Added delay functions

SHAL/Src/Core/SHAL_CORE.cpp

@@ -0,0 +1,31 @@
+//
+// 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 start = SysTick->VAL;
+    uint32_t ticks = us * (SystemCoreClock / 1000000U);
+
+    //handle wraparound with 24-bit mask
+    while (((start - SysTick->VAL) & 0x00FFFFFF) < ticks) { }
+}
+
+void SHAL_delay_ms(uint32_t ms){
+    while(ms-- > 0){
+        SHAL_delay_us(1000);
+    }
+}