#include <windows.h>

// размер буфера для определения скорости
#define TESTBUF_SIZE 34100

// наполнение буфера
#define TESTBUF_FILL "This is a speed test"

// прием данных из порта
void Receive(HANDLE hComm){
	DWORD dwRead;
	char  chRead;
	do {
		chRead=0;
		if (ReadFile(hComm, &chRead, 1, &dwRead, NULL)){
			if(dwRead){
				if(chRead!=10){
					printf("%c",chRead);
					if(chRead==13)
						printf("%c",10);
				}
			}
		}else{
			printf("An error occurred in the ReadFile call (%x)!\n",GetLastError());
			exit(1);
		}
	} while (dwRead);
}

// передача данных в порт
void Send(HANDLE hComm){
	char c;
	DWORD dwWritten;
	char*buf;
	
	union{
		FILETIME ft;
		ULONGLONG ull;
		ULONG ul;
	} ft1,ft2;
	
	while(_kbhit()){
		c=_getch();
		if(c==27){
			printf("\n\nEnded.\n");
			exit(0);
		}
		if(c==0){
			c=_getch();
			if(c==0x3b){ // F1 pressed
				printf("\n\n--- speedtest started ---\n",TESTBUF_SIZE);
				buf=(char*)calloc(1,TESTBUF_SIZE);
				while(strlen(buf)+strlen(TESTBUF_FILL)<TESTBUF_SIZE)
					strcat(buf,TESTBUF_FILL);
				
				GetSystemTimeAsFileTime(&ft1.ft);
				WriteFile(hComm, buf, TESTBUF_SIZE, &dwWritten, 0);
				GetSystemTimeAsFileTime(&ft2.ft);
				
				ft2.ull-=ft1.ull;
				ft2.ull/=10000;
				
				free(buf);
				printf("--- ended. result: %lu bps ---\n",dwWritten*8/(ft2.ul/1000));
				return;
			}
		}
		printf("%c",c);
		WriteFile(hComm, &c, 1, &dwWritten, 0);
		if(c==13){
			c=10;
			printf("%c",c);
			WriteFile(hComm, &c, 1, &dwWritten, 0);
		}
	}
}

int main(int argc,char*argv[]){

	HANDLE hComm;
	char portName[10];
	
	HANDLE hStdout = GetStdHandle(STD_OUTPUT_HANDLE);
	
	if(argc!=2){
		printf("Please specify com port number in cmdline!\n");
		return 1;
	}
	
	sprintf(portName,"COM%s",argv[1]);
	
	printf("opening %s...\n",portName);
	
	// открываем порт
	hComm = CreateFile(portName,GENERIC_READ|GENERIC_WRITE,0,0,OPEN_EXISTING,0,0); 
	
	if (hComm == INVALID_HANDLE_VALUE){
		printf("Error opening port!\n");
		return 1;
	}
	
	printf("Opened. Ready! (press F1 for speed-test)\n\n");
	
	while(1){
		SetConsoleTextAttribute(hStdout, FOREGROUND_GREEN|FOREGROUND_INTENSITY);
		// читаем
		Receive(hComm);
	
		SetConsoleTextAttribute(hStdout, FOREGROUND_BLUE|FOREGROUND_GREEN|FOREGROUND_RED);
		// пишем
		Send(hComm);
		
		// спим =)
		Sleep(1);
	}
	
	return 0;
}