USB驱动程序实现的结合和结构。

I am trying to create host usb drivers for a printer device using the PIC32mx series . I am using the Microchip Library Application sample example . Wherein iI see that in order to send the BDT, the below mentioned structure is used. Now the BDT should be in all 8 bytes as documented in the Application note , But when I check the size of the BD_ENTRY union variable I see that it is different- 12 bytes. It should be 8 bytes if i am right. I tried to compile this particular part of the same code using Mikroc and simulated it using proteus and I find the byte length (sizeof) to be 8 bytes.I am trying to create host usb drivers for a pr