Function soft_core_divider 

pub fn soft_core_divider(opcode: u8, a: i32, b: i32) -> i32

The Rust model of the soft-core’s shared_divider unit (truncated signed division): Div / ExactDiv → quotient, Mod → remainder (dividend’s sign), FloorDiv → floor-adjusted quotient; b==0 → 0. run_soft_core issues opcodes 12/13/14/15 here instead of the combinational ALU, mirroring the RTL (the divider is proven == this by iverilog tb_shared_divider).