in picorv32_modified_core/approx/approx_mul.v the top module of the pcpi module can be found
picorv32_modified_core/approx/synt.ys synthesizes the top module to approx_mul_opt.v, this single .v-file is used in all consequent steps
to change emulated program edit:
picorv32_modified_core/firmware/approxmul.c
to change flashed programm edit:
picorv32_modified_core/picosov/firmware.c
change path to correct multiplier
somehow write C file with direct assembly instruction : asm (".insn r 0xB, 0x0, 0x1, %0, %1, %2": "=r" (result) : "r" (a), "r" (b));