getchar()

I am trying to "echo" any input over the UART, back to the console, as it is entered.

So I am trying to use getchar(). However, when I step through it on the debugger, I see that I don't have anything in the buffer for getchat() to pull out, until I hit enter in the terminal. Then the buffer is full of everything I just typed, and getchar() will go through and pull them out one at a time.
However I know that my terminal is sending every character as I type it.

I have read on this forum that the UART has a buffer. Is it storing up my input until I hit enter, and thus preventing getchar() from getting it as I type it?

Any help would be really helpful. Is there maybe a way to disable the UART buffer? Or to flush it every time a character is received?

0 Former Member over 8 years ago

I think that getchar() waits for the 'enter' by design. You can use the inbyte() function to get each character as you type it.

-Gary
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0 Former Member over 8 years ago in reply to Former Member

Thank you Gary, that was exactly what I was looking for. I only wish I could have found it while searching online.

In case it helps someone at a later date, here is my code to echo input as it is written:
void echo(void)
{
memset(command, '0', 64);//"reset" our holder string
tint i = 0;
tdo{
tcommand[i] = inbyte();
tprintf("%c", command[i]);
tfflush(stdout);
ti++;
t}while(command[i-1] != 'r');//Our "command" will have a return character included at the end.
tprintf("
");//But we still need a new line character (if we want one)
}//It is possible to overwrite the null terminating character at the end of the string. Fix if needed.
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0 Former Member over 8 years ago in reply to Former Member

meant
putchar(command[i]);
instead of
printf("%c", command[i]);
Waste not, want not.
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0 Former Member over 8 years ago

Now featuring 100% more backspace implementation:
char command[64];//Can be any size, though out of bounds isn't checked for.
void echo(void)
{
tmemset(command, '0', 64);
tint i = 0;

tdo{
tcommand[i] = inbyte();
tputchar(command[i]);
tfflush(stdout);
tif(command[i] == 'b')
t{
ttcommand[i] = '0';
ttcommand[i-1] = '0';
tti = (i-2);
ttputchar(' ');
ttputchar('b');
ttfflush(stdout);
ttif(i<-1){i=-1;}
t}
ti++;
t}while(command[i-1] != 'r');
tprintf("
");
}
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