# Variables used in uIP device drivers
[The uIP TCP/IP stack]

Collaboration diagram for Variables used in uIP device drivers:

## Variables
u16_t | uip_len

## Detailed Description

uIP has a few global variables that are used in device drivers for uIP.

## Variable Documentation

u16_t uip_len

The length of the packet in the uip_buf buffer.

The global variable uip_len holds the length of the packet in the uip_buf buffer.

When the network device driver calls the uIP input function, uip_len should be set to the length of the packet in the uip_buf buffer.

When sending packets, the device driver should use the contents of the uip_len variable to determine the length of the outgoing packet.