From 6883adcd71e0e1eceddaf7b6a0e94d965351d897 Mon Sep 17 00:00:00 2001
From: n loewen <nick@nloewen.com>
Date: Wed, 2 Aug 2023 15:28:18 +0100
Subject: [PATCH] Fix/implement relocatable display memory

---
 assembler.js                           | 4 ++--
 display.js                             | 5 +++--
 machine.config.js                      | 2 +-
 test-programs/relocate-display-mem.asm | 8 ++++++++
 4 files changed, 14 insertions(+), 5 deletions(-)
 create mode 100644 test-programs/relocate-display-mem.asm

diff --git a/assembler.js b/assembler.js
index a2ebae4..37d31f9 100644
--- a/assembler.js
+++ b/assembler.js
@@ -1,5 +1,5 @@
 const { logMemory, num2hex } = require('./logging.js');
-const { INITIAL_IP_ADDRESS, START_OF_DISPLAY_MEM } = require('./machine.config.js');
+const { INITIAL_IP_ADDRESS, POINTER_TO_START_OF_DISPLAY_MEM } = require('./machine.config.js');
 
 // 1 = verbose
 // 2 = what i'm currently focusing on
@@ -30,7 +30,7 @@ function decodeInstructions(str) {
   let lines = str.split(/\n/); // returns an array of lines
 
   let machineCode = new Array(INITIAL_IP_ADDRESS).fill(0);
-  machineCode[0] = START_OF_DISPLAY_MEM;
+  machineCode[0] = POINTER_TO_START_OF_DISPLAY_MEM;
 
   let labels = {};
   let IP = INITIAL_IP_ADDRESS;
diff --git a/display.js b/display.js
index 09da52e..c5e5a16 100644
--- a/display.js
+++ b/display.js
@@ -1,8 +1,9 @@
-const { START_OF_DISPLAY_MEM } = require('./machine.config');
+const { POINTER_TO_START_OF_DISPLAY_MEM } = require('./machine.config');
 const { num2hex } = require('./logging.js');
 
 exports.printDisplay = (mem) => {
-  const disp = START_OF_DISPLAY_MEM;
+  const disp = mem[POINTER_TO_START_OF_DISPLAY_MEM];
+  console.log('disp', disp);
   for (let i = disp; i < disp + 16; i += 4) {
     console.log(`${num2hex(mem[i])} ${num2hex(mem[i+1])} ${num2hex(mem[i+2])} ${num2hex(mem[i+3])}`);
   }
diff --git a/machine.config.js b/machine.config.js
index c95aba7..d8dac63 100644
--- a/machine.config.js
+++ b/machine.config.js
@@ -1,6 +1,6 @@
 module.exports = {
   "INITIAL_IP_ADDRESS":  48,
-  "START_OF_DISPLAY_MEM": 0,
+  "POINTER_TO_START_OF_DISPLAY_MEM": 0,
 
   // max number of times to step the CPU,
   // to stop endless loops
diff --git a/test-programs/relocate-display-mem.asm b/test-programs/relocate-display-mem.asm
new file mode 100644
index 0000000..f9e5cc4
--- /dev/null
+++ b/test-programs/relocate-display-mem.asm
@@ -0,0 +1,8 @@
+;; test re-locating display memory
+LDA $10
+STO $00 ; change pointer-to-display-memory to $10
+STO $10
+STO $11
+STO $12
+STO $13
+END
\ No newline at end of file