host-aprom/NUC123/system_NUC123.c

/**************************************************************************//**
 * @file     system_NUC123.c
 * @version  V3.0
 * $Revision: 5 $
 * $Date: 15/07/02 11:21a $
 * @brief    NUC123 Series CMSIS System File
 *
 * @note
 * SPDX-License-Identifier: Apache-2.0
 * Copyright (C) 2014~2015 Nuvoton Technology Corp. All rights reserved.
 *
 ******************************************************************************/
#include <stdint.h>

#include "NUC123.h"

/*----------------------------------------------------------------------------
  Clock Variable definitions
 *----------------------------------------------------------------------------*/
uint32_t SystemCoreClock = __HSI;         /*!< System Clock Frequency (Core Clock) */
uint32_t CyclesPerUs = (__HSI / 1000000); /* Cycles per micro second */
uint32_t PllClock = __HSI;                /*!< PLL Output Clock Frequency */
uint32_t gau32ClkSrcTbl[] = { __HXT, NULL, __HSI, __LIRC, NULL, NULL, NULL, __HIRC };

/*----------------------------------------------------------------------------
  Clock functions
  This function is used to update the variable SystemCoreClock
  and must be called whenever the core clock is changed.
 *----------------------------------------------------------------------------*/
void SystemCoreClockUpdate(void) /* Get Core Clock Frequency      */
{
    uint32_t u32Freq, u32ClkSrc;
    uint32_t u32HclkDiv;

    /* Update PLL Clock */
    PllClock = CLK_GetPLLClockFreq();

    u32ClkSrc = CLK->CLKSEL0 & CLK_CLKSEL0_HCLK_S_Msk;

    if (u32ClkSrc == CLK_CLKSEL0_HCLK_S_PLL) {
        /* Use PLL clock */
        u32Freq = PllClock;
    } else if (u32ClkSrc == CLK_CLKSEL0_HCLK_S_PLL_DIV2) {
        /* Use PLL/2 clock */
        u32Freq = PllClock >> 1;
    } else {
        /* Use the clock sources directly */
        u32Freq = gau32ClkSrcTbl[u32ClkSrc];
    }

    u32HclkDiv = (CLK->CLKDIV & CLK_CLKDIV_HCLK_N_Msk) + 1;

    /* Update System Core Clock */
    SystemCoreClock = u32Freq / u32HclkDiv;

    CyclesPerUs = (SystemCoreClock + 500000) / 1000000;
}