search for: asr18

...or is as follows: === To accelerate DSP algorithms, two multiply&accumulate instructions are implemented: UMAC and SMAC. The UMAC performs an unsigned 16-bit multiply, producing a 32-bit result, and adds the result to a 40-bit accumulator made up by the 8 lsb bits from the %y register and the %asr18 register. The least significant 32 bits are also written to the destination register. SMAC works similarly but performs signed multiply and accumulate. The MAC instructions execute in one clock but have two clocks latency, meaning that one pipeline stall cycle will be inserted if the following inst...

I've been looking to see if there's a way to get the instruction below (SMAC) emitted from a higher-level construct, but I'm starting to think this is unrealistic. To do so, I'd have to tie-in two other instructions: Firstly, clearing the ASR18 and Y register somewhere near the start of the method, then copying out the value of these registers somewhere near the end of the method, or wherever the value needs to be used. In addition, it would only make sense to use the construct inside a loop of some form, otherwise, some variation on MUL...