From d092ccd36292364c8557c87b1daa872f3944023f Mon Sep 17 00:00:00 2001
From: Luca <luca.lizaranzu@gmail.com>
Date: Thu, 28 Aug 2025 22:02:08 -0700
Subject: [PATCH] Made timer constructor unaccessable by user

---
 Core/Include/Reg/SHAL_TIM_REG.h | 26 +++++++++++++++++++-------
 Core/Include/SHAL_TIM.h         | 23 ++++++++++++++++++++---
 Core/Src/Reg/SHAL_TIM.cpp       | 19 +++++++++++++++++++
 Core/Src/main.cpp               |  4 ++--
 4 files changed, 60 insertions(+), 12 deletions(-)

diff --git a/Core/Include/Reg/SHAL_TIM_REG.h b/Core/Include/Reg/SHAL_TIM_REG.h
index 2f369bb..8295639 100644
--- a/Core/Include/Reg/SHAL_TIM_REG.h
+++ b/Core/Include/Reg/SHAL_TIM_REG.h
@@ -2,8 +2,10 @@
 #define SHAL_TIM_REG_H
 
 #include <cstdint>
+#include <cassert>
 #include <stm32f072xb.h>
 
+
 enum class Bus {
     AHB,
     APB1,
@@ -25,7 +27,8 @@ enum class Timer_Key { //For STM32F072
     S_TIM15,
     S_TIM16,
     S_TIM17,
-    NUM_TIMERS
+    NUM_TIMERS,
+    S_TIM_INVALID
 };
 
 
@@ -39,10 +42,13 @@ constexpr RCC_Peripheral getTimerRCC(Timer_Key t) {
         case Timer_Key::S_TIM15: return {Bus::APB2, &RCC->APB2ENR, RCC_APB2ENR_TIM15EN};
         case Timer_Key::S_TIM16: return {Bus::APB2, &RCC->APB2ENR, RCC_APB2ENR_TIM16EN};
         case Timer_Key::S_TIM17: return {Bus::APB2, &RCC->APB2ENR, RCC_APB2ENR_TIM17EN};
-        case Timer_Key::NUM_TIMERS: return {Bus::INVALID, nullptr, 0};;
+        case Timer_Key::NUM_TIMERS:
+        case Timer_Key::S_TIM_INVALID:
+            assert(false);
+            return {Bus::INVALID, nullptr, 0};; //Unreachable
     }
 
-    return {Bus::APB2, &RCC->APB2ENR, RCC_APB2ENR_TIM1EN};
+    __builtin_unreachable();
 }
 
 //Get actual register value based on enum
@@ -55,9 +61,12 @@ constexpr volatile TIM_TypeDef* getTimerRegister(Timer_Key t) {
         case Timer_Key::S_TIM15:  return TIM15;
         case Timer_Key::S_TIM16:  return TIM16;
         case Timer_Key::S_TIM17:  return TIM17;
-        case Timer_Key::NUM_TIMERS: return nullptr;
+        case Timer_Key::NUM_TIMERS:
+        case Timer_Key::S_TIM_INVALID:
+            assert(false);
+            return nullptr; //Unreachable
     }
-    return TIM1;
+    __builtin_unreachable();
 }
 
 constexpr IRQn_Type getIRQn(Timer_Key t) {
@@ -69,9 +78,12 @@ constexpr IRQn_Type getIRQn(Timer_Key t) {
         case Timer_Key::S_TIM15: return TIM15_IRQn;
         case Timer_Key::S_TIM16: return TIM16_IRQn;
         case Timer_Key::S_TIM17: return TIM17_IRQn;
-        case Timer_Key::NUM_TIMERS: return TIM1_BRK_UP_TRG_COM_IRQn;
+        case Timer_Key::NUM_TIMERS:
+        case Timer_Key::S_TIM_INVALID:
+            assert(false);
+            return TIM1_BRK_UP_TRG_COM_IRQn; //Unreachable
     }
-    return TIM1_BRK_UP_TRG_COM_IRQn;
+    __builtin_unreachable();
 }
 
 
diff --git a/Core/Include/SHAL_TIM.h b/Core/Include/SHAL_TIM.h
index 024b38a..a1022b8 100644
--- a/Core/Include/SHAL_TIM.h
+++ b/Core/Include/SHAL_TIM.h
@@ -4,10 +4,11 @@
 #include "SHAL_TIM_REG.h"
 #include "SHAL_TIM_CALLBACK.h"
 
-class Timer {
-public:
+#include <array>
 
-    explicit Timer(Timer_Key t);
+class Timer {
+    friend class TimerManager;
+public:
 
     //Starts the counter
     void start();
@@ -31,9 +32,25 @@ public:
 
 private:
 
+    explicit Timer(Timer_Key t);
+    Timer();
+
     Timer_Key timer;
     volatile TIM_TypeDef* timer_reg;
 
 };
 
+#define getTimer(timer_key) TimerManager::get(timer_key);
+
+//Manages all timers so user does not have to personally initialize
+class TimerManager{
+public:
+
+    static Timer& get(Timer_Key);
+    TimerManager() = delete;
+
+private:
+    inline static Timer timers[static_cast<int>(Timer_Key::NUM_TIMERS)] = {};
+};
+
 #endif
\ No newline at end of file
diff --git a/Core/Src/Reg/SHAL_TIM.cpp b/Core/Src/Reg/SHAL_TIM.cpp
index 3322ff5..cb432d0 100644
--- a/Core/Src/Reg/SHAL_TIM.cpp
+++ b/Core/Src/Reg/SHAL_TIM.cpp
@@ -3,12 +3,17 @@
 //
 
 #include "SHAL_TIM.h"
+#include <cassert>
 
 Timer::Timer(Timer_Key t) : timer(t), timer_reg(getTimerRegister(t)){
     RCC_Peripheral rcc = getTimerRCC(timer);
     *rcc.reg |= rcc.bitmask;
 }
 
+Timer::Timer() : timer(Timer_Key::S_TIM_INVALID), timer_reg(nullptr){
+
+}
+
 void Timer::start() {
     timer_reg->CR1 |= TIM_CR1_CEN;
     timer_reg->EGR |= TIM_EGR_UG; //load prescaler reg and ARR
@@ -33,3 +38,17 @@ void Timer::enableInterrupt() {
 }
 
 
+Timer &TimerManager::get(Timer_Key timer_key) {
+
+    //Ensure that we don't try to get invalid timers
+    assert(timer_key != Timer_Key::S_TIM_INVALID && timer_key != Timer_Key::NUM_TIMERS);
+
+    Timer& selected = timers[static_cast<int>(timer_key)];
+
+    //Timer queried is not initialized yet (defaults to invalid)
+    if(selected.timer == Timer_Key::S_TIM_INVALID){
+        timers[static_cast<int>(timer_key)] = Timer(timer_key); //Initialize timer
+    }
+
+    return timers[static_cast<int>(timer_key)];
+}
diff --git a/Core/Src/main.cpp b/Core/Src/main.cpp
index bfc4d14..035e611 100644
--- a/Core/Src/main.cpp
+++ b/Core/Src/main.cpp
@@ -16,10 +16,10 @@ int main() {
     RCC->AHBENR |= RCC_AHBENR_GPIOAEN;
     RCC->AHBENR |= RCC_AHBENR_GPIOBEN;
 
-    auto timer2 = Timer(Timer_Key::S_TIM2);
+    Timer timer2 = getTimer(Timer_Key::S_TIM2);
 
     timer2.setPrescaler(8000 - 1);
-    timer2.setARR(250 - 1);
+    timer2.setARR(500 - 1);
     timer2.setCallbackFunc(tim2Handler);
     timer2.start();