C macht mich wahnsinnig

[jagdfalke]

schaut euch mal das hier an:

char inStr[500];
int inCnt = 0;
char stopsign = 'a';
char startsign = 'b';

SIGNAL(SIG_USART_RECV) {
	inStr[inCnt] = uart_readChar();

	switch (inStr[inCnt])
	{
	case stopsign:
		printf("STOPBIT EMPFANGEN: %s\n\r", inStr);
		inCnt=0;
		break;
	case startsign:
		printf("RESTART");
		inCnt=0;
		break;
	default:
		inCnt++;
		break;
	}
}

Die Fehlermeldung hier lautet:

test.c: In function '__vector_13':
test.c:53: error: case label does not reduce to an integer constant
test.c:57: error: case label does not reduce to an integer constant
make: *** [test.o] Fehler 1

Was bedeutet das? "does not reduce to an integer constant" ???

mfg
jagdfalke