#include "CH32V20xxx.h"
extern "C" void SystemInit ();
enum CLKSRC : uint32_t {
  CLK_HSI = 0u,
  CLK_HSE,
  CLK_PLL,
};
// HSE i HSI mají frekvenci 8 MHz
void SystemInit(void) {
  /// TODO
  EXTEND.EXTEND_CTR.B.PLL_HSI_PRE = SET; // HSI used for PLL, not divided
  RCC.CFGR0.modify([](RCC_Type::CFGR0_DEF & r) -> uint32_t {
    r.B.PLLMUL = 0xFu;  // 8x18 = 144
    r.B.PPRE1  = 4u;    // 100: HCLK divided by 2 (PB1)
    return r.R;         // HB, PB2 not divided
  });
  RCC.CTLR.modify([](RCC_Type::CTLR_DEF & r) -> uint32_t {
    r.B.HSITRIM = 0x10u;
    r.B.HSION   = SET;
  //r.B.HSEBYP  = SET;
    r.B.CSSON   = SET;  // Enable clock security system
    r.B.PLLON   = SET;
    return r.R;
  });
  
  RCC.INTR.R = 0x009F0000u;   // clear interrupts
  while (RCC.CTLR.B.PLLRDY == RESET);
  // USE PLL
  RCC.CFGR0.B.SW          = CLK_PLL ;
  while (RCC.CFGR0.B.SWS != CLK_PLL);
}