编译源代码

To compile the source code, perform the following:

点击test-gpio.c下载测试源代码文件，保存到 Ubuntu 下的目标目录。例如，应用程序目录：

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/stat.h>


#define GPIO44 	492	
#define GPIO22 	470

#define GPIO_KEY1     GPIO44
#define FISCV_GPIO    GPIO22                
#define MAX_BUF	      128                   //Define array size
#define StarF_Gpio_Dir "/sys/class/gpio"    //GPIO control paths
/**********************************************************************
* Function Name: StarF_gpio_export
* Description:   Set the pin number 			
* return value:  0 Success; Others: fail
*    Data	       version	    Author		 Application Name  
* ----------------------------------------------------------------------
* 2021/12/08        V1.0	   zheng.xu		  test gpio
 ***********************************************************************/
int StarF_gpio_export(unsigned int gpio)
{
    int fd, len;
    char buf[MAX_BUF];
	// /sys/class/gpio/export
    fd = open( "/sys/class/gpio/export", O_WRONLY);  
    if (fd < 0) {
        perror("gpio/export");
        return fd;
    }

    len = snprintf(buf, sizeof(buf), "%d", gpio);   
    write(fd, buf, len);                             
    close(fd);                                     
 
    return 0;
}

/**********************************************************************
* Function Name: StarF_gpio_unexport
* Description:   Cancel the GPIO pin number		
* return value:  0 Success; Others: fail
*    Data	       version	    Author		 Application Name  
* ----------------------------------------------------------------------
* 2021/12/08        V1.0	   zheng.xu		  test gpio
 ***********************************************************************/
int StarF_gpio_unexport(unsigned int gpio)
{
    int fd, len;
    char buf[MAX_BUF];
	// /sys/class/gpio/unexport
    fd = open("/sys/class/gpio/unexport", O_WRONLY);
    if (fd < 0) {
        perror("gpio/export");
        return fd;
    }
 
    len = snprintf(buf, sizeof(buf), "%d", gpio);  
    write(fd, buf, len);                           
    close(fd);                                      
    return 0;
}

/**********************************************************************
* Function Name: StarF_gpio_set_dir
* Description:   Set GPIO pin I/O	
* return value:  0 Success; Others: fail
*    Data	       version	    Author		 Application Name  
* ----------------------------------------------------------------------
* 2021/12/08        V1.0	   zheng.xu		  test gpio
 ***********************************************************************/
 
int StarF_gpio_set_dir(unsigned int gpio, unsigned int out_flag)
{
    int fd, len;
    char buf[MAX_BUF];
	// /sys/class/gpio/gpioN/direction
    len = snprintf(buf, sizeof(buf), StarF_Gpio_Dir "/gpio%d/direction", gpio);
 
    fd = open(buf, O_WRONLY);
    if (fd < 0) {
        perror(buf);
        return fd;
    }
 
    if (out_flag)                   //'1' set to output
        write(fd, "out", 4);
    else                            //‘0’ set input
        write(fd, "in", 3);
 
    close(fd);
    return 0;
}
/**********************************************************************
* Function Name: StarF_gpio_set_dir
* Description:   Set GPIO high & low levels
* function parameters:@GPIO   Set GPIO number for the output level
                       value   1: Set gpio output to high level；  0: Set gpio output to low level.  
* return value:  0 Success; Others: fail
*    Data	       version	    Author		 Application Name  
* ----------------------------------------------------------------------
* 2021/12/08        V1.0	   zheng.xu		  test gpio
 ***********************************************************************/
 
int StarF_gpio_set_value(unsigned int gpio, unsigned int value)
{
    int fd, len;
    char buf[MAX_BUF];
	// /sys/class/gpio/gpioN/value
    len = snprintf(buf, sizeof(buf), StarF_Gpio_Dir "/gpio%d/value", gpio); 
    fd = open(buf, O_WRONLY);	    
    if (fd < 0) {
        perror(buf);
        return fd;
    }
 
    if (value)                       //'1' output is high level
        write(fd, "1", 2);
    else                             //'0' output is Low level
        write(fd, "0", 2);
 
    close(fd);
    return 0;
}

/**********************************************************************
* Function Name: StarF_gpio_get_value
* Description:   Read GPIO high & low levels
* function parameters:@GPIO   Set GPIO number for the output level
                       value   1: Set gpio output to high level；  0: Set gpio output to low level.  
* return value:  0 Success; Others: fail
*    Data	       version	    Author		 Application Name  
* ----------------------------------------------------------------------
* 2021/12/08        V1.0	   zheng.xu		  test gpio
 ***********************************************************************/
 
int StarF_gpio_get_value(unsigned int gpio, unsigned int *value)
{
    int fd, len;
    char buf[MAX_BUF];
    char ch;
	// /sys/class/gpio/gpioN/value
    len = snprintf(buf, sizeof(buf), StarF_Gpio_Dir "/gpio%d/value", gpio);
 
    fd = open(buf, O_RDONLY);     
    if (fd < 0) {
        perror("gpio/get-value");
        return fd;
    }
 
    read(fd, &ch, 1);                //Read the external input level

    if (ch != '0') {                 //'1' Input is high level
        *value = 1;                  
    } else {                         //'0' Input is Low level
        *value = 0;                  
    }
 
    close(fd);			   
    return 0;
}

/**********************************************************************
* FunctionName: main
* Description: 
* function parameters: 
* return value:  0 Success; Others: fail
*    Data	       version	    Author		 Application Name  
* ----------------------------------------------------------------------
* 2021/12/08        V1.0	   zheng.xu		  test gpio
 ***********************************************************************/
 
int main(int argc, char **argv) {
    unsigned int i;
    unsigned int value1,value2;
   
    printf("\t********************************************\n");
    printf("\t********  StarF_GPIO_TEST_DEMO  ************\n");
    printf("\t********  Version date: 2021/12 ************\n");
    printf("\t********************************************\n");    
    printf("Gpio begin to init\r\n");
    StarF_gpio_export(FISCV_GPIO);                    //export gpio Gpio

    StarF_gpio_set_dir(FISCV_GPIO, 1);                //set as output
    printf("Gpio init ok\r\n");


    /* Confirm INIT_B Pin as High */
	while(1)
	{ 
		StarF_gpio_set_value(FISCV_GPIO, 1);       //output high 
		printf("Gpio off\r\n");
		usleep(500000);	                           //delay	
		StarF_gpio_set_value(FISCV_GPIO, 0);       //output low 
		printf("Gpio on\r\n");
		usleep(500000);                            //delay
    }
	
    StarF_gpio_unexport(FISCV_GPIO);              //unexport gpio Gpio

    return 0;
}

（可选）安装编译工具。以下是安装示例：
```
sudo apt-get install gcc-riscv64-linux-gnu
```
Information:
- 如已安装该工具，则可跳过此步。
- 安装完成后，运行以下代码，以确认版本是否已更新：linus@starfive$ riscv64-linux-gnu-gcc -v：
  图 1. 输出示例
结果：
系统在当前目录生成了名为test-gpio 的可执行文件。

执行以下命令，以编译源代码：

riscv64-linux-gnu-gcc -o test-gpio test-gpio.c

执行以下命令，以测试编译是否成功：

file test-gpio

Result: 在输出结果中出现 UCB RISC-V，则表示编译成功：

Riscv@starfive:~/work/app$ file test-gpio
test-gpio: ELF 64-bit LSB executable, UCB RISC-V, version 1 (SYSV), dynamically linked, interpreter /lib/ld-linux-riscv64-lp64d.so.1, for GNU/Linux 4.15.0, BuildID[sha1]=476d5a99c84f995d03227a18285222ac25e2cd0d, not stripped
c-v2x@starfive:~/work/app$