Hi, this will be found in Assembler but its really simple code, you can find it on the
Bootloader application Note from microchip for pics 18F. This code has a nice
autoBaud detection routine at the begining.

AN851

http://ww1.microchip.com/downloads/e...eDoc/00851.zip

My guess, since i am not a great ASM coder is that they always send a $0F a the beggining of each packet, this $0F is used to measure the baud rate.

Since the BootLoader applies to 16F877 it will help you.