STM8S怎么用printf？

/**

  ******************************************************************************

  * [url=home.php?mod=space&uid=288409]@file[/url] UART1_Printf\main.c

  * [url=home.php?mod=space&uid=247401]@brief[/url] This file contains the main function for: retarget the C library printf

  *        /scanf functions to the UART1 example.

  * [url=home.php?mod=space&uid=187600]@author[/url]  MCD Application Team

  * [url=home.php?mod=space&uid=895143]@version[/url] V2.0.4

  * [url=home.php?mod=space&uid=212281]@date[/url]     26-April-2018

  ******************************************************************************

  * @attention

  *

  * <h2><center>&copy; COPYRIGHT 2014 STMicroelectronics</center></h2>

  *

  * Licensed under MCD-ST Liberty SW License Agreement V2, (the "License");

  * You may not use this file except in compliance with the License.

  * You may obtain a copy of the License at:

  *

  *        http://www.st.com/software_license_agreement_liberty_v2

  *

  * Unless required by applicable law or agreed to in writing, software 

  * distributed under the License is distributed on an "AS IS" BASIS, 

  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

  * See the License for the specific language governing permissions and

  * limitations under the License.

  *

  ******************************************************************************

  */ 



/* Includes ------------------------------------------------------------------*/

#include "stm8s.h"

#include "stdio.h"

/**

  * @addtogroup UART1_Printf

  * @{

  */

/* Private typedef -----------------------------------------------------------*/

/* Private define ------------------------------------------------------------*/

#ifdef _RAISONANCE_

#define PUTCHAR_PROTOTYPE int putchar (char c)

#define GETCHAR_PROTOTYPE int getchar (void)

#elif defined (_COSMIC_)

#define PUTCHAR_PROTOTYPE char putchar (char c)

#define GETCHAR_PROTOTYPE char getchar (void)

#else /* _IAR_ */

#define PUTCHAR_PROTOTYPE int putchar (int c)

#define GETCHAR_PROTOTYPE int getchar (void)

#endif /* _RAISONANCE_ */

/* Private macro -------------------------------------------------------------*/

/* Private variables ---------------------------------------------------------*/

/* Private function prototypes -----------------------------------------------*/

/* Private functions ---------------------------------------------------------*/

/**

  * @brief  Main program.

  * @param  None

  * @retval None

  */

void main(void)

{

  char ans;

  /*High speed internal clock prescaler: 1*/

  CLK_HSIPrescalerConfig(CLK_PRESCALER_HSIDIV1);

    

  UART1_DeInit();

  /* UART1 configuration ------------------------------------------------------*/

  /* UART1 configured as follow:

        - BaudRate = 115200 baud  

        - Word Length = 8 Bits

        - One Stop Bit

        - No parity

        - Receive and transmit enabled

        - UART1 Clock disabled

  */

  UART1_Init((uint32_t)115200, UART1_WORDLENGTH_8D, UART1_STOPBITS_1, UART1_PARITY_NO,

              UART1_SYNCMODE_CLOCK_DISABLE, UART1_MODE_TXRX_ENABLE);



  /* Output a message on Hyperterminal using printf function */

  printf("\n\rUART1 Example :retarget the C library printf()/getchar() functions to the UART\n\r");

  printf("\n\rEnter Text\n\r");



  while (1)

  {

    ans = getchar();

    printf("%c", ans);  

  }

}



/**

  * @brief Retargets the C library printf function to the UART.

  * @param c Character to send

  * @retval char Character sent

  */

PUTCHAR_PROTOTYPE

{

  /* Write a character to the UART1 */

  UART1_SendData8(c);

  /* Loop until the end of transmission */

  while (UART1_GetFlagStatus(UART1_FLAG_TXE) == RESET);



  return (c);

}



/**

  * @brief Retargets the C library scanf function to the USART.

  * @param None

  * @retval char Character to Read

  */

GETCHAR_PROTOTYPE

{

#ifdef _COSMIC_

  char c = 0;

#else

  int c = 0;

#endif

  /* Loop until the Read data register flag is SET */

  while (UART1_GetFlagStatus(UART1_FLAG_RXNE) == RESET);

    c = UART1_ReceiveData8();

  return (c);

}



#ifdef USE_FULL_ASSERT



/**

  * @brief  Reports the name of the source file and the source line number

  *   where the assert_param error has occurred.

  * @param file: pointer to the source file name

  * @param line: assert_param error line source number

  * @retval None

  */

void assert_failed(uint8_t* file, uint32_t line)

{ 

  /* User can add his own implementation to report the file name and line number,

     ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */



  /* Infinite loop */

  while (1)

  {

  }

}

#endif



/**

  * @}

  */





/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/