Beginning of cross platform support

SHAL/Src/STM32L4XX/Core/SHAL_CORE.cpp

@@ -0,0 +1,42 @@
+//
+// Created by Luca on 9/15/2025.
+//
+
+#include "SHAL_CORE.h"
+
+void SHAL_init(){
+    systick_init(); //Just this for now
+}
+
+
+void systick_init(){
+    SysTick->CTRL = 0;           //Disable first
+    SysTick->LOAD = 0xFFFFFF;    //Max 24-bit
+    SysTick->VAL  = 0;           //Clear
+    SysTick->CTRL = SysTick_CTRL_CLKSOURCE_Msk | SysTick_CTRL_ENABLE_Msk;
+}
+
+
+void SHAL_delay_us(uint32_t us){
+    uint32_t ticks = us * (SystemCoreClock / 1000000U);
+    uint32_t start = SysTick->VAL;
+
+    //Calculate target value (may wrap around)
+    uint32_t target = (start >= ticks) ? (start - ticks) : (start + 0x01000000 - ticks);
+    target &= 0x00FFFFFF;
+
+    //Wait until we reach the target
+    if (start >= ticks) {
+        //No wraparound case
+        while (SysTick->VAL > target) {}
+    } else {
+        while (SysTick->VAL <= start) {} //Wait for wraparound
+        while (SysTick->VAL > target) {} //Wait for target
+    }
+}
+
+void SHAL_delay_ms(uint32_t ms){
+    while(ms-- > 0){
+        SHAL_delay_us(1000);
+    }
+}