io_lib.c

CGI程序实例

#include "io_lib.h"

// read from device file and return value of byte
unsigned long int read_dev(files file)
{
	char string[STRING_LEN]={0};
	FILE *f=NULL;
	int i=0;
	// open requested file for reading
	switch(file)
	{
		case switches:
			f=fopen(SWITCHES,"r");
		break;
		case buttons:
			f=fopen(BUTTONS,"r");
		break;		
	}
	// read line
	while((i<10) && (string[i++]=fgetc(f)));
	fclose(f);
	// return value
	return atol(string);
}

// write byte(s) to device file
void write_dev(files file, char *val)
{
	FILE *f=NULL;
	// open requested file for writing
	switch(file)
	{
		case leds_red:
			f=fopen(LEDS_RED,"r+");
		break;
		case leds_green:
			f=fopen(LEDS_GREEN,"r+");
		break;
		case seg7:
			f=fopen(SEG7,"r+");
		break;
	}
	fprintf(f,val);
	fclose(f);
}

int write_lcd(char *msg)
{
	int i, file_desc, ret_val;
	char msg32[33];
	
	file_desc = open(DEVICE_FILE_NAME, 0);
	if (file_desc < 0) {
		printf("Can't open device file: %s\n", DEVICE_FILE_NAME);
		return -1;
	}

	if (strlen(msg) >=0 && strlen(msg) < 32) {
		strcpy(msg32, msg);			// copy the short string		
		for(i = strlen(msg); i<32 ;i++)		// fill the rest with space symbols
			msg32[i] = (char)0x20;
	
   	} else
		strncpy(msg32, msg, 32);		// if string is equal or greater copy just 32 characters
    	
	msg32[32] = '\0';				// terminate string
	
	// calls IOCTL_SET_MSG command of lcd device driver
	if(ioctl(file_desc, IOCTL_SET_MSG, msg32) < 0)
		return -2;

	close(file_desc);
	return 0;
}