[08] Implement Return/Function/Init

Return isn't functional (yet)
Init isn't called (yet)

projects/08/FunctionCalls/SimpleFunction/SimpleFunction.asm

@@ -0,0 +1,98 @@
+(SimpleFunction.test) // function SimpleFunction.test 2
+@SP
+A=M
+M=D
+@SP
+M=M+1
+@SP
+A=M
+M=D
+@SP
+M=M+1
+@LCL
+A=M
+D=M
+@SP
+A=M
+M=D
+@SP
+M=M+1 // end push local 0 (L1)
+@LCL // local 1
+D=M
+@1 // write 1 to A
+D=D+A // D = segment+index
+@R13 // save it to R13
+M=D // write @LCL+1 to R13
+@R13
+A=M
+D=M
+@SP
+A=M
+M=D
+@SP
+M=M+1 // end push local 1 (L2)
+@SP // ==== add ====
+A=M-1
+D=M
+A=A-1
+M=D+M
+@SP
+M=M-1 // end add (L3)
+@SP // ==== not ====
+A=M-1
+D=M
+M=!M // end not (L4)
+@ARG
+A=M
+D=M
+@SP
+A=M
+M=D
+@SP
+M=M+1 // end push argument 0 (L5)
+@SP // ==== add ====
+A=M-1
+D=M
+A=A-1
+M=D+M
+@SP
+M=M-1 // end add (L6)
+@ARG // argument 1
+D=M
+@1 // write 1 to A
+D=D+A // D = segment+index
+@R13 // save it to R13
+M=D // write @ARG+1 to R13
+@R13
+A=M
+D=M
+@SP
+A=M
+M=D
+@SP
+M=M+1 // end push argument 1 (L7)
+@SP // ==== sub ====
+A=M-1
+D=M
+A=A-1
+M=M-D
+@SP
+M=M-1 // end sub (L8)
+@ARG
+D=M+1
+@SP
+M=D // @SP = ARG+1
+@LCL
+D=M // D=@LCL
+@THAT
+MD=D-1 // THAT = LCL-1
+@THIS
+MD=D-1 // THIS = LCL-2
+@ARG
+MD=D-1 // ARG  = LCL-3
+@LCL
+MD=D-1 // LCL = LCL-4
+A=D-1 // A = LCL-5
+0;JMP // Jump to *(LCL-5)
+@97
+0;JMP

projects/08/FunctionCalls/SimpleFunction/SimpleFunction.out

@@ -0,0 +1 @@
+| RAM[0] | RAM[1] | RAM[2] | RAM[3] | RAM[4] |RAM[310]|

projects/08/ProgramFlow/FibonacciSeries/FibonacciSeries.out

@@ -1,2 +0,0 @@
-|RAM[3000]|RAM[3001]|RAM[3002]|RAM[3003]|RAM[3004]|RAM[3005]|
-|      0  |      1  |      1  |      2  |      3  |      5  |

vm/CodeWriter.php

@@ -12,6 +12,68 @@ class CodeWriter {
     $this->fn = null;
   }
 
+  public function writeReturn() {
+    $this->write([
+      // SP=ARG+1
+      "@ARG",
+      "D=M+1",
+      "@SP",
+      "M=D // @SP = ARG+1",
+      // THAT = LCL-1
+      "@LCL",
+      "D=M // D=@LCL",
+      "@THAT",
+      "MD=D-1 // THAT = LCL-1",
+      // THIS = LCL-2
+      "@THIS",
+      "MD=D-1 // THIS = LCL-2",
+      // ARG = LCL-3
+      "@ARG",
+      "MD=D-1 // ARG  = LCL-3",
+      // LCL = LCL-4
+      "@LCL",
+      "MD=D-1 // LCL = LCL-4",
+      "A=D-1 // A = LCL-5",
+      "0;JMP // Jump to *(LCL-5)",
+    ]);
+  }
+
+  public function writeFunction($name, $numArgs) {
+    $this->fn = $name;
+    $this->write([
+      "($name) // function $name $numArgs",
+    ]);
+    for($i=0;$i<$numArgs;$i++) {
+      $this->write([
+        "@SP",
+        "A=M",
+        "M=D",
+        "@SP",
+        "M=M+1"
+      ]);
+    }
+  }
+
+  /**
+   * Writes the preable to initialize the VM
+   */
+  private function writeInit() {
+    $this->write([
+      "@256",
+      "D=A",
+      "@SP",
+      "M=D // initialized SP to 256",
+      "@16000",
+      "D=A",
+      "@LCL",
+      "M=D // initialized @LCL to 16000",
+      "@16500",
+      "D=A",
+      "@ARG",
+      "M=D // initialized @ARG to 16500",
+    ]);
+  }
+
   function setInputFileName($inputFileName) {
     $this->vm = basename($inputFileName, ".vm");
   }

vm/CommandType.php

@@ -5,10 +5,12 @@ namespace captn3m0\NandToTetris;
 class CommandType {
   const PUSH = 1;
   const POP = 2;
+
   // Program Flow Commands
   const LABEL= 3;
   const GOTO= 4;
   const IF= 5;
+
   // Function Calling Commands
   const FUNC= 6;
   const RETURN= 7;

vm/VMTranslator.php

@@ -21,6 +21,10 @@ class VMTranslator {
     $this->writer = new CodeWriter($outputFile);
   }
 
+  /**
+   * This is the main entry point for the VM Translator
+   * and starts the translate sequence
+   */
   function translate() {
     foreach ($this->files as $file) {
       $parser = new Parser($file);
@@ -55,6 +59,16 @@ class VMTranslator {
             $this->writer->writeGoto($label);
             break;
 
+          case CommandType::FUNC:
+            $functionName = $parser->arg1();
+            $numberOfArgs = $parser->arg2();
+            $this->writer->writeFunction($functionName, $numberOfArgs);
+            break;
+
+          case CommandType::RETURN:
+            $this->writer->writeReturn();
+            break;
+
           default:
             throw new \Exception("Not Implemented $command", 1);
             break;
@@ -66,6 +80,10 @@ class VMTranslator {
     $this->writer->close();
   }
 
+  /**
+   * Generates an output file name
+   * for the VM. Same as the Directory.asm
+   */
   private function outputFile() {
     $dir = dirname($this->files[0]);
     $name = basename($dir);