From 6545df9cfdc5241ec4fb5e846cf89ca5c248433d Mon Sep 17 00:00:00 2001
From: n loewen <nick@nloewen.com>
Date: Mon, 28 Aug 2023 09:10:21 -0400
Subject: [PATCH] cpu - WIP - Start re-configuring CLI interface, in order to
 allow passing clock speed as a CLI argument (while also keeping a defualt
 value in machine.config.js)

---
 cpu.js         |  6 +++---
 issues/todo.md |  4 ++++
 run-cpu.js     | 40 ++++++++++++++++++++++++++++------------
 3 files changed, 35 insertions(+), 15 deletions(-)

diff --git a/cpu.js b/cpu.js
index dbfa40c..fa1d567 100644
--- a/cpu.js
+++ b/cpu.js
@@ -3,7 +3,7 @@ const readlineSync = require('readline-sync');
 
 const {
   INITIAL_IP_ADDRESS,
-  CYCLE_LIMIT,
+  DEFAULT_CYCLE_LIMIT,
   KEYPAD_ADDR,
   KEY_MAP,
 } = require('./machine.config');
@@ -340,8 +340,8 @@ async function stepCPU(debugInfo, debug = false, prettyPrintDisplay = false) {
     CPU.cycleCounter += 1;
   }
   logCPUState(debugInfo, debug, prettyPrintDisplay);
-  if (CYCLE_LIMIT) { // Temporary limit as a lazy way to halt infinite loops
-    if (CPU.cycleCounter >= CYCLE_LIMIT) {
+  if (DEFAULT_CYCLE_LIMIT) { // Temporary limit as a lazy way to halt infinite loops
+    if (CPU.cycleCounter >= DEFAULT_CYCLE_LIMIT) {
       console.warn('  HALTING - reached cycle limit');
       CPU.running = false;
     }
diff --git a/issues/todo.md b/issues/todo.md
index 77380a2..e29a352 100644
--- a/issues/todo.md
+++ b/issues/todo.md
@@ -8,6 +8,9 @@ For extended commentary, see [issues](issues.md).
 
 ### Todo
 
+- Finish WIP on run-cli arg parsing
+- Pass CYCLE_COUNT as a cli arg
+
 - (cpu) !! Fix overflow flag
 - Add a flag for bank-switching to the ~zero-page
 - Remove run-scripts and add the ability to run `./cpu.js` and `./assembler.js` directly -- cf. [#1](issues.md#1---improve-cli-interface)
@@ -15,6 +18,7 @@ For extended commentary, see [issues](issues.md).
 
 ### Features
 
+- (cpu) allow arrow keys, too
 - [fix] (cpu) Execute `JMP $FF` on startup / Implement ROM — see [#2](issues.md#2---startup-execute-jmp-ff)
 - (assembler) Validate labels
 - (assembler) Extract debugging to its own module
diff --git a/run-cpu.js b/run-cpu.js
index a9cd7d1..face7d4 100755
--- a/run-cpu.js
+++ b/run-cpu.js
@@ -7,19 +7,13 @@ const computer = require('./cpu.js');
 const assembler = require('./assembler.js');
 const { logRunningHeader } = require('./logging.js');
 
-
 // Load file...
 
-let filename = null;
-process.argv.forEach((arg, index) => {
-  if (arg === '-f' && process.argv.length > (index -1)) {
-    filename = process.argv[index + 1];
-  }
-});
-
-if (!filename) {
-  console.error('Filename required');
-  console.error('eg: run-cpu.js -f code.asm');
+let filename;
+try {
+  filename = getArgumentValue('-f', `Missing filename`);
+} catch (error) {
+  console.error(error.message);
   process.exit()
 }
 
@@ -52,4 +46,26 @@ computer.runProgram(
   singleStep,
   prettyPrint,
   speed
-);
\ No newline at end of file
+);
+
+
+// CLI args TODO
+// - check if value is the name of another arg
+// - usage info
+// - catch nonexistant flags
+
+/**
+ * @param {string}   flag    - The command line flag, eg. '-f'
+ * @param {string}    errorMessage  - The error to throw if a value isn't found
+ * @returns {string}
+ **/
+function getArgumentValue(flag, errorMessage) {
+  let value = null;
+  process.argv.forEach((arg, index) => {
+    if (arg === flag && process.argv.length > (index -1)) {
+      value = process.argv[index + 1];
+    }
+  });
+  if (!value) throw new Error(errorMessage);
+  return value;
+}