ADC-按键例测试例程：学习回调函数

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <signal.h>
#include <pthread.h>
#include <sys/select.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <linux/input.h>

#define DEV_ENENT  "/dev/input/event2"
#define EVENT_STACK_SIZE 16

#define BUTTON_LONG_PRESS_TIME 1500 //ms
#define OUT_HANDLE_CODE 4

enum ButtonStatusCode {
	BUTTON_LONG_PRESS,
	BUTTON_SHORT_PRESS,
};
typedef void (*KeyCallBack)(int code, int value, int type);

struct input_event event_stack[EVENT_STACK_SIZE];
static pthread_t KeyThreadId;

void KeyHandle(int code, int value, KeyCallBack cb)
{
	static struct timeval OldTimer;
	struct timeval CurrentTimer;
	static int OldCode = 0;

#if 0
	printf("code: %d, value: %d\n", code, value);
	if (code == OUT_HANDLE_CODE) {
		printf("release code\n");
		cb(code, value, BUTTON_SHORT_PRESS);
		return;
	}
#endif
	if (code == OldCode) {
		gettimeofday(&CurrentTimer, NULL);
		long TmpCurTimer = CurrentTimer.tv_sec * 1000 + CurrentTimer.tv_usec/1000;
		long TmpOldTimer = OldTimer.tv_sec * 1000 + OldTimer.tv_usec/1000;
		if ((TmpCurTimer - TmpOldTimer) > BUTTON_LONG_PRESS_TIME) {
			printf("long press\n");
			cb(code, value, BUTTON_LONG_PRESS);
		} else {
			printf("short press\n");
			cb(code, value, BUTTON_SHORT_PRESS);
            
            switch(code)
            {
                case KEY_1://音量-
                    printf("--Volume down--\n");
                    break;
                case KEY_2://音量+
                    printf("--Volume up--\n");
                    break;
                case KEY_3://对话
                    printf("--Chat--\n");
                    break;
                case KEY_4://下一曲
                    printf("--Netx music--\n");
                    break;
                case KEY_5://上一曲
                    printf("--Pre music--\n");
                    break;
                case KEY_6://播放
                    printf("--Play--\n");
                    break;
				default:
					printf("--Invalid key code--\n");

            }

                  
		}
		OldCode = 0;
	} else {
		OldCode = code;
		gettimeofday(&OldTimer, NULL);
	}
}

void *KeyStart(void *param)
{
	if (param == NULL) {
		printf("button callback is null\n");
		pthread_exit(NULL);
	}
	KeyCallBack cb = (KeyCallBack)param;

	int Fd = -1;
	int Size = 0;
	int i;
	int retval;
	fd_set rfds;

	Fd = open(DEV_ENENT, O_RDONLY | O_NONBLOCK);
	if(Fd < 0)
	{
		perror(DEV_ENENT);
		goto fail;
	}
	while(1)
	{
		FD_ZERO(&rfds);
		FD_SET(Fd, &rfds);
		retval = select(Fd + 1, &rfds, NULL, NULL, NULL);
		if (retval == -1)
		{
			perror("select()");
			continue;
		}
		else if (retval)
			printf("Data is available now.\n");
		else
			continue;
		Size = read(Fd, event_stack, sizeof(event_stack));
		if(Size >= 0)
		{
			for(i = 0; i < Size/sizeof(event_stack[0]); i++) {
				//printf("type = %d code = %d value = %d\n", event_stack[i].type, event_stack[i].code, event_stack[i].value);
				if (event_stack[i].type == 1) {
					KeyHandle(event_stack[i].code, event_stack[i].value, cb);
				}
			}
		}
		else
		{
			perror(DEV_ENENT);
		}
	}
	close(Fd);
fail:
	pthread_exit(NULL);
}

int KeyInit(KeyCallBack cb)
{
	int ret = pthread_create(&KeyThreadId, NULL, KeyStart, (void*)cb);
    if(ret != 0)
    {
        printf("Create Key thread fail\n");
    }

	pthread_detach(KeyThreadId);
	return 0;
}

void KeyUninit()
{
	pthread_cancel(KeyThreadId);
	pthread_join(KeyThreadId, NULL);
	printf("Button thread uninit\n");
}


//------------------------> example <----------------------------
void tmp_key(int code, int value, int type)
{
	printf("cb code: %d, value: %d, type: %d\n", code, value, type);
}
#if 1
//void KeyMain(void)
int main(void)
{
	KeyInit(tmp_key);
	sleep(10);
	KeyUninit();
    return 0;
}
#endif
//------------------------> example <----------------------------

参考：

C语言中的回调函数（Callback Function）

回调函数基本介绍和基本使用场景