Question

in my function I allocate memory for and fill a structure called messagePacket

struct messagePacket *packet = malloc(sizeof(struct messagePacket));
//fill

When I try to cast the pointer as a (uint8_t *), gcc throws a warning that says: large integer implicitly truncated to unsigned type

sendBuf(..., (uint8_t *)packet);

I’ve been able to do the following just fine, and I understand I can use this approach as a workaround. I’m here because I would rather learn from this than work around it.

uint8_t *buf = malloc(sizeof(struct messagePacket));

The size of struct messagePacket = 1209 B. My best guess is that the chunk of memory is super large that I gets stored in a high memory address, such as a 16 bye address? But that doesn’t fit with the fact that I can malloc a uint8_t * of the same size.

Answer 1

I think the warning is about some other argument. Please provide the full code for that line, the prototype for the sendBuf() function, and the full compiler warning for the line in question.

As a general idea, the sendBuf() function should probably use a const void * rather than a const uint8_t * for the data to send. See send() and friends.