I wrote this code to demonstrate something I found in the KSDK USB library. I took (interpreted?) this code from usb_device_ch9.c starting around line 862.
typedef struct _usb_device_control_request_struct
{
usb_setup_struct_t *setup; /*!< The pointer of the setup packet data. */
uint8_t *buffer; /*!< Pass the buffer address. */
uint32_t length; /*!< Pass the buffer length or requested length. */
uint8_t isSetup; /*!< Indicates whether a setup packet is received. */
} usb_device_control_request_struct_t;
void main()
{
function1();
}
void function1()
{
uint8_t *buffer = (uint8_t *)NULL;
uint32_t length = 0U;
usb_device_control_request_struct_t controlRequest;
controlRequest.buffer = (uint8_t *)NULL
function2(&controlRequest);
length = controlRequest.length;
buffer = controlRequest.buffer;
}
void function2(void* param)
{
usb_device_control_request_struct_t* controlRequest = (usb_device_control_request_struct_t*)param;
function3(controlRequest)
}
uint8_t buffer[8]
void function3(usb_device_control_request_struct_t* controlRequest)
{
controlRequest.buffer = buffer;
controlRequest.length = 8;
}
The expectation is function2 will give controlRequest.buffer something to point to but controlRequest.buffer is still null when in the context of function1() just after calling function2(). I would never do it this way but this is the framework of the KSDK USB driver. I'm probably forgetting to explain something here but hopefully I can at least get a conversation going?
