function asking for unsigned char *

[davo666]

hello,

i have a function which is asking for an unsigned char * but when i initialise an unsigned char array

unsigned char data[1024];

and pass it like so:

ouput((unsigned car *)data)

it givese me a bus error

does anyone know what is happening
(no compiler warnings) i have -Wall on

thanks

[tabstop]

Note that you have defined an array, but you have not initialized it. If your output function expects a null-terminated string, for instance, then you will very likely be Really Out of Luck.

So: do you put valid data in the data variable before passing it on? And why do you cast it anyway?

[davo666]

lol sorry

unsigned char data[1024] = {  0x0a, 0x00 };

thats how i initialise it

-- if i dont cast it gives errors

[MK27]

I would Call That Strange. Why don't you post the mystery function prototype?

[davo666]

phew! i though i was going insane

int output(unsigned char *data); //prototype

[tabstop]

If data is defined as

unsigned char data[1024] = {  0x0a, 0x00 };

and if output is declared as

int output(unsigned char *data); //prototype

then

output(data);

must compile and if it doesn't your compiler is broken. Provide more details.

[MK27]

So you could use that like this:

#include <stdio.h>

int output(unsigned char *data) {
	printf("%s\n",data);
	return 42;
}

int main() {
	unsigned char string[]="number of the beast";
	output(string);
	return 0;
}

You could replace the declaration with:

unsigned char data[1024] = {  0x0a, 0x00 };

which won't hurt -- just the final result is spookier.

[davo666]

hmm, I think maybe my problem is in output()

here it is

int output(unsigned char *data) {

int num_bytes =2;

	// use the rfcomm_pcb passed into the rfcomm_connected function as the 'global' pcb 
	
	// Put data into rfcomm_pcb payload, send it out then free the buffer
	struct pbuf *p;
	p = pbuf_alloc(PBUF_RAW, num_bytes, PBUF_RAM);
	memcpy( ((u8_t *)p->payload) , data, num_bytes); // <----------is this whats stuffing?

if (0) {
printf("\n sending via rfcomm... \n");
int i;
for (i=0; i< num_bytes; i++) {
	printf("data[%d] = %d \n", i, ((u8_t *)p->payload)[i] );
}
}
	if(rfcomm_cl(global_pcb)) {
		// why 6 credits??
//		printf("using uih_credits = 6 \n");
		rfcomm_uih_credits(global_pcb, 6,  p);
	} else {
		rfcomm_uih(global_pcb, rfcomm_cn(global_pcb), p);
	}

	pbuf_free(p);

	return ERR_OK;

}

thanks for your help

[davo666]

yes, its definately with the function, i can print my bytes inside it and the error is occuring elsewhere in that func -- thanks for your help!