From f7b1fedfb43f7c4b702bf22b32cbc9aa722f3c8e Mon Sep 17 00:00:00 2001
From: Loic Guegan <loic.guegan@mailbox.org>
Date: Tue, 26 Dec 2023 19:27:23 +0100
Subject: [PATCH] Cleaning code

---
 src/main.c | 13 ++++++-------
 src/mem.c  | 11 ++++++++++-
 src/vcpu.c | 45 ++++++++++++++++++++++++++++++---------------
 src/vcpu.h |  8 +++++++-
 4 files changed, 53 insertions(+), 24 deletions(-)

diff --git a/src/main.c b/src/main.c
index de3ae0d..2f2f9d0 100644
--- a/src/main.c
+++ b/src/main.c
@@ -5,6 +5,9 @@
 
 #include <stdio.h>
 
+#define SCREEN_WIDTH 1000
+#define SCREEN_HEIGHT 500
+
 int main(int argc, char *argv[])
 {
   // Parse argument
@@ -17,11 +20,8 @@ int main(int argc, char *argv[])
   }
 
   // Initialize
-  MemInit();
-  MemLoadROM(argv[1]);
-  ScreenInit(1000,500);
-  VCPUInit();
-  SpeakerInit();
+  VCPUInit(SCREEN_WIDTH, SCREEN_HEIGHT);
+  MemLoadROM(argv[1]); // Load ROM into main memory
 
   // Set game to run at very high FPS (prevent raylib to interfer with emulator CPU frequency)
   SetTargetFPS(VCPU_FREQ*100);
@@ -32,8 +32,7 @@ int main(int argc, char *argv[])
   }
 
   // Finish
-  SpeakerFinish();
-  ScreenClose();
+  VCPUFinish();
 
   return 0;
 }
diff --git a/src/mem.c b/src/mem.c
index ec34750..aba34fc 100644
--- a/src/mem.c
+++ b/src/mem.c
@@ -16,13 +16,22 @@ void MemSet(int addr, unsigned char value, int size){
 }
 
 void MemStore(unsigned char *data, int size, int addr){
-  for(int i=0;i<size;i++)
+  for(int i=0;i<size;i++){
+    if(addr+i>4096){
+      printf("Illegal memory access (store): addr=%d\n",addr+i);
+      return;
+    }
     memory[addr+i]=data[i];
+  }
 }
 
 void MemLoad(unsigned char *data, int size, int addr){
   int location=addr;
   for(int i=0;i<size;i++){
+    if(addr+i>4096){
+      printf("Illegal memory access (load): addr=%d\n",addr+i);
+      return;
+    }
     data[i]=memory[addr+i];
   }
 }
diff --git a/src/vcpu.c b/src/vcpu.c
index 4bfd86b..fb73eeb 100644
--- a/src/vcpu.c
+++ b/src/vcpu.c
@@ -12,7 +12,11 @@
 // Current VCPU state
 VCPU_State State;
 
-void VCPUInit(){
+void VCPUInit(int width, int height){
+  MemInit();
+  ScreenInit(width,height);
+  SpeakerInit();
+
   State.PC=ADDR_ROM;
   State.S=0;
   State.dt_ticks=0;
@@ -22,6 +26,11 @@ void VCPUInit(){
   srand(time(NULL));
 }
 
+void VCPUFinish(){
+  SpeakerFinish();
+  ScreenClose();
+}
+
 void VCPUFetch(){
   unsigned char byte[2];
   MemLoad(byte,2,State.PC); // Little indian to -1 no +1
@@ -64,7 +73,7 @@ void VCPUDoubleDabble(unsigned char x, unsigned char *u, unsigned char *t, unsig
 }
 
 void VCPUExecute(){
-  //  VCPUDump();
+  // Very big switch case... Thinking about it, ifelse would have been cleaner for the reader
   switch(State.opcode >> 12){
   case 0x0: // Clear screen or return from subroutine
     if(State.N == 0x0){ // Clear screen
@@ -259,7 +268,7 @@ void VCPUExecute(){
       MemStore(&hundreds,1,State.I);
       MemStore(&tens,1,State.I+1);
       MemStore(&units,1,State.I+2);
-      //printf("hundreds:%d tens:%d units:%d byte:%d\n",hundreds,tens,units,State.V[State.X]);
+      // printf("hundreds:%d tens:%d units:%d byte:%d\n",hundreds,tens,units,State.V[State.X]);
       break;
       
     case 0x55:
@@ -279,32 +288,29 @@ void VCPUTick(){
   struct timespec start, stop;
   double duration, delay;
 
+  // Start CPU pipeline instrumentation
+  clock_gettime(CLOCK_REALTIME, &start);
+
   // Update keypressed
   int key=KeypadGetPressed();
   if(key>=0){
     State.keypressed=1;
     State.key=key&0xF;
-    //printf("Keypressed: %x\n",State.key);
+    // printf("Keypressed: %x\n",State.key);
   }
-  else
+  else{
     State.keypressed=0;
+  }
   
-  // Run and benchmark CPU pipeline
-  clock_gettime(CLOCK_REALTIME, &start);  
+  // Execute next instruction
   VCPUFetch();
   VCPUDecode();
   VCPUExecute();
+
+  // Update ticks
   State.dt_ticks++;
   State.st_ticks++;
   State.screen_ticks++;
-  clock_gettime(CLOCK_REALTIME, &stop);
-
-  // Adjust pipeline duration
-  duration=(stop.tv_sec - start.tv_sec) + (stop.tv_nsec - start.tv_nsec)*1e-9;
-  delay=1.0/VCPU_FREQ-duration;
-  if(delay>0){
-    usleep(delay*1e6);
-  }
 
   // Update Delay Timer
   if(State.dt_ticks>=(1.0*VCPU_FREQ/DTST_FREQ)){
@@ -330,6 +336,15 @@ void VCPUTick(){
     ScreenUpdate();
   }
 
+  // End instrumentation
+  clock_gettime(CLOCK_REALTIME, &stop);
+
+  // Adjust pipeline duration
+  duration=(stop.tv_sec - start.tv_sec) + (stop.tv_nsec - start.tv_nsec)*1e-9;
+  delay=1.0/VCPU_FREQ-duration;
+  if(delay>0){
+    usleep(delay*1e6);
+  }
 }
 
 void VCPUDump(){
diff --git a/src/vcpu.h b/src/vcpu.h
index 4266ac4..09bfd4e 100644
--- a/src/vcpu.h
+++ b/src/vcpu.h
@@ -51,7 +51,7 @@ typedef struct VCPU_State {
  * @brief Must be called first!
  * 
  */
-void VCPUInit();
+void VCPUInit(int width, int height);
 
 /**
  * @brief Fetch instruction from memory
@@ -92,3 +92,9 @@ void VCPUDoubleDabble(unsigned char x, unsigned char *u, unsigned char *t, unsig
  * 
  */
 void VCPUDump();
+
+/**
+ * @brief To call before terminating the application
+ *
+ */
+void VCPUFinish();