SIM900的USSD测试小程序

关键代码如下
enum STATUS {UssdStart=1, UssdReply, UssdRetCode0, UssdRetCode1, UssdRetCode2, UssdInteraction, UssdDisp, UssdSend, UssdEnd, UssdTimeout };

int main(int argc, char** argv)
{
	char UssdNO[50]={0};
	char InteractBuff[50]={0};
	char outbuff[1024]={0};
	enum STATUS Status = UssdStart;


	int fd = open("/dev/ttyS0",O_RDWR | O_NONBLOCK);
	if(fd == -1)
	{
		printf("open ttyS0 error!\n");
	}
	else
	{
		SetSpeed(fd, 115200);
		if (SetParity(fd,8,1,'N') == FALSE)  {
			printf("Set Parity Error\n");
		}
		SetRawMode(fd);		
	}


	WriteToSIMCOM(fd, "ATE0\r");
	if(ReadSIMCOMLine(fd, outbuff, 5, 0) == 1)
	{
		if(strstr(outbuff, "OK"))
		{
			
		}
	}
	else
		Status = UssdTimeout;


	while(1)
	{
		switch(Status)
		{
			case UssdStart:
				printf("Please enter the USSD number:\n");
				gets(UssdNO);


				WriteToSIMCOM(fd, PackUSSDStr(UssdNO));
				
				if(ReadSIMCOMLine(fd, outbuff, 15, 0) == 1)
				{
					if(strstr(outbuff, "OK"))
					{
						//printf("outbuff:%s\n", outbuff);
						Status++;
					}
				}
				else
					Status = UssdTimeout;
					
				break;	
			
			case UssdReply:
				if(ReadSIMCOMLine(fd, outbuff, 5, 0) == 1)
				{
					if(strstr(outbuff, "+CUSD: "))
					{
						char UssdRetCode = GetUssdRetStatus(outbuff);
						//printf("UssdReply:UssdRetCode:%c\n", UssdRetCode);
						
						if(UssdRetCode == '0')
							Status = UssdRetCode0;
						else if(UssdRetCode == '1')
							Status = UssdRetCode1;
						else if(UssdRetCode == '2')
							Status = UssdRetCode2;
						else
							Status = UssdEnd;
					}
				}
				else
					Status = UssdTimeout;
					
				break;
				
			case UssdRetCode0:
				printf("\n%s\n", UnPackUSSDStr(outbuff));
				Status = UssdEnd;
				break;
				
			case UssdRetCode1:
				Status = UssdDisp;
				break;
				
			case UssdRetCode2://need to ATD
				WriteToSIMCOM(fd, PackATDStr(UssdNO));
				
				if(ReadSIMCOMLine(fd, outbuff, 15, 0) == 1)
				{
					if(strstr(outbuff, "NO CARRIER"))
					{
						//printf("outbuff:%s\n", outbuff);
						Status = UssdInteraction;
					}
				}
				else
					Status = UssdTimeout;
					
				break;
			
			case UssdInteraction:
				if(ReadSIMCOMLine(fd, outbuff, 5, 0) == 1)
				{
					if(strstr(outbuff, "+CUSD: "))
					{
						char UssdRetCode = GetUssdRetStatus(outbuff);
						//printf("UssdInteraction:UssdRetCode:%c\n", UssdRetCode);
						
						if(UssdRetCode == '0')
							Status = UssdRetCode0;
						else if(UssdRetCode == '1')
							Status = UssdDisp;
						else if(UssdRetCode == '2')
							Status = UssdRetCode2;
						else
							Status = UssdEnd;
					}
				}
				else
					Status = UssdTimeout;
					
				break;
			
			case UssdDisp:
				printf("\n%s\n", UnPackUSSDStr(outbuff));
				Status++;
				break;
				
			case UssdSend:
				printf(">");
				memset(InteractBuff, 0, sizeof(InteractBuff));
				gets(InteractBuff);
				
				WriteToSIMCOM(fd, PackUSSDStr(InteractBuff));
				
				if(ReadSIMCOMLine(fd, outbuff, 5, 0) == 1)
				{
					if(strstr(outbuff, "OK"))
					{
						//printf("outbuff:%s\n", outbuff);
						Status = UssdInteraction;
					}
				}
				else
					Status = UssdTimeout;
					
				break;
				
			case UssdEnd:
				printf("Ussd finished!\n");
				exit(0);
				break;
				
			case UssdTimeout:
				printf("Ussd receive timeout!\n");
				exit(0);
				break;
		}
	}
	return 0;
}

目前存在的疑问
1、不知道如何中断当前的USSD连接，ATH试过是不行的
2、返回+CUSD: 0 和 +CUSD: 2时不知道如何做通用的处理