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use std::collections::HashMap;
use std::error::Error;
use crate::instruction::instruction::{Instruction, Opcode};
use crate::extension::extension::Extension;
#[derive(Default)]
pub struct GPRegisters {
pub registers: [u32; 32]
}
#[derive(Default)]
pub struct SMRegisters {
sie: u32,
stvec: u32,
}
#[derive(Default)]
pub struct MMRegisters {
pub mie: u32,
pub mtvec: u32,
pub mepc: u32,
pub mcause: u32,
pub mhart: u32,
}
#[derive(Default)]
pub struct State {
pub pc: u32,
pub gp_regs: GPRegisters,
pub sm_regs: SMRegisters,
pub mm_regs: MMRegisters,
}
pub struct Rv32Cpu {
decoders: HashMap<Opcode, Box<dyn Instruction>>,
state: State,
}
impl Rv32Cpu {
pub fn new(id: u32) -> Self {
let mut state = State::default();
state.mm_regs.mhart = id;
Rv32Cpu {
decoders: HashMap::new(),
state
}
}
pub fn add_extension<T: Extension>(mut self) -> Self {
T::add_instructions(&mut self);
self
}
pub fn add_decode(&mut self, key: Opcode, instruction: Box<dyn Instruction>) {
self.decoders.insert(key, instruction);
}
fn decode(decoders: &HashMap<Opcode, Box<dyn Instruction>>, instruction: u32) -> Result<&Box<dyn Instruction>, Box<dyn Error>> {
if instruction & 0x3 != 0x3 {
return Err("Invalid opcode".into());
}
let op: [u32; 3] = [(instruction >> 2) & 0x1F, (instruction >> 12) & 0x7, (instruction >> 27) & 0x7F];
let key3 = Opcode{opcode6_2: op[0], opcode14_12: Some(op[1]), opcode31_27: Some(op[2])};
if let Some(x) = decoders.get(&key3) {
return Ok(x);
}
let key2 = Opcode{opcode6_2: op[0], opcode14_12: Some(op[1]), opcode31_27: None};
if let Some(x) = decoders.get(&key2) {
return Ok(x);
}
let key1 = Opcode{opcode6_2: op[0], opcode14_12: None, opcode31_27: None};
if let Some(x) = decoders.get(&key1) {
return Ok(x);
}
Err("Invalid opcode".into())
}
pub fn execute(&mut self, instruction: u32) -> Result<(), Box<dyn Error>> {
let instr: &Box<dyn Instruction> = Self::decode(&self.decoders, instruction)?;
instr.execute(instruction, &mut self.state)?;
Ok(())
}
}
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