Witch of Git - jade-mouse/blob - toolchain/src/inst/encode.rs

   1 use crate::inst::{Addr, Cond, Inst, LdSt, Reg, Size, I5, I7, U4, U7};
   2 use bitmatch::bitmatch;
   3 use std::io::{self, Write};
   4
   5 pub trait Encode {
   6     fn encode(&self, out: &mut impl Write) -> io::Result<()>;
   7 }
   8
   9 fn unpack_cond(c: Cond) -> (u8, u8, Reg, Reg) {
  10     use Cond::*;
  11     let (o2, o1, ra, rb) = match c {
  12         Eql(ra, rb) => (0, 0, ra.min(rb), ra.max(rb)),
  13         Neq(ra, rb) => (0, 0, ra.max(rb), ra.min(rb)),
  14         Test(ra, rb) => (0, 1, ra.min(rb), ra.max(rb)),
  15         TestNot(ra, rb) => (0, 1, ra.max(rb), ra.min(rb)),
  16         Lt(ra, rb) => (1, 0, ra, rb),
  17         Ult(ra, rb) => (1, 1, ra, rb),
  18     };
  19     debug_assert_ne!(ra, rb, "ra == rb reserved for fixed addressing");
  20     (o2, o1, ra, rb)
  21 }
  22
  23 impl Encode for Inst {
  24     #[bitmatch]
  25     fn encode(&self, out: &mut impl Write) -> io::Result<()> {
  26         use Inst::*;
  27         match *self {
  28             Halt => out.write_all(&[0x00])?,
  29             Nope => out.write_all(&[0x01])?,
  30             Alu2(rd, op, r2) => {
  31                 out.write_all(&[0x00 | (op as u8) << 4 | (rd as u8) << 2 | r2 as u8])?
  32             }
  33             Jalr(r) => out.write_all(&[0x80 | (r as u8) << 2 | r as u8])?,
  34             Move(rd, r2) => {
  35                 debug_assert_ne!(rd, r2, "Can't move to self");
  36                 out.write_all(&[0x80 | (rd as u8) << 2 | r2 as u8])?
  37             }
  38             Alu1(r, op) => out.write_all(&[0x90 | (r as u8) << 2 | op as u8])?,
  39             Mem(op, r_data, Addr::Reg(r_addr)) => {
  40                 out.write_all(&[0xa0 | (op as u8) << 4 | (r_data as u8) << 2 | r_addr as u8])?
  41             }
  42             Branch(cond, I7(i)) => {
  43                 let (o, p, a, b) = unpack_cond(cond);
  44                 out.write_all(&[bitpack!("110o_aabb"), bitpack!("piii_iiii")])?
  45             }
  46             JumpI(off) => out.write_all(&[0xc0, off as u8])?,
  47             Mem(f, a, Addr::Fixed(U7(i))) => {
  48                 let b = a;
  49                 out.write_all(&[bitpack!("1101_aabb"), bitpack!("fiii_iiii")])?
  50             }
  51             AddI(rd, imm) => out.write_all(&[0xe0 | (rd as u8) << 2, imm as u8])?,
  52             AluCompact(rd, op, U4(imm)) => {
  53                 out.write_all(&[0xe1 | (rd as u8) << 2, (op as u8) << 4 | imm as u8])?
  54             }
  55             LdImm(h, a, i) => out.write_all(&[bitpack!("1110_aa1h"), bitpack!("iiii_iiii")])?,
  56             Mem(
  57                 op,
  58                 a,
  59                 Addr::Extended {
  60                     base: b,
  61                     offset: I5(i),
  62                     stack: p,
  63                     size,
  64                 },
  65             ) => {
  66                 let w = op == LdSt::St;
  67                 let s = size == Size::Word;
  68                 out.write_all(&[bitpack!("1111_aabb"), bitpack!("wpsi_iiii")])?
  69             }
  70         }
  71         Ok(())
  72     }
  73 }