I am relatively new to audio programming, but I have a task that requires converting between various audio formats:

unsigned 16 bit linear to signed 16 bit linear
u_law to signed 16 bit linear
a_law to signed 16 bit linear
unsigned 8 bit linear to signed 16 bit
signed 8 bit linear to signed 16 bit

Anyone know what the conversion functions for these would look like?  Or even what a good reference is where I can find these?  I have been googling around for about an hour and I have come up empty.