case 0x95: case 0x8D: case 0x9D: case 0x99: case 0x81: case 0x91:
+              STA(this); break;
+            case 0x9A: case 0xBA: case 0x48: case 0x68: case 0x08: case 0x28:
+              STACK(this); break;
+            case 0x86: case 0x96: case 0x8E:
+              STX(this); break;
+            case 0x84: case 0x94: case 0x8C:
+              STY(this); break;
+          }
+        }
       }).bind(this);
     }
     return this.__clkfn;
   }
-
-  memory(mem){
-    if (!(mem instanceof Memory))
-      throw new ValueError("Expected Memory instance object.");
-    this.__mem = mem;
-  }
 }
 
 module.exports = CPU;