tofro wrote:Not sure how multiply and add help here - I would use it to shift by 8 bits and mask in a lower byte - But that's not the case here. But maybe I simply don't see it.
You can shift out the upper byte of a long by multiplying with 256, then shift back with an expensive instruction - Not much help, but could replace step 3 above, but costing more than the 1.5 units we had there.
BTW I think the "multiply and add" above that Peter referred to was an FPGA function - The m68k doesn't have such an instruction. I would guess Peter uses it to implement the MULx instructions of the 68k (that "only" multiply) and simply adds 0 - always.
Please stay in 16 bit screen modes, otherwise my poor brain just can not follow
I believe I start seeing my wrong reasoning anyway.
I need to see the MUL and MUL with addition syntax to make sure.