XCore Exchange

Posted: **Mon Aug 10, 2020 6:03 pm**

Hi,

I'm trying to use the interface "usb_ep0_callback_if" from the xmos usb lib. The function "get_interface_descriptor" of this interface has the weird parameter "const ep0_descriptor * unsafe &descs", I have no clue how to use. I am confused by using both operators together "*" and "&". "ep0_descriptor" is defined as:

Code: Select all

typedef struct ep0_descriptor {
  const char * unsafe desc;
  size_t len;
} ep0_descriptor;

I would expect, that I could use it like this:

Code: Select all

size_t my_len = 20;
unsafe {
	descs->desc = &my_array;
	desc->len = &my_len;
}

Unfortunately, it does not work. What is the right syntax? It would help me, if you explain the syntax.

Posted: **Sun Aug 16, 2020 4:27 am**

Try

Code: Select all

size_t my_len = 20;
unsafe {
	descs->desc = &my_array;
	descs->len = my_len;
}

Posted: **Mon Aug 17, 2020 8:20 am**

What a stupid mistake! Have focused all the time on the string but "len" was the problem. Thanks mon2.

XCore Exchange

Syntax problem with struct and pointers

Syntax problem with struct and pointers

Re: Syntax problem with struct and pointers

Re: Syntax problem with struct and pointers