division with microcontrollers

I've been working with an AT32UC3C1512C microcontroller using the ADC to 
read four values from a PSD. I then want to apply an equation to the 
four digital outputs to obtain a position, but it involves dividing some 
of these outputs. Here I have run into a bit of a wall. Just using plain 
division (/) won't work because it doesn't give me the correct value 
when I pass it through the DAC and read it out. Therefore I tried to 
look at some digital division algorithms, but that would involve the use 
of assembly, and I'm not sure how to integrate this with a 32 bit 
microcontroller. I found an application note from Atmel on how to 
combine assembler and C, but I can't find the example code which the 
whole note is based on, and so it doesn't help at all. Does anyone know 
how to get around this?