From da0ababc5998264729614ccfd67fad979ec6b730 Mon Sep 17 00:00:00 2001
From: n loewen <nick@nloewen.com>
Date: Tue, 1 Aug 2023 13:30:48 +0100
Subject: [PATCH] Initialize instruction pointer based on a constant, to move
 it after screen memory

---
 sketches/assembler.js           | 5 +++--
 sketches/simulator-sketch-v3.js | 7 +++++--
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/sketches/assembler.js b/sketches/assembler.js
index c00932a..af14567 100644
--- a/sketches/assembler.js
+++ b/sketches/assembler.js
@@ -15,6 +15,7 @@ const printMemory = require('./print-memory.js');
 // 2 = what i'm currently focusing on
 // 3 = always print
 const DEBUG = 2;
+const INITIAL_IP_ADDRESS = 32;
 
 const mnemonicsWithOptionalArgs = ['end', 'cfc', 'chp'];
 const mnemonics2opcodes = {
@@ -31,9 +32,9 @@ const mnemonics2opcodes = {
 
 function decodeInstructions(str) {
   let lines = str.split(/\n/); // returns an array of lines
-  let machineCode = [];
+  let machineCode = new Array(INITIAL_IP_ADDRESS).fill(0);
   let labels = {};
-  let byteCursor = 0;
+  let byteCursor = INITIAL_IP_ADDRESS;
   for (let i = 0; i < lines.length; i++) {
     console.log();
     console.group(`Input line ${i}, cursor ${byteCursor}`);
diff --git a/sketches/simulator-sketch-v3.js b/sketches/simulator-sketch-v3.js
index bda3fe2..df7edcd 100644
--- a/sketches/simulator-sketch-v3.js
+++ b/sketches/simulator-sketch-v3.js
@@ -3,13 +3,15 @@
 // - instructions are two bytes long:
 //   one byte for the opcode, one for the argument
 
+const INITIAL_IP_ADDRESS = 32;
 const CYCLE_LIMIT = 64; // max number of times to step the CPU, to stop endless loops
 
-// STATE
+const display = require('./display.js');
 
+// STATE
 const CPU = {
   running: false,
-  IP: 0,
+  IP: INITIAL_IP_ADDRESS,
   CF: 0,
   Acc: 0,
   memory: null,
@@ -188,6 +190,7 @@ exports.runProgram = (code) => {
     if (!CPU.running) break;
     if (CPU.IP >= CPU.memory.length) break;
     stepCPU();
+    display.printDisplay(CPU.memory);
   };
 }