1 files changed, 92 insertions, 0 deletions
diff --git a/src/arm32/instruction_codec/encode_thumb.rs b/src/arm32/instruction_codec/encode_thumb.rs
new file mode 100644
index 0000000..f2fa0b8
--- /dev/null
+++ b/src/arm32/instruction_codec/encode_thumb.rs
@@ -0,0 +1,92 @@
+// Copyright 2024 Gabriel Bjørnager Jensen.
+//
+// This file is part of Pollex.
+//
+// Pollex is free software: you can redistribute it
+// and/or modify it under the terms of the GNU Af-
+// fero General Public License as published by the
+// Free Software Foundation, either version 3 of
+// the License, or (at your option) any later ver-
+// sion.
+//
+// Pollex is distributed in the hope that it will
+// be useful, but WITHOUT ANY WARRANTY; without
+// even the implied warranty of MERCHANTABILITY or
+// FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Af-
+// fero General Public License along with Pollex.
+// If not, see <https://www.gnu.org/licenses/>.
+
+use crate::{assert_or_err, Error, Result};
+use crate::arm32::{
+ Instruction,
+ InstructionCodec,
+ Predicate,
+ Shifter,
+ ThumbOpcode,
+};
+
+impl InstructionCodec {
+ /// Encodes the given Thumb instruction.
+ ///
+ /// # Errors
+ ///
+ /// If the given instruction cannot be encoded for Thumb, an error is returned.
+ pub fn encode_thumb(&mut self, instruction: Instruction) -> Result<ThumbOpcode> {
+ use Instruction::*;
+
+ let mut opcode = 0b00000000_00000000_u16;
+
+ match instruction {
+ Move {
+ predicate,
+ destination,
+ source,
+ s,
+ } => {
+ assert_or_err!(predicate == Predicate::Always, Error::IllegalPredicate);
+
+ if s.is_on() {
+ if let Shifter::Immediate { source } = source {
+ assert_or_err!(destination.is_low(), Error::IllegalRegister);
+ assert_or_err!(source <= 0xFF, Error::IllegalRegister);
+
+ opcode |= 0b00100000_00000000;
+ opcode |= source as u16;
+ opcode |= (destination as u16) << 0x8;
+
+ } else if let Shifter::LogicalShiftLeftImmediate { source, shift: 0x0 } = source {
+ assert_or_err!(destination.is_low(), Error::IllegalRegister);
+ assert_or_err!(source.is_low(), Error::IllegalRegister);
+
+ opcode |= 0b00100000_00000000;
+ opcode |= destination as u16;
+ opcode |= (source as u16) << 0x3;
+ } else {
+ return Err(Error::IllegalInstruction);
+ }
+ } else if let Shifter::LogicalShiftLeftImmediate { source, shift: 0x0 } = source {
+ opcode |= 0b01000110_00000000;
+
+ let h0 = destination.is_high();
+ let h1 = source.is_high();
+
+ opcode |= destination as u16 & 0b00000000_00000111;
+ opcode |= (source as u16 & 0b00000000_00000111) << 0x3;
+ opcode |= u16::from(h0) << 0x6;
+ opcode |= u16::from(h1) << 0x7;
+ } else {
+ // TODO: Shifters &c.
+ todo!();
+ }
+ }
+
+ _ => return Err(Error::IllegalInstruction),
+ }
+
+ self.address += ThumbOpcode::SIZE;
+ Ok(opcode.into())
+ }
+}