From 3a0a3c4047ba6282fd2258728e72d8db472bdca3 Mon Sep 17 00:00:00 2001
From: JanNeuendorf <jan@xps-2.1>
Date: Sat, 21 Dec 2024 00:54:47 +0100
Subject: [PATCH] Implemented the new buffer in the emulator

---
 Cargo.lock    |  2 +-
 Cargo.toml    |  2 +-
 src/engine.rs | 39 ++++++++++++++++++++++++++++++---------
 3 files changed, 32 insertions(+), 11 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index ae95496..f968e2e 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1813,7 +1813,7 @@ checksum = "7da8b5736845d9f2fcb837ea5d9e2628564b3b043a70948a3f0b778838c5fb4f"
 
 [[package]]
 name = "svc16"
-version = "0.5.0"
+version = "0.6.0"
 dependencies = [
  "anyhow",
  "clap",
diff --git a/Cargo.toml b/Cargo.toml
index 9bceb05..702c6fd 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "svc16"
-version = "0.5.0"
+version = "0.6.0"
 edition = "2021"
 authors = ["Jan Neuendorf"]
 description = "An emulator for a simple virtual computer"
diff --git a/src/engine.rs b/src/engine.rs
index 6ef09c7..4821e78 100644
--- a/src/engine.rs
+++ b/src/engine.rs
@@ -22,11 +22,13 @@ const SYNC: u16 = 15;
 
 pub struct Engine {
     memory: [u16; MEMSIZE],
-    screen: [u16; MEMSIZE],
+    screen_buffer: [u16; MEMSIZE],
+    utility_buffer: [u16; MEMSIZE],
     instruction_pointer: u16,
     pos_code: u16,
     key_code: u16,
     sync_called: bool,
+    expansion_triggered: bool,
 }
 
 #[derive(Debug, Error)]
@@ -57,11 +59,13 @@ impl Engine {
         }
         Self {
             memory,
-            screen: [0; MEMSIZE],
+            screen_buffer: [0; MEMSIZE],
+            utility_buffer: [0; MEMSIZE],
             instruction_pointer: 0,
             pos_code: 0,
             key_code: 0,
             sync_called: false,
+            expansion_triggered: false,
         }
     }
     pub fn wants_to_sync(&self) -> bool {
@@ -79,7 +83,7 @@ impl Engine {
     ) -> () {
         self.set_input(pos_code, key_code);
         self.sync_called = false;
-        *buffer = self.screen;
+        *buffer = self.screen_buffer;
     }
 }
 impl Engine {
@@ -89,11 +93,17 @@ impl Engine {
     fn set(&mut self, index: u16, value: u16) {
         self.memory[index as usize] = value;
     }
-    fn get_screen(&self, index: u16) -> u16 {
-        return self.screen[index as usize];
+    fn get_screen_buffer(&self, index: u16) -> u16 {
+        return self.screen_buffer[index as usize];
     }
-    fn set_screen(&mut self, index: u16, value: u16) {
-        self.screen[index as usize] = value;
+    fn get_utility_buffer(&self, index: u16) -> u16 {
+        return self.utility_buffer[index as usize];
+    }
+    fn set_screen_buffer(&mut self, index: u16, value: u16) {
+        self.screen_buffer[index as usize] = value;
+    }
+    fn set_utility_buffer(&mut self, index: u16, value: u16) {
+        self.utility_buffer[index as usize] = value;
     }
     pub fn read_instruction(&self) -> [u16; 4] {
         return [0, 1, 2, 3].map(|o| self.get(self.instruction_pointer.wrapping_add(o)));
@@ -168,11 +178,19 @@ impl Engine {
                 self.advance_inst_ptr();
             }
             PRINT => {
-                self.set_screen(self.get(arg2), self.get(arg1));
+                if arg3 == 0 {
+                    self.set_screen_buffer(self.get(arg2), self.get(arg1));
+                } else {
+                    self.set_utility_buffer(self.get(arg2), self.get(arg1));
+                }
                 self.advance_inst_ptr();
             }
             READ => {
-                self.set(arg2, self.get_screen(self.get(arg1)));
+                if arg3 == 0 {
+                    self.set(arg2, self.get_screen_buffer(self.get(arg1)));
+                } else {
+                    self.set(arg2, self.get_utility_buffer(self.get(arg1)));
+                }
                 self.advance_inst_ptr();
             }
             BAND => {
@@ -189,6 +207,9 @@ impl Engine {
                 self.sync_called = true;
                 self.set(arg1, self.pos_code);
                 self.set(arg2, self.key_code);
+                if arg3 > 0 {
+                    self.expansion_triggered = true;
+                }
                 self.advance_inst_ptr();
             }
             _ => return Err(EngineError::InvalidInstruction),