Changed R4 format excecution to use bit masking
Changed R4 format excecution to use bit masking

Within function riscvstep()
gemusehaken/sunflower-simulator,gemusehaken/sunflower-simulator,gemusehaken/sunflower-simulator,gemusehaken/sunflower-simulator,gemusehaken/sunflower-simulator,gemusehaken/sunflower-simulator,gemusehaken/sunflower-simulator,gemusehaken/sunflower-simulator