Module instruction_executor

An InstructionProcessor that executes instructions.

The InstructionExecutor takes a HartState and a Memory. The HartState is updated by the instruction execution using the Memory for all memory accesses. A InstructionExecutor::step function is provided to deal with reading the next instruction from the memory, updating the PC appropriately and wraps the call to process_instruction()`.

Example

use rrs_lib::HartState;
use rrs_lib::memories::VecMemory;
use rrs_lib::instruction_executor::{InstructionExecutor, InstructionException};

let mut hart = HartState::new();
// Memory contains these instructions:
// lui x2, 0x1234b
// lui x3, 0xf387e
// add x1, x2, x3
let mut mem = VecMemory::new(vec![0x1234b137, 0xf387e1b7, 0x003100b3]);

hart.pc = 0;

let mut executor = InstructionExecutor {
    hart_state: &mut hart,
    mem: &mut mem,
};

assert_eq!(executor.step(), Ok(()));
assert_eq!(executor.hart_state.registers[2], 0x1234b000);
assert_eq!(executor.step(), Ok(()));
assert_eq!(executor.hart_state.registers[3], 0xf387e000);
assert_eq!(executor.step(), Ok(()));
assert_eq!(executor.hart_state.registers[1], 0x05bc9000);
// Memory only contains three instructions so next step will produce a fetch error
assert_eq!(executor.step(), Err(InstructionException::FetchError(0xc)));

Structs

InstructionExecutor

An InstructionProcessor that execute instructions, updating hart_state as appropriate.

Enums

InstructionException

Different exceptions that can occur during instruction execution