--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Small_CPU/Src/system_stm32f4xx.c	Sat Apr 28 11:52:34 2018 +0200
@@ -0,0 +1,280 @@
+/**
+  ******************************************************************************
+  * @file    system_stm32f4xx.c
+  * @author  MCD Application Team
+  * @version V1.1.0
+  * @date    26-June-2014
+  * @brief   CMSIS Cortex-M4 Device Peripheral Access Layer System Source File.
+  *
+  *   This file provides two functions and one global variable to be called from 
+  *   user application:
+  *      - SystemInit(): This function is called at startup just after reset and 
+  *                      before branch to main program. This call is made inside
+  *                      the "startup_stm32f4xx.s" file.
+  *
+  *      - SystemCoreClock variable: Contains the core clock (HCLK), it can be used
+  *                                  by the user application to setup the SysTick 
+  *                                  timer or configure other parameters.
+  *                                     
+  *      - SystemCoreClockUpdate(): Updates the variable SystemCoreClock and must
+  *                                 be called whenever the core clock is changed
+  *                                 during program execution.
+  *
+  *
+  ******************************************************************************
+  * @attention
+  *
+  * <h2><center>&copy; COPYRIGHT 2014 STMicroelectronics</center></h2>
+  *
+  * Redistribution and use in source and binary forms, with or without modification,
+  * are permitted provided that the following conditions are met:
+  *   1. Redistributions of source code must retain the above copyright notice,
+  *      this list of conditions and the following disclaimer.
+  *   2. Redistributions in binary form must reproduce the above copyright notice,
+  *      this list of conditions and the following disclaimer in the documentation
+  *      and/or other materials provided with the distribution.
+  *   3. Neither the name of STMicroelectronics nor the names of its contributors
+  *      may be used to endorse or promote products derived from this software
+  *      without specific prior written permission.
+  *
+  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+  * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+  *
+  ******************************************************************************
+  */
+
+/** @addtogroup CMSIS
+  * @{
+  */
+
+/** @addtogroup stm32f4xx_system
+  * @{
+  */  
+  
+/** @addtogroup STM32F4xx_System_Private_Includes
+  * @{
+  */
+
+#include <stdint.h>
+
+#include "stm32f4xx_hal.h"
+
+#if !defined  (HSE_VALUE) 
+  #define HSE_VALUE    ((uint32_t)8000000) /*!< Default value of the External oscillator in Hz */
+#endif /* HSE_VALUE */
+
+#if !defined  (HSI_VALUE)
+  #define HSI_VALUE    ((uint32_t)16000000) /*!< Value of the Internal oscillator in Hz*/
+#endif /* HSI_VALUE */
+
+/**
+  * @}
+  */
+
+/** @addtogroup STM32F4xx_System_Private_TypesDefinitions
+  * @{
+  */
+
+/**
+  * @}
+  */
+
+/** @addtogroup STM32F4xx_System_Private_Defines
+  * @{
+  */
+
+/************************* Miscellaneous Configuration ************************/
+
+/*!< Uncomment the following line if you need to relocate your vector Table in
+     Internal SRAM. */
+/* #define VECT_TAB_SRAM */
+#define VECT_TAB_OFFSET  0x00 /*!< Vector Table base offset field. 
+                                   This value must be a multiple of 0x200. */
+/******************************************************************************/
+
+/**
+  * @}
+  */
+
+/** @addtogroup STM32F4xx_System_Private_Macros
+  * @{
+  */
+
+/**
+  * @}
+  */
+
+/** @addtogroup STM32F4xx_System_Private_Variables
+  * @{
+  */
+  /* This variable is updated in three ways:
+      1) by calling CMSIS function SystemCoreClockUpdate()
+      2) by calling HAL API function HAL_RCC_GetHCLKFreq()
+      3) each time HAL_RCC_ClockConfig() is called to configure the system clock frequency 
+         Note: If you use this function to configure the system clock; then there
+               is no need to call the 2 first functions listed above, since SystemCoreClock
+               variable is updated automatically.
+  */
+  uint32_t SystemCoreClock = 16000000;
+  __I uint8_t AHBPrescTable[16] = {0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 3, 4, 6, 7, 8, 9};
+
+/**
+  * @}
+  */
+
+/** @addtogroup STM32F4xx_System_Private_FunctionPrototypes
+  * @{
+  */
+
+/**
+  * @}
+  */
+
+/** @addtogroup STM32F4xx_System_Private_Functions
+  * @{
+  */
+
+/**
+  * @brief  Setup the microcontroller system
+  *         Initialize the FPU setting, vector table location and External memory 
+  *         configuration.
+  * @param  None
+  * @retval None
+  */
+void SystemInit(void)
+{
+  /* FPU settings ------------------------------------------------------------*/
+  #if (__FPU_PRESENT == 1) && (__FPU_USED == 1)
+    SCB->CPACR |= ((3UL << 10*2)|(3UL << 11*2));  /* set CP10 and CP11 Full Access */
+  #endif
+  /* Reset the RCC clock configuration to the default reset state ------------*/
+  /* Set HSION bit */
+  RCC->CR |= (uint32_t)0x00000001;
+
+  /* Reset CFGR register */
+  RCC->CFGR = 0x00000000;
+
+  /* Reset HSEON, CSSON and PLLON bits */
+  RCC->CR &= (uint32_t)0xFEF6FFFF;
+
+  /* Reset PLLCFGR register */
+  RCC->PLLCFGR = 0x24003010;
+
+  /* Reset HSEBYP bit */
+  RCC->CR &= (uint32_t)0xFFFBFFFF;
+
+  /* Disable all interrupts */
+  RCC->CIR = 0x00000000;
+
+  /* Configure the Vector Table location add offset address ------------------*/
+#ifdef VECT_TAB_SRAM
+  SCB->VTOR = SRAM_BASE | VECT_TAB_OFFSET; /* Vector Table Relocation in Internal SRAM */
+#else
+  SCB->VTOR = FLASH_BASE | VECT_TAB_OFFSET; /* Vector Table Relocation in Internal FLASH */
+#endif
+}
+
+/**
+   * @brief  Update SystemCoreClock variable according to Clock Register Values.
+  *         The SystemCoreClock variable contains the core clock (HCLK), it can
+  *         be used by the user application to setup the SysTick timer or configure
+  *         other parameters.
+  *           
+  * @note   Each time the core clock (HCLK) changes, this function must be called
+  *         to update SystemCoreClock variable value. Otherwise, any configuration
+  *         based on this variable will be incorrect.         
+  *     
+  * @note   - The system frequency computed by this function is not the real 
+  *           frequency in the chip. It is calculated based on the predefined 
+  *           constant and the selected clock source:
+  *             
+  *           - If SYSCLK source is HSI, SystemCoreClock will contain the HSI_VALUE(*)
+  *                                              
+  *           - If SYSCLK source is HSE, SystemCoreClock will contain the HSE_VALUE(**)
+  *                          
+  *           - If SYSCLK source is PLL, SystemCoreClock will contain the HSE_VALUE(**) 
+  *             or HSI_VALUE(*) multiplied/divided by the PLL factors.
+  *         
+  *         (*) HSI_VALUE is a constant defined in stm32f4xx_hal_conf.h file (default value
+  *             16 MHz) but the real value may vary depending on the variations
+  *             in voltage and temperature.   
+  *    
+  *         (**) HSE_VALUE is a constant defined in stm32f4xx_hal_conf.h file (its value
+  *              depends on the application requirements), user has to ensure that HSE_VALUE
+  *              is same as the real frequency of the crystal used. Otherwise, this function
+  *              may have wrong result.
+  *                
+  *         - The result of this function could be not correct when using fractional
+  *           value for HSE crystal.
+  *     
+  * @param  None
+  * @retval None
+  */
+void SystemCoreClockUpdate(void)
+{
+  uint32_t tmp = 0, pllvco = 0, pllp = 2, pllsource = 0, pllm = 2;
+  
+  /* Get SYSCLK source -------------------------------------------------------*/
+  tmp = RCC->CFGR & RCC_CFGR_SWS;
+
+  switch (tmp)
+  {
+    case 0x00:  /* HSI used as system clock source */
+      SystemCoreClock = HSI_VALUE;
+      break;
+    case 0x04:  /* HSE used as system clock source */
+      SystemCoreClock = HSE_VALUE;
+      break;
+    case 0x08:  /* PLL used as system clock source */
+
+      /* PLL_VCO = (HSE_VALUE or HSI_VALUE / PLL_M) * PLL_N
+         SYSCLK = PLL_VCO / PLL_P
+         */    
+      pllsource = (RCC->PLLCFGR & RCC_PLLCFGR_PLLSRC) >> 22;
+      pllm = RCC->PLLCFGR & RCC_PLLCFGR_PLLM;
+      
+      if (pllsource != 0)
+      {
+        /* HSE used as PLL clock source */
+        pllvco = (HSE_VALUE / pllm) * ((RCC->PLLCFGR & RCC_PLLCFGR_PLLN) >> 6);
+      }
+      else
+      {
+        /* HSI used as PLL clock source */
+        pllvco = (HSI_VALUE / pllm) * ((RCC->PLLCFGR & RCC_PLLCFGR_PLLN) >> 6);
+      }
+
+      pllp = (((RCC->PLLCFGR & RCC_PLLCFGR_PLLP) >>16) + 1 ) *2;
+      SystemCoreClock = pllvco/pllp;
+      break;
+    default:
+      SystemCoreClock = HSI_VALUE;
+      break;
+  }
+  /* Compute HCLK frequency --------------------------------------------------*/
+  /* Get HCLK prescaler */
+  tmp = AHBPrescTable[((RCC->CFGR & RCC_CFGR_HPRE) >> 4)];
+  /* HCLK frequency */
+  SystemCoreClock >>= tmp;
+}
+
+/**
+  * @}
+  */
+
+/**
+  * @}
+  */
+  
+/**
+  * @}
+  */    
+/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/